Bestrophin-3 (vitelliform macular dystrophy 2-like 3 protein) is essential for the cGMP-dependent calcium-activated chloride conductance in vascular smooth muscle cells.
Although the biophysical fingerprints (ion selectivity, voltage-dependence, kinetics, etc) of Ca(2+)-activated Cl(-) currents are well established, their molecular identity is still controversial. Several molecular candidates have been suggested; however, none of them has been fully accepted. We have recently characterized a cGMP-dependent Ca(2+)-activated Cl(-) current with unique characteristics in smooth muscle cells. This novel current has been shown to coexist with a "classic" (cGMP-independent) Ca(2+)-activated Cl(-) current and to have characteristics distinct from those previously known for Ca(2+)-activated Cl(-) currents. Here, we suggest that a bestrophin, a product of the Best gene family, is responsible for the cGMP-dependent Ca(2+)-activated Cl(-) current based on similarities between the membrane currents produced by heterologous expressions of bestrophins and the cGMP-dependent Ca(2+)-activated Cl(-) current. This is supported by similarities in the distribution pattern of the cGMP-dependent Ca(2+)-activated Cl(-) current and bestrophin-3 (the product of Best-3 gene) expression in different smooth muscle. Furthermore, downregulation of Best-3 gene expression with small interfering RNA both in cultured cells and in vascular smooth muscle cells in vivo was associated with a significant reduction of the cGMP-dependent Ca(2+)-activated Cl(-) current, whereas the magnitude of the classic Ca(2+)-activated Cl(-) current was not affected. The majority of previous suggestions that bestrophins are a new Cl(-) channel family were based on heterologous expression in cell culture studies. Our present results demonstrate that at least 1 family member, bestrophin-3, is essential for a well-defined endogenous Ca(2+)-activated Cl(-) current in smooth muscles in the intact vascular wall.
Matchkov
Vladimir V
VV
Water and Salt Centre, Institute of Physiology and Biophysics, University of Aarhus, 8000 Aarhus C, Denmark. vvm@fi.au.dk
Larsen
Per
P
Bouzinova
Elena V
EV
Rojek
Aleksandra
A
Boedtkjer
Donna M Briggs
DM
Golubinskaya
Veronika
V
Pedersen
Finn Skou
FS
Aalkjaer
Christian
C
Nilsson
Holger
H
D000818:Animals; D001011:Aorta / Q000378:metabolism; D000075002:Bestrophins; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials; D008638:Mesenteric Arteries / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D009544:Niflumic Acid / Q000494:pharmacology; D011651:Pulmonary Artery / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection
C568920:Best3 protein, rat; D000075002:Bestrophins; D018118:Chloride Channels; D002712:Chlorides; D009124:Muscle Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D009544:Niflumic Acid; D006152:Cyclic GMP; D002118:Calcium