Smoothelin Expression Characteristics: Development of a Smooth Muscle Cell in vitro System and Identification of a Vascular Variant

Cell Structure and Function

Maureen C.W. Völler¹  Frans C.S. Ramaekers²  Xander H.T. Wehrens²  Erika D.J. Timmer²  Frank T.L. van der Loop²  J. Vic Small³  Guillaume J.J.M. van Eys²  Jack A. Schalken¹ 

[1] Urology Research Laboratory, University of Nijmegen;Department of Molecular Cell Biology and Genetics, Maastricht University, Cardiovascular Research Institute Maastricht;Institute of Molecular Biology, Austrian Acad. Sci.

关键词: actin;    exchangeability;    cardiomyocyte;    fibroblast;    photobleach;   

DOI  :  10.1247/csf.22.65

学科分类：分子生物学，细胞生物学和基因

来源: Japan Society for Cell Biology

【 摘 要 】

References(38)Cited-By(20)Recently we described a protein, smoothelin, that has been exclusively found in smooth muscle cells (SMC). The human cDNA has been cloned from a colon cDNA library and the putative protein sequence was deduced. Smoothelin does not belong to a known protein family but shows a partial homology with members of the spectrin family. Transfection studies revealed that smoothelin has an affinity for actin and is either capable of forming filamentous structures or colocalizes with such structures. The protein is expressed in visceral as well as vascular tissues of all vertebrate classes. A study on the distribution of smoothelin in the vascular and placental system showed that smoothelin expression was largely restricted to the muscular pulsating blood vessels. Therefore, we hypothesized that smoothelin is expressed in contractile SMC only (36, 37). No expression of smoothelin was observed in established cell lines of SMC. In tissue explants smoothelin mRNA concentration decreases to undetectable levels within 12 hours after dissection as was in general the case in primary cell cultures. Here we report on continued smoothelin expression for several passages observed in a human prostate primary cell culture system. Smoothelin was demonstrated to colocalize with actin stress fibers but not with desmin filaments. This culture system offers opportunities to study the cytological localization of smoothelin, interactions with other proteins and should provide a system to test the promoter of the smoothelin gene. On immunoblots the molecular weight of smoothelin differed between visceral and vascular smooth muscle tissue with apparent molecular weights of respectively 59 kDa and 94 kDa. There is no evidence for the existence of another gene coding for the 94 kDa smoothelin. Thus, posttranslational modification, alternative splicing and dual promoter control are the alternatives for the expression of two isoforms of smoothelin.

【 授权许可】

Unknown