Intracellular trafficking and secretion of adiponectin is dependent on GGA-coated vesicles
Intracellular trafficking and secretion of adiponectin is dependent on GGA-coated vesicles
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DOI：
10.1074/jbc.m511313200
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发表时间：
2006-03-17
影响因子：
4.8
通讯作者：
Mora, S
中科院分区：
文献类型：
--
作者：
Xie, LL;Boyle, D;Mora, S
脂联素（Acrp 30）是一种胰岛素增敏激素，仅由脂肪组织产生和分泌。共聚焦荧光显微镜证实了脂联素与高尔基体膜标记物p115、β-COP和跨高尔基体网络标记物突触融合蛋白6的共定位。用布雷菲德菌素A处理细胞将脂联素重新分配到内质网，在内质网中脂联素与伴侣蛋白BIP共定位并抑制脂联素的分泌，表明脂联素释放需要功能性高尔基体。共聚焦荧光显微镜也显示了内源性脂联素与表达的GGA 1 myc（高尔基体定位γ-适应素耳同源性ARF结合蛋白）的共定位，但脂联素与GGA 2 myc或GGA 3 myc亚型之间没有显著重叠。与共聚焦荧光显微镜一致，透射电子显微镜证实了GGA 1与脂联素的共定位。虽然GGA 1不直接与脂联素蛋白相互作用，但脂肪细胞的脂联素富集膜区室被GST-GGA 1货物结合结构域（VHS）融合蛋白沉淀，但不被GST-GGA 2 VHS或GST-GGA 3 VHS融合蛋白沉淀。此外，脂联素与GGA 1显性干扰突变体（GGA 1-VHS GAT结构域）的共表达导致3 T3 L1脂肪细胞和HEK 293细胞中脂联素分泌的显著抑制，而截短突变体GGA 2-VHSGAT或GGA 3-VHSGAT则未检测到抑制。此外，野生型GGA 1与脂联素的共表达增强了脂联素的分泌。有趣的是，瘦素分泌不受野生型形式或GGA 1突变体的影响。总之，这些数据表明脂联素通过其分泌途径的运输依赖于GGA包被的囊泡。
Adiponectin (Acrp30) is an insulin-sensitizing hormone produced and secreted exclusively by adipose tissue. Confocal fluorescent microscopy demonstrated the colocalization of adiponectin with the Golgi membrane markers p115, beta-COP, and the trans-Golgi network marker, syntaxin 6. Treatment of cells with brefeldin A redistributed adiponectin to the endoplasmic reticulum where it colocalized with the chaperone protein BIP and inhibited secretion of adiponectin demonstrating a requirement for a functional Golgi apparatus for adiponectin release. Confocal fluorescent microscopy also demonstrated a colocalization of endogenous adiponectin with that of expressed GGA1myc (Golgi-localizing gamma-adaptin ear homology ARF-binding protein) but with no significant overlap between adiponectin and the GGA2myc or GGA3myc isoforms. Consistent with confocal fluorescent microscopy, transmission electron microscopy demonstrated the colocalization of GGA1 with adiponectin. Although GGA1 did not directly interact with the adiponectin protein, the adiponectin enriched membrane compartments of adipocyte were precipitated by a GST-GGA1 cargo binding domain (VHS) fusion protein but not with a GST-GGA2 VHS or GST-GGA3 VHS fusion proteins. Moreover, co-expression of adiponectin with a GGA1 dominant-interfering mutant (GGA1-VHS GAT domain) resulted in a marked inhibition of adiponectin secretion in both 3T3L1 adipocytes and HEK293 cells, whereas no inhibition was detected with the truncated mutants GGA2-VHSGAT or GGA3-VHSGAT. Moreover, co-expression of wild type GGA1 with adiponectin enhanced secretion of adiponectin. Interestingly, leptin secretion was unaffected by neither the wild type form or GGA1 mutant. Taken together these data demonstrate that the trafficking of adiponectin through its secretory pathway is dependent on GGA-coated vesicles.