Opposing Pathways in Mammalian Sex Determination

哺乳动物性别决定的相反途径

• 批准号: 10404067
• 负责人: Blanche Capel
• 金额: $ 40.71万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10404067
• 关键词: 3-Dimensional; ATAC-seq; BHLH Protein; Berlin; Binding; Binding Sites; Biological Process; Cell Differentiation process; Cell Lineage; Cells; ChIP-seq; Chromatin; Chromatin Loop; Code; Collaborations; Competence; Complex; DNA Methylation; Data Set; Development; Dimerization; Embryo; Enhancers; Epigenetic Process; Epithelial; FOXL2 gene; Family; Feedback; Female; Genes; Genetic Transcription; Gonadal structure; Helix-Turn-Helix Motifs; Hi-C; Histones; Lead; Libido; Licensing; Link; Mammals; Maps; Mediating; Modeling; Modification; Molecular Conformation; Mutant Strains Mice; Notch Signaling Pathway; Nucleosomes; Numbness; Ovary; Pathway interactions; Polycomb; Positioning Attribute; Proteins; Quantitative Reverse Transcriptase PCR; Repression; Somatic Cell; Structure; Supporting Cell; System; TCF7L2 gene; Testing; Testis; Time; Work; granulosa cell; histone modification; inhibitor; male; methylome; mutant; notch protein; progenitor; promoter; sertoli cell; sex determination; stem; transcription factor; transcriptome

ABSTRACT Sex determination in mammals is a complex biological process leading to the differentiation of the bipotential gonad into a testis or ovary. It is initiated by a cell fate decision in a subset of somatic cells called the supporting cell lineage. These cells carry bivalent histone marks at many genes associated with sex determination pathways and are poised for direction into either the Sertoli cell lineage (leading to testis development) or the granulosa cell lineage (leading to ovary development). Commitment to Sertoli or granulosa fate is characterized by the loss of repressive histone marks at genes associated with the active pathway, and expansion of repressive marks at genes associated with the alternative pathway. Repression, which we hypothesize is mediated in part by chromatin conformational changes, is important to stabilize fate commitment. However, how epigenetic modifications and transcription factor cascades are integrated to drive sex determination is not understood. It is well established that the key step in activating Sertoli cell differentiation is the transient activation of the Y-encoded transcription factor (TF), SRY, and its direct downstream target, SOX9. However, since our discovery that supporting cells are derived from the coelomic epithelium (CE), it has been unclear why Sry and female pathway genes are only activated in cells once they leave the CE and enter the gonad. We recently showed that NUMB, an inhibitor of the Notch signaling pathway, is asymmetrically distributed to cells that enter the gonad from the CE and is required for gonadal cell differentiation. These findings imply that a factor(s) activated in Numb+/Notchlo cells confers competence for differentiation. Exploration of our transcriptome, ATAC-seq, and histone modification datasets, revealed that 2 E-box family HLH transcription factors, Tcf4 and Tcf12, are expressed at high levels in the bipotential gonad, remain highly expressed in the granulosa lineage, but are downregulated in the Sertoli lineage where they map as binding targets of SOX9 and could be targets of feedback repression to block the granulosa pathway in XY gonads. E-box binding motifs are enriched in the nucleosome-depleted regions near granulosa genes but are absent from Sertoli genes, with the exception of Sry itself. Our findings suggest that TCF4 and TCF12, activated in Numb+/Notchlo cells, license differentiation of the supporting cell lineage, serving as activators of the granulosa pathway and of Sry in the XY gonad; whereas, SOX9, activated by SRY, acts in a feedback loop to down-regulate Tcf4 and Tcf12 transcription. In Aim 1, we will test the hypothesis that bHLH TFs are downstream of Numb, comprise an HLH “code” for differentiation of the supporting cell lineage, and are repressed by SOX9. In Aim 2, we will test the hypothesis that epigenetic and chromatin conformation changes occur during Sertoli fate commitment, mediated in part by competition between SOX9 and HLH proteins, and function to stabilize the male pathway by modulating accessibility of promoters and enhancers and the expansion of silencing marks at genes associated with the alternative granulosa pathway.

抽象的 哺乳动物中的性别确定是一个复杂的生物学过程，导致双能分化 性腺进入睾丸或卵巢。它是由细胞命运决定在一个称为的体细胞中引发的 支持细胞谱系。这些细胞在与性别相关的许多基因上携带二价组蛋白标记 确定途径，并被毒化到塞托利细胞谱系的方向（导致睾丸 发育）或颗粒细胞谱系（导致卵巢发育）。对Sertoli或 颗粒的命运的特征是在与活性相关的基因处失去反射性组蛋白标记 途径和与替代途径相关的基因上反射标记的扩展。抑制， 我们假设的部分是由染色质构象变化部分介导的，对于稳定命运很重要 承诺。但是，如何整合表观遗传修饰和转录因子级联 性别决定是不了解的。众所周知，激活Sertoli细胞的关键步骤 分化是Y编码转录因子（TF），SRY及其直接的瞬态激活 下游目标Sox9。但是，由于我们发现载体细胞是从腔内得出的 上皮（CE），尚不清楚为什么仅在细胞中激活SRY和女性途径基因 离开CE并进入性腺。我们最近表明Numb是Notch信号的抑制剂 途径不对称分布到从CE进入性腺的细胞中，是性腺所必需的 细胞分化。这些发现表明，在numb+/notchlo细胞中激活的一个因素承认能力 用于分化。揭示了我们的转录组，ATAC-SEQ和HISSTONE修改数据集的探索 在两电位中，2个E-box家族HLH转录因子TCF4和TCF12在高水平上表达 性腺，仍然在颗粒谱系中高度表达，但在Sertoli谱系中被下调 它们映射为Sox9的结合目标，可以是反馈表达的目标以阻止颗粒 XY性腺的途径。电子盒结合基序富集在颗粒附近的核小体耗尽区域 基因，但没有Sertoli基因，除了SRY本身。我们的发现表明TCF4和 TCF12，在numb+/notchlo单元中激活，许可的辅助细胞谱系分化，用作 XY性腺中颗粒途径和SRY的激活剂；而Sox9被Sry激活，作用于 反馈回路下调TCF4和TCF12转录。在AIM 1中，我们将测试BHLH的假设 TF是Numb的下游，包括用于区分支​​撑元谱线的HLH“代码”，并且 被Sox9压抑。在AIM 2中，我们将测试表观遗传和染色质构象的假设 Sertoli故障承诺期间发生变化，部分是由Sox9和HLH之间的竞争介导的 蛋白质，并通过调节启动子和增强子的可及性来稳定男性途径的功能 以及与替代颗粒途径相关的基因上的沉默痕迹的扩展。