Bomar Jacqueline, Moreira Pedro, Balise John J, Collas Philippe
Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst 01003, USA.
J Cell Sci. 2002 Jul 15;115(Pt 14):2931-40. doi: 10.1242/jcs.115.14.2931.
A-kinase anchoring protein AKAP95 is implicated in somatic mitotic chromosome condensation by recruiting the condensin complex. Here, we report a differential regulation of condensation of maternal and paternal chromosomes mediated by AKAP95 in mitotic mouse zygotes. AKAP95 is synthesized upon oocyte activation, targeted to the female pronucleus and specifically associates with maternal chromosomes at mitosis. AKAP95 mRNA is highly restricted to the vicinity of the meiotic spindle in metaphase II oocytes. In vivo displacement of endogenous AKAP95 in female pronuclei by microinjection of competitor peptides and rescue experiments show that AKPA95 is required for recruitment of the mCAP-D2 condensin subunit to, and condensation of, maternal chromosomes. In contrast, AKAP95 is dispensable for mCAP-D2 recruitment to, and condensation of, paternal chromosomes. Our results indicate that at first embryonic mitosis, paternal chromosomes target condensins and condense independently of AKAP95, whereas maternal chromosomes require AKAP95 for condensin recruitment and condensation. We propose a concept whereby condensation of chromosomes in gametes, zygotes and somatic cells involves related but distinct mechanisms.
A激酶锚定蛋白AKAP95通过募集凝聚素复合物参与体细胞有丝分裂染色体凝聚。在此，我们报道了在有丝分裂的小鼠受精卵中，AKAP95介导的母源和父源染色体凝聚的差异调控。AKAP95在卵母细胞激活时合成，靶向雌性原核，并在有丝分裂时特异性地与母源染色体结合。AKAP95 mRNA在中期II卵母细胞中高度局限于减数分裂纺锤体附近。通过显微注射竞争肽在体内置换雌性原核中的内源性AKAP95以及拯救实验表明，AKPA95是将mCAP-D2凝聚素亚基募集到母源染色体并使其凝聚所必需的。相比之下，AKAP95对于将mCAP-D2募集到父源染色体并使其凝聚是可有可无的。我们的结果表明，在第一次胚胎有丝分裂时，父源染色体靶向凝聚素并独立于AKAP95进行凝聚，而母源染色体则需要AKAP95来募集凝聚素并进行凝聚。我们提出了一个概念，即配子、受精卵和体细胞中的染色体凝聚涉及相关但不同的机制。
