PDF(Pubmed)
Abstract：
Phospholipase A2 receptor 1 (PLA2R1) is a 180-kDa transmembrane protein that plays a role in inflammation and cancer and is the major autoantigen in membranous nephropathy, a rare but severe autoimmune kidney disease. A soluble form of PLA2R1 has been detected in mouse and human serum. It is likely produced by proteolytic shedding of membrane-bound PLA2R1 but the mechanism is unknown. Here, we show that human PLA2R1 is cleaved by A Disintegrin And Metalloprotease 10 (ADAM10) and ADAM17 in HEK293 cells, mouse embryonic fibroblasts, and human podocytes. By combining site-directed mutagenesis and sequencing, we determined the exact cleavage site within the extracellular juxtamembrane stalk of human PLA2R1. Orthologs and paralogs of PLA2R1 are also shed. By using pharmacological inhibitors and genetic approaches with RNA interference and knock-out cellular models, we identified a major role of ADAM10 in the constitutive shedding of PLA2R1 and a dual role of ADAM10 and ADAM17 in the stimulated shedding. We did not observe evidence for cleavage by β- or γ-secretase, suggesting that PLA2R1 may not be a substrate for regulated intramembrane proteolysis. PLA2R1 shedding occurs constitutively and can be triggered by the calcium ionophore ionomycin, the protein kinase C activator PMA, cytokines, and lipopolysaccharides, in vitro and in vivo. Altogether, our results show that PLA2R1 is a novel substrate for ADAM10 and ADAM17, producing a soluble form that is increased in inflammatory conditions and likely exerts various functions in physiological and pathophysiological conditions including inflammation, cancer, and membranous nephropathy.
摘要：
磷脂酶A2受体1（PLA2R1）是一种180kDa的跨膜蛋白，在炎症和癌症中起作用，是膜性肾病（MN）的主要自身抗原，一种罕见但严重的自身免疫性肾病.已在小鼠和人血清中检测到PLA2R1的可溶形式。它可能是由膜结合的PLA2R1的蛋白水解脱落产生的，但机制尚不清楚。这里,我们显示人PLA2R1在HEK293细胞中被去整合素和金属蛋白酶10（ADAM10）和ADAM17切割，小鼠胚胎成纤维细胞和人足细胞。通过结合定点诱变和测序，我们确定了人PLA2R1的细胞外近膜茎内的确切切割位点。PLA2R1的直系同源物和旁系同源物也脱落。通过使用药理学抑制剂和遗传方法与RNA干扰和敲除细胞模型，我们确定了ADAM10在PLA2R1的组成型脱落中的主要作用，以及ADAM10和ADAM17在刺激脱落中的双重作用。我们没有观察到β-或γ-分泌酶切割的证据，这表明PLA2R1可能不是调节的膜内蛋白水解的底物。PLA2R1脱落是组成型发生的，可以由钙离子载体离子霉素触发，蛋白激酶C诱导剂PMA，细胞因子和脂多糖，在体外和体内。总之,我们的结果表明，PLA2R1是ADAM10和ADAM17的新型底物，产生在炎症条件下增加的可溶性形式，并可能在包括炎症在内的生理和病理生理条件下发挥各种功能，癌症和MN
