Project description:Dendritic epidermal T cells (DETC) reside in murine skin and participate in homeostasis and wound repair. Upon wounding, DETC become activated through the recognition of an unidentified ligand expressed by keratinocytes proximal to sites of injury. Such DETC activation is mediated through a monoclonal T cell receptor (TCR). Using a soluble form of this monoclonal TCR, we have shown that keratinocytes upregulate DETC TCR ligands in wounded tissue within 2 hours following wounding. Down-modulation of the ligand is seen 3 hours following wounding, and no expression is evident in non-wounded skin. In vitro studies on cell lines which express this unknown ligand indicate that antigen recognition by the DETC TCR is dependent upon N-linked glycosylation of the ligand. Given the glycosylation sensitivity of the ligand and the restricted expression following wounding, we are interested in pursuing microarray analysis to identify genes that are modulated in keratinocytes in response to wounding.
Project description:Dendritic epidermal T cells (DETC) reside in murine skin and participate in homeostasis and wound repair. Upon wounding, DETC become activated through the recognition of an unidentified ligand expressed by keratinocytes proximal to sites of injury. Such DETC activation is mediated through a monoclonal T cell receptor (TCR). Using a soluble form of this monoclonal TCR, we have shown that keratinocytes upregulate DETC TCR ligands in wounded tissue within 2 hours following wounding. Down-modulation of the ligand is seen 3 hours following wounding, and no expression is evident in non-wounded skin. In vitro studies on cell lines which express this unknown ligand indicate that antigen recognition by the DETC TCR is dependent upon N-linked glycosylation of the ligand. Given the glycosylation sensitivity of the ligand and the restricted expression following wounding, we are interested in pursuing microarray analysis to identify genes that are modulated in keratinocytes in response to wounding. Keratinocytes represent 90% of the cells in the epidermis (DETC and Langerhan’s cells make up the remaining 10%). As such, we propose to isolate RNA from whole epidermis under either wounded or resting conditions. In addition to comparing RNA from wounded and non-wounded epidermis, we would like to compare RNA from tissue that has been wounded for different times. Initially, we would like to analyze 4 sampes (non-wounded epidermis, and epidermal cells isolated 30 minutes, 2 hours, and 4 hours following wounding). These time points would correlate to a period prior to cell surface expression of ligand (30 minutes), during cell surface expression (2 hours), and following down regulation of cell surface expression (4 hours). In addition to providing possible identification of the unknown DETC TCR ligand, such analysis would provide novel information about early responses by keratinocytes in response to physical wounding in vivo. We propose to isolate RNA from whole epidermis under either wounded or resting conditions. In addition to comparing RNA from wounded and non-wounded epidermis, we would like to compare RNA from tissues that has been wounded for different times.
Project description:Sex differences in liver gene expression are dictated by sex-differences in circulating growth hormone (GH) profiles. Presently, the pituitary hormone dependence of mouse liver gene expression was investigated on a global scale to discover sex-specific early GH response genes that might contribute to sex-specific regulation of downstream GH targets and to ascertain whether intrinsic sex-differences characterize hepatic responses to plasma GH stimulation. RNA expression analysis using 41,000-feature microarrays revealed two distinct classes of sex-specific mouse liver genes: genes subject to positive regulation (class-I) and genes subject to negative regulation by pituitary hormones (class-II). Genes activated or repressed in hypophysectomized (Hypox) mouse liver within 30-90min of GH pulse treatment at a physiological dose were identified as direct targets of GH action (early response genes). Intrinsic sex-differences in the GH responsiveness of a subset of these early response genes were observed. Notably, 45 male-specific genes, including five encoding transcriptional regulators that may mediate downstream sex-specific transcriptional responses, were rapidly induced by GH (within 30min) in Hypox male but not Hypox female mouse liver. The early GH response genes were enriched in 29 male-specific targets of the transcription factor Mef2, whose activation in hepatic stellate cells is associated with liver fibrosis leading to hepatocellular carcinoma, a male-predominant disease. Thus, the rapid activation by GH pulses of certain sex-specific genes is modulated by intrinsic sex-specific factors, which may be associated with prior hormone exposure (epigenetic mechanisms) or genetic factors that are pituitary-independent, and could contribute to sex-differences in predisposition to liver cancer or other hepatic pathophysiologies.