Membrane Depolarization Mediates Phosphorylation and Nuclear Translocation of CREB in Vascular Smooth Muscle Cells

• Published in: Experimental cell research 2001-02, Vol.263 (1), p.118-130
• Main Authors: Stevenson, Andrá S., Cartin, Laura, Wellman, Theresa L., Dick, Melissa H., Nelson, Mark T., Lounsbury, Karen M.
• Format: Article
• Language: English
• Subjects: Actins - metabolism; Active Transport, Cell Nucleus - drug effects; Animals; Aorta - cytology; Aorta - metabolism; calcium; Calcium - metabolism; Calcium Channel Blockers - pharmacology; Calcium Channels, L-Type - metabolism; Calcium Signaling; cAMP response element; Cell Nucleus - metabolism; Cells, Cultured; Colforsin - pharmacology; CREB; Cyclic AMP Response Element-Binding Protein - metabolism; Cyclic AMP-Dependent Protein Kinases - pharmacology; Female; Flow Cytometry; gene transcription; Genes, fos - genetics; Immunohistochemistry; In Vitro Techniques; Membrane Potentials - physiology; Microinjections; Models, Biological; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - metabolism; Nimodipine - pharmacology; nuclear transport; nucleus; phosphorylation; Phosphorylation - drug effects; Platelet-Derived Growth Factor - pharmacology; Ran; ran GTP-Binding Protein - genetics; ran GTP-Binding Protein - metabolism; Rats; Signal Transduction; Transfection; vascular smooth muscle
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1006/excr.2000.5107

Diverse signals have the potential to modulate gene transcription through the Ca2+ and cAMP response element binding protein (CREB) in vascular smooth muscle cells (VSMCs). A key step in the transmission of these signals is import into the nucleus. Here, we provide evidence that the Ran GTPase, which regulates nuclear import, exerts different regulation over PDGF-BB, Ca2+, and cAMP signaling to CREB in VSMCs. PDGF-BB, membrane depolarization, and forskolin increased levels of activated CREB (P-CREB) and c-fos in VSMCs and intact aorta. The calcium channel antagonist nimodipine reduced the level of P-CREB stimulated by membrane depolarization, but not by PDGF-BB or forskolin. Block of Ran-mediated nuclear import, by wheat germ agglutinin or an inactivating Ran mutant (T24N Ran), significantly reduced nuclear P-CREB in response to PDGF-BB or membrane depolarization, but enhanced levels of P-CREB in response to forskolin. Contrary to expectation, block of nuclear import led to the appearance of P-CREB in the cytoplasm after depolarization. Furthermore, blocking nuclear export with leptomycin B reduced P-CREB stimulation by both depolarization and PDGF-BB. These results suggest that translocation of CREB between the nucleus and the cytoplasm provides an important role in CREB activating pathways in VSMCs.