Recent Publications

Zandi PP, Zöllner S, Avramopoulos D, Willour VL, Chen Y, Qin ZS, Burmeister M, Miao K, Gopalakrishnan S, McEachin R, Potash JB, Depaulo JR, McInnis MG

Intention to exercise in patients with obstructive sleep apnea.

J Clin Sleep Med. 2007 Dec 15;3(7):689-94

Authors: Smith SS, Doyle G, Pascoe T, Douglas JA, Jorgensen G

Obstructive sleep apnea (OSA) is a common and serious health issue that is strongly associated with excess weight. Exercise may be an effective mechanism for reducing the severity of OSA both in association with, and independent of, reduction in body weight. As such, increased exercise has been suggested as a potential intervention for OSA, particularly for patients with mild to moderate clinical severity. However, it is unknown how ready to engage in exercise patients with OSA are. Self-reported exercise intention was assessed in 206 consecutive patients attending a large tertiary sleep disorders service in Australia. Classification of the patients by Stage of Change, a construct of the Transtheoretical Model of behavior change, was supported by differences between the groups in level of habitual self-reported exercise. Cluster analysis identified 4 potential patient types, with differing profiles in perceived costs and benefits of exercise, and exercise-related self-efficacy. The validity of these patient clusters was also supported by differences between the groups in current self-reported exercise levels. The results may help to identify patients who are more likely to engage in increased exercise, and to identify barriers to exercise in patients less inclined to increase their exercise.

PMID: 18198801 [PubMed - in process]

Durkin SG, Ragland RL, Arlt MF, Mulle JG, Warren ST, Glover TW

Family-based SNP association study on 8q24 in bipolar disorder.

Am J Med Genet B Neuropsychiatr Genet. 2007 Dec 28;

Authors: Zandi PP, Zöllner S, Avramopoulos D, Willour VL, Chen Y, Qin ZS, Burmeister M, Miao K, Gopalakrishnan S, McEachin R, Potash JB, Depaulo JR, McInnis MG

Previous linkage studies have identified chromosome 8q24 as a promising positional candidate region to search for bipolar disorder (BP) susceptibility genes. We, therefore, sought to identify BP susceptibility genes on chromosome 8q24 using a family-based association study of a dense panel of SNPs selected to tag the known common variation across the region of interest. A total of 1,458 SNPs across 16 Mb of 8q24 were examined in 3,512 subjects, 1,954 of whom were affected with BP, from 737 multiplex families. Single-locus tests were carried out with FBAT and Geno-PDT, and multi-locus test were carried out with HBAT and multi-locus Geno-PDT. None of the SNPs were associated with BP in the single-locus tests at a level that exceeded our threshold for study-wide significance (P < 3.00 x 10(-5)). However, there was consistent evidence at our threshold for the suggestive level (P < 7.00 x 10(-4)) from both the single locus and multi-locus tests of associations with SNPs in the genes ADCY8, ST3GAL1, and NSE2. Multi-locus analyses suggested joint effects between ADCY8 and ST3GAL1 (P = 3.00 x 10(-4)), with at least one copy of the "high risk" allele required at both genes for association with BP, consistent with a jointly dominant-dominant model of action. These findings with ADCY8 and ST3GAL1 warrant further investigation in order to confirm the observed associations and their functional significance for BP susceptibility. (c) 2007 Wiley-Liss, Inc.

PMID: 18163389 [PubMed - as supplied by publisher]

Jajoo S, Mukherjea D, Brewer GJ, Ramkumar V

Replication stress induces tumor-like microdeletions in FHIT/FRA3B.

Proc Natl Acad Sci U S A. 2008 Jan 8;105(1):246-51

Authors: Durkin SG, Ragland RL, Arlt MF, Mulle JG, Warren ST, Glover TW

Common fragile sites (CFSs) are loci that preferentially exhibit metaphase chromosome gaps and breaks after partial inhibition of DNA synthesis. The fragile site FRA3B, which lies within the FHIT tumor-suppressor gene, is a site of frequent heterozygous and homozygous deletions in many cancer cells and precancerous lesions. The great majority of FHIT and other CFS-associated gene rearrangements in tumors are submicroscopic, intralocus deletions of hundreds of kilobases that often result in inactivation of associated genes. Although CFS instability leads to chromosome gaps and breaks and translocations, there has been no direct evidence showing that CFS instability or replication stress can generate large submicroscopic deletions of the type seen in cancer cells. Here, we have produced FHIT/FRA3B deletions closely resembling those in tumors by exposing human-mouse chromosome 3 somatic hybrid cells to aphidicolin-mediated replication stress. Clonal cell populations were analyzed for deletions by using PCR, array comparative genomic hybridization (aCGH), and FISH. Thirteen percent to 23% of clones exhibited submicroscopic FHIT deletions spanning approximately 200-600 kb within FRA3B. Chromosomes with FRA3B deletions exhibited significantly decreased fragility of this locus, with a 2- to 12-fold reduction in metaphase gaps and breaks compared with controls. Sequence analysis showed no regions of homology at breakpoints and suggests involvement of NHEJ in generating the deletions. Our results demonstrate that replication stress induces a remarkably high frequency of tumor-like microdeletions that reduce fragility at a CFS in cultured cells and suggests that similar conditions during tumor formation lead to intralocus deletion and inactivation of genes at CFSs and perhaps elsewhere in the genome.

PMID: 18162546 [PubMed - in process]

Moran JL, Bristow P, Solomon PJ, George C, Hart GK,

Pertussis toxin B-oligomer suppresses human immunodeficiency virus-1 Tat-induced neuronal apoptosis through feedback inhibition of phospholipase C-beta by protein kinase C.

Neuroscience. 2008 Jan 24;151(2):525-32

Authors: Jajoo S, Mukherjea D, Brewer GJ, Ramkumar V

Human immunodeficiency virus (HIV)-1 Tat is a multifunctional protein involved in viral replication, inflammation and apoptosis. Tat activates phospholipase C-beta (PLC-beta), presumably via a pertussis toxin (PTX) sensitive G(i) protein, which is critical for neuronal apoptosis. In this study, we show that Tat-mediated intracellular Ca(2+) release in rat pheochromocytoma (PC-12) cells and rat primary cortical neuronal cultures was abrogated by pretreatment with either pertussis toxin and/or its B-oligomer subunit (PTX-B), devoid of ADP ribosyltransferase activity. PTX-B pretreatment also inhibited intracellular Ca(2+) release by bradykinin and 2,4,6-trimethyl-N-(m-3-trifluoromethylphenyl) benzenesulfonamide (m-3M3FBS), a director activator of phospholipase C. Activation of protein kinase C (PKC) by phorbol 12,13-dibutyrate (PdBu) mimicked the PTX-B-mediated inhibition of m-3M3FBS-stimulated intracellular Ca(2+) increase, while inhibition of PKC by bisindolylmaleimide I hydrochloride (BIM) reversed the inhibitory action of PTX-B. Functionally, PTX-B reduced Tat-induced Bax and caspase-3 proteins and reduced cell apoptosis. We conclude that PTX inhibition of Tat-mediated intracellular Ca(2+) release is independent of ADP ribosylation of the G(i) protein via the A protomer, but mediated by the B-oligomer. Furthermore, PTX-B suppresses HIV-1 Tat-mediated apoptosis by reducing its activation of PLC-beta through a PKC activation pathway.

