The Mechanism of Cryptorchidism in LH Receptor Knockout Animals

LH受体敲除动物隐睾发生机制

• 批准号: 7798505
• 负责人: ZHENMIN LEI
• 金额: $ 29.01万
• 依托单位: UNIVERSITY OF LOUISVILLE
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7798505
• 关键词: Adult; Age; Androgen Receptor; Androgens; Animals; Applications Grants; Bilateral; Blood Circulation; Cell Proliferation; Cell division; Cells; Congenital Abnormality; Cryptorchidism; Defect; Development; Estradiol; Estrogens; Exhibits; G-Protein-Coupled Receptors; Gene Expression; Gene Targeting; Genes; Histology; Human; In Vitro; Incidence; Insulin; LH Receptors; Leucine-Rich Repeat; Mediating; Mesenchymal; Messenger RNA; Molecular; Mus; Muscle Cells; Mutant Strains Mice; Nerve; Notch Signaling Pathway; Organ Culture Techniques; Pathway interactions; Peptides; Phase; Phenotype; Play; Process; Recovery; Relaxin; Role; Scrotum; Serum; Siblings; Signal Pathway; Signal Transduction; Staging; System; Testis; Testosterone; cremaster muscle; insight; knockout animal; leydig interstitial cell; male; morphometry; myogenesis; notch protein; postnatal; prevent; testosterone replacement therapy

DESCRIPTION (provided by applicant): Cryptorchidism is by far the most common defect of sexual differentiation in humans. Testicular descent can be anatomically divided into two stages, i.e., transabdominal and inguinoscrotal phases. It is known that both insulin-like peptide 3 (INSL3) and androgen signaling pathways play critical roles in the control of the transabdominal phase of testis descent. However, the mechanism that regulates the inguinoscrotal phase is not completely understood, even though the incidence of this defect is much more common clinically. Targeted disruption of luteinizing hormone receptor (LHRKO) in mouse impaired development of adult-type Leydig cells which resulted in a dramatic reduction of INSL3 and testosterone levels. Surprisingly, serum estradiol levels were significantly increased. LHRKO males exhibited a bilateral cryptorchid phenotype resulting from a defect in inguinoscrotal testis descent. Histology, morphometry, cell proliferation and differentiation analyses demonstrated the defect was due to a reduction in mesenchymal cell division and differentiation into cremaster muscle cells during the second stage of testis descent. The expression of several genes in the gubernaculum that are known to be involved in gubernacular development, such as Hoxa10, Hoxa11, Wt1, Dll1 and Desrt, were not altered in mutant mice, while Lgr8, Notch1 and Numb mRNA levels were drastically deceased as compared with age-matched wild type siblings. In contrast, the expressions of Esr1 (ER1) and Esr2 (ER2) were significantly elevated. Postnatal testosterone replacement therapy (TRT) completed testicular descent into the scrotum and concomitantly normalized estradiol concentrations in the circulation and Esr1, Esr2, Lgr8, Notch1 and Numb mRNA levels in the gubernaculum. Remedy of the defect by TRT was neither dependent on recovery of adult-type Leydig cells nor the genitofemoral nerve but required androgen receptor activity in the gubernaculum. Using organ culture of the gubernaculum in vitro, androgen alone did not significantly stimulate proliferation of gubernacular mesenchymal cells without activation of the leucine-rich repeat-containing G-protein coupled receptor 8 (LGR8) signaling pathway by addition of INSL3 or relaxin. Co-treatment of estrogen with androgen prevented androgen-induced Lgr8 expression. Cotreatment of INSL3 and androgen increased Notch1 but not Numb mRNA levels. Taking these results together, we hypothesize that induction of the Lgr8 gene expression by androgen and activation of LGR8 signal impinging on the Notch system to stimulate gubernacular cell proliferation, differentiation and myogenesis are the essential molecular pathways in the control of gubernacular development to facilitate inguinoscrotal testis descent. In addition to androgen deficiency, unbalanced androgen/estrogen signals also play a role in contributing to the cryptorchid phenotype in LHR null animals. In this grant application, we propose four specific aims to verify our hypotheses: (1) to define the underlying mechanism by which androgen modulates the Lgr8 gene expression in the gubernaculum; (2) to assess the role of the LGR8 signaling pathway in androgen-induced inguinoscrotal testis descent in LHR null males; (3) to determine the importance of the Notch signaling pathway in mediating androgen and LGR8 signals to regulate gubernaculum development during inguinoscrotal testis descent and (4) to investigate the effect of estrogen on androgen-induced inguinoscrotal testis descent in LHR null males. Cryptorchidism is by far the most common birth defect in males. Although inguinoscrotal testis descent is known to be androgen dependent, the underlying mechanism remains unclear. The current proposal is focusing on determining androgen downstream target genes and subsequent signaling network during the process of inguinoscrotal testis descent, which may provide new insight into the causes of testis maldescent.

