Natori Y, O'Meara Y M, Manning E C, Minto A W, Levine J S, Weise W J, Salant D J
Evans Memorial Department of Clinical Research, University Hospital, Boston University Medical Center, Massachusetts 02118.
Am J Physiol. 1992 Jan;262(1 Pt 2):F131-7. doi: 10.1152/ajprenal.1992.262.1.F131.
To study the formation of basement membrane by glomerular epithelial cells (GECs), production and secretion of type IV collagen and laminin by rat GECs in culture were evaluated. GECs produced two chains of type IV collagen (180 and 170 kDa) in the ratio of approximately 2 to 1, when immunoprecipitated with antibody to type IV collagen of mouse Engelbreth-Holm-Swarm (EHS) sarcoma. GECs also produced proteins that were precipitated by antibody to EHS laminin, i.e., two bands each in the positions of the A and B chains of mouse laminin. On enzyme-linked immunosorbent assay (ELISA), type IV collagen and laminin were found mainly in the cell-associated fraction and in the subepithelial culture medium. Confluent GECs on membrane filters formed a tight barrier against the flux of macromolecules. Under these conditions, 80% of newly synthesized and secreted matrix proteins were detected in the basolateral medium. Moreover, treatment with ammonium chloride, which is known to affect polarized secretion, caused both type IV collagen and laminin to be secreted via the basolateral and apical surfaces in similar amounts. These results indicate that cultured GECs are polarized and that they produce and secrete basement membrane components via the basolateral side.
为研究肾小球上皮细胞（GECs）基底膜的形成，对培养的大鼠GECs中IV型胶原蛋白和层粘连蛋白的产生及分泌进行了评估。当用小鼠Engelbreth-Holm-Swarm（EHS）肉瘤的IV型胶原蛋白抗体进行免疫沉淀时，GECs产生了两条IV型胶原蛋白链（180 kDa和170 kDa），比例约为2比1。GECs还产生了能被EHS层粘连蛋白抗体沉淀的蛋白质，即在小鼠层粘连蛋白A链和B链位置各有两条条带。在酶联免疫吸附测定（ELISA）中，IV型胶原蛋白和层粘连蛋白主要存在于细胞相关部分和上皮下培养基中。膜滤器上汇合的GECs形成了对大分子通量的紧密屏障。在这些条件下，80%新合成并分泌的基质蛋白在基底外侧培养基中被检测到。此外，已知会影响极化分泌的氯化铵处理导致IV型胶原蛋白和层粘连蛋白以相似的量通过基底外侧和顶端表面分泌。这些结果表明，培养的GECs是极化的，并且它们通过基底外侧产生和分泌基底膜成分。
