Acquisition of competence to condense metaphase I chromosomes during spermatogenesis
Acquisition of competence to condense metaphase I chromosomes during spermatogenesis
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DOI：
10.1006/dbio.1998.9101
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发表时间：
1999-01-01
影响因子：
2.7
通讯作者：
Handel, MA
中科院分区：
文献类型：
--
作者：
Cobb, J;Cargile, B;Handel, MA
关于小鼠精子发生过程中减数分裂前期事件的发生时间以及这些事件与细胞周期进程的关系知之甚少。这项工作的目的是测试的时间和生化相关的发展收购的能力，以凝聚二价同源染色体对交叉举行在一起的假设。实验方法利用冈田酸（OA）处理粗线期精母细胞导致早熟进入减数分裂中期I（MI）的事实。柔线期和偶线期（L/Z）精母细胞不能对OA产生反应，并出现交叉二价染色体的凝聚。在减数分裂前期粗线期的中期，同源染色体完全突触后几天，获得了交叉二价体的MI凝聚能力。组蛋白H1 t在粗线期中期精母细胞核中的积累是MI能力获得的主要原因。生化差异之间也存在不称职的L/Z精母细胞和主管粗线期精母细胞。两者都具有中期促进因子、CDC 2和细胞周期蛋白B1的分子组分;然而，不胜任的L/Z精母细胞的中期促进因子的组蛋白HI激酶活性不被OA激活，因为它在胜任的粗线期精母细胞中。此外，CDC 25 C蛋白磷酸酶存在于有能力的粗线期精母细胞中，但不存在于无能力的L/Z或早期粗线期精母细胞中。不称职和称职的精母细胞积累MPM-2磷酸化表位和磷酸化组蛋白H3在响应OA处理，表明这些抗原的存在是不足以促进减数分裂染色体的凝聚。这些数据表明，精母细胞减数分裂能力是在同源染色体配对建立后获得的，并且与精母细胞中组蛋白Hit和CDC 25 C蛋白磷酸酶的首次出现相一致。(C)北京：科学出版社.
Little is known about the timing of meiotic prophase events during spermatogenesis in the mouse or how these events are related to cell-cycle progression. This work was designed to test hypotheses about the timing and biochemical correlates of developmental acquisition of competence to condense bivalent pairs of homologous chromosomes held together by chiasmata. The experimental approach takes advantage of the fact that okadaic acid (OA) treatment of pachytene spermatocytes causes precocious entry into metaphase I(MI) of meiosis. Leptotene and zygotene (L/Z) spermatocytes are not competent to respond to OA with condensation of chiasmate bivalent chromosomes. Competence for MI condensation of chiasmate bivalents is acquired by the middle of the pachytene stage of meiotic prophase, several days after homologous chromosomes become fully synapsed. The acquisition of MI competence is paralleled by the accumulation of histone H1t in the nuclei of mid- pachytene spermatocytes. Biochemical differences also exist between the incompetent L/Z spermatocytes and the competent pachytene spermatocytes. Both have the molecular components of metaphase promoting factor, CDC2 and CYCLIN B1; however, the histone HI kinase activity of metaphase promoting factor of incompetent L/Z spermatocytes is not activated by OA, as it is in competent pachytene spermatocytes. Additionally, the CDC25C protein phosphatase is present in competent pachytene spermatocytes, but not in incompetent L/Z or early pachytene spermatocytes. Both incompetent and competent spermatocytes accumulate MPM-2 phosphoepitopes and phosphorylated histone H3 in response to OA treatment, indicating that presence of these antigens is not sufficient to promote condensation of meiotic chromosomes. These data demonstrate that meiotic competence of spermatocytes is acquired after homologous chromosome pairing is established and is coincident with first appearance of histone Hit and CDC25C protein phosphatase in spermatocytes. (C) 1999 Academic Press.