Novel Role of TRPML2 in the Regulation of the Innate Immune Response.
Novel Role of TRPML2 in the Regulation of the Innate Immune Response.
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DOI：
10.4049/jimmunol.1500163
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发表时间：
2015-11-15
期刊：
影响因子：
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通讯作者：
Puertollano R
中科院分区：
文献类型：
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作者：
Sun L;Hua Y;Vergarajauregui S;Diab HI;Puertollano R
TRPML（或粘脂）构成与瞬时受体电位（TRP）超家族具有同源性的内体阳离子通道家族。在哺乳动物中，TRPML家族包括三个成员，TRPML 1 -3。虽然TRPML 1和TRPML 3已经被很好地表征，但TRPML 2的细胞功能仍然难以捉摸。为了解决TRPML 2在生理相关细胞类型中的功能，我们首先分析了TRPML 2在不同小鼠组织和器官中的表达，发现TRPML 2主要在淋巴器官和肾脏中表达。定量RT-PCR显示TRPML 2在转录水平上受到严格调控。虽然TRPML 2表达在静息巨噬细胞中可以忽略不计，但TRPML 2 mRNA和蛋白水平在体外和体内均响应于Toll样受体（TLR）活化而显著增加。相反，TRPML 1和TRPML 3水平在TLR激活后没有变化。免疫荧光分析表明，内源性TRPML 2主要定位于回收内体在培养和原代细胞，与TRPML 1和TRPML 3，分布到晚期和早期内体途径，分别。为了更好地理解TRPML 2的体内功能，我们产生了TRPML 2敲除小鼠。我们发现，TRPML 2基因敲除小鼠的几种趋化因子，特别是CCL 2的产生严重减少。此外，TRPML 2基因敲除小鼠表现出外周巨噬细胞对LPS或活细菌的腹膜内注射的应答受损，表明免疫应答中的潜在缺陷。总的来说，我们的研究揭示了TRPML家族成员的调节和分布的有趣差异，并确定了TRPML 2在先天免疫应答中的新作用。
TRPMLs (or mucolipins) constitute a family of endosomal cation channels with homology to the transient receptor potential (TRP) superfamily. In mammals, the TRPML family includes three members, TRPML1-3. While TRPML1 and TRPML3 have been well characterized, the cellular function of TRPML2 has remained elusive. To address TRPML2 function in a physiologically relevant cell type, we first analyzed TRPML2 expression in different mouse tissues and organs and found that TRPML2 was predominantly expressed in lymphoid organs and kidney. Quantitative RT-PCR revealed tight regulation of TRPML2 at the transcriptional level. While TRPML2 expression was negligible in resting macrophages, TRPML2 mRNA and protein levels dramatically increased in response to toll-like receptor (TLR) activation both in vitro and in vivo. Conversely, TRPML1 and TRPML3 levels did not change upon TLR activation. Immunofluorescence analysis demonstrated that endogenous TRPML2 primarily localized to recycling endosomes both in culture and primary cells, in contrast with TRPML1 and TRPML3 that distribute to the late and early endosomal pathway, respectively. To better understand the in vivo function of TRPML2 we generated a TRPML2 knockout mouse. We found that the production of several chemokines, in particular CCL2, was severely reduced in TRPML2 knockout mice. Furthermore, TRPML2 knockout mice displayed impaired recruitment of peripheral macrophages in response to intra-peritoneal injections of either LPS or live bacteria, suggesting a potential defect in immune response. Overall, our study reveals interesting differences in the regulation and distribution of the members of the TRPML family and identifies a novel role for TRPML2 in innate immune response.