Caveolin regulates microtubule polymerization in the vascular smooth muscle cells.
Microtubule and caveolin have common properties in intracellular trafficking and the regulation of cellular growth. Overexpression of caveolin in vascular smooth muscle cells increased the polymer form of microtubule without changing in the total amount of tubulin, and downregulation of caveolin decreased the polymer form of microtubule. Fractionation of cellular proteins followed by immunodetection as well as immunostaining of caveolin and microtubule revealed that caveolin and a portion of microtubule were co-localized in caveolar fractions. A caveolin scaffolding domain peptide, which mimics caveolin function, did not alter the polymerization of microtubule in vitro, but dramatically inhibited the depolymerization of microtubule induced by stathmin, a microtubule destabilizing protein, which was also found in caveolar fractions. Accordingly, it is most likely that caveolin increased the polymer form of microtubule through the inhibition of a microtubule destabilizer, stathmin, suggesting a novel role of caveolin in regulating cellular network and trafficking.
Kawabe
Jun-ichi
J
Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA. kawabeju@asahikawa-med.ac.jp
Okumura
Satoshi
S
Nathanson
Mark A
MA
Hasebe
Naoyuki
N
Ishikawa
Yoshihiro
Y
D000818:Animals; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D021941:Caveolae / Q000378:metabolism; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism*; D051244:Caveolin 3 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D015536:Down-Regulation; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D021381:Protein Transport; D051381:Rats; D050777:Stathmin / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism
D001704:Biopolymers; D051242:Caveolin 1; D051244:Caveolin 3; D010446:Peptide Fragments; D050777:Stathmin; D014404:Tubulin