PMID: 18093742 [PubMed - in process]

Sampath S, Moran JL, Graham PL, Rockliff S, Bersten AD, Abrams KR

Mortality and length-of-stay outcomes, 1993-2003, in the binational Australian and New Zealand intensive care adult patient database.

Crit Care Med. 2008 Jan;36(1):46-61

Authors: Moran JL, Bristow P, Solomon PJ, George C, Hart GK,

OBJECTIVE:: Intensive care unit (ICU) outcomes have been the subject of controversy. The objective was to model hospital mortality and ICU length-of-stay time-change of patients recorded in the Australian and New Zealand Intensive Care Society adult patient database. DESIGN:: Retrospective, cohort study of prospectively collected data on index patient admissions. SETTING:: Australian and New Zealand ICUs, 1993-2003. PATIENTS:: The Australian and New Zealand Intensive Care Society adult patient database, which contains data for 223,129 patients. INTERVENTIONS:: None. MEASUREMENTS AND MAIN RESULTS:: Hospital mortality and ICU length of stay were modeled using logistic and linear regression, respectively, with determination (80%) and validation (20%) data sets. Model adequacy was assessed by discrimination (receiver operating characteristic curve area, AZ) and calibration (Hosmer-Lemeshow C) for mortality and R for length of stay. Predictor variables included patient demographics, severity score, surgical and ventilation status, ICU categories, and geographical locality. The data set comprised 223,129 patients: Their mean (sd) age was 59.2 (18.9) yrs, 41.7% were female, their mean (sd) Acute Physiology and Chronic Health Evaluation (APACHE) III score was 53 (31), they had 16.1% overall mortality rate, and 45.7% were mechanically ventilated. ICU length of stay was 3.6 (5.6) days. AZ, C statistic, and R for developmental and validation model data sets were 0.88, 17.64 (p = .02), and 0.18; and 0.88, 12.32 (p = .26), and 0.18, respectively. Variables with mortality impact (p </= .001) were age (odds ratio [OR] 1.023), gender (OR 1.16; males vs. females), APACHE III score (OR 1.06), mechanical ventilation (OR 1.66), and surgical status (elective, OR 0.17; emergency, OR 0.47; compared with nonsurgical). ICU level and locality had significant mortality-time effects. Similar variables were found to predict length of stay. Risk-adjusted mortality declined, during 1993-2003, from 0.19 (95% confidence interval 0.17-0.21) to 0.15 (0.13-0.16) and similarly for ventilated patients: 0.26 (0.24-0.29) to 0.23 (0.21-0.25). Predicted mean ICU length of stay (days) demonstrated minimal overall time-change: 3.4 (2.2) in 1993 to 3.5 (2.7) in 2003, peaking at 3.7 (2.4) in 2000. CONCLUSIONS:: Overall hospital mortality rate in patients admitted to Australian and New Zealand ICUs decreased 4% over 11 yrs. A similar trend occurred for mechanically ventilated patients. Length of stay changed minimally over this period.

PMID: 18090383 [PubMed - as supplied by publisher]

Lo AC, Kleer CG, Banerjee M, Omar S, Khaled H, Eissa S, Hablas A, Douglas JA, Alford SH, Merajver SD, Soliman AS

The efficacy of loop diuretics in acute renal failure: assessment using Bayesian evidence synthesis techniques.

Crit Care Med. 2007 Nov;35(11):2516-24

Authors: Sampath S, Moran JL, Graham PL, Rockliff S, Bersten AD, Abrams KR

OBJECTIVE: To quantify the therapeutic efficacy of loop diuretics in acute renal failure using Bayesian evidence synthesis, because despite widespread use, the role of diuretics is controversial. DATA SOURCE: Randomized controlled trials or nonrandomized studies, 1966 to January 2007, identified from MEDLINE and EMBASE databases and manual bibliographic search. STUDY SELECTION: Studies with assessable predefined end points, exclusive of those pertaining to acute renal failure prophylaxis or chronic renal failure. DATA EXTRACTION: Data extraction was performed jointly by the first two authors; independent study assessment was via standard checklist, unblinded. DATA SYNTHESIS: The primary outcome was mortality; secondary outcomes were time to renal function normalization and total number of dialyses. Bayesian hierarchical random effects estimates of treatment effects were determined as risk ratio for mortality, incidence rate ratio for dialysis number, and mean difference for continuous measures. Bayesian outcome probabilities were calculated as probability (P) that risk ratio or incidence rate ratio of loop diuretics >1 and probability that mean difference >0. Five randomized controlled trials and eight nonrandomized studies were identified. Loop diuretics were not associated with decreased mortality in either randomized controlled trials or nonrandomized studies: overall risk ratio 1.10; 95% credible interval 0.85, 1.42; P(risk ratio >1) > 83.8%. The oliguric period was decreased by loop diuretics: overall mean difference -7.70 days; 95% credible interval -12.51, -2.08; P (mean difference >0) = 0.7%. Although the dialysis rate credible interval, loop diuretics vs. control, spanned unity (incidence rate ratio 0.71; 95% credible interval 0.47, 1.06), the probability that the incidence rate ratio exceeded unity indicated a substantial benefit: P (incidence rate ratio >1 = 4.1%. Uremic duration was not substantially different, loop diuretics vs. control: overall mean difference -1.54 days; 95% credible interval -5.62, 2.46; P [mean difference >0] = 17.8%). CONCLUSIONS: Loop diuretics were not associated with improved survival benefit in acute renal failure, despite reduction in oliguric period and high probability of a significant reduction in dialysis numbers. Further studies to clarify this dichotomy appear mandated.

PMID: 18084840 [PubMed - in process]

Interaction on health care teams. 1980.

Molecular epidemiologic features of inflammatory breast cancer: a comparison between Egyptian and US patients.

Breast Cancer Res Treat. 2007 Dec 4;

Authors: Lo AC, Kleer CG, Banerjee M, Omar S, Khaled H, Eissa S, Hablas A, Douglas JA, Alford SH, Merajver SD, Soliman AS

Background Inflammatory breast cancer (IBC) is a lethal form of breast cancer with unknown etiology. A higher frequency of IBC and a more aggressive IBC phenotype was reported in Egypt than in the United States. This difference in disease frequency and presentation might be related to molecular epidemiologic factors. Methods We used tumor blocks and demographic, epidemiologic, and clinical data of 48 IBC patients from Egypt and 12 patients from the United States. We counted tumor emboli in tumors before and after immunohistochemical staining with lymphatic vessel endothelial receptor-1 (LYVE-1), and measured the expression of RhoC GTPase protein in the two groups. Results Erythema, edema, and peau d'orange were found in 77% of the Egyptian patients as compared with 29% found in the US patients (P = 0.02). The number of tumor emboli was significantly higher in tumors from Egypt (mean +/- SD, 14.1 +/- 14.0) than in the tumors from the United States (5.0 +/- 4.0, P = 0.01). The number of tumor emboli in LYVE-1 positive vessels was higher in tumors from Egypt (3.5 +/- 2.8) than tumors from the United States (1.6 +/- 0.5, P = 0.15). We detected a high level of RhoC in 87% of the tumors from Egypt and 14% of the tumors from the United States (P = 0.0003). Conclusion Patients from Egypt have a more aggressive form of IBC than those in the United States. Our analysis of IBC patients shows that distinct molecular phenotypes can be found when these two study populations are compared. Future studies should explore the epidemiologic and environmental exposures and the genetic factors that might lead to the different clinical and molecular features of IBC in patients from these two countries.

