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.
Project description:The satellite cell of skeletal muscle provides a paradigm for quiescent and activated tissue stem cell states. We have carried out transcriptome analyses by comparing satellite cells from adult skeletal muscles, where they are mainly quiescent, with cells from growing muscles, regenerating (mdx) muscles, or with cells in culture, where they are activated. Our study gives new insights into the satellite cell biology during activation and in respect with its niche. We used microarrays to study the global programme of gene expression underlying adult satellite cell quiescence compared to activation states and to identify distinct classes of up-regulated genes in these two different states Skeletal muscle satellite cells were isolated by flow cytrometry using the GFP fluorescence marker from Pax3GFP/+ mice skeletal muscle. The transcriptome of quiescent satellite cells from adult Pax3GFP/+ muscle was compared to the transcriptome of activated satellite cells obtained from three different samples: 1) regenerating Pax3GFP/+:mdx/mdx muscle (Ad.mdx) , 2) growing 1 week old Pax3GFP/+ muscle (1wk), and 3) adult Pax3GFP/+ cells after 3 days in culture (Ad.cult).
Project description:A transcriptome study in mouse hematopoietic stem cells was performed using a sensitive SAGE method, in an attempt to detect medium and low abundant transcripts expressed in these cells. Among a total of 31,380 unique transcript, 17,326 (55%) known genes were detected, 14,054 (45%) low-copy transcripts that have no matches to currently known genes. 3,899 (23%) were alternatively spliced transcripts of the known genes and 3,754 (22%) represent anti-sense transcripts from known genes.