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巨噬細胞功能新發現：分化關鍵蛋白Trib1
點擊次數：3104 發布時間：2013-4-9
巨噬細胞至少有兩個亞類，即M1型和M2型。人類全基因組關聯研究表明TRIB1參與脂質代謝。現在大阪大學WPI免疫前沿研究中心等處的研究人員發現TRIB1通過控制M2類巨噬細胞的分化，在脂肪組織維持和脂質代謝紊亂上發揮關鍵作用。
巨噬細胞至少有兩個亞類，即M1型和M2型。M1型巨噬細胞參與促炎反應，且在宿主防御細菌和病毒感染中發揮核心作用。M2巨噬細胞與抗炎反應、寄生蟲感染、組織重構、纖維化以及腫瘤疾病發展相關。 Trib1是個銜接蛋白，與泛素連接酶COP1相互作用參與蛋白降解。人類全基因組關聯研究表明TRIB1參與脂質代謝。
現在，大阪大學WPI免疫前沿研究中心等處的研究人員，發現Trib1對F4/80 + MR +組織內在巨噬細胞的分化至關重要，且這些巨噬細胞和M2巨噬細胞、酸性粒細胞具有共同的特性（稱之為M2類巨噬細胞）。但是，Trib1在M1髓系細胞就不會發揮這種作用。相關研究論文于2013年3月20日發表在Nature雜志上。
Trib1缺陷導致各種器官中M2類巨噬細胞急劇減少，如骨髓、脾臟、肺以及脂肪組織。在Trib1缺失的骨髓細胞中，C / EBP α的異常表達要為巨噬細胞分化缺陷負責。沒有想到的是，造血細胞缺乏 Trib1的小鼠，減少了脂肪組織塊，并伴隨著脂肪分解增加，即使是在正常飲食條件下。
M2類巨噬細胞的補充可緩解這種病理學現象。這表明，這類巨噬細胞的缺乏是引發脂肪分解的原因。為了應對高脂肪飲食，造血細胞缺乏 Trib1的小鼠發育中會呈現高甘油三酯血癥、胰島素抗性，同時增加促炎細胞基因誘導。
總之，這些結果表明Trib1在脂肪組織維持和脂質代謝紊亂上發揮關鍵作用，而其作用是通過控制組織內在M2類巨噬細胞的分化實現的。
原文摘要：
Critical role of Trib1 in differentiation of tissue-resident M2-like macrophages
Macrophages consist of at least two subgroups, M1 and M2 （refs 1, 2, 3）. Whereas M1 macrophages are proinflammatory and have a central role in host defence against bacterial and viral infections4, 5, M2 macrophages are associated with responses to anti-inflammatory reactions, helminth infection, tissue remodelling, fibrosis and tumour progression6. Trib1 is an adaptor protein involved in protein degradation by interacting with COP1 ubiquitin ligase7. Genome-wide association studies in humans have implicated TRIB1 in lipid metabolism8, 9, 10. Here we show that Trib1 is critical for the differentiation of F4/80+MR+ tissue-resident macrophages—that share characteristics with M2 macrophages （which we term M2-like macrophages）—and eosinophils but not for the differentiation of M1 myeloid cells. Trib1 deficiency results in a severe reduction of M2-like macrophages in various organs, including bone marrow, spleen, lung and adipose tissues. Aberrant expression of C/EBPα in Trib1-deficient bone marrow cells is responsible for the defects in macrophage differentiation. Unexpectedly, mice lacking Trib1 in haematopoietic cells show diminished adipose tissue mass accompanied by evidence of increased lipolysis, even when fed a normal diet. Supplementation of M2-like macrophages rescues the pathophysiology, indicating that a lack of these macrophages is the cause of lipolysis. In response to a high-fat diet, mice lacking Trib1 in haematopoietic cells develop hypertriglyceridaemia and insulin resistance, together with increased proinflammatory cytokine gene induction. Collectively, these results demonstrate that Trib1 is critical for adipose tissue maintenance and suppression of metabolic disorders by controlling the differentiation of tissue-resident M2-like macrophages.