PMID: 18058225 [PubMed - as supplied by publisher]

Thornton BC, McCoy ED, Glover TW, Baldwin DC

Wang S, Lewis CM, Jakobsson M, Ramachandran S, Ray N, Bedoya G, Rojas W, Parra MV, Molina JA, Gallo C, Mazzotti G, Poletti G, Hill K, Hurtado AM, Labuda D, Klitz W, Barrantes R, Bortolini MC, Salzano FM, Petzl-Erler ML, Tsuneto LT, Llop E, Rothhammer F, Excoffier L, Feldman MW, Rosenberg NA, Ruiz-Linares A

Interaction on health care teams. 1980.

J Interprof Care. 2007 Oct;21 Suppl 1:76-85

Authors: Thornton BC, McCoy ED, Glover TW, Baldwin DC

PMID: 17917945 [PubMed - indexed for MEDLINE]

Ellsworth BS, Butts DL, Camper SA

Genetic Variation and Population Structure in Native Americans.

PLoS Genet. 2007 Nov 23;3(11):e185

Authors: Wang S, Lewis CM, Jakobsson M, Ramachandran S, Ray N, Bedoya G, Rojas W, Parra MV, Molina JA, Gallo C, Mazzotti G, Poletti G, Hill K, Hurtado AM, Labuda D, Klitz W, Barrantes R, Bortolini MC, Salzano FM, Petzl-Erler ML, Tsuneto LT, Llop E, Rothhammer F, Excoffier L, Feldman MW, Rosenberg NA, Ruiz-Linares A

We examined genetic diversity and population structure in the American landmass using 678 autosomal microsatellite markers genotyped in 422 individuals representing 24 Native American populations sampled from North, Central, and South America. These data were analyzed jointly with similar data available in 54 other indigenous populations worldwide, including an additional five Native American groups. The Native American populations have lower genetic diversity and greater differentiation than populations from other continental regions. We observe gradients both of decreasing genetic diversity as a function of geographic distance from the Bering Strait and of decreasing genetic similarity to Siberians-signals of the southward dispersal of human populations from the northwestern tip of the Americas. We also observe evidence of: (1) a higher level of diversity and lower level of population structure in western South America compared to eastern South America, (2) a relative lack of differentiation between Mesoamerican and Andean populations, (3) a scenario in which coastal routes were easier for migrating peoples to traverse in comparison with inland routes, and (4) a partial agreement on a local scale between genetic similarity and the linguistic classification of populations. These findings offer new insights into the process of population dispersal and differentiation during the peopling of the Americas.

PMID: 18039031 [PubMed - as supplied by publisher]

Sharma MR, Petty EM, Lesperance MM

Mechanisms underlying pituitary hypoplasia and failed cell specification in Lhx3-deficient mice.

Dev Biol. 2008 Jan 1;313(1):118-29

Authors: Ellsworth BS, Butts DL, Camper SA

The LIM homeodomain transcription factor, LHX3, is essential for pituitary development in mouse and man. Lhx3 engineered null mice have profound pituitary hypoplasia that we find is attributable to an increase in cell death early in pituitary development. Dying cells are localized to regions of TPIT expression indicating that cell death may contribute to the severe reduction in differentiated corticotrope cells and lower expression of the corticotrope transcription factors, TPIT and NEUROD1. Lhx3 deficiency also results in dorsal ectopic expression of transcription factors characteristic of gonadotropes, SF1 and ISL1, but no gonadotropin expression. This apparent disturbance of cell differentiation may be due, in part, to loss of NOTCH2. NOTCH2 is normally expressed in the pituitary at the boundary between dorsal, proliferating cells and ventral, differentiating cells and is important for maintaining dorsal-ventral patterning in other organs. Thus, Lhx3 contributes significantly to pituitary development by maintaining normal dorsal-ventral patterning, cell survival, and normal expression of corticotrope-specific transcription factors, which are necessary for repressing ectopic gonadotrope differentiation.

PMID: 18037398 [PubMed - in process]

Zhang Y, Zolov SN, Chow CY, Slutsky SG, Richardson SC, Piper RC, Yang B, Nau JJ, Westrick RJ, Morrison SJ, Meisler MH, Weisman LS

Airway obstruction caused by PTEN hamartoma (Bannayan-Riley-Ruvalcaba) syndrome.

Arch Otolaryngol Head Neck Surg. 2007 Nov;133(11):1157-60

Authors: Sharma MR, Petty EM, Lesperance MM

PMID: 18025323 [PubMed - indexed for MEDLINE]

Leder A, McMenamin J, Zhou F, Moran JL, Beier DR, Leder P

Loss of Vac14, a regulator of the signaling lipid phosphatidylinositol 3,5-bisphosphate, results in neurodegeneration in mice.

Proc Natl Acad Sci U S A. 2007 Oct 30;104(44):17518-23

Authors: Zhang Y, Zolov SN, Chow CY, Slutsky SG, Richardson SC, Piper RC, Yang B, Nau JJ, Westrick RJ, Morrison SJ, Meisler MH, Weisman LS

The signaling lipid, phosphatidylinositol 3,5-bisphosphate (PI(3,5)P(2)), likely functions in multiple signaling pathways. Here, we report the characterization of a mouse mutant lacking Vac14, a regulator of PI(3,5)P(2) synthesis. The mutant mice exhibit massive neurodegeneration, particularly in the midbrain and in peripheral sensory neurons. Cell bodies of affected neurons are vacuolated, and apparently empty spaces are present in areas where neurons should be present. Similar vacuoles are found in cultured neurons and fibroblasts. Selective membrane trafficking pathways, especially endosome-to-TGN retrograde trafficking, are defective. This report, along with a recent report on a mouse with a null mutation in Fig4, presents the unexpected finding that the housekeeping lipid, PI(3,5)P(2), is critical for the survival of neural cells.

PMID: 17956977 [PubMed - indexed for MEDLINE]

Rao A, Hero AO, States DJ, Engel JD

Genome-wide SNP analysis of Tg.AC transgenic mice reveals an oncogenic collaboration between v-Ha-ras and Ink4a, which is absent in p53 deficiency.

