The role of VRK-1 during the meiotic divisions of C. elegans embryos

VRK-1是C.在整个发育过程中具有多种功能。 它是胚胎发育过程中核膜形成和幼虫发育过程中生殖系增殖和外阴形态发生所必需的。 果蝇的直系同源物NHK-1是一种组蛋白激酶，其突变等位基因影响卵母细胞中的染色体形态。 我们一直对影响C染色体减数分裂过程中染色体形态和行为的蛋白质感兴趣。优雅 我们一直在使用RNAi来表征vrk-1基因缺失的胚胎的表型。 我们已经观察到高度渗透性的胚胎致死性。 这些胚胎在减数分裂中表现出缺陷，并且不能使染色质去致密。 因此，这些胚胎作为具有很少DNA的多细胞胚胎而停止。 这种缺陷不是发育中卵母细胞核被膜缺陷的结果，但似乎确实影响了染色质与卵母细胞核被膜的结合。 我们正在使用表达GFP标记的组蛋白的活胚胎的真实的时间成像来跟踪VRK-1缺失的卵母细胞和胚胎中卵母细胞成熟期间减数分裂染色体的行为。 我们还使用免疫细胞化学来确定是否有任何特定的组蛋白修饰或染色质相关因子在这个时候受到干扰，以解释所观察到的减数分裂缺陷。 在过去的一年里，我们还从20年前发表的胚胎致死筛选中鉴定出了vrk-1的突变等位基因（缺失等位基因也存在并导致不育）。 这种新的突变体显示出许多我们通过RNAi表征的相同表型。 然而，这个等位基因现在允许我们通过询问其他基因的突变是否可以增强或抑制vrk-1突变体来进行更直接的遗传测试。 该等位基因在不久的将来也将用于遗传抑制筛选，以鉴定在VRK-1通路中起作用的其他因子。

VRK-1, a vaccinia-related kinase in C. elegans, has multiple functions throughout development. It is required for nuclear envelope formation during embryogenesis and for germ line proliferation and vulval morphogenesis during larval development. The Drosophila ortholog, NHK-1, is a histone kinase, mutant alleles of which affect chromosome morphology in oocytes. We have an ongoing interest in proteins that influence chromosome morphology and behavior during the meiotic divisions in C. elegans. We have been characterizing the phenotypes of embryos depleted of the vrk-1 gene, using RNAi. We have observed highly penetrant embryonic lethality. These embryos display defects in the meiotic divisions as well as a failure to decondense chromatin. As a result, these embryos arrest as multicellular embryos with very little DNA. This defect is not a result of nuclear envelope defects in the developing oocytes but does appear to affect the association of chromatin with the oocyte nuclear envelope. We are using real time imaging of live embryos expressing GFP-tagged histones to follow the behavior of the meiotic chromosomes during oocyte maturation in VRK-1-depleted oocytes and embryos. We are also using immunocytochemistry to determine whether any specific histone modifications or chromatin-associated factors are perturbed at this time to account for the observed meiotic defects. In the past year, we have also identified a mutant allele of vrk-1 from an embryonic lethal screen published 20 years ago (a deletion allele also exists and results in sterility). This new mutant displays many of the same phenotypes we have characterized by RNAi. This allele however now allows us to perform more directed genetic tests by asking whether mutations in other genes can enhance or suppress the vrk-1 mutant. This allele will also be useful in the near future for genetic suppressor screens to identify other factors that function in the VRK-1 pathway.