Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Department of Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
J Cell Sci. 2021 Apr 1;134(7). doi: 10.1242/jcs.258391. Epub 2021 Apr 15.
Germ cells undergo distinct nuclear processes as they differentiate into gametes. Although these events must be coordinated to ensure proper maturation, the stage-specific transport of proteins in and out of germ cell nuclei remains incompletely understood. Our efforts to genetically characterize Drosophila genes that exhibit enriched expression in germ cells led to the finding that loss of the highly conserved Importin β/karyopherin family member Importin-9 (Ipo9, herein referring to Ranbp9) results in female and male sterility. Immunofluorescence and fluorescent in situ hybridization revealed that Ipo9KO mutants display chromosome condensation and segregation defects during meiosis. In addition, Ipo9KO mutant males form abnormally structured sperm and fail to properly exchange histones for protamines. Ipo9 physically interacts with proteasome proteins, and Ipo9 mutant males exhibit disruption of the nuclear localization of several proteasome components. Thus, Ipo9 coordinates the nuclear import of functionally related factors necessary for the completion of gametogenesis. This article has an associated First Person interview with the first author of the paper.
生殖细胞在分化为配子的过程中经历不同的核过程。尽管这些事件必须协调一致以确保适当的成熟，但生殖细胞核内外蛋白质的特定阶段运输仍不完全了解。我们努力从遗传上表征在生殖细胞中表达丰富的果蝇基因，结果发现高度保守的 Importin β/核孔蛋白家族成员 Importin-9（Ipo9，本文中称为 Ranbp9）的缺失导致雌性和雄性不育。免疫荧光和荧光原位杂交显示，Ipo9KO 突变体在减数分裂过程中表现出染色体浓缩和分离缺陷。此外，Ipo9KO 突变体雄性形成结构异常的精子，并且不能正确地将组蛋白交换为鱼精蛋白。Ipo9 与蛋白酶体蛋白发生物理相互作用，并且 Ipo9 突变体雄性表现出几种蛋白酶体成分的核定位中断。因此，Ipo9 协调对于配子发生完成必需的功能相关因子的核输入。本文有与该论文第一作者的相关第一人称访谈。
