Transcriptional mechanisms of lower urinary tract development

描述（由申请人提供）： 产前超声诊断先天性上尿路（肾脏）和下尿路（输尿管、膀胱、尿道和外生殖器）畸形的比率为1/500。这些疾病导致受影响儿童的慢性发病率很高，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的理解是有限的。 我的导师Xue（Sean）Li博士已经证明，Six1-Eya1转录复合物对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-Eya 1转录复合物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基因的小鼠胚胎显示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期间下尿路和肠道/直肠道未能分离。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泌尿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（-/-）：：Eya 1（-/-）双缺失突变胚胎中持续泄殖腔表型的组织学和分子起源。这一目标将测试的假设，Six1-Eya 1转录复合物调节的目标基因的表达所需的泌尿生殖系统结构的形态发生。目的2：利用Cre/loxP位点特异性DNA重组基因定位技术，确定下尿路的细胞起源。这一目标将检验Six1表达细胞直接参与下泌尿生殖道组织的假设。目的3、探讨TGF β-Smad4信号通路在下泌尿生殖道发育过程中的作用。这一目的将检验TGF β-Smad4信号通路对于泌尿生殖结构的发育是必不可少的这一假设。 沿着这些科学目标，我和我的导师们为我在K08期间的学术技能的深入发展制定了详细的策略。该培训计划将在波士顿儿童医院进行，这是生物医学研究和职业发展的杰出环境。 与公共卫生的关系：泄殖腔异常可导致慢性尿路感染、梗阻、肾衰竭、尿失禁和自尊心下降。对分隔过程的透彻理解可能在将来能够早期识别和预防这些泌尿道和肠道的致残性畸形。

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.