Low-density lipoproteins induce heat shock protein 27 dephosphorylation, oligomerization, and subcellular relocalization in human vascular smooth muscle cells.
OBJECTIVE
High levels of circulating low-density lipoproteins (LDL) are a major atherosclerotic risk factor. The effects of intimal LDL on vascular smooth muscle cell (VSMC) phenotype and function during plaque remodeling and vascular repair are not fully understood. We have investigated whether exposure of VSMC to LDL induces changes on the proteomic profile of the heat shock protein (HSP) family-molecular chaperones involved in atherosclerosis. Methods & Results- 2D electrophoresis demonstrates that LDL modifies the proteomic profile of HSP27 (HSPB1). Western blot analysis evidenced a significant HSP27 dephosphorylation after exposure of cells to native LDL (nLDL) and aggregated-LDL (agLDL) for 24 hours (P<0.05). Dephosphorylation of HSP27 was not related to changes in p38(MAPK) phosphorylation. Both nLDL and agLDL induced relocalization of unphosphorylated HSP27 to the tip of actin stress fibers and focal adhesion structures in VSMC. During cell adhesion, phospho-HSP27 was located at the cell surface contact region in LDL-treated cells, whereas it remained cytosolic in control cells. Immunohistochemistry studies showed that phosphorylated HSP27 is rarely found in lipid-rich areas of atherosclerotic plaques in human coronary arteries.


CONCLUSIONS
Our results indicate that in VSMC, LDL modulate HSP27 phosphorylation and subcellular localization, affecting actin polymerization and cytoskeleton dynamics.
García-Arguinzonis
Maísa
M
Cardiovascular Research Center, Consejo Superior de Investigaciones Científicas, Instituto Catalán de Ciencias Cardiovasculares, Hospital Santa Creu i Sant Pau (UAB), Barcelona, Spain.
Padró
Teresa
T
Lugano
Roberta
R
Llorente-Cortes
Vicenta
V
Badimon
Lina
L
D000199:Actins / Q000378:metabolism; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D003324:Coronary Artery Disease / Q000378:metabolism / Q000473:pathology; D015180:Electrophoresis, Gel, Two-Dimensional; D022001:Focal Adhesions / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins; D006801:Humans; D007150:Immunohistochemistry; D008077:Lipoproteins, LDL / Q000378:metabolism*; D018613:Microscopy, Confocal; D018832:Molecular Chaperones; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D055503:Protein Multimerization; D054648:Protein Phosphatase 2 / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D040901:Proteomics / Q000379:methods; D012720:Severity of Illness Index; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D022502:Stress Fibers / Q000378:metabolism; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D000199:Actins; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D008077:Lipoproteins, LDL; D018832:Molecular Chaperones; D048051:p38 Mitogen-Activated Protein Kinases; D054648:Protein Phosphatase 2