MOLECULAR GENETICS OF BHLH-ZIP TRANSCRIPTION FACTORS

BHLH-ZIP 转录因子的分子遗传学

• 批准号: 6423819
• 负责人: NANCY JENKINS COPELAND
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6423819
• 关键词: Waardenburg syndrome; biological signal transduction; cell type; developmental genetics; dimer; embryonic stem cell; gene mutation; gene targeting; genetic screening; genetically modified animals; hearing disorders; laboratory mouse; mast cell; melanocyte; microphthalmos; osteoclasts; pigmentation disorders; protein binding; protein structure function; transcription factor

We are conducting studies to determine the function of the Mi-Tfe family of basic helix-loop-helix leucine zipper (bHLH-Zip) transcription factors in mammalian development. The Mi-Tfe family consists of four related genes- Mitf, Tfe3, Tfeb, and Tfec. The Mitf gene encodes the microphthalmia transcription factor (Mift). Mutations in the human MITF gene are responsible for a common human pigmentation and hearing disorder, Waardenburg syndrome type 2 (WS2). More than 20 independent Mitf mutations have been isolated in the mouse and shown to affect a number of cell types, including melanocytes, osteoclasts, and mast cells. In contrast, Tfeb, Tfe3, and Tfec were isolated by biochemical means and little is known about their function in vivo. In collaborative studies, we showed that the Mitf-Tfe proteins can bind the E-box sequence as homodimers or as heterodimers with other family members. To investigate the function of the Tfe genes in mammalian development, we used embryonic stem (ES) cell knockout technology to make germline null mutations in the three mouse Tfe genes. The effect of each mutation on development was then measured alone or in combination with mutations in other Mitf-Tfe family members. Surprisingly, these studies did not identify any essential functions for Mitf-Tfe heterodimers in development. This is in marked contrast to what has been observed for the Myc/Max/Mad family of bHLH-Zip proteins, where the heterodimers are thought to have essential functions. Future studies will attempt to use chemical mutagenesis and genetic modifier screens to identify other proteins in the Mitf signal transduction pathway.

我们正在进行研究，以确定在哺乳动物发育的碱性螺旋-环-螺旋亮氨酸拉链（bHLH-Zip）转录因子的Mi-Tfe家族的功能。 Mi-Tfe家族由四个相关基因组成- Mitf、Tfe 3、Tfeb和Tfec。 Mitf基因编码小眼症转录因子（Mift）。 人类MITF基因的突变导致了一种常见的人类色素沉着和听力障碍，Waardenburg综合征2型（WS 2）。 已经在小鼠中分离出超过20种独立的Mitf突变，并显示其影响许多细胞类型，包括黑素细胞、破骨细胞和肥大细胞。 相反，Tfeb、Tfe 3和Tfec是通过生化手段分离的，关于它们在体内的功能知之甚少。 在合作研究中，我们发现Mitf-Tfe蛋白可以与其他家族成员以同源二聚体或异源二聚体的形式结合E-box序列。 为了研究Tfe基因在哺乳动物发育中的功能，我们利用胚胎干细胞（ES）敲除技术在三个小鼠Tfe基因中制造生殖系无效突变。 然后单独或与其他Mitf-Tfe家族成员中的突变组合测量每个突变对发育的影响。 令人惊讶的是，这些研究没有确定Mitf-Tfe异二聚体在发育中的任何基本功能。 这与已经观察到的bHLH-Zip蛋白的Myc/Max/Mad家族形成鲜明对比，其中异二聚体被认为具有基本功能。 未来的研究将尝试使用化学诱变和遗传修饰筛选来鉴定Mitf信号转导途径中的其他蛋白质。