Faculty Bibliography

Sexual dimorphism requires the integration of positional information in the embryo with the sex determination pathway. Homeotic genes are a major source of positional information responsible for patterning along the anterior-posterior axis in embryonic development, and are likely to play a critical role in sexual dimorphism. Here, we investigate the role of homeotic genes in the sexually dimorphic development of the gonad in Drosophila. We have found that Abdominal-B (ABD-B) is expressed in a sexually dimorphic manner in the embryonic gonad. Furthermore, Abd-B is necessary and sufficient for specification of a sexually dimorphic cell type, the male-specific somatic gonadal precursors (msSGPs). In Abd-B mutants, the msSGPs are not specified and male gonads now resemble female gonads with respect to these cells. Ectopic expression of Abd-B is sufficient to induce formation of extra msSGPs in additional segments of the embryo. Abd-B works together with abdominal-A to pattern the non-sexually dimorphic somatic gonad in both sexes, while Abd-B alone specifies the msSGPs. Our results indicate that Abd-B acts at multiple levels to regulate gonad development and that Abd-B class homeotic genes are conserved factors in establishing gonad sexual dimorphism in diverse species.

Disseminated superficial porokeratosis (DSP) is a rare autosomal dominant epidermal keratinization disorder of lesions characterized by cornoid lamella with parakeratosis, hyperkeratosis, and loss of granular layers. The genetic basis for this disease is unknown. Through a proband with a diagnosis of DSP, we identified a large four-generation Chinese family with multiple DSP-affected members from Anhui province in China. After excluding the linkage of the disease phenotype to two known loci for disseminated superficial actinic porokeratosis in this family, we performed a genome-wide linkage analysis using 387 microsatellite markers and identified a novel disease locus for DSP at 18p11.3. Our subsequent fine mapping and haplotype analyses further narrowed down the disease locus into an 18.7 cM region between the telomere and D18S391 with a maximum two-point LOD (logarithm of the odds) score of 4.82 (theta =0.00) at D18S1138. Therefore, this study provides strong linkage evidence for a DSP locus at 18p11.3.

Coordinate expression of BMPs and their receptors and inhibitors is likely necessary for physiologic BMP regulation and activity. To characterize the expression of such factors in fetal, normal adult, and end-stage osteoarthritic articular cartilage, samples from these sources were analyzed. PCR-amplified sequences (BMPs 1-11), receptors (IA, IB, II), TGF- [Formula: see text] , TGF- [Formula: see text] , inhibitors noggin and follistatin, CDMP-1, COMP, and GAPDH from cDNAs generated from extracted total RNA were resolved by gel electrophoresis. Protein levels of BMPs 3, 7, and 8 were also analyzed by SDS-PAGE and Western blotting. RT-PCR revealed that BMPs 1, 2, 4-6, and 11, BMPR-IA and II, noggin, follistatin, CDMP-1, COMP, and GAPDH mRNAs were expressed in similar fashion in both fetal and adult (normal or osteoarthritic) cartilage. BMPs 9 and 10 mRNAs were not expressed in either group. BMPs 7, 8, and BMPR-IB mRNAs were consistently expressed in fetal but not in adult cartilage. BMP-3 mRNA was expressed in fetal and normal adult, but not in osteoarthritic samples. TGF- [Formula: see text] was expressed in both adult normal and osteoarthritic, but not fetal, samples. Similarly, Western blotting demonstrated BMPs 7 and 8 to be present in fetal but not in adult samples. BMP-3 protein was present in fetal and adult normal samples, to a lesser extent, but absent in osteoarthritic cartilage

Effective therapies for stroke must interdict multiple parallel and sequential pathophysiological events. A paradigm which offers insight into multivalent but thoughtfully coordinated protective programs is ischemic preconditioning. A central hypothesis of our group and others is that pharmacological agents that activate programs of gene expression normally induced by ischemic preconditioning will be effective agents for the prevention and treatment of stroke. Inhibitors of a class of enzymes, the hypoxia inducible factor-1 (HIF-1) prolyl hydroxylases stabilize the transcriptional activator HIF-1 and activate target genes involved in compensation for ischemia, including erythropoeitin (Epo) and vascular endothelial growth factor (VEGF). Here, we review evidence suggesting that the HIF-1 prolyl hyroxylases are inhibited during ischemic preconditioning and that pharmacological inhibitors of these enzymes are viable targets for stroke therapy.