Oncogene. 2007 Oct 22;

Authors: Leder A, McMenamin J, Zhou F, Moran JL, Beier DR, Leder P

Oncogenesis is a progressive process often involving collaboration between various oncogenes and tumor suppressors. To identify those genes that collaborate with oncogenic ras, we took advantage of the Tg.AC transgenic mouse, a line that harbors the v-Ha-ras transgene and spontaneously develops an array of malignant tumors. By crossing Tg.AC mice on an inbred FVB background to other inbred strains, F1 mice were created that could be analysed using genome wide, single nucleotide polymorphism (SNP) screens. Loss of heterozygosity (LOH) in tumors and tumor cell lines marked a somatic event, possibly the inactivation of tumor suppressor gene(s). LOH could also represent DNA damage, a sign of genomic instability in the pretransformed cell. Nonetheless, the screens showed no evidence of such generalized genomic instability. Instead, they revealed a single region of LOH on chromosome 4 that occurred via somatic recombination/gene conversion, generating a region of isoparental disomy. This LOH provided a clue that linked v-Ha-ras to the inactivation of the Ink4a locus in 25 of 32 tumor cell lines. This collaboration is seen regardless of tumor type or genetic background. In contrast, tumors that develop in bitransgenic mice bearing both the v-Ha-ras gene and a heterozygous mutant p53 allele tend to retain the Ink4a locus and instead lose the p53 wild-type allele. This suggests that different strategies can be selected to collaborate with v-Ha-ras in tumorigenesis.Oncogene advance online publication, 22 October 2007; doi:10.1038/sj.onc.1210866.

PMID: 17952114 [PubMed - as supplied by publisher]

Using directed information to build biologically relevant influence networks.

Comput Syst Bioinformatics Conf. 2007;6:145-56

Authors: Rao A, Hero AO, States DJ, Engel JD

The systematic inference of biologically relevant influence networks remains a challenging problem in computational biology. Even though the availability of high-throughput data has enabled the use of probabilistic models to infer the plausible structure of such networks, their true interpretation of the biology of the process is questionable. In this work, we propose a network inference methodology, based on the directed information (DTI) criterion, which incorporates the biology of transcription within the framework, so as to enable experimentally verifiable inference. We use publicly available embryonic kidney and T-cell microarray datasets to demonstrate our results. We present two variants of network inference via DTI (supervised and unsupervised) and the inferred networks relevant to mammalian nephrogenesis as well as T-cell activation. We demonstrate the conformity of the obtained interactions with literature as well as comparison with the coefficient of determination (CoD) method. Apart from network inference, the proposed framework enables the exploration of specific interactions, not just those revealed by data.

PMID: 17951820 [PubMed - indexed for MEDLINE]

Zhang K, Rosenberg NA

Robins DM, Albertelli MA, O'mahony OA

On the genealogy of a duplicated microsatellite.

Genetics. 2007 Dec;177(4):2109-22

Authors: Zhang K, Rosenberg NA

When a microsatellite locus is duplicated in a diploid organism, a single pair of PCR primers may amplify as many as four distinct alleles. To study the evolution of a duplicated microsatellite, we consider a coalescent model with symmetric stepwise mutation. Conditional on the time of duplication and a mutation rate, both in a model of completely unlinked loci and in a model of completely linked loci, we compute the probabilities for a sampled diploid individual to amplify one, two, three, or four distinct alleles with one pair of microsatellite PCR primers. These probabilities are then studied to examine the nature of their dependence on the duplication time and the mutation rate. The mutation rate is observed to have a stronger effect than the duplication time on the four probabilities, and the unlinked and linked cases are seen to behave similarly. Our results can be useful for helping to interpret genetic variation at microsatellite loci in species with a very recent history of gene and genome duplication.

PMID: 17947445 [PubMed - in process]

Utsch B, McCabe CD, Galbraith K, Gonzalez R, Born M, Dötsch J, Ludwig M, Reutter H, Innis JW

Androgen receptor variants and prostate cancer in humanized AR mice.

J Steroid Biochem Mol Biol. 2007 Sep 7;

Authors: Robins DM, Albertelli MA, O'mahony OA

Androgen, acting via the androgen receptor (AR), is central to male development, differentiation and hormone-dependent diseases such as prostate cancer. AR is actively involved in the initiation of prostate cancer, the transition to androgen independence, and many mechanisms of resistance to therapy. To examine genetic variation of AR in cancer, we created mice by germ-line gene targeting in which human AR sequence replaces that of the mouse. Since shorter length of a polymorphic N-terminal glutamine (Q) tract has been linked to prostate cancer risk, we introduced alleles with 12, 21 or 48 Qs to test this association. The three "humanized" AR mouse strains (h/mAR) are normal physiologically, as well as by cellular and molecular criteria, although slight differences are detected in AR target gene expression, correlating inversely with Q tract length. However, distinct allele-dependent differences in tumorigenesis are evident when these mice are crossed to a transgenic prostate cancer model. Remarkably, Q tract variation also differentially impacts disease progression following androgen depletion. This finding emphasizes the importance of AR function in androgen-independent as well as androgen-dependent disease. These mice provide a novel genetic paradigm in which to dissect opposing functions of AR in tumor suppression versus oncogenesis.

PMID: 17936615 [PubMed - as supplied by publisher]

Drews VL, Shi K, de Haan G, Meisler MH

Molecular characterization of HOXA13 polyalanine expansion proteins in hand-foot-genital syndrome.

Am J Med Genet A. 2007 Dec 15;143(24):3161-8

Authors: Utsch B, McCabe CD, Galbraith K, Gonzalez R, Born M, Dötsch J, Ludwig M, Reutter H, Innis JW

We report on a father and daughter with hand-foot-genital syndrome (HFGS) with typical skeletal and genitourinary anomalies due to a 14-residue polyalanine expansion in HOXA13. This is the largest (32 residues) polyalanine tract so far described for any polyalanine mutant protein. Polyalanine expansion results in protein misfolding, cytoplasmic aggregation and degradation; however, HOXA13 polyalanine expansions appear to act as loss of function mutations in contrast to gain of function for HOXD13 polyalanine expansions. To address this paradox we examined the cellular consequences of polyalanine expansions on HOXA13 protein using COS cell transfection and immunocytochemistry. HOXA13 polyalanine expansion proteins form cytoplasmic aggregates, and distribution between cytoplasmic aggregates or the nucleus is polyalanine tract size-dependent. Geldanamycin, an Hsp90 inhibitor, reduces the steady-state abundance of all polyalanine-expanded proteins in transfected cells. We also found that wild-type HOXA13 or HOXD13 proteins are sequestered in HOXA13 polyalanine expansion cytoplasmic aggregates. Thus, the difference between HOXA13 polyalanine expansion loss-of-function and HOXD13 polyalanine expansion dominant-negative effect is not the ability to aggregate wild-type group 13 paralogs but perhaps to variation in activities associated with refolding, aggregation or degradation of the proteins.

PMID: 17935235 [PubMed - indexed for MEDLINE]

Peterson EA, Kalikin LM, Steels JD, Estey MP, Trimble WS, Petty EM

Identification of evolutionarily conserved, functional noncoding elements in the promoter region of the sodium channel gene SCN8A.

