p63-Dependent Checkpoints in Oocytes

哺乳动物雌性生殖系的减数分裂以减数分裂I期极长的停滞为特征 同源染色体重组和排卵之间的关系，在人类中， 几十年在此停滞期，卵母细胞非常容易受到内源性DNA损伤， 环境或治疗起源。DNA损伤如何触发这些被捕卵母细胞的死亡 目前对p63的认识还不多，但我们现在知道，p63是p53肿瘤抑制基因的同源物， 在这些卵母细胞中表达，并在它们暴露于电离辐射后的死亡中起重要作用。 辐射这些基于小鼠基因敲除模型的发现， 关于平衡女性生育力与需要防止基因突变的战略的问题 有限的卵母细胞池。这些问题在两个具体目标中得到解决。目标1：确定 如果p63还具有清除被同源性高致突变步骤损伤的卵母细胞的功能， 染色体重组我们还想确定TAp63是否也有助于卵母细胞死亡， 正在接受癌症化疗的年轻女性。我们对目标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， 化疗药物与卵巢衰竭有关。在这个目标中，我们将评估TAp63 null 小鼠中的突变，以挽救在缺乏关键基因的情况下伴随减数分裂的卵母细胞死亡 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 放疗化疗和同源染色体重组我们的初步数据显示 提示促凋亡Puma基因参与卵母细胞死亡，该基因在卵母细胞死亡中的作用将 在小鼠敲除模型中进行探测。我们预计这些研究将揭示很多关于如何 卵母细胞保持高度的基因组保真度，化疗如何导致女性不育， 并深入了解p53家族如何消除DNA损伤细胞以促进肿瘤 镇压

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.