RSL, A NOVEL REGULATOR OF SEXUALLY DIMORPHIC LIVER GENES

RSL，一种新型的性二态性肝基因调节剂

• 批准号: 6381145
• 负责人: DIANE M. ROBINS
• 金额: $ 26.66万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6381145
• 关键词: DNA binding protein; DNA footprinting; animal puberty; artificial chromosomes; developmental genetics; expression cloning; female; gel mobility shift assay; gender difference; gene expression; gene induction /repression; genetic mapping; genetic regulation; genetic regulatory element; genetic transcription; genetically modified animals; hormone regulation /control mechanism; liver; male; nuclear runoff assay; nucleic acid sequence; transcription factor

Differences between men and women, from physiological to molecular levels, occur in systems far more diverse than those primarily involved in reproduction. A known paradigm is the sex- specific pattern of gene expression in liver for a broad array of proteins that metabolize steroids and drugs, or function in pregnancy. These distinctions in expression are induced by the sex steroids acting via the pituitary to direct a specific profile of growth hormone secretion. Although studied mostly in rodents, this regulatory axis exists also in humans, where it may impact sex differences in drug sensitivity, incidence of certain liver diseases, or complications in pregnancy. Therefore, it is critical to ascertain mechanisms in such precise tissue-specific and hormonal control. An androgen-independent control in male-specific liver gene expression is revealed by mice carrying rsl alleles (regulator of sex-limitation). Rsl is involved in regulation of the mouse sex- limited protein (Slp) gene, which is normally restricted in expression to adult male liver and kidney. In mice homozygous for rsl, Slp also is expressed in females at puberty. Slp synthesis is also increased in the rsl males, and occurs even in rsl mice lacking androgen receptor, indicating that this regulation is independent of androgen induction. We have shown that the rsl effect is liver-specific and does not act on Slp in kidney, and that it affects the array of male-specific liver genes, including P450s and mouse urinary proteins (MUPs), to cause their expression in females. The rsl variant reveals that wild type Rsl's normal function enforces dimorphic liver gene expression by negative regulation that silences male-specific genes in females. A likely mechanism is via transcriptional repression that acts on Rsl target genes in both sexes, and is overcome in males by puberal hormonal induction. The overall goal of this project is to characterize this novel tissue- and gene-specific negative regulatory pathway and to identify the Rsl gene. We will: I) Clone the Rsl gene based on its chromosomal position, which is already narrowed to a genetic interval of 1.2 cM; II) Define the molecular basis of action by identifying Slp cis-acting elements that are targets of the Rsl pathway; III) Define temporal and spatial interaction between Rsl control and hormonal induction of the target genes. Establishing the basis of the Rsl pathway will enhance our understanding of basic mechanisms of gene expression. Further, Rsl control in mice may yield unique insights into regulation of liver genes in humans.

男性和女性之间的差异，从生理到分子水平，发生在比主要涉及生殖的系统更多样化的系统中。一个已知的范例是肝脏中代谢类固醇和药物或在怀孕期间发挥作用的一系列蛋白质的性别特异性基因表达模式。这些差异的表达是由通过脑下垂体作用的性类固醇诱导的，以指导特定的生长激素分泌。尽管主要在啮齿动物中进行研究，但这种调节轴在人类中也存在，它可能会影响药物敏感性的性别差异、某些肝病的发病率，或者怀孕期间的并发症。因此，确定这种精确的组织特异性和激素控制的机制是至关重要的。携带RSL等位基因(性别限制的调节器)的小鼠揭示了雄性特异性肝脏基因表达的雄激素非依赖性控制。RSL参与了小鼠性别限制蛋白(SLP)基因的调控，该基因通常仅在成年男性肝脏和肾脏中表达。在RSL纯合子的小鼠中，SLP也在青春期的雌性小鼠中表达。在雄性RSL小鼠中SLP合成也增加，甚至在缺乏雄激素受体的RSL小鼠中也能发生，表明这种调节独立于雄激素诱导。我们已经证明RSL效应是肝脏特异性的，不作用于肾脏中的SLP，并且它影响男性特异性肝脏基因的阵列，包括P450和小鼠尿蛋白(MUP)，导致它们在女性中表达。RSL变异体表明，野生型RSL的正常功能通过负调控沉默雌性男性特有的基因来强制执行二态肝脏基因的表达。一种可能的机制是通过转录抑制，作用于RSL目标基因，在两性中，并在雄性被青春期激素诱导所克服。这个项目的总体目标是描述这一新的组织和基因特异性的负调控途径，并鉴定RSL基因。我们将：i)根据其染色体位置克隆RSL基因，它的遗传间隔已经缩小到1.2 cM；ii)通过识别作为RSL途径靶标的SLP顺式作用元件来确定作用的分子基础；iii)确定RSL控制和目标基因的激素诱导之间的时空相互作用。建立RSL途径的基础将加深我们对基因表达的基本机制的理解。此外，在小鼠中进行RSL控制可能会对人类肝脏基因的调控产生独特的见解。