12S-lipoxygenase protein associates with alpha-actin fibers in human umbilical artery vascular smooth muscle cells.
The current study sets out to characterize the intracellular localization of the platelet-type 12S-lipoxygenase (12-LO), an enzyme involved in angiotensin-II induced signaling in vascular smooth muscle cells (VSMC). Immunohistochemical analysis of VSMC in vitro or human umbilical arteries in vivo showed a clear cytoplasmic localization. On immunogold electron microscopy, 12-LO was found primarily associated with cytoplasmic VSMC muscle fibrils. Upon angiotensin-II treatment of cultured VSMC, immunoprecipitated 12-LO was found bound to alpha-actin, a component of the cytoplasmic myofilaments. 12-LO/alpha-actin binding was blocked by VSMC pretreatment with the 12-LO inhibitors, baicalien or esculetine and the protein synthesis inhibitor, cycloheximide. Moreover, the binding of 12-LO to alpha-actin was not associated with 12-LO serine or tyrosine phosphorylation. These observations suggest a previously unrecognized angiotensin-II dependent protein interaction in VSMC through which 12-LO protein may be trafficked, for yet undiscovered purposes towards the much more abundantly expressed cytoskeletal protein alpha-actin.
Weisinger
Gary
G
Institute of Endocrinology, Metabolism and Hypertension, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Israel. gary_w@tasmc.health.gov.il
Limor
Rona
R
Marcus-Perlman
Yonit
Y
Knoll
Esther
E
Kohen
Fortune
F
Schinder
Vera
V
Firer
Michael
M
Stern
Naftali
N
D000199:Actins / Q000378:metabolism*; D000804:Angiotensin II / Q000502:physiology; D001092:Arachidonate 12-Lipoxygenase / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000502:physiology; D008854:Microscopy, Electron; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D021381:Protein Transport; D013347:Subcellular Fractions / Q000201:enzymology; D014469:Umbilical Arteries / Q000166:cytology / Q000378:metabolism
D000199:Actins; D007527:Isoenzymes; D000804:Angiotensin II; D001092:Arachidonate 12-Lipoxygenase