p63-Dependent Checkpoints in Oocytes

哺乳动物雌性种系的减数分裂的特点是减数分裂I期的停滞时间过长。 同源染色体重组和排卵之间的关系，在人类中可以持续五年 几十年。在此停滞期内，卵母细胞极易受到内源性DNA损伤， 环境原因，或治疗原因。DNA损伤如何触发这些受阻卵母细胞的死亡 人们对此知之甚少，但我们现在知道，p63，一种p53肿瘤抑制基因的同源物，是高度 在这些卵母细胞中表达，并在其暴露于电离后死亡中起重要作用 辐射。这些基于小鼠基因敲除模型的发现提出了基本的 关于平衡女性生育能力和防止基因突变的需要的战略的问题 有限的卵母细胞池。这些问题有两个具体目标。目标1是确定 If p63还可以清除被同源基因高度突变的步骤破坏的卵母细胞 染色体重组。我们还想确定TAp63是否也与卵母细胞死亡有关 正在接受癌症化疗的年轻女性。我们关于AIM 1的初步数据支持 TAp63在粗线期后检查点和卵母细胞死亡中都起作用的概念 与卵巢衰竭有关的化疗药物。在这个目标中，我们将评估TAp63 Null的能力 在缺乏关键基因的情况下，小鼠突变以挽救伴随减数分裂而来的卵母细胞死亡 例如ATM、DCM、MHL和SPO11。目标2是确定 致死和亚致死剂量电离辐射后卵母细胞中TAp63蛋白的转录靶点 放射治疗、化疗和同源染色体重组。我们的初步数据显示 Puma基因与卵母细胞死亡有关，而该基因在卵母细胞死亡中的作用将 在老鼠击倒模型中被探测。我们预计，这些研究将揭示更多关于 卵母细胞保持高度的基因组保真度，化疗如何导致女性不孕， 以及对P53家族如何作用于消除DNA损伤的细胞以促进肿瘤的洞察 压制。

Meiosis in the female germline of mammals is marked by an exceedingly prolonged arrest in meiosis I between homologous chromosome recombination and ovulation, which in humans can last five decades. During this arrest period, oocytes are highly vulnerable to DNA damage from endogenous, environmental, or therapeutic origins. How DNA damage triggers the death of these arrested oocytes is poorly understood but we now know that p63, a homolog of the p53 tumor suppressor, is highly expressed in these oocytes and plays an essential role in their death following exposure to ionizing radiation. These findings, based on mouse gene knockout models, have raised fundamental questions regarding the strategies to balance female fertility with the need for preventing mutations in a limited pool of oocytes. These questions are addressed in two specific aims. Aim 1 is to determine if p63 also functions to eradicate oocytes damaged by the highly mutagenic steps of homologous chromosome recombination. We also want to determine if TAp63 also contributes to oocyte death in young women undergoing chemotherapy for cancer. Our preliminary data for Aim 1 support the concept that TAp63 functions both in a post-pachytene checkpoint and in oocyte death due to chemotherapeutic drugs linked to ovarian failure. In this aim we will assess the ability of TAp63 null mutations in mice to rescue oocyte death that accompanies meiosis in the absence of key genes such as ATM, DCM, MHL, and SPO11 using specific mouse mutants. Aim 2 is to identify the transcriptional targets of TAp63 protein in oocytes following lethal and sub-lethal doses of ionizing radiation, chemotherapy, and homologous chromosome recombination. Our preliminary data strongly implicates the proapoptotic Puma gene in oocyte death, and the role of this gene in oocyte death will be probed in mouse knockout models. We anticipate that these studies will reveal much about how the oocyte maintains a high degree of genomic fidelity, how chemotherapy leads to female infertility, and insights into how the p53 family acts to eliminate cells with DNA damage to promote tumor suppression.