Regulation of vascular smooth muscle proliferation and migration by beta2-chimaerin, a non-protein kinase C phorbol ester receptor.

Abstract

The proliferation and migration of vascular smooth muscle cells (SMC) are important aspects of atherogenesis. Activated growth factor signaling in injured vessels subsequently promotes a number of intracellular events resulting in the phenotypic modulation of SMC. Here, we investigated the role of beta2-chimaerin, a non-protein kinase C phorbol ester receptor with Rac-GTPase-activating protein activity, in growth factor-stimulated SMC. The endogenous expression of beta2-chimaerin was detected in cultured human SMC by reverse transcription-polymerase chain reaction and immunohistochemistry. Next, the overexpression of HA-tagged wild-type human beta2-chimaerin was attempted using cultured rat SMC with a recombinant adenovirus (Adv-beta2-Chim). Adv-LZ encoding beta-galactosidase (LacZ) was used as the control. The proliferation of SMC stimulated by platelet-derived growth factor (PDGF-BB, 10 ng/ml), as measured by cell-counting and 5-bromo-2'deoxyuridine incorporation assay, was suppressed by infection with Adv-beta2-Chim (50-200 MOI), but not with control viruses. PDGF-induced SMC migration was inhibited by approximately 25% after infection with Adv-beta2-Chim (200 MOI) using a modified Boyden's chamber assay with a fibronectin-coated membrane. Confocal microscopy revealed that PDGF stimulation altered the sub-cellular localization of beta2-chimaerin. The administration of 12-O-tetradecanoyl phorbol 13-acetate also induced changes in the sub-cellular localization of beta2-chimaerin, which was not affected by a presence of the PKC inhibitor (GF109203X). Finally, PDGF-induced Rac1 activation was found to be inhibited in the Adv-beta2-Chim-infected cells. Thus, we demonstrated that beta2-chimaerin regulates the proliferation and migration of SMC downstream of growth factor signaling pathway via the regulation of Rac1 activity. The signaling mediated by beta2-chimaerin may play a role in the regulation of SMC phenotypes, thereby implicating human atherogenesis.

• Authors: Mitsuhide Maeda, Seiya Kato, Shintro Fukushima, Utako Kaneyuki, Teruhiko Fujii, Marcelