Wakayama Tomohiko, Iseki Shoichi
Department of Histology and Embryology, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-machi, Kanazawa, 920-8640, Japan.
Anat Sci Int. 2009 Sep;84(3):112-21. doi: 10.1007/s12565-009-0034-1. Epub 2009 Apr 1.
Endocrine and local secretory factors have long been known to be required for spermatogenesis. Evidence has been accumulating in recent years indicating that direct contact between spermatogenic and Sertoli cells is also required for spermatogenesis. Cell adhesion molecules of various types have been found in the mammalian testis that are expressed in spermatogenic and/or Sertoli cells and involved in homophilic and/or heterophilic binding. We have cloned a novel cell adhesion molecule, cell adhesion molecule-1 (CADM1), also known as immunoglobulin superfamily 4A or spermatogenic immunoglobulin superfamily, from the mouse testis. CADM1 belongs to the immunoglobulin superfamily and is composed of three immunoglobulin-like domains, a transmembrane domain, and a short intracellular domain. In the seminiferous epithelium, CADM1 is expressed in intermediate spermatogonia through to early pachytene spermatocytes as well as in elongating spermatids--but not in round spermatids, mature spermatozoa, or Sertoli cells. One of the heterophilic binding partners of CADM1 has proven to be a poliovirus receptor, another member of the immunoglobulin superfamily that is expressed in Sertoli cells. Knockout mice for CADM1 develop male infertility due to defective spermatogenesis. These findings suggest that cell adhesion molecules between spermatogenic and Sertoli cells play essential roles in spermatogenesis.
长期以来，人们一直认为内分泌和局部分泌因子是精子发生所必需的。近年来，越来越多的证据表明，生精细胞与支持细胞之间的直接接触也是精子发生所必需的。在哺乳动物睾丸中发现了多种类型的细胞黏附分子，它们在生精细胞和/或支持细胞中表达，并参与同嗜性和/或异嗜性结合。我们从小鼠睾丸中克隆了一种新型细胞黏附分子，即细胞黏附分子-1（CADM1），也称为免疫球蛋白超家族4A或生精免疫球蛋白超家族。CADM1属于免疫球蛋白超家族，由三个免疫球蛋白样结构域、一个跨膜结构域和一个短的细胞内结构域组成。在生精上皮中，CADM1在中间型精原细胞到早期粗线期精母细胞以及伸长型精子细胞中表达，但在圆形精子细胞、成熟精子或支持细胞中不表达。已证实CADM1的异嗜性结合伴侣之一是脊髓灰质炎病毒受体，它是免疫球蛋白超家族的另一个成员，在支持细胞中表达。CADM1基因敲除小鼠由于精子发生缺陷而出现雄性不育。这些发现表明，生精细胞与支持细胞之间的细胞黏附分子在精子发生中起着至关重要的作用。
