HORMONE CONTROL OF SPERMATOGONIAL ARREST IN MUTANT MICE

突变小鼠精原细胞停滞的激素控制

• 批准号: 6863639
• 负责人: Marvin L. Meistrich
• 金额: $ 27万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6863639
• 关键词: Leydig cells; Sertoli cells; androgen inhibitor; androgen receptor; cell differentiation; developmental genetics; estradiol; estrogen receptors; follicle stimulating hormone; gene expression; gene mutation; gonadotropin releasing factor; hormone regulation /control mechanism; laboratory mouse; messenger RNA; microarray technology; mutant; recombinase; sperm; spermatogenesis; testis; testosterone; tissue /cell culture; vascular smooth muscle

Juvenile spermatogonial depletion (jsd) mice initiate a wave of spermatogenesis at puberty, but then sperm differentiation ceases despite the continued presence of A spermatogonia. Although the mechanism is not known, we showed that testosterone (T) inhibits spermatogonial differentiation, which can be restored with GnRH antagonist or estradiol (E2). We hypothesize that inhibition of spermatogonial differentiation in jsd mice is due to the action of T on gene expression in a specific somatic cell (Sertoli, Leydig, peritubular myoid, or arteriolar smooth muscle). We utilize the power of mouse genetics to elucidate the mechanism by which T mediates spermatogonial "arrest" in jsd mice and begin identifying the cell type and hormonally regulated gene(s) involved in the following Aims: (I) To establish the specific role of androgen and not FSH, we will complete studies using jsd mice also carrying mutations in the androgen receptor (AR) and FSHbeta genes. To determine the mode and the site of action of E2, the restoration of spermatogenesis with GnRH-antagonist and E2 treatment will be compared in jsd mice with that in jsd mice carrying mutations for estrogen receptor (ER)-alpha or for ERbeta. (II) To establish that the hormones affect spermatogonial differentiation by direct action on the testis and/or seminiferous tubules, we will examine their effects on spermatogonia in in vitro cultures of testicular tissue and tubules from jsd mice. (III) To identify the cell that is the target for hormonal inhibition of spermatogonial differentiation, we will transplant tubules between jsd mice and AR-deficient jsd mice and use cell-type specific elimination of an AR gene with loxP sites using Cre-recombinase driven by promoters specific for the different somatic cells. (IV) To identify the responsible gene, we will differentially screen for candidate hormone-regulated genes in the target cell of jsd mice using microarrays. A good candidate gene must have its level changed by GnRH antagonist in one direction and by T in the opposite direction. Elucidation of the mechanism of this spermatogonial "arrest" and its reversal in the jsd mouse could apply to cases of genetically determined male infertility. Because of its remarkable similarity to the failure of spermatogonial differentiation in toxicant-treated and aging rats, these results could also apply to azoospermia induced by reproductive toxicants and the decline in spermatogenesis with aging.

幼年精原细胞耗竭 (jsd) 小鼠在青春期启动一波精子发生，但随后尽管 A 精原细胞持续存在，精子分化仍停止。 尽管机制尚不清楚，但我们发现睾酮 (T) 会抑制精原细胞分化，而 GnRH 拮抗剂或雌二醇 (E2) 可以恢复精原细胞分化。 我们假设 jsd 小鼠精原细胞分化的抑制是由于 T 对特定体细胞（支持细胞、间质细胞、管周肌样细胞或小动脉平滑肌）基因表达的作用。 我们利用小鼠遗传学的力量来阐明 T 介导 jsd 小鼠精原细胞“停滞”的机制，并开始鉴定参与以下目标的细胞类型和激素调节基因：（I）确定雄激素而不是 FSH，我们将使用同样携带雄激素受体 (AR) 和 FSHbeta 基因突变的 jsd 小鼠完成研究。 为了确定 E2 的作用方式和位点，将 jsd 小鼠中用 GnRH 拮抗剂和 E2 治疗恢复精子发生的情况与携带雌激素受体 (ER)-α 或 ERbeta 突变的 jsd 小鼠进行比较。 (II) 为了确定激素通过直接作用于睾丸和/或生精小管来影响精原细胞分化，我们将在 jsd 小鼠睾丸组织和小精管的体外培养物中检查它们对精原细胞的影响。 (III) 为了鉴定激素抑制精原细胞分化的靶细胞，我们将在 jsd 小鼠和 AR 缺陷型 jsd 小鼠之间移植肾小管，并使用 Cre 重组酶驱动的细胞类型特异性消除具有 loxP 位点的 AR 基因通过针对不同体细胞的特异性启动子。 (IV)为了鉴定负责基因，我们将使用微阵列在jsd小鼠的靶细胞中差异筛选候选激素调节基因。 一个好的候选基因必须通过 GnRH 拮抗剂在一个方向改变其水平，并通过 T 在相反方向改变其水平。阐明这种精原细胞“停滞”的机制及其在 jsd 小鼠中的逆转可能适用于遗传决定的男性不育病例。 由于其与毒物处理和衰老大鼠中精原细胞分化失败的显着相似性，这些结果也适用于生殖毒物引起的无精子症以及随着衰老而导致的生精能力下降。