Calcium sensing receptor mutations implicated in pancreatitis and idiopathic epilepsy syndrome disrupt an arginine-rich retention motif.
Calcium sensing receptor mutations implicated in pancreatitis and idiopathic epilepsy syndrome disrupt an arginine-rich retention motif.
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与胰腺炎和特发性癫痫综合征有关的钙感应受体突变破坏了富含精氨酸的保留基序。
DOI：
10.1159/000320560
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Breitwieser,GerdaE
中科院分区：
文献类型：
--
作者：
Stepanchick,Ann;McKenna,Jennifer;McGovern,Olivia;Huang,Ying;Breitwieser,GerdaE
与家族性低钙高钙血症、胰腺炎和特发性癫痫综合征相关的钙敏感受体（CaSR）突变与近端羧基端一个扩展的富含精氨酸的区域有关。富含精氨酸的基元介导内质网保留和/或多亚基蛋白的恢复，因此我们询问这些突变，R886P， R896H或R898Q是否改变了靶向质膜的CaSR。这三种突变都增强了靶向性，Ca2+刺激的ERK1/2磷酸化增加了R896H和R898Q。为了确定扩展的富含精氨酸区域在CaSR运输中的作用，我们独立确定了R890/R891和/或R896/K897/R898基序通过突变对丙氨酸的贡献。基序的破坏显著增加了相对于wt CaSR的表面表达和功能。富含精氨酸的区域两侧是S892（蛋白激酶C）和S899（蛋白激酶A）的磷酸化位点。S899的磷酸化状态调节了对富含精氨酸区域的识别；S899D表面局部化增强。CaSR在内质网中以共价二硫键二聚体的形式组装，我们确定了保留是否需要在两个亚基中存在富含精氨酸的区域。二聚体中一个富含精氨酸的区域足以产生与wt CaSR相当的细胞内保留。我们已经在CaSR的近羧基端（残基R890 - R898）发现了一个扩展的富含精氨酸的区域，该区域促进CaSR的细胞内保留并受磷酸化调节。因此，在慢性胰腺炎和特发性癫痫综合征中发现的突变增加了CaSR的质膜靶向，可能导致这些疾病的Ca2+信号特征改变。
Calcium sensing receptor (CaSR) mutations implicated in familial hypocalciuric hypercalcemia, pancreatitis and idiopathic epilepsy syndrome map to an extended arginine-rich region in the proximal carboxyl terminus. Arginine-rich motifs mediate endoplasmic reticulum retention and/or retrieval of multisubunit proteins so we asked whether these mutations, R886P, R896H or R898Q, altered CaSR targeting to the plasma membrane. Targeting was enhanced by all three mutations, and Ca2+-stimulated ERK1/2 phosphorylation was increased for R896H and R898Q. To define the role of the extended arginine-rich region in CaSR trafficking, we independently determined the contributions of R890/R891 and/or R896/K897/R898 motifs by mutation to alanine. Disruption of the motif(s) significantly increased surface expression and function relative to wt CaSR. The arginine-rich region is flanked by phosphorylation sites at S892 (protein kinase C) and S899 (protein kinase A). The phosphorylation state of S899 regulated recognition of the arginine-rich region; S899D showed increased surface localization. CaSR assembles in the endoplasmic reticulum as a covalent disulfide-linked dimer and we determined whether retention requires the presence of arginine-rich regions in both subunits. A single arginine-rich region within the dimer was sufficient to confer intracellular retention comparable to wt CaSR. We have identified an extended arginine-rich region in the proximal carboxyl terminus of CaSR (residues R890 - R898) which fosters intracellular retention of CaSR and is regulated by phosphorylation. Mutation(s) identified in chronic pancreatitis and idiopathic epilepsy syndrome therefore increase plasma membrane targeting of CaSR, likely contributing to the altered Ca2+signaling characteristic of these diseases.