Rab39a binds caspase-1 and is required for caspase-1-dependent interleukin-1beta secretion.
Rab39a binds caspase-1 and is required for caspase-1-dependent interleukin-1beta secretion.
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DOI：
10.1074/jbc.m109.046102
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发表时间：
2009-12-11
期刊：
影响因子：
--
通讯作者：
O'Neill LA
中科院分区：
文献类型：
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作者：
Becker CE;Creagh EM;O'Neill LA
白细胞介素-1 β（IL-1β）是一种重要的促炎细胞因子，以caspase-1依赖的方式通过非常规途径分泌。使用一步免疫沉淀法分离内源性胱天蛋白酶-1单核细胞THP 1细胞系，我们确定了以前未描述的结合伙伴使用质谱。其中一种蛋白质是Rab 39 a，它是Rab GT3家族的成员，Rab GT3家族是一组在蛋白质运输和分泌中起重要作用的蛋白质。我们通过免疫共沉淀证实Rab 39 a与caspase-1结合。用小干扰RNA敲低Rab 39 a导致分泌的IL-1β水平降低，但对脂多糖诱导的pro-IL-1β mRNA没有影响。Rab 39 a含有高度保守的caspase-1切割位点，并且在重组caspase-1或脂多糖存在下被切割。最后，Rab 39 a的过表达导致IL-1β分泌的增加，此外，缺乏半胱天冬酶-1切割位点的Rab 39 a构建体的过表达导致IL-1β分泌的额外增加。总之，我们的研究结果表明Rab 39 a与caspase-1相互作用，并表明Rab 39 a作为连接caspase-1与IL-1β分泌的运输衔接子发挥作用。
Interleukin-1β (IL-1β) is an important pro-inflammatory cytokine that is secreted by unconventional means in a caspase-1-dependent manner. Using a one-step immunoprecipitation approach to isolate endogenous caspase-1 from the monocytic THP1 cell line, we identified previously undescribed binding partners using mass spectrometry. One of the proteins identified was Rab39a, a member of the Rab GTPase family, a group of proteins that have important roles in protein trafficking and secretion. We confirmed by co-immunoprecipitation that Rab39a binds caspase-1. Knock down of Rab39a with small interfering RNA resulted in diminished levels of secreted IL-1β but had no effect on induction of pro-IL-1β mRNA by lipopolysaccharide. Rab39a contains a highly conserved caspase-1 cleavage site and was cleaved in the presence of recombinant caspase-1 or lipopolysaccharide. Finally, overexpression of Rab39a results in an increase in IL-1β secretion, and furthermore, overexpression of a Rab39a construct lacking the caspase-1 cleavage site leads to an additional increase in IL-1β secretion. Altogether, our findings show that Rab39a interacts with caspase-1 and suggest that Rab39a functions as a trafficking adaptor linking caspase-1 to IL-1β secretion.