Voltage-dependent anion channel 2 modulates resting Ca²⁺ sparks, but not action potential-induced Ca²⁺ signaling in cardiac myocytes

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• 作者：Krishna Prasad Subedi^a ; Joon-Chul Kim^a ; Moonkyung Kang^b ; Min-Jeong Son^a ; Yeon-Soo Kim^b ; Sun-Hee Woo^a ; ^{shwoo@cnu.ac.kr}
• 关键词：Voltage-dependent anion channel 2 ; Knock down ; Ca²⁺ spark ; Cardiac Ca²⁺ signaling ; Lentivirus ; HL-1 cell
• 刊名：Cell Calcium
• 出版年：2011
• 出版时间：February 2011
• 年：2011
• 卷：49
• 期：2
• 页码：136-143
• 全文大小：964 K

文摘

Voltage-dependent anion channels (VDACs) are pore forming proteins predominantly found in the outer mitochondrial membrane and are thought to transport Ca²⁺. In this study, we have investigated the possible role of type 2 VDAC (VDAC2) in cardiac Ca²⁺ signaling and Ca²⁺ sparks using a lentiviral knock-down (KD) technique and two-dimensional confocal Ca²⁺ imaging in immortalized autorhythmic adult atrial cells, HL-1. We confirmed high expression of VDAC2 protein in ventricular, atrial, and HL-1 cells using Western blot analysis. Infection of HL-1 cells with VDAC2-targeting lentivirus reduced the level of VDAC2 protein to 10 % . Comparisons of autorhythmic Ca²⁺ transients between wild-type (WT) and VDAC2 KD cells showed no significant change in the magnitude, decay, and beating rate of the Ca²⁺ transients. Caffeine (10 mM)-induced Ca²⁺ release, which indicates sarcoplasmic reticulum (SR) Ca²⁺ content, was not altered by VDAC2 KD. Interestingly, however, the intensity, width, and duration of the individual Ca²⁺ sparks were significantly increased by VDAC2 KD in resting conditions, with no change in the frequency of sparks. VDAC2 KD significantly delayed mitochondrial Ca²⁺ uptake during artificial Ca²⁺ pulses in permeabilized HL-1 cells. These results suggest that VDAC2 may facilitate mitochondrial Ca²⁺ uptake and restrict Ca²⁺ spark expansion without regulating activations of sparks under resting conditions, thereby providing evidence on the functional role of VDAC2 in cardiac local Ca²⁺ signaling.