BACKGROUND: Heat shock proteins (HSPs) are a family of highly conserved proteins found ubiquitously in mammalian cells, believed to be regulators of normal cell physiology and the cellular stress response. In addition, the small 27-kDa heat shock protein (HSP27) has previously been found to be a differentiation marker for keratinocytes and a prognostic marker associated with increased survival in certain cancerous tumors. METHODS: Using immunohistochemistry on routinely processed paraffin sections, we examined skin biopsies from 15 invasive melanomas, 13 intradermal nevi, and two compound nevi immunostained with a mouse monoclonal antibody to HSP27. In addition, cultured melanocytes were heat stressed at 45 degrees C for 1 h and then fixed and immunostained in order to localize HSP27 expression intracellularly. RESULTS: We found cytoplasmic and strong perinuclear staining of HSP27 in melanocytes in normal skin, in melanomas, and in nevi. Nuclear reactivity was absent. In addition, in cultured non-malignant melanocytes, HSP27 expression relocated from the cytoplasm to the nucleus with heat stress. CONCLUSIONS: To our knowledge, this investigation is the first to demonstrate that HSP27 is expressed in melanocytes in normal skin, in nevi, and in non-malignant cultured melanocytes

BACKGROUND: We have developed a novel, microsphere-based universal array platform referred to as the Tag-It platform. This platform is suitable for high-throughput clinical genotyping applications and was used for multiplex analysis of a panel of thrombophilia-associated single-nucleotide polymorphisms (SNPs). METHODS: Genomic DNA from 132 patients was amplified by multiplex PCR using 6 primer sets, followed by multiplex allele-specific primer extension using 12 universally tagged genotyping primers. The products were then sorted on the Tag-It array and detected by use of the Luminex xMAP system. Genotypes were also determined by sequencing. RESULTS: Empirical validation of the universal array showed that the highest nonspecific signal was 3.7% of the specific signal. Patient genotypes showed 100% concordance with direct DNA sequencing data for 736 SNP determinations. CONCLUSIONS: The Tag-It microsphere-based universal array platform is a highly accurate, multiplexed, high-throughput SNP-detection platform.

The cerebellum consists of a highly organized set of folia that are largely generated postnatally during expansion of the granule cell precursor (GCP) pool. Since the secreted factor sonic hedgehog (Shh) is expressed in Purkinje cells and functions as a GCP mitogen in vitro, it is possible that Shh influences foliation during cerebellum development by regulating the position and/or size of lobes. We studied how Shh and its transcriptional mediators, the Gli proteins, regulate GCP proliferation in vivo, and tested whether they influence foliation. We demonstrate that Shh expression correlates spatially and temporally with foliation. Expression of the Shh target gene Gli1 is also highest in the anterior medial cerebellum, but is restricted to proliferating GCPs and Bergmann glia. By contrast, Gli2 is expressed uniformly in all cells in the developing cerebellum except Purkinje cells and Gli3 is broadly expressed along the anteroposterior axis. Whereas Gli mutants have a normal cerebellum, Gli2 mutants have greatly reduced foliation at birth and a decrease in GCPs. In a complementary study using transgenic mice, we show that overexpressing Shh in the normal domain does not grossly alter the basic foliation pattern, but does lead to prolonged proliferation of GCPs and an increase in the overall size of the cerebellum. Taken together, these studies demonstrate that positive Shh signaling through Gli2 is required to generate a sufficient number of GCPs for proper lobe growth

Factors of both cytoplasmic and nuclear origin regulate metaphase chromosome alignment and spindle checkpoint during mitosis. Most aneuploidies associated with maternal aging are believed to derive from nondisjunction and meiotic errors, such as aberrations in spindle formation and chromosome alignment at meiosis I. Senescence-accelerated mice (SAM) exhibit aging-associated meiotic defects, specifically chromosome misalignments at meiosis I and II that resemble those found in human female aging. How maternal aging disrupts meiosis remains largely unexplained. Using germinal vesicle nuclear transfer, we found that aging-associated misalignment of metaphase chromosomes is predominately associated with the nuclear factors in the SAM model. Cytoplasm of young hybrid B6C3F1 mouse oocytes could partly rescue aging-associated meiotic chromosome misalignment, whereas cytoplasm of young SAM was ineffective in preventing the meiotic defects of old SAM oocytes, which is indicative of a deficiency of SAM oocyte cytoplasm. Our results demonstrate that both nuclear and cytoplasmic factors contribute to the meiotic defects of the old SAM oocytes and that the nuclear compartment plays the predominant role in the etiology of aging-related meiotic defects