Mamm Genome. 2007 Oct;18(10):723-31

Authors: Drews VL, Shi K, de Haan G, Meisler MH

SCN8A is a major neuronal sodium channel gene expressed throughout the central and peripheral nervous systems. Mutations of SCN8A result in movement disorders and impaired cognition. To investigate the basis for the tissue-specific expression of SCN8A, we located conserved, potentially regulatory sequences in the human, mouse, chicken, and fish genes by 5' RACE of brain RNA and genomic sequence comparison. A highly conserved 5' noncoding exon, exon 1c, is present in vertebrates from fish to mammals and appears to define the ancestral promoter region. The distance from exon 1c to the first coding exon increased tenfold during vertebrate evolution, largely by insertion of repetitive elements. The mammalian gene acquired three novel, mutually exclusive noncoding exons that are not represented in the lower vertebrates. Within the shared exon 1c, we identified four short sequence elements of 10-20 bp with an unusually high level of evolutionary conservation. The conserved elements are most similar to consensus sites for the transcription factors Pou6f1/Brn5, YY1, and REST/NRSF. Introduction of mutations into the predicted Pou6f1 and REST sites reduced promoter activity in transfected neuronal cells. A 470-bp promoter fragment containing all of the conserved elements directed brain-specific expression of the LacZ reporter in transgenic mice. Transgene expression was highest in hippocampal neurons and cerebellar Purkinje cells, consistent with the expression of the endogenous gene. The compact cluster of conserved regulatory elements in SCN8A provides a useful target for molecular analysis of neuronal gene expression.

PMID: 17924165 [PubMed - indexed for MEDLINE]

Smith SS, Oei TP, Douglas JA, Brown I, Jorgensen G, Andrews J

Characterization of a SEPT9 interacting protein, SEPT14, a novel testis-specific septin.

Mamm Genome. 2007 Nov;18(11):796-807

Authors: Peterson EA, Kalikin LM, Steels JD, Estey MP, Trimble WS, Petty EM

Septins are a highly conserved family of GTP-binding cytoskeletal proteins implicated in multiple cellular functions, including membrane transport, apoptosis, cell polarity, cell cycle regulation, cytokinesis, and oncogenesis. Here we describe the characterization of a novel interacting partner of the septin family, initially cloned from a human testis expression library following yeast two-hybrid isolation to identify SEPT9 binding partners. Upon further genomic characterization and bioinformatics analyses it was determined that this novel septin-interacting partner was also a new member of the mammalian septin family, named SEPT14. SEPT14 maps to 7p11.2 in humans and includes a conserved GTPase domain and a predicted carboxy-terminus coiled-coil domain characteristic of other septins. Three potential translational start methionines were identified by 5' RACE-PCR encoding proteins of 432-, 427-, and 425-residue peptides, respectively. SEPT14 shares closest homology to SEPT10, a human dendritic septin, and limited homology to SEPT9 isoforms. SEPT14 colocalized with SEPT9 when coexpressed in cell lines, and epitope-tagged forms of these proteins coimmunoprecipitated. Moreover, SEPT14 was coimmunoprecipitated from rat testes using SEPT9 antibodies, and yeast two-hybrid analysis suggested SEPT14 interactions with nine additional septins. Multitissue Northern blotting showed testis-specific expression of a single 5.0-kb SEPT14 transcript. RT-PCR analysis revealed that SEPT14 was not detectable in normal or cancerous ovarian, breast, prostate, bladder, or kidney cell lines and was only faintly detected in fetal liver, tonsil, and thymus samples. Interestingly, SEPT14 was expressed in testis but not testicular cancer cell lines by RT-PCR, suggesting that further investigation of SEPT14 as a testis-specific tumor suppressor is necessary.

PMID: 17922164 [PubMed - in process]

Brinkmeier ML, Potok MA, Davis SW, Camper SA

Confirmatory factor analysis of the Epworth Sleepiness Scale (ESS) in patients with obstructive sleep apnoea.

Sleep Med. 2007 Oct 5;

Authors: Smith SS, Oei TP, Douglas JA, Brown I, Jorgensen G, Andrews J

BACKGROUND: The Epworth Sleepiness Scale (ESS [Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep 1991;14(6):540-5]) has been used frequently to assess daytime sleepiness, particularly in the context of clinical sleep disorders. Its psychometric properties are still unclear, particularly when used to evaluate sleep propensity in patients with obstructive sleep apnoea. METHODS: The present study used confirmatory factor analysis (CFA) to investigate a potential single-factor structure of the ESS in a sample of 759 Australian patients with a diagnosis of obstructive sleep apnoea by the treating physicians. RESULTS: CFA results from showed that the original single-factor structure proposed by Johns [Johns MW. Reliability and factor analysis of the Epworth Sleepiness Scale. Sleep 1992;15(4):376-81] did not adequately fit the data. A re-specified single-factor solution provided a good fit for data, and this improved fit was confirmed on a second CFA. CONCLUSIONS: The findings suggest that standard scoring of the ESS should be interpreted cautiously for patients with obstructive sleep apnoea.

PMID: 17921053 [PubMed - as supplied by publisher]

Albertelli MA, O'Mahony OA, Brogley M, Tosoian J, Steinkamp M, Daignault S, Wojno K, Robins DM

TCF4 deficiency expands ventral diencephalon signaling and increases induction of pituitary progenitors.

Dev Biol. 2007 Nov 15;311(2):396-407

Authors: Brinkmeier ML, Potok MA, Davis SW, Camper SA

The anterior and intermediate lobes of the pituitary gland are formed from Rathke's pouch. FGF, BMP and WNT signals emanating from the ventral diencephalon influence pouch growth and development. In order to examine the role of canonical WNT signaling during pituitary development we examined the pituitary expression of the TCF/LEF family of transcription factors, which mediate WNT signaling through the binding of beta-catenin. We report here the expression of several members of this family during pituitary development and the functional role of one member, TCF4 (TCF7L2), in the induction of the pituitary primordium. TCF4 is expressed in the ventral diencephalon early in pituitary development, rostral to a domain of BMP and FGF expression. Tcf4 deficient mice express Fgf10 and Bmp4; however, the Bmp and Fgf expression domains are expanded rostrally. As a result, additional pituitary progenitor cells are recruited into Rathke's pouch in Tcf4 mutants. Mutants also exhibit an expansion of the Six6 expression domain within Rathke's pouch, which may increase the number of proliferating pouch cells, resulting in a greatly enlarged anterior pituitary gland. This suggests that TCF4 negatively regulates pituitary growth through two mechanisms. The first mechanism is to restrict the domains of BMP and FGF signaling in the ventral diencephalon, and the second mechanism is the restriction of Six6 within Rathke's pouch. Thus, TCF4 is necessary both intrinsically and extrinsically to Rathke's pouch to ensure the proper growth of the pituitary gland.

PMID: 17919533 [PubMed - in process]

Karolyi IJ, Dootz GA, Halsey K, Beyer L, Probst FJ, Johnson KR, Parlow AF, Raphael Y, Dolan DF, Camper SA

Glutamine tract length of human androgen receptors affects hormone-dependent and -independent prostate cancer in mice.

Hum Mol Genet. 2008 Jan 1;17(1):98-110

Authors: Albertelli MA, O'Mahony OA, Brogley M, Tosoian J, Steinkamp M, Daignault S, Wojno K, Robins DM

The androgen receptor (AR) is involved in the initiation and progression of prostate cancer and its transition to androgen independence. Genetic variation in AR may contribute to disease risk and has been studied for a polymorphic N-terminal glutamine (Q) tract that shows population heterogeneity. While the length of this tract is known to affect AR in vitro, association with disease is complicated by genetic and environmental factors that have led to discordant epidemiological findings. To clarify the effect of Q tract polymorphism on prostate cancer, we created mice bearing humanized AR genes (h/mAr) varying in Q tract length. ARs with short Q tracts (12Q), which are transcriptionally more active, induce earlier disease in the transgene-induced TRAMP prostate cancer model than alleles with median (21Q) or long (48Q) tracts. Disease length varies within each genotype, with greater differentiation and AR expression in slower growing tumors. Remarkably, following androgen ablation, Q tract length has effects that are also allele-dependent and in directions opposite to those in hormone intact mice. Differences in AR activity conferred by Q tract length thus appear to direct distinct pathways of androgen-independent as well as androgen-dependent progression, and highlight substantial risk that may be associated with alterations in the androgen axis. This AR allelic series in humanized mice provides an experimental paradigm to dissect the role of AR in prostate cancer initiation and progression, to model response to treatment and to test therapies targeted specifically to the human AR.