描述（由申请人提供）：迄今为止，隐齿术是人类性别差异的最常见缺陷。睾丸下降可以解剖分为两个阶段，即腹部和inguinoinscrotal阶段。众所周知，胰岛素样肽3（INSL3）和雄激素信号通路在控制睾丸下降的腹相中都起着关键作用。然而，即使该缺陷的发生率在临床上更为常见，但尚未完全了解调节烟丝界相的机制。在小鼠中，有针对性破坏了黄体生成激素受体（LHRKO）的成人型leydig细胞的发展，从而导致INSL3和睾丸激素水平的急剧降低。令人惊讶的是，血清雌二醇水平显着升高。 Lhrko雄性表现出双侧隐式表型，这是由于粘膜睾丸下降的缺陷而导致的。组织学，形态计量学，细胞增殖和分化分析表明，缺陷是由于睾丸下降的第二阶段中间充质细胞分裂的降低以及分化为Cremaster肌肉细胞的原因。已知与Gubernacular发育有关的几种基因的表达，例如Hoxa10，Hoxa11，Wt1，Dll1和Desrt，在突变小鼠中并未改变，而LGR8，Notch1和Nungch1和Numb mRNA水平与年龄匹配的野生类型相比已急剧死亡。相反，ESR1（ER1）和ESR2（ER2）的表达显着升高。产后睾丸激素替代疗法（TRT）完成了睾丸下降到阴囊中，并在Gubernaculum中循环，ESR1，ESR2，LGR8，NOTCH1，NOTCH1，NOTCH1，NOTCH1，NOTCH1，NOTCH1和NUMB MRNA的雌二醇浓度同时归一化。 TRT对缺陷的补救措施既不取决于成年型Leydig细胞的恢复，也不取决于Gubernaculum中需要的雄激素受体活性。仅使用Gubernaculum在体外的器官培养，仅雄激素就不会显着刺激Gubernacular间充质细胞的增殖，而不会通过添加INSL3或Leasein的添加而激活富含亮氨酸的重复含有G蛋白的G蛋白偶联受体8（LGR8）信号途径。雌激素与雄激素共同治疗可阻止雄激素诱导的LGR8表达。 INSL3和雄激素的共同处理增加了Notch1，而不是麻木的mRNA水平。将这些结果共同完成，我们假设通过雄激素和LGR8信号撞击Notch系统上的LGR8基因表达，以刺激州长细胞的增殖，分化和肌发生是控制人群发育的基本分子途径，以促进促进性交杂菌睾丸的后代。除了雄激素缺乏外，不平衡的雄激素/雌激素信号在促进LHR无效动物的隐式表型方面也起作用。在此赠款应用中，我们提出了四个特定的目的旨在验证我们的假设：（1）定义雄激素调节Gubernaculum中LGR8基因表达的潜在机制； （2）评估LGR8信号通路在雄激素诱导的LHR无效男性中的粘膜睾丸下降中的作用； （3）确定Notch信号通路在介导雄激素和LGR8信号中的重要性，以调节gubernaculum在gubernaculum tescent中调节Gubernaculum的发育，以及（4）研究雌激素对雄激素诱导的LHR Null Null Null雄性雄激素诱导的睾丸血液的影响。迄今为止，cryptorchidism是男性最常见的先天缺陷。尽管已知inguinoscrotal睾丸下降是雄激素依赖性的，但潜在的机制尚不清楚。当前的建议集中于确定iguinoscrotal睾丸下降过程中雄激素下游靶基因以及随后的信号网络，这可能会为睾丸马尔丁的原因提供新的见解。