Acid-sensing ion channel 3 (ASIC3) cell surface expression is modulated by PSD-95 within lipid rafts
Acid-sensing ion channel 3 (ASIC3) cell surface expression is modulated by PSD-95 within lipid rafts
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DOI：
10.1152/ajpcell.00514.2007
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发表时间：
2008-09-01
影响因子：
5.5
通讯作者：
Benson, Christopher J.
中科院分区：
文献类型：
--
作者：
Eshcol, Jayasheel O.;Harding, Anne Marie S.;Benson, Christopher J.
酸敏感离子通道3(ASIC3)是一种Hα门控阳离子通道，主要存在于感觉神经元中，在代谢紊乱或疼痛条件下，它可以作为pH传感器发挥作用。我们先前发现，ASIC3通过其COOH末端与突触后密度蛋白PSD-95相互作用，导致ASIC3细胞表面表达减少，H(+)门控电流减少。PSD-95与向脂筏募集蛋白质有关，脂筏是富含胆固醇和鞘磷脂的膜微域，组织受体/信号复合体。我们发现ASIC3和PSD-95在抗洗涤剂膜组分中共沉淀。当细胞暴露于甲基-β-环糊精以耗尽膜胆固醇和破坏脂筏时，PSD-95对脂筏部分的定位被取消，不再抑制ASIC3电流。同样，PSD-95中两个半胱氨酸残基的突变经历了棕榈酰化(一种针对PSD-95到脂筏的脂质修饰)，阻止了它对ASIC3电流和细胞表面表达的抑制。此外，我们还发现细胞表面的ASIC3富含脂筏组分。这些数据表明，PSD-95和ASIC3在脂筏内相互作用，这种RAFT相互作用是PSD-95调节ASIC3所必需的。
Acid-sensing ion channel 3 (ASIC3) is a H alpha-gated cation channel primarily found in sensory neurons, where it may function as a pH sensor in response to metabolic disturbances or painful conditions. We previously found that ASIC3 interacts with the postsynaptic density protein PSD-95 through its COOH terminus, which leads to a decrease in ASIC3 cell surface expression and H(+)-gated current. PSD-95 has been implicated in recruiting proteins to lipid rafts, which are membrane microdomains rich in cholesterol and sphingolipids that organize receptor/ signaling complexes. We found ASIC3 and PSD-95 coimmunoprecipitated within detergent-resistant membrane fractions. When cells were exposed to methyl-beta-cyclodextrin to deplete membrane cholesterol and disrupt lipid rafts, PSD-95 localization to lipid raft fractions was abolished and no longer inhibited ASIC3 current. Likewise, mutation of two cysteine residues in PSD-95 that undergo palmitoylation (a lipid modification that targets PSD-95 to lipid rafts) prevented its inhibition of ASIC3 current and cell surface expression. In addition, we found that cell surface ASIC3 is enriched in the lipid raft fraction. These data suggest that PSD-95 and ASIC3 interact within lipid rafts and that this raft interaction is required for PSD-95 to modulate ASIC3.