PMID: 17906287 [PubMed - in process]

Gonzalez ME, Peterson EA, Privette LM, Loffreda-Wren JL, Kalikin LM, Petty EM

Dietary thyroid hormone replacement ameliorates hearing deficits in hypothyroid mice.

Mamm Genome. 2007 Aug;18(8):596-608

Authors: Karolyi IJ, Dootz GA, Halsey K, Beyer L, Probst FJ, Johnson KR, Parlow AF, Raphael Y, Dolan DF, Camper SA

Thyroid hormone (TH) insufficiency causes variable hearing impairment and mental deficiency in humans. Rodents lacking TH have congenital hearing deficiency that has been attributed to physiologic, morphologic, and developmental abnormalities of the auditory system. We examined four genetically defined strains of hypothyroid mice for development of hearing and response to TH replacement initiated during late gestation and continued through six weeks of age. Auditory brain stem response studies showed variable hearing impairment in homozygous mutants of each strain at three weeks of age relative to normal littermates. Mutants from three of the strains still had hearing deficiencies at six weeks of age. TH-enriched diet significantly improved hearing in three-week-old mutants of each strain relative to untreated mutants. Differences in the level of hearing impairment between the Prop1df and Pit1dw mutants, which have defects in the same developmental pathway, were determined to be due to genetic background modifier genes. Further physiologic and morphologic studies in the Cgatm1Sac strain indicated that poor hearing was due to cochlear defects. We conclude that TH supplement administered during the critical period of hearing development in mice can prevent deafness associated with congenital hypothyroidism of heterogeneous genetic etiology.

PMID: 17899304 [PubMed - indexed for MEDLINE]

Hughes ED, Qu YY, Genik SJ, Lyons RH, Pacheco CD, Lieberman AP, Samuelson LC, Nasonkin IO, Camper SA, Van Keuren ML, Saunders TL

High SEPT9_v1 expression in human breast cancer cells is associated with oncogenic phenotypes.

Cancer Res. 2007 Sep 15;67(18):8554-64

Authors: Gonzalez ME, Peterson EA, Privette LM, Loffreda-Wren JL, Kalikin LM, Petty EM

Altered expression of the human septin gene, SEPT9, and its murine homologue, Sept9, has been implicated in neoplasia. However, their role(s) in oncogenesis remains poorly understood. We found amplification of SEPT9 in 67% of breast cancer cells (BCC) when compared with immortalized human mammary epithelial cells (IHMEC) as well as high levels of SEPT9 expression in the majority (61%) of the BCCs studied, unlike IHMECs. Expression profiling of variant SEPT9 transcripts and translated products revealed that high expression of the variant, SEPT9_v1, in contrast to other variants, was widespread in BCCs (55% of the BCCs) but not in IHMECs. High expression of SEPT9_v1 was also observed in primary breast cancer samples by immunohistochemical studies. We subsequently examined the phenotypic consequences of SEPT9_v1 expression in human breast cells. Retroviral expression of SEPT9_v1 in IHMEC cell culture models showed that SEPT9_v1 accelerated growth kinetics, stimulated cell motility, promoted invasion in Matrigel Transwell assays, increased genomic instability with the development of aneuploidy, and stimulated morphologic changes. Significant cytokinesis defects and disruption of tubulin microfilaments were also observed by immunofluorescence when SEPT9_v1 was ectopically expressed in IHMECs. Furthermore, SEPT9_v1 markedly enhanced neoplastic transformation in Hs578T cells, a BCC with no endogenous expression of the SEPT9_v1 isoform. Small interfering RNA-mediated and short hairpin RNA-mediated inhibition of SEPT9_v1 expression in two BCCs with high levels of endogenous SEPT9_v1 expression inhibited neoplastic growth properties of the cells. Taken together, our findings suggest that increased SEPT9_v1 expression contributes to the malignant pathogenesis of some breast tumors.

PMID: 17875694 [PubMed - indexed for MEDLINE]

Genetic variation in C57BL/6 ES cell lines and genetic instability in the Bruce4 C57BL/6 ES cell line.

Mamm Genome. 2007 Aug;18(8):549-58

Authors: Hughes ED, Qu YY, Genik SJ, Lyons RH, Pacheco CD, Lieberman AP, Samuelson LC, Nasonkin IO, Camper SA, Van Keuren ML, Saunders TL

Genetically modified mouse strains derived from embryonic stem (ES) cells are powerful tools for gene function analysis. ES cells from the C57BL/6 mouse strain are not widely used to generate mouse models despite the advantage of a defined genetic background. We assessed genetic variation in six such ES cell lines with 275 SSLP markers. Compared to C57BL/6, Bruce4 differed at 34 SSLP markers and had significant heterozygosity on three chromosomes. BL/6#3 and Dale1 ES cell lines differed at only 3 SSLP makers. The C2 and WB6d ES cell lines differed at 6 SSLP markers. It is important to compare the efficiency of producing mouse models with available C57BL/6 ES cells relative to standard 129 mouse strain ES cells. We assessed genetic stability (the tendency of cells to become aneuploid) in 110 gene-targeted ES cell clones from the most widely used C57BL/6 ES cell line, Bruce4, and 710 targeted 129 ES cell clones. Bruce4 clones were more likely to be aneuploid and unsuitable for ES cell-mouse chimera production. Despite their tendency to aneuploidy and consequent inefficiency, use of Bruce4 ES cells can be valuable for models requiring behavioral studies and other mouse models that benefit from a defined C57BL/6 background.

PMID: 17828574 [PubMed - indexed for MEDLINE]

Brewer GJ

Nam Y, Brewer GJ, Wheeler BC

Causes and diagnosis of copper deficiency.

Am J Hematol. 2008 Jan;83(1):87-88

Authors: Brewer GJ

PMID: 17724702 [PubMed - as supplied by publisher]

Development of astroglial cells in patterned neuronal cultures.

J Biomater Sci Polym Ed. 2007;18(8):1091-100

Authors: Nam Y, Brewer GJ, Wheeler BC

The purpose of this work was to study the development of astroglial cells in patterned neuronal cultures. Hippocampal neurons, derived from embryonic stage (E18) rats and cultured in serum-free Neurobasal/B27 medium, grew to follow patterns of poly(D-lysine) created by micro-contact printing. The growth of the astroglial cells and the co-localization of neurons and astroglial cells were measured for up to one month using fluorescence immunostaining of neurons and astroglial cells. Neurons grew to form square patterns within 2 weeks, while astroglia only started to emerge in the same period. Astroglial cells continued to proliferate for a month following a general growth curve. Over 90% of the astroglial cell area co-localized with neurons (within 2 mum) at an early stage of astroglial development (13 DIV). Over the remaining period, astroglial cells proliferated and the co-localization was 80%. Hence, in these culture conditions astroglial cells develop 2-3 weeks later than neurons but remain highly co-localized with neurons.

