Transcriptional mechanisms of lower urinary tract development

描述(由申请人提供)： 先天性上(肾)和下(输尿管、膀胱、尿道和外生殖器)尿路异常的产前超声诊断率为1/500。这些情况在受影响儿童中造成严重的慢性发病率，需要多次手术和终身治疗。目前，我们对这些疾病的根本原因(S)的了解是有限的。 我的导师薛(Sean)Li博士已经证明，SIX1-Eya1转录复合体对于肾脏发育是不可或缺的，因为SIX1或Eya1的突变会导致小鼠肾脏发育不全。我随后证明，SIX1-Eya1转录复合体也是下尿路形成所必需的。在初步研究中，我发现没有SIX1和Eya1基因的小鼠胚胎表现出类似于人类持续性泄殖腔综合征的形态缺陷。这种综合征的特征是在胚胎发育过程中下尿路和肠/直肠无法分离。为了了解这些缺陷的细胞和分子起源，并开始阐明哺乳动物下尿路系统发育的分子机制，我提出了以下具体目标： 目的1、研究SIX1(-/-)：：EYA1(-/-)双零突变胚胎中持续泄殖腔表型的组织学和分子起源。这一目标将检验这样的假设，即SIX1-Eya1转录复合体调节生殖系统结构形态发生所需的靶基因的表达。目的2，应用Cre/loxP位点特异性DNA重组命运定位策略定位下尿路的细胞起源。这一目标将检验这样一个假设，即表达SIX1的细胞直接对下生殖道组织做出贡献。目的3、探讨转化生长因子(-Smad4)信号通路在下生殖道发育过程中的作用。这一目标将检验这样一种假设，即转化生长因子(-Smad4)信号通路对泌尿生殖系统结构的发育是必不可少的。 除了这些科学目标，我和我的导师们还制定了一个详细的战略，以便在K08期间深入发展我的学术技能。该培训计划将在波士顿儿童医院进行，该医院是生物医学研究和职业发展的杰出场所。 公共卫生相关性：泄殖腔异常可导致慢性尿路感染、梗阻、肾功能衰竭、大小便失禁和自尊低下。对分流过程的透彻了解可能在将来能够及早识别和预防这些致残性的尿路和肠道畸形。

DESCRIPTION (provided by applicant): Congenital abnormalities of the upper (kidney) and lower (ureter, bladder, urethra and external genitalia) urinary tracts are diagnosed at a rate of 1 in 500 prenatal ultrasounds. These conditions contribute to significant chronic morbidity in affected children, necessitating multiple surgeries and life-long treatment. Currently, our understanding of the underlying cause(s) of these disorders is limited. My mentor, Dr. Xue (Sean) Li, has shown that the Six1-Eya1 transcriptional complex is indispensable to kidney development because a mutation in either Six1 or Eya1 causes renal agenesis in the mouse. I have subsequently demonstrated that the Six1-Eya1 transcriptional complex is also required for lower urinary tract formation. In the preliminary studies, I found that mouse embryos without Six1 and Eya1 genes display morphological defects similar to the human persistent cloaca syndrome. This syndrome is characterized by a failure of the lower urinary and intestinal/rectal tracts to separate during embryonic development. To understand the cellular and molecular origins of these defects and to begin to shed light onto the molecular mechanisms of mammalian lower urinary system development, I propose the following specific aims: Aim 1, To characterize the histological and molecular origins of the persistent cloaca phenotype seen in the Six1(-/-)::Eya1(-/-) double null mutant embryos. This aim will test the hypothesis that the Six1-Eya1 transcriptional complex regulates expression of target genes that are required for the morphogenesis of the genitourinary structures. Aim 2, To pinpoint the cellular origins of the lower urinary tract using a Cre/loxP site-specific DNA recombination fate mapping strategy. This aim will test the hypothesis that Six1-expressing cells contribute directly to lower genitourinary tract tissues. Aim 3, To determine if the TGF(-Smad4 signaling pathway is required in the process of lower genitourinary tract development. This aim will test the hypothesis that the TGF(-Smad4 signaling pathway is essential for development of the urogenital structures. Along with these scientific goals, my mentors and I have devised a detailed strategy for in-depth development of my academic skills during the K08 period. This training program will be conducted at Children's Hospital Boston, an outstanding setting for biomedical research and career development. PUBLIC HEALTH RELEVANCE: Cloacal anomalies can cause chronic urinary tract infections, obstruction, renal failure, incontinence and poor self esteem. A thorough understanding of the septation process may in the future enable early identification and prevention of these disabling deformities of the urinary tract and intestines.