S1P1 receptor localization confers selectivity for Gi-mediated cAMP and contractile responses
S1P1 receptor localization confers selectivity for Gi-mediated cAMP and contractile responses
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DOI：
10.1074/jbc.m707422200
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发表时间：
2008-05-02
影响因子：
4.8
通讯作者：
Brown, Joan Heller
中科院分区：
文献类型：
--
作者：
Means, Christopher Kable;Miyamoto, Shigeki;Brown, Joan Heller
成年小鼠心肌细胞表达S1P(1)、S1P(2)和S1P(3)受体。S1P通过百日咳毒素敏感(G(i/o)介导)途径激活成年小鼠心室肌细胞Akt和ERK。S1P对AKT和ERK的激活作用与S1P(3)和S1P(2)受体敲除心肌细胞的30%和60%相似。随着S1P(2，3)受体的联合缺失，Akt的激活被取消，ERK的激活减少了近90%。因此，S1P(1)受体虽然存在于S1P(2，3)受体敲除的心肌细胞中，但不能介导Akt或ERK的激活。相反，在WT和S1P(2，3)受体敲除的心肌细胞中，S1P诱导百日咳毒素敏感地抑制异丙肾上腺素刺激的cAMP积聚，表明S1P(1)受体可以与G(I)功能偶联。S1P(1)受体选择性激动剂SEW2871也可减少cAMP积聚，但不能激活ERK或Akt。为了确定S1P(1)受体的定位是否介导了这种信号特异性，用甲基-β-环糊精(M-βCD)处理来破坏小窝。S1P(1)受体主要集中在小窝部分，并与小窝蛋白-3结合，这种定位被MβCD干扰。MβCD不减弱S1P对ERK或Akt的激活作用，但可完全消除S1P和SEW2871对cAMP聚集的抑制作用。S1P抑制对异丙肾上腺素的正性变力反应，这种反应也是通过S1P(1)受体介导的，并在小窝破裂后消失。因此，S1P(1)受体需要定位于小窝，以抑制腺苷环化酶和收缩能力，但影响受体与Akt和ERK的偶联。
Adult mouse ventricular myocytes express S1P(1), S1P(2), and S1P(3) receptors. S1P activates Akt and ERK in adult mouse ventricular myocytes through a pertussis toxin-sensitive (G(i/o)-mediated) pathway. Akt and ERK activation by S1P are reduced similar to 30% in S1P(3) and 60% in S1P(2) receptor knock- out myocytes. With combined S1P(2,3) receptor deletion, activation of Akt is abolished and ERK activation is reduced by nearly 90%. Thus the S1P(1) receptor, while present in S1P(2,3) receptor knock- out myocytes, is unable to mediate Akt or ERK activation. In contrast, S1P induces pertussis toxin-sensitive inhibition of isoproterenol-stimulated cAMP accumulation in both WT and S1P(2,3) receptor knock- out myocytes demonstrating that the S1P(1) receptor can functionally couple to G(i). An S1P(1) receptor selective agonist, SEW2871, also decreased cAMP accumulation but failed to activate ERK or Akt. To determine whether localization of the S1P(1) receptor mediates this signaling specificity, methyl-beta-cyclodextrin (M beta CD) treatment was used to disrupt caveolae. The S1P(1) receptor was concentrated in caveolar fractions, and associated with caveolin-3 and this localization was disrupted by M beta CD. S1P-mediated activation of ERK or Akt was not diminished but inhibition of cAMP accumulation by S1P and SEW2871 was abolished by M beta CD treatment. S1P inhibits the positive inotropic response to isoproterenol and this response is also mediated through the S1P(1) receptor and lost following caveolar disruption. Thus localization of S1P(1) receptors to caveolae is required for the ability of this receptor to inhibit adenylyl cyclase and contractility but compromises receptor coupling to Akt and ERK.