PMID: 17706000 [PubMed - indexed for MEDLINE]

Brewer GJ

Levin AM, Zuhlke KA, Ray AM, Cooney KA, Douglas JA

A brand new mechanism for copper toxicity.

J Hepatol. 2007 Oct;47(4):621-2

Authors: Brewer GJ

PMID: 17697726 [PubMed]

Peter JV, Moran JL, Graham PL

Sequence variation in alpha-methylacyl-CoA racemase and risk of early-onset and familial prostate cancer.

Prostate. 2007 Oct 1;67(14):1507-13

Authors: Levin AM, Zuhlke KA, Ray AM, Cooney KA, Douglas JA

BACKGROUND: Expression of the alpha-methylacyl-CoA racemase (AMACR) gene has been established as a sensitive and specific biomarker for the diagnosis of prostate cancer. An initial study has also suggested that the risk of familial (but not sporadic) prostate cancer may be associated with germline variation in the AMACR gene. METHODS: In a study of brothers discordant for the diagnosis of prostate cancer (including 449 affected and 394 unaffected men) from 332 familial and early-onset prostate cancer families, we used conditional logistic regression and family-based association tests to investigate the association between prostate cancer and five single nucleotide polymorphisms (SNPs) tagging common haplotype variation within the coding and regulatory regions of AMACR. RESULTS: The strongest evidence for prostate cancer association was for SNP rs3195676, with an estimated odds ratio of 0.58 (95% confidence interval = 0.38-0.90; P = 0.01 for a recessive model). This non-synonymous SNP (nsSNP) results in a methionine-to-valine substitution at codon 9 (M9V) in exon 2 of the AMACR gene. Three additional nsSNPs showed suggestive evidence for prostate cancer association (P < or = 0.10). CONCLUSIONS: Our results confirm an initial report of association between the AMACR gene and the risk of familial prostate cancer. These findings emphasize the value of studying early-onset and familial prostate cancer when attempting to identify genetic variation associated with prostate cancer.

PMID: 17683075 [PubMed - indexed for MEDLINE]

Joseph JA, Carey A, Brewer GJ, Lau FC, Fisher DR

Advances in the management of organophosphate poisoning.

Expert Opin Pharmacother. 2007 Jul;8(10):1451-64

Authors: Peter JV, Moran JL, Graham PL

Organophosphate (OP) poisoning is commonly encountered in agricultural communities. The mainstay of therapy in OP poisoning is the use of atropine. However, several other therapies have been evaluated. Although oxime has been the most studied antidote, results in humans have been disappointing and limited by the lack of well-designed, prospective, randomised controlled trials. The key factor in determining outcomes in OP poisoning appears to be the timing of antidote administration. Other adjuvants, such as magnesium, fresh frozen plasma and haemoperfusion appear promising, and need to be explored further. A multi-faceted approach may be the answer to improving outcomes in OP poisoning. This review evaluates the advances in OP management over the last 20 years.

PMID: 17661728 [PubMed - indexed for MEDLINE]

Howell VM, Jones JM, Bergren SK, Li L, Billi AC, Avenarius MR, Meisler MH

Dopamine and Abeta-induced stress signaling and decrements in Ca2+ buffering in primary neonatal hippocampal cells are antagonized by blueberry extract.

J Alzheimers Dis. 2007 Jul;11(4):433-46

Authors: Joseph JA, Carey A, Brewer GJ, Lau FC, Fisher DR

We have shown previously that dietary blueberry (BB) extract supplementation (S) reversed several parameters of neuronal and behavioral (e.g., cognition) aging in rodents. Additionally, findings indicate that COS-7 cells transfected with muscarinic receptor subtypes (e.g., M1) showed decrements in Ca;{2+} clearance following depolarization (Ca;{2+} Recovery time, Ca;{2+}RT) that were antagonized by BB. Since it has been postulated that at least part of the loss of cognitive function in aging may be dependent upon a dysregulation in calcium homeostasis (i.e., Ca;{2+}RT), we assessed whether: a) Ca;{2+}RT would be altered in dopamine (DA)- or amyloid beta (Abeta)-exposed cultured primary hippocampal neuronal cells (HNC), and b) BB pre-treatment of the cells would prevent these deficits. Thus, control or BB (0.5 mg/ml)-treated HNC were exposed to DA (0.1 mM, 2 hrs), Abeta(40) (25 microM, 24 hrs), Abeta(42) (25 microM, 24 hrs), and Abeta(25-35) (25 microM, 24 hrs), and Ca;{2+}RT following KCl-induced depolarization assessed. Ca;{2+}RT was assessed as the % of HNC showing recovery to 50%-70% of control at 5, 10, or 15 min after depolarization. Results indicated that DA significantly lowered Ca;{2+}RT in the HNC at all time points examined after depolarization. However, BB treatment selectively prevented these declines in Ca;{2+}RT. In the case of Abeta, the greatest effects on Ca;{2+}RT were seen when the hippocampal cells were Abeta(42)-treated. These effects were antagonized by BB treatment. Abeta(40) produced fewer deficits on Ca;{2+}RT than those seen when the HNC were pre-treated with either A;{2+}(42) or A;{2+}(25-35), but BB was relatively ineffective in antagonizing the deficits in Ca;{2+}RT produced by A;{2+}(40) or A;{2+}(25-35). Additional analyses indicated that BBs may be exerting their protective effects in the hippocampal cells by altering levels of phosphorylated MAPK, PKCgamma, and phosphorylated CREB. Therefore it appears that at least part of the protective effect of BBs may involve alterations in stress signaling.

PMID: 17656822 [PubMed - indexed for MEDLINE]

Pomerleau OF, Burmeister M, Madden P, Long JC, Swan GE, Kardia SL

Evidence for a direct role of the disease modifier SCNM1 in splicing.

Hum Mol Genet. 2007 Oct 15;16(20):3506-16

Authors: Howell VM, Jones JM, Bergren SK, Li L, Billi AC, Avenarius MR, Meisler MH

We originally isolated Scnm1 as a disease modifier gene that is required for efficient in vivo splicing of a mutant splice donor site in the sodium channel Scn8a. It was previously unclear whether the modifier effect on splicing was direct or indirect. We now report evidence that sodium channel modifier 1 (SCNM1) has a direct role in splicing. SCNM1 protein interacts with the spliceosome protein U1-70K in the yeast two-hybrid system, and is co-localized with U1-70K in nuclear speckles in mammalian cells. SCNM1 is also co-immunoprecipitated with the spliceosomal core Smith (Sm) proteins and demonstrates functional activity in a minigene splicing assay. In a yeast two-hybrid screen, SCNM1 interacted with LUC7L2, a mammalian homolog of a yeast protein involved in recognition of non-consensus splice donor sites. This interaction requires the acidic C-terminal domain of SCNM1 which is truncated by the disease susceptibility variant Scnm1(R187X) in mouse strain C57BL/6J. Luc7L2 transcripts are widely distributed in mammalian tissues, and undergo alternative splicing and polyadenylation. LUC7L2 is also co-localized with U1-70K and may function with SCNM1 in recognition of weak splice donor sites. In summary, Scnm1 is the first example of a modifier gene which influences disease severity through a trans-effect on splicing of the disease gene transcript.

