视网膜电压依赖性阴离子通道：特性与细胞定位

Retinal voltage-dependent anion channel: characterization and cellular localization.

作者信息

Gincel Dan, Vardi Noga, Shoshan-Barmatz Varda

机构信息

Department of Life Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

出版信息

Invest Ophthalmol Vis Sci. 2002 Jul;43(7):2097-104.

PMID:12091402

Abstract

PURPOSE

To characterize and localize retinal voltage-dependent anion channel (VDAC) and to understand its possible contribution to mitochondrial function and dysfunction.

METHODS

VDAC was characterized by a method involving purification from isolated mitochondria and reconstitution into a planar lipid bilayer (PLB). The permeability transition pore (PTP) was monitored by Ca(2+) accumulation in isolated mitochondria and swelling of mitochondria. Localization was studied by immunocytochemistry and in situ hybridization.

RESULTS

Retinal VDACs exhibited the electrophysiological fingerprint of the VDAC superfamily. It had a maximal chord conductance of 3.7 +/- 0.1 nanosiemens (nS) in 1 M NaCl, and a voltage-dependent conductance that was highest at transmembrane potential close to zero. It was modulated by glutamate, which decreased the channel's open probability, and by La(3+) and ruthenium amine binuclear complex (Ru360), which closed the channel. Energized and freshly prepared retinal mitochondria accumulated Ca(2+) that is inhibited by La(3+) ruthenium red and Ru360. Subsequent to Ca(2+) accumulation, mitochondria released the accumulated Ca(2+), probably through activation of the PTP. Ru360 inhibited Ca(2+) release and mitochondrial swelling. VDAC was present in mitochondria of all retinal cell types: photoreceptor, bipolar, horizontal, amacrine, and ganglion cells. Most cells primarily expressed VDAC-1, but they also expressed VDAC-2 and -3.

CONCLUSIONS

These results suggest that VDAC is involved in PTP activity and/or regulation and thus is an important player in retinal degeneration associated with PTP-mediated mitochondrial dysfunction.

摘要

目的

对视网膜电压依赖性阴离子通道（VDAC）进行表征和定位，并了解其对线粒体功能及功能障碍可能产生的影响。

方法

通过从分离的线粒体中纯化并重组到平面脂质双层（PLB）中的方法对VDAC进行表征。通过分离的线粒体中Ca(2+)积累和线粒体肿胀来监测通透性转换孔（PTP）。通过免疫细胞化学和原位杂交研究定位。

结果

视网膜VDAC表现出VDAC超家族的电生理特征。在1 M NaCl中其最大弦电导为3.7±0.1纳西门子（nS），在跨膜电位接近零时电压依赖性电导最高。它受谷氨酸调节，谷氨酸降低通道的开放概率，还受La(3+)和钌胺双核配合物（Ru360）调节，后者使通道关闭。活跃且新制备的视网膜线粒体积累Ca(2+)，这一过程受La(3+)、钌红和Ru360抑制。Ca(2+)积累后，线粒体释放积累的Ca(2+)，可能是通过PTP的激活。Ru360抑制Ca(2+)释放和线粒体肿胀。VDAC存在于所有视网膜细胞类型的线粒体中：光感受器细胞、双极细胞、水平细胞、无长突细胞和神经节细胞。大多数细胞主要表达VDAC-1，但也表达VDAC-2和-3。