Pai R, Ha H, Kirschenbaum M A, Kamanna V S
Department of Veterans Affairs Medical Center, Long Beach, CA 90822, USA.
J Am Soc Nephrol. 1996 Jun;7(6):914-23. doi: 10.1681/ASN.V76914.
Monocyte chemotactic protein-1 (MCP-1), a specific chemoattractant for monocytes, has been thought to play an important role in the recruitment and accumulation of monocytes within the glomerulus seen in glomerular diseases. This study examined the role of tumor necrosis factor (TNF)-alpha-mediated cellular signal transduction pathways on mesangial cell MCP-1 gene expression and monocyte migration. Incubation of mesangial cells with TNF-alpha stimulated MCP-1 mRNA expression in a dose- and time-dependent manner. Phorbol myristate acetate (PMA), a protein kinase C (PKC) activator, increased MCP-1 message by mesangial cells while depleting PKC decreased MCP-1 gene expression to control levels. Activation of PKC-depleted mesangial cells with PMA but not with TNF-alpha inhibited MCP-1 mRNA expression. Similarly, calphostin C, a PKC inhibitor, failed to inhibit TNF-alpha-induced MCP-1 expression. The incubation of mesangial cells with various protein tyrosine kinase inhibitors (PTK, e.g., herbimycin, tyrphostin, genistein) blocked TNF-alpha-induced MCP-1 mRNA message. Additional experiments examining the role of cAMP on MCP-1 expression indicated that the preincubation of mesangial cells with various cAMP generating substances (pertussis toxin, isoproterenol, dbcAMP) did not induce mesangial cell MCP-1 mRNA transcripts. However, the coincubation of mesangial cells with TNF-alpha and dbcAMP completely inhibited TNF-alpha-induced MCP-1 gene expression. Finally, TNF-alpha-activated mesangial cell media increased monocyte transmigration that could be blocked by neutralizing anti-MCP-1. These studies indicate that TNF-alpha facilitates monocyte transmigration into the glomerulus mediated by the increased expression of MCP-1 by mesangial cells. TNF-alpha-induced mesangial cell MCP-1 expression is regulated by signal transduction pathways involving PTK but not those dependent on PKC or cAMP.
单核细胞趋化蛋白-1（MCP-1）是一种针对单核细胞的特异性趋化因子，被认为在肾小球疾病中肾小球内单核细胞的募集和积聚过程中发挥重要作用。本研究探讨了肿瘤坏死因子（TNF）-α介导的细胞信号转导通路对系膜细胞MCP-1基因表达和单核细胞迁移的作用。用TNF-α孵育系膜细胞，以剂量和时间依赖性方式刺激MCP-1 mRNA表达。佛波酯肉豆蔻酸酯（PMA）是一种蛋白激酶C（PKC）激活剂，可增加系膜细胞的MCP-1信息，而耗尽PKC则将MCP-1基因表达降低至对照水平。用PMA而非TNF-α激活耗尽PKC的系膜细胞可抑制MCP-1 mRNA表达。同样，PKC抑制剂钙泊三醇C未能抑制TNF-α诱导的MCP-1表达。用各种蛋白酪氨酸激酶抑制剂（PTK，如除莠霉素、 tyrphostin、染料木黄酮）孵育系膜细胞可阻断TNF-α诱导的MCP-1 mRNA信息。进一步研究cAMP对MCP-1表达作用的实验表明，用各种cAMP生成物质（百日咳毒素、异丙肾上腺素、二丁酰环磷腺苷）预孵育系膜细胞不会诱导系膜细胞MCP-1 mRNA转录本。然而，将系膜细胞与TNF-α和二丁酰环磷腺苷共同孵育可完全抑制TNF-α诱导的MCP-1基因表达。最后，TNF-α激活的系膜细胞培养基增加了单核细胞的迁移，这可被中和性抗MCP-1阻断。这些研究表明，TNF-α通过系膜细胞MCP-1表达增加促进单核细胞迁移到肾小球。TNF-α诱导的系膜细胞MCP-1表达受涉及PTK的信号转导通路调节，而非依赖PKC或cAMP的信号转导通路。
