TRPP2 and STIM1 form a microdomain to regulate store-operated Ca2+ entry and blood vessel tone

Jizheng Guo,Ren Zhao,Jiexia Chen,Muyao Zhou,Juan Du,Bing Shen,Jie Li,Xiaoqiang Yao

doi:10.1186/s12964-020-00560-7

Abstract

BackgroundPolycystin-2 (TRPP2) is a Ca2+ permeable nonselective cationic channel essential for maintaining physiological function in live cells. Stromal interaction molecule 1 (STIM1) is an important Ca2+ sensor in store-operated Ca2+ entry (SOCE). Both TRPP2 and STIM1 are expressed in endoplasmic reticular membrane and participate in Ca2+ signaling, suggesting a physical interaction and functional synergism.MethodsWe performed co-localization, co-immunoprecipitation, and fluorescence resonance energy transfer assay to identify the interactions of TRPP2 and STIM1 in transfected HEK293 cells and native vascular smooth muscle cells (VSMCs). The function of the TRPP2-STIM1 complex in thapsigargin (TG) or adenosine triphosphate (ATP)-induced SOCE was explored using specific small interfering RNA (siRNA). Further, we created TRPP2 conditional knockout (CKO) mouse to investigate the functional role of TRPP2 in agonist-induced vessel contraction.ResultsTRPP2 and STIM1 form a complex in transfected HEK293 cells and native VSMCs. Genetic manipulations with TRPP2 siRNA, dominant negative TRPP2 or STIM1 siRNA significantly suppressed ATP and TG-induced intracellular Ca2+ release and SOCE in HEK293 cells. Inositol triphosphate receptor inhibitor 2-aminoethyl diphenylborinate (2APB) abolished ATP-induced Ca2+ release and SOCE in HEK293 cells. In addition, TRPP2 and STIM1 knockdown significantly inhibited ATP- and TG-induced STIM1 puncta formation and SOCE in VSMCs. Importantly, knockdown of TRPP2 and STIM1 or conditional knockout TRPP2 markedly suppressed agonist-induced mouse aorta contraction.ConclusionsOur data indicate that TRPP2 and STIM1 are physically associated and form a functional complex to regulate agonist-induced intracellular Ca2+ mobilization, SOCE and blood vessel tone.D6Kq4S1Z2iQsuoA7W_wV84Video abstract

Highlights

Polycystin-2 (TRPP2) is a Ca2+ permeable nonselective cationic channel essential for maintaining physiological function in live cells
Physical interaction between heterologously expressed TRPP2 and Stromal interaction molecule 1 (STIM1) in human embryonic kidney 293 (HEK293) cells Both TRPP2 and STIM1 are expressed in the endoplasmic reticulum (ER) membrane
We used sensitized emission Fluorescence resonance energy transfer (FRET), a powerful tool to identify protein-protein interactions [26], to probe if TRPP2 and STIM1 directly interact with each other. Because both the N- and C-termini of TRPP2 as well as the C-terminus of STIM1 are all located at the cytoplasmic side of the ER membrane [14, 37], we reasoned that if the two proteins interact, one of the cytoplasmic termini of TRPP2 should be in close proximity with the STIM1 C-terminus

Summary

Introduction

Polycystin-2 (TRPP2) is a Ca2+ permeable nonselective cationic channel essential for maintaining physiological function in live cells. Stromal interaction molecule 1 (STIM1) is an important Ca2+ sensor in storeoperated Ca2+ entry (SOCE) Both TRPP2 and STIM1 are expressed in endoplasmic reticular membrane and participate in Ca2+ signaling, suggesting a physical interaction and functional synergism. TRPP2 is encoded by the PKD2 gene and commonly thought to assemble with the polycystic kidney disease 1 (PKD1) protein to form a receptor-ion channel complex, which is widely expressed in a variety of cell types and tissues including renal epithelium, hepatic bile ducts, pancreatic ducts, vascular smooth muscle cells (VSMCs), and endothelial cells. TRPP2 may assemble with TRPC1 or TRPV4 to form heteromeric channels participating in mechanosensing and cilium-based Ca2+ signaling [4, 5]. TRPP2 has been shown to regulate cilia movement, apoptosis, mechanosensing, left-right asymmetry, sperm movement and male fertility, and cardiovascular function [9,10,11,12]

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