PMID: 17656373 [PubMed - in process]

Mustapha M, Beyer LA, Izumikawa M, Swiderski DL, Dolan DF, Raphael Y, Camper SA

Genetic research on complex behaviors: an examination of attempts to identify genes for smoking.

Nicotine Tob Res. 2007 Aug;9(8):883-901

Authors: Pomerleau OF, Burmeister M, Madden P, Long JC, Swan GE, Kardia SL

A conference on the conduct of genomic research on complex behaviors was convened at the University of Michigan to demystify genetic research by describing the tools and methodologies for identifying genes and to assess the feasibility of conducting genomic research on smoking, a complex behavior with major public health import. These proceedings are excerpts based on the presentations at the conference.

PMID: 17654301 [PubMed - indexed for MEDLINE]

Chromosome fragile sites.

Whirler mutant hair cells have less severe pathology than shaker 2 or double mutants.

J Assoc Res Otolaryngol. 2007 Sep;8(3):329-37

Authors: Mustapha M, Beyer LA, Izumikawa M, Swiderski DL, Dolan DF, Raphael Y, Camper SA

MYOSIN XV is a motor protein that interacts with the PDZ domain-containing protein WHIRLIN and transports WHIRLIN to the tips of the stereocilia. Shaker 2 (sh2) mice have a mutation in the motor domain of MYOSIN XV and exhibit congenital deafness and circling behavior, probably because of abnormally short stereocilia. Whirler (wi) mice have a similar phenotype caused by a deletion in the third PDZ domain of WHIRLIN. We compared the morphology of Whrn (wi/wi) and Myo15 (sh2/sh2) sensory hair cells and found that Myo15 (sh2/sh2) have more frequent pathology at the base of inner hair cells than Whrn (wi/wi), and shorter outer hair cell stereocilia. Considering the functional and morphologic similarities in the phenotypes caused by mutations in Myo15 and Whrn, and the physical interaction between their encoded proteins, we used a genetic approach to test for functional overlap. Double heterozygotes (Myo15 (sh2/+), Whrn (wi/+)) have normal hearing and no increase in hearing loss compared to normal littermates. Single and double mutants (Myo15 (sh2/sh2), Whrn (wi/wi)) exhibit abnormal persistence of kinocilia and microvilli, and develop abnormal cytoskeletal architecture. Double mutants are also similar to the single mutants in viability, circling behavior, and lack of a Preyer reflex. The morphology of cochlear hair cell stereocilia in double mutants reflects a dominance of the more severe Myo15 (sh2/sh2) phenotype over the Whrn (wi/wi) phenotype. This suggests that MYOSIN XV may interact with other proteins besides WHIRLIN that are important for hair cell maturation.

PMID: 17619105 [PubMed - indexed for MEDLINE]

Durkin SG, Glover TW

Poirier C, Moran JL, Kovanci E, Petit DC, Beier DR, Bishop CE

Chromosome fragile sites.

Annu Rev Genet. 2007;41:169-92

Authors: Durkin SG, Glover TW

Chromosomal fragile sites are specific loci that preferentially exhibit gaps and breaks on metaphase chromosomes following partial inhibition of DNA synthesis. Their discovery has led to novel findings spanning a number of areas of genetics. Rare fragile sites are seen in a small proportion of individuals and are inherited in a Mendelian manner. Some, such as FRAXA in the FMR1 gene, are associated with human genetic disorders, and their study led to the identification of nucleotide-repeat expansion as a frequent mutational mechanism in humans. In contrast, common fragile sites are present in all individuals and represent the largest class of fragile sites. Long considered an intriguing component of chromosome structure, common fragile sites have taken on novel significance as regions of the genome that are particularly sensitive to replication stress and that are frequently rearranged in tumor cells. In recent years, much progress has been made toward understanding the genomic features of common fragile sites and the cellular processes that monitor and influence their stability. Their study has merged with that of cell cycle checkpoints and DNA repair, and common fragile sites have provided insight into understanding the consequences of replication stress on DNA damage and genome instability in cancer cells.

PMID: 17608616 [PubMed - in process]

Privette LM, González ME, Ding L, Kleer CG, Petty EM

Three loci on mouse chromosome 5 and 10 modulate sex determination in XX Ods/+ mice.

Genesis. 2007 Jul;45(7):452-5

Authors: Poirier C, Moran JL, Kovanci E, Petit DC, Beier DR, Bishop CE

In mouse, XY embryos are committed to the male sex determination pathway after the transient expression of the Y-linked Sry gene in the Sertoli cell lineage between 10.5 and 12.5 dpc. In the C57BL/6J strain, male sex determination program can be modulated by some autosomal genes. The C57BL/6J alleles at these autosomal loci can antagonize male sex determination in combination with specific Sry alleles. In this report, the authors have identified an effect of these C57BL/6J specific alleles in combination with a mutated Sox9 allele, Sox9(Ods). Authors report the mapping of three of these genetic loci on mouse chromosome 5 and 10 in a backcross of the Ods mutation to the C57BL/6J background. Our study confirms the importance of the strain C57BL/6J for the investigation of the genetic mechanisms that control sex determination.

PMID: 17607692 [PubMed - indexed for MEDLINE]

Sheldon JP, Pfeffer CA, Jayaratne TE, Feldbaum M, Petty EM

Altered expression of the early mitotic checkpoint protein, CHFR, in breast cancers: implications for tumor suppression.

Cancer Res. 2007 Jul 1;67(13):6064-74

Authors: Privette LM, González ME, Ding L, Kleer CG, Petty EM

Checkpoint with FHA and Ring Finger (CHFR) is hypothesized to mediate a delay in cell cycle progression early in mitosis in response to microtubule stress, independent of the spindle assembly checkpoint. As a potential regulator of cell cycle progression, CHFR naturally becomes an interesting target for understanding cancer cells. In recent years, there has been increasing evidence supporting the role of CHFR as a tumor suppressor, most of which report loss of expression, occasionally due to promoter hypermethylation, in cancers compared with patient-matched normal tissues. We studied both a panel of breast cancer cell lines as well as primary tissue samples from breast cancer patients to investigate CHFR as a relevant tumor suppressor in breast cancer and to determine whether CHFR expression was associated with clinical and pathologic variables. We report that 41% of cell lines and 36% of patient samples showed low or negative CHFR protein expression or staining. In addition, lack of CHFR detection was associated with increased tumor size and weakly correlated with estrogen receptor-negative tumors from patients. To study the effects of low CHFR expression in vitro, we stably expressed a short hairpin RNA construct targeting CHFR in two lines of immortalized human mammary epithelial cells. Notably, decreased CHFR expression resulted in the acquisition of many phenotypes associated with malignant progression, including accelerated growth rates, higher mitotic index, enhanced invasiveness, increased motility, greater aneuploidy, and amplified colony formation in soft agar, further supporting the role of CHFR as a tumor suppressor in breast cancer.

PMID: 17596595 [PubMed - indexed for MEDLINE]