Cloning, characterization, and chromosomal localization of human superillin (SVIL)

Robert K. Pope
Kersi N. Pestonjamasp
K. P. Smith
J. D. Wulfkuhle
C. P. Strassel
Jeanne B. Lawrence, University of Massachusetts Medical School
Elizabeth J. Luna, University of Massachusetts Medical School

Abstract

Supervillin is a 205-kDa F-actin binding protein originally isolated from bovine neutrophils. This protein is tightly associated with both actin filaments and plasma membranes, suggesting that it forms a high-affinity link between the actin cytoskeleton and the membrane. Human supervillin cDNAs cloned from normal human kidney and from the cervical carcinoma HeLa S3 predict a bipartite structure with three potential nuclear localization signals in the NH2-terminus and three potential actin-binding sequences in the COOH-terminus. In fact, throughout its length, the COOH-terminal half of supervillin is similar to segments 2-6 plus the COOH-terminal "headpiece" of villin, an actin-binding protein in intestinal microvilli. A comparison of the bovine and human sequences indicates that supervillin is highly conserved at the amino acid level, with 79.2% identity of the NH2-terminus and conservation of three of the four nuclear localization signals found in bovine supervillin. The COOH-terminus is even more conserved, with 95.1% amino acid identity overall and 100% conservation of the villin-like headpiece. Supervillin mRNAs are expressed in all human tissue tested, bu are most abundant in muscle, bone marrow, thyroid gland, and salivary gland; comparatively little message is found in brain. Human supervillin mRNA is approximately 7.5 kb; this message is especially abundant in HeLa S3 cervical carcinoma, SW480 adenocarcinoma, and A549 lung carcinoma cell lines. The human supervillin gene (SVIL) is localized to a single chromosomal locus at 10p11.2, a region that is deleted in some prostate tumors.