PARACRINE REGULATION: SERTOLI/GERM CELL INTERACTIONS

涉及特异性DNA结合域的蛋白质-蛋白质相互作用似乎在基因转录及其调控中起关键作用。 我们的工作假设是，这种调节机制同时存在于支持细胞和减数分裂生殖细胞中，并介导细胞因子响应基因启动子中元件（例如STAT-GAS DNA结合复合物）的转录激活，从而影响表型表达的关键转变。 我们的工作计划将使用功能丧失和获得的实验模型来解决STAT-4，STAT-6和酪氨酸激酶JAK 3在减数分裂和早期单倍体基因表达中的作用。使用减数分裂前期作为一个焦点，我们将检查是否关键的转变点的影响，激活和/或抑制精母细胞STAT-DNA结合。 在减数分裂前、减数分裂前期和早期单倍体生殖细胞中，我们提出测试转录因子STAT-4和STAT-6是否将定义（a）在细胞因子信号后形成的DNA结合复合物的平台特征，（B）转录控制这些阿片样物质的潜力（例如生殖细胞特异性脑啡肽启动子）和减数分裂基因（例如联会复合体），其启动子含有功能性和独特的STAT结合元件，（c）以阶段特异性方式介导生殖细胞和支持细胞之间的旁分泌相互作用的分子机制（例如体细胞脑啡肽启动子和阿片受体）。特定目的1和3中提出的研究将检验白细胞介素-12、白细胞介素-4和干扰素-α/γ代表影响减数分裂基因表达和向早期单倍体表型进展的阳性和阴性自分泌/旁分泌线索的假设。 在特定目标2中计划的这些研究将表征支持细胞特异性机制，该机制介导白细胞介素和阿片样生长因子所引起的旁分泌相互作用。我们预计，我们的研究结果将确定和进一步表征新的转录因子参与调节减数分裂的男性生殖系。 睾丸代表了一个独特的系统，其中描述了JAK 3酪氨酸磷酸化的后果，发育期间通过白细胞介素-4和白细胞介素-12的细胞间信号传导，以及STAT-4和STAT-6在基因转录中的不同作用，提供了可能与淋巴细胞发育和免疫疾病相关的机制见解。

Protein-protein interactions involving specific DNA binding domains appear to play a critical role in gene transcription and its regulation. Our working hypothesis is that such regulatory mechanisms exist in both Sertoli cells and meiotic germ cells and mediate transcriptional activation of elements (e.g. STAT-GAS DNA binding complexes) in the promoters of cytokine-responsive genes, thereby influencing critical transitions in phenotypic expression. Our workplan will use both loss- and gain- of function experimental models to address the roles of STAT-4, STAT-6 and the tyrosine kinase JAK3 in meiotic and early haploid gene expression. Using meiotic prophase as a focal point, we will examine whether critical transition points are influenced by the activation and/or inhibition of spermatocyte STAT-DNA binding. In the pre- meiotic, meiotic prophase and early haploid germ cells, we propose to test whether the transcription factors STAT-4 and STAT-6 will define (a) the platform characteristics of the DNA binding complexes formed following a cytokine signal, (b) the potential for transcriptional control of those opioid (e.g. germ cell specific enkephalin promoter) and meiotic genes (e.g. synaptonemal complex) whose promoters contain functional and distinctive STAT-binding elements and, (c) molecular mechanism(s) mediating the paracrine interactions between germ cells and Sertoli cells (e.g. somatic cell enkephalin promoter and opioid receptors) in a stage-specific manner. Studies proposed in Specific Aims 1 and 3 will test the hypothesis that interleukin-12, interleukin-4, and interferon- alpha/gamma represent both positive and negative autocrine/paracrine cues that influence meiotic gene expression and progression to the early haploid phenotype. Those studies planned in Specific Aim 2 will characterize the Sertoli cell- specific mechanisms that mediate the paracrine interactions subserved by interleukin and opioid growth factors. We anticipate that the results of our studies will identify and further characterize novel transcription factors involved in the regulation of meiosis in the male germ line. The testis represents a unique system in which to delineate the consequences of JAK3 tyrosine phosphorylation, cell-to-cell signalling via interleukin-4 and interleukin-12 during development, and the distinct roles of STAT-4 and STAT-6 in gene transcription, providing mechanistic insight that ma also be relevant to lymphocyte development and immune disorders.