Department of Genetics and Development, Columbia University Medical Center, New York, New York 10032, USA.
Microsc Res Tech. 2010 Jun;73(6):583-96. doi: 10.1002/jemt.20797.
Retinoic acid receptor alpha (RARalpha)-deficient mice are sterile, with abnormalities in the progression of spermatogenesis and spermiogenesis. In this study, we investigated whether defective retinoid signaling involved at least in part, disrupted cell-cell interactions. Hypertonic fixation approaches revealed defects in the integrity of the Sertoli-cell barrier in the tubules of RARalpha-deficient testes. Dye transfer experiments further revealed that coupling between cells from the basal to adluminal compartments was aberrant. There were also differences in the expression of several known retinoic acid (RA)-responsive genes encoding structural components of tight junctions and gap junctions. Immunostaining demonstrated a delay in the incorporation of zonula occludens (ZO-1), a peripheral component protein of tight junctions, into the Sertoli cell tight junctions. Markedly reduced expression of connexin-40 in mutant pachytene spermatocytes and round spermatids was found by in situ hybridization. An ectopic distribution of vimentin and disrupted cyclic expression of vimentin, which is usually tightly regulated during spermiogenesis, was found in RARalpha-deficient testes at all ages examined. Thus, the specific defects in spermiogenesis in RARalpha-deficient testes may correlate with a disrupted cyclic expression of RA-responsive structural components, including vimentin, a downregulation of connexin-40 in spermatogenic cells, and delayed assembly of ZO-1 into Sertoli cell tight junctions. Interestingly, bioinformatic analysis revealed that many genes that are components of tight junctions and gap junctions contained potential retinoic acid response element binding sites.
视黄酸受体α（RARα）缺陷型小鼠不育，其精子发生和精子形成过程存在异常。在这项研究中，我们研究了视黄酸信号传导缺陷是否至少部分涉及细胞-细胞相互作用的破坏。高渗固定方法显示 RARα 缺陷型睾丸小管中的 Sertoli 细胞屏障完整性存在缺陷。染料转移实验进一步表明，基底到腔室的细胞连接异常。一些已知的视黄酸（RA）反应基因的表达也存在差异，这些基因编码紧密连接和缝隙连接的结构成分。免疫染色显示，紧密连接外周成分蛋白 ZO-1 进入 Sertoli 细胞紧密连接的整合延迟。原位杂交显示，突变型粗线期精母细胞和圆形精子中的连接蛋白 40 的表达明显减少。在所有检查的年龄中，RARα 缺陷型睾丸中均发现波形蛋白的异位分布和波形蛋白的周期性表达中断，而波形蛋白在精子发生过程中通常受到严格调控。因此，RARα 缺陷型睾丸中精子发生的特定缺陷可能与 RA 反应性结构成分（包括波形蛋白）的周期性表达中断、生精细胞中连接蛋白 40 的下调以及 ZO-1 到 Sertoli 细胞紧密连接的组装延迟有关。有趣的是，生物信息学分析显示，许多作为紧密连接和缝隙连接组成部分的基因含有潜在的视黄酸反应元件结合位点。
