Requirement for Sun1 in the expression of meiotic reproductive genes and piRNA

The inner nuclear envelope (NE) proteins interact with the nuclear lamina and participate in the architectural compartmentalization of chromosomes. The association of NE proteins with DNA contributes to the spatial rearrangement of chromosomes and their gene expression. Sun1 is an inner nuclear membrane (INM) protein that locates to telomeres and anchors chromosome movement in the prophase of meiosis. Here, we have created Sun1-/- mice and found that these mice are born and grow normally but are reproductively infertile. Detailed molecular analyses showed that Sun1-/- P14 testes are repressed for the expression of reproductive genes and have no detectable piRNA. These findings raise a heretofore unrecognized role of Sun1 in the selective gene expression of coding and non-coding RNAs needed for gemetogenesis. Total RNA was isolated from E14.5 mouse embryonic fibroblasts (MEFs) and and day 9 and 14 mouse whole testes. cDNA samples from paired (same parents) wt (Cy3-labled) and Sun1-/- (Cy5-labled) mice were mixed and hybridized.核被膜（nuclear envelope, NE）内的蛋白质可与核纤层相互作用，并参与染色体的结构区室化过程。核被膜蛋白与DNA的结合有助于染色体的空间重排及其基因表达调控。Sun1是一种定位于端粒、可在减数分裂前期锚定染色体运动的内核膜（inner nuclear membrane, INM）蛋白。本研究构建了Sun1基因敲除（Sun1-/-）小鼠，发现该小鼠可正常出生与生长，但存在生殖不育表型。详细的分子分析显示，Sun1-/-小鼠出生后第14天（postnatal day 14, P14）的睾丸组织中，生殖相关基因的表达受到抑制，且无法检测到piwi互作RNA（piRNA）。上述研究结果揭示了Sun1此前未被认知的功能：其在配子发生（gametogenesis）所需的编码RNA与非编码RNA的选择性基因表达中发挥作用。本研究从胚胎发育第14.5天（E14.5）的小鼠胚胎成纤维细胞（mouse embryonic fibroblasts, MEFs）以及出生后第9天和第14天的小鼠全睾丸组织中分离总RNA。将来自同亲代野生型（wild type, wt，Cy3标记）与Sun1-/-（Cy5标记）小鼠的互补DNA（complementary DNA, cDNA）样品混合后进行杂交实验。