Cathepsin B is involved in the trafficking of TNF-α-containing vesicles to the plasma membrane in macrophages
Cathepsin B is involved in the trafficking of TNF-α-containing vesicles to the plasma membrane in macrophages
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DOI：
10.4049/jimmunol.181.1.690
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发表时间：
2008-07-01
影响因子：
4.4
通讯作者：
Kim, Sung Ouk
中科院分区：
文献类型：
--
作者：
Ha, Soon-Duck;Martins, Andrew;Kim, Sung Ouk
tnf - α是一种强效的促炎细胞因子，在启动先天免疫应答以抵抗入侵微生物中至关重要，并且是参与急性和慢性炎症疾病发病机制的关键介质。为了鉴定参与tnf - α产生的分子，我们使用了一种功能基因鉴定方法，使用逆转录病毒整合介导的诱变，然后在巨噬细胞中进行lps刺激的tnf - α产生分析。我们发现组织蛋白酶B，一种溶酶体半胱氨酸蛋白酶，是对细菌细胞壁成分LPS的最佳翻译后处理tnf - α所必需的。来自组织蛋白酶B缺陷小鼠的小鼠骨髓源性巨噬细胞和经组织蛋白酶B特异性化学抑制剂CA074甲酯或小干扰RNA处理的巨噬细胞分泌的tnf - α显著低于野生型或未处理的巨噬细胞。我们进一步发现，组织蛋白酶B的抑制引起了26-kDa前含tnf囊泡的积累。gfp偶联的前tnf的异位表达进一步表明，在没有细胞内组织蛋白酶B活性的情况下，前tnf无法到达质膜。总之，这些数据表明细胞内组织蛋白酶B活性参与了含有tnf α的囊泡向质膜的运输。
TNF-alpha is a potent proinflammatory cytokine, essential for initiating innate immune responses against invading microbes and a key mediator involved in the pathogenesis of acute and chronic inflammatory diseases. To identify molecules involved in the production of TNF-alpha, we used a functional gene identification method using retroviral integration-mediated mutagenesis, followed by LPS-stimulated TNF-alpha production analysis in macrophages. We found that cathepsin B, a lysosomal cysteine proteinase, was required for optimal posttranslational processing of TNF-alpha in response to the bacterial cell wall component LPS. Mouse bone marrow-derived macrophages from cathepsin B-deficient mice and macrophages treated with the cathepsin B-specific chemical inhibitor CA074 methyl ester or small interfering RNA against cathepsin B secreted significantly less TNF-alpha than wild-type or nontreated macrophages. We further showed that the inhibition of cathepsin B caused accumulation of 26-kDa pro-TNF-containing vesicles. Ectopic expression of GFP-conjugated pro-TNF further suggests that pro-TNF failed to reach the plasma membrane without intracellular cathepsin B activity. Altogether, these data suggest that intracellular cathepsin B activity is involved in the TNF-alpha-containing vesicle trafficking to the plasma membrane.