Nef stimulates proliferation of glomerular podocytes through activation of Src-dependent Stat3 and MAPK1,2 pathways
Nef stimulates proliferation of glomerular podocytes through activation of Src-dependent Stat3 and MAPK1,2 pathways
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DOI：
10.1172/jci200421004
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发表时间：
2004-09-01
影响因子：
15.9
通讯作者：
Klotman, PE
中科院分区：
文献类型：
--
作者：
He, JCJ;Husain, M;Klotman, PE
在HIV相关性肾病（HIVAN）的局灶节段性肾小球硬化（FSGS）中，足细胞表现出高增殖率和分化标志物的丢失。我们以前已经发现HIV-1的nef基因负责这些变化。在这里，我们研究了Nef诱导的信号通路及其在HIVAN发病机制中的作用。使用分化后的条件永生化足细胞，我们发现nef感染足细胞增加Src激酶活性和信号转导和转录激活因子3（Stat 3）磷酸化，并激活Ras-c-Raf-MAPK 1，2途径。Src的显性负性突变体消除了Nef效应，而MAPK 1，2或显性负性Stat 3的抑制部分降低了Nef效应。用小干扰RNA降低Nef的表达逆转了Nef的作用。Nef在PxxP或R105 R106基序的突变减少了Nef信号传导和足细胞中的表型变化。与同窝小鼠相比，HIV-1转基因小鼠肾脏足细胞的磷酸化MAPK 1，2和磷酸化Stat 3染色均增加，与非HIV肾病患者或非HIV患者的特发性FSGS，经典FSGS或微小病变疾病相比，HIV患者肾脏足细胞的磷酸化MAPK 1，2和磷酸化Stat 3染色均增加。这些数据表明，Nef诱导的激活Stat 3和Ras-MAPK 1，2通过Src依赖性途径是负责足细胞增殖和去分化，在崩溃FSGS的HIVAN的特征性发现。
In collapsing focal segmental glomerulosclerosis (FSGS) of HIV-associated nephropathy (HIVAN), podocytes exhibit a high proliferation rate and loss of differentiation markers. We have found previously that the nef gene of HIV-1 is responsible for these changes. Here, we investigated the signaling pathways induced by Nef and its role in the pathogenesis of HIVAN. Using conditionally immortalized podocytes after differentiation, we found that infection of podocytes with nef increased Src kinase activity and signal transducer and activator of transcription 3 (Stat3) phosphorylation and activated the Ras-c-Raf-MAPK1,2 pathway. A dominant negative mutant of Src abolished the Nef effect, whereas inhibition of MAPK1,2 or dominant negative Stat3 reduced Nef effects partially. Reducing the expression of Nef with small interference RNA reversed the Nef effect. Mutation of Nefin the PxxP or R105R106 Motifs diminished Nef signaling and the phenotypic changes in podocytes. Both phospho-MAPK1,2 and phospho-Stat3 staining increased in podocytes of kidneys from HIV-1 transgenic mice compared with their littermates and in podocytes of kidneys from HIVAN patients compared with HIV patients with non-HIVAN kidney diseases or non-HIV patients with idiopathic FSGS, classic FSGS, or minimal-change disease. These data suggest that Nef-induced activation of Stat3 and Ras-MAPK1,2 via Src-dependent pathways is responsible for podocyte proliferation and dedifferentiation, a characteristic finding in collapsing FSGS of HIVAN.