Polycystin-1 and polycystin-2 are both required to amplify inositol-trisphosphate-induced Ca²⁺ release

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• 作者：D. Mekahli^a ; ^b ; E. Sammels^c ; T. Luyten^a ; K. Welkenhuyzen^a ; L.P. van den Heuvel^b ; E.N. Levtchenko^b ; R. Gijsbers^d ; G. Bultynck^a ; J.B. Parys^a ; H. De Smedt^a ; ^{humbert.desmedt@med.kuleuven.be} ; L. Missiaen^a
• 关键词：Polycystin ; ADPKD ; Inositol 1 ; 4 ; 5-trisphosphate receptor ; Endoplasmic reticulum ; Ca2+ release
• 刊名：Cell Calcium
• 出版年：2012
• 期刊代码：7_01434160
• 类别：bio
• 出版时间：June, 2012
• 卷：51
• 期：6
• 页码：452-458
• 文件大小：431 K

摘要

Autosomal dominant polycystic kidney disease is caused by loss-of-function mutations in the PKD1 or PKD2 genes encoding respectively polycystin-1 and polycystin-2. Polycystin-2 stimulates the inositol trisphosphate (IP₃) receptor (IP₃R), a Ca²⁺-release channel in the endoplasmic reticulum (ER). The effect of ER-located polycystin-1 is less clear. Polycystin-1 has been reported both to stimulate and to inhibit the IP₃R. We now studied the effect of polycystin-1 and of polycystin-2 on the IP₃R activity under conditions where the cytosolic Ca²⁺ concentration was kept constant and the reuptake of released Ca²⁺ was prevented. We also studied the interdependence of the interaction of polycystin-1 and polycystin-2 with the IP₃R. The experiments were done in conditionally immortalized human proximal-tubule epithelial cells in which one or both polycystins were knocked down using lentiviral vectors containing miRNA-based short hairpins. The Ca²⁺ release was induced in plasma membrane-permeabilized cells by various IP₃ concentrations at a fixed Ca²⁺ concentration under unidirectional ⁴⁵Ca²⁺-efflux conditions. We now report that knock down of polycystin-1 or of polycystin-2 inhibited the IP₃-induced Ca²⁺ release. The simultaneous presence of the two polycystins was required to fully amplify the IP₃-induced Ca²⁺ release, since the presence of polycystin-1 alone or of polycystin-2 alone did not result in an increased Ca²⁺ release. These novel findings indicate that ER-located polycystin-1 and polycystin-2 operate as a functional complex. They are compatible with the view that loss-of-function mutations in PKD1 and in PKD2 both cause autosomal dominant polycystic kidney disease.