Mechanical strain induces monocyte chemotactic protein-1 gene expression in endothelial cells. Effects of mechanical strain on monocyte adhesion to endothelial cells.
Monocyte chemotactic protein-1 (MCP-1), a potent monocyte chemoattractant secreted by endothelial cells (ECs), is believed to play a key role in the early events of atherogenesis. Since vascular ECs are constantly subjected to mechanical stresses, we examined how cyclic strain affects the expression of the MCP-1 gene in human ECs grown on a flexible membrane base deformed by sinusoidal negative pressure (peak level, -16 kPa at 60 cycles per minute). Northern blot analysis demonstrated that the MCP-1 mRNA levels in ECs subjected to strain for 1, 5, or 24 hours were double those in control ECs (P < .05). This strain-induced increase was mainly serum independent, and MCP-1 mRNA level returned to its control basal level 3 hours after release of strain. Culture media from strained ECs contained approximately twice the MCP-1 concentration and more than twice the monocyte chemotactic activity of media from control ECs (P < .05). Pretreatment of collected media with anti-MCP-1 antibody suppressed such activity. Monocyte adhesion to ECs subjected to strain for 12 hours was 1.8-fold greater than adhesion to unstrained control ECs (P < .05). A protein kinase C inhibitor, calphostin C, abolished the strain-induced MCP-1 gene expression. In addition, cAMP- or cGMP-dependent protein kinase inhibitors (KT5720 and KT5823, respectively) partially inhibited such expression. Pretreatment with EGTA or the intracellular Ca2+ chelator BAPTA/AM strongly suppressed the strain-induced MCP-1 mRNA. Verapamil, a Ca2+ channel blocker, greatly reduced MCP-1 mRNA levels in both strained and unstrained ECs.(ABSTRACT TRUNCATED AT 250 WORDS)
Wang
D L
DL
Cardiovascular Division, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, ROC.
Wung
B S
BS
Shyy
Y J
YJ
Lin
C F
CF
Chao
Y J
YJ
Usami
S
S
Chien
S
S
D000704:Analysis of Variance; D001161:Arteriosclerosis / Q000209:etiology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D018932:Chemokine CCL2; D002630:Chemotactic Factors / Q000032:analysis / Q000235:genetics*; D016207:Cytokines / Q000235:genetics*; D004730:Endothelium, Vascular / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D009000:Monocytes / Q000502:physiology*; D011494:Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction; D013314:Stress, Mechanical; D000267:Tissue Adhesions; D014471:Umbilical Veins
D018932:Chemokine CCL2; D002630:Chemotactic Factors; D016207:Cytokines; D012333:RNA, Messenger; D011494:Protein Kinases; D002118:Calcium