Role of mitogen-activated protein kinases in pulmonary endothelial cells exposed to cyclic strain

Abstract

The aim of this study was to examine the role of mitogen-activated protein kinases (MAPKs) activation in bovine pulmonary arterial endothelial cells (EC) exposed to cyclic strain. EC were subjected to 10% average strain at 60 cycles/min. Cyclic strain induced activation of extracellular signal-regulated kinase (ERK; 1.5-fold), c-Jun NH(2)-terminal protein kinase (JNK; 1.9-fold), and p38 (1. 5-fold) with a peak at 30 min. To investigate the functional role of the activated MAPKs, we analyzed cells after treatment with PD-98059, a specific ERK kinase inhibitor, or SB-203580, a catalytic inhibitor for p38, and after transient transfection with JNK(K-R), and MEKK(K-M) the respective catalytically inactive mutants of JNK1 and MAPK kinase kinase-1. Cyclic strain increased activator protein-1 (AP-1) binding activity, which was blocked by PD-98059 and SB-203580. Activity of AP-1-dependent luciferase reporter driven by 12-O-tetradecanoyl-phorbol-13-acetate-responsive element (TRE) was induced by cyclic strain, and this was attenuated by PD-98059, MEKK(K-M), JNK(K-R), and SB-203580. PD-98059 and SB-203850 did not inhibit cell alignment and migration induced by cyclic strain. MEKK(K-M) and JNK(K-R) transfection did not block cyclic strain-induced cell alignment. In conclusion, cyclic strain activates ERK, JNK, and p38, and their activation plays a role in transcriptional activation of AP-1/TRE but not in cell alignment and migration changes in bovine pulmonary arterial EC.

Mitogen-activated protein kinases mediate stretch-induced c-fos mRNA expression in myometrial smooth muscle cells

“…Our finding of stretch-induced phosphorylation of ERK1/2, JNK, and p38 in myometrial SMCs in vitro is consistent with data from endothelial cells (24), vascular SMCs (28), mesangial cells (17), and cardiac myocytes (42). Importantly, our finding that ERK1/2 and p38 phosphorylation are increased in gravid (but not nongravid) myometrium before the onset of labor indicate that our in vitro data are informative of physio- 6.…”

“…Similarly, Kito et al (24) showed that specific inhibitors and dominant negative mutants that target any one MAPK pathway completely abolished stretch-induced AP-1 binding and activity. It is conceivable that activation of all three MAPKs is necessary to properly activate the downstream target, Elk-1, which requires phosphorylation of several residues in the carboxy terminus.…”

“…Studies have implicated p38 and JNK pathways in increased AP-1 activity in response to mechanical forces. Nuclear extracts from stretched mesangial cells (19) and endothelial cells (24) have increased DNA binding activity to the AP-1 consensus sequence, which can be attenuated by blocking the ERK or p38 pathway. Furthermore, transfection experiments using an AP-1 binding site-containing reporter gene reveal that stretch-induced AP-1 activity in endothelial cells is dependent on the ERK, JNK, and p38 pathways (24).…”

“…Studies in other cell types that employed in vitro stretch systems have demonstrated that cellular mechanotransduction activates multiple signaling molecules (41), including phospholipase C (PLC)-protein kinase C (PKC) (41), cAMP-protein kinase A (PKA) (8), the Janus kinasesignal transducers and activators of transcription (JAK-STAT) pathways (38), phosphatidylinositol 3-kinase (12), G proteins (13), small GTPases (1), receptor and nonreceptor tyrosine kinases (5,15,20,21,30), and, most notably, members of the mitogen-activated protein kinase (MAPK) family (24,28,42,44).…”

“…All three are serine-threonine kinases that transmit extracellular signals to the nucleus to control gene expression and regulate cellular process such as growth, differentiation, and apoptosis. Mechanical stimulation activates ERK, JNK, and p38 in a number of cell types including vascular SMCs (28), endothelial cells (24), cardiac myocytes (42), and mesangial cells (19).…”