AUTOSOMAL MECHANISMS OF TESTIS INDUCTION

描述：(摘自申请者摘要)基因鉴定 睾丸的决定途径增加了我们对 这一决定途径的复杂性，并提供了分子诊断和 预防影响性发育的遗传性疾病。SRY是 在哺乳动物中被认为是编码睾丸决定因子的基因，但 直接受Sry影响的基因尚不清楚。其中一个这样的基因可能是 对于Sry阴性的XX性逆转，其中常染色体基因诱导睾丸 缺乏Sry和Y染色体个体的发育。这不太可能 这些基因将在人类身上被发现，因为小家庭规模和 遗传异质性是连锁分析的严重障碍。动物模型 缺乏这些缺点，并提供了研究分子事件的手段 胚胎组织。性别决定在真兽类中预计是相似的 哺乳动物，所有哺乳动物共有的步骤也应该适用于人类。 家犬模型中SRY阴性的XX性反转为常染色体遗传 隐性性状。患者具有女性核型(78，XX)和 睾丸(XX个雄性)或卵巢(XX个真正的两性人)。那只狗 综合症与人类家族中Sry阴性的XXSR惊人地相似， 其中XX个雄性和XX个真两性作为完全兄弟姐妹出现。基因 在这两个物种中，病因尚不清楚。睾丸诱导的特征 在没有SIY的情况下，机制将大大增加我们对 在分子水平上进行睾丸诱导。我们的长期目标是剖析 睾丸决定途径，通过表征具有睾丸诱导作用的基因 并解释其作用的分子机制。具体目标 这一建议的主要内容是：(1)鉴定与犬类有关的常染色体基因 SRY阴性的XXSR，通过连锁分析和筛选BAC文库。(2) 感染胚胎和对照胚胎性腺基因表达谱的比较 在正常的睾丸测定期间(D28-32)。(3)基因比对 正常胚胎和对照胚胎性腺中的表达模式 睾丸测定周期(d32-40)。对于目标2和目标3，我们将使用 定量逆转录聚合酶链式反应及全基因组检测 原位杂交法比较Sox9、MIS/AMH、 SF1、Daxl、Wt-1和Sry.在此授权期结束时，我们将拥有 确定了导致这种疾病的基因和睾丸途径中的步骤 通过基因的时间、数量或位置的突变而改变 表情。

DESCRIPTION: (Scanned from the applicant's abstract) Identification of genes in the testis determination pathway has increased our understanding of the complexity of this decision pathway and provided molecular diagnosis and prevention for inherited disorders affecting sexual development. Sry is accepted as the gene encoding the testis-determining factor in mammals, yet genes directly affected by Sry are unknown. One such gene may be responsible for Sry-negative XX sex reversal, wherein an autosomal gene induces testis development in individuals lacking Sry and the Y chromosome. It is unlikely that these genes will be identified in humans because small family sizes and genetic heterogeneity are severe impediments to linkage analysis. Animal models lack these disadvantages and provide the means to study molecular events in embryonic tissue. Sex determination is expected to be similar among eutherian mammals, and steps common to all mammals should be applicable to humans. Sry-negative XX sex reversal in the canine model is inherited as an autosomal recessive trait. Affected individuals have a female karyotype (78,XX) and either testes (XX males) or ovotestes (XX true hermaphrodites). The canine syndrome is strikingly similar to familial Sry-negative XXSR in humans, in which XX males and XX true hermaphrodites occur as full siblings. The genetic etiology is unknown in both species. Characterization of the testis induction mechanism in the absence of Siy would greatly increase our understanding of testis induction at the molecular level. Our long term goal is to dissect the testis determination pathway, by characterizing genes having a testis induction role and explaining the molecular mechanism of their actions. The specific aims of this proposal are: (1) Identify the autosomal gene responsible for canine Sry-negative XXSR, through linkage analysis and screening a BAC library. (2) Compare the gene expression pattern in gonads of affected embryos and controls during the normal period of testis determination (d28-32). (3) Compare the gene expression pattern in gonads of affected embryos and controls after the normal period of testis determination (d32-40). For Aims 2 and 3 we will use quantitative reverse transcriptase polymerase chain reaction and whole mount in situ hybridization to compare embryonic gonadal expression of Sox9, MIS/AMh, Sf1, Daxl, Wt-1 and Sry. At the end of this grant period, we will have identified the gene causing this disorder and the step in the testis pathway that is altered by the mutation in timing, quantity, or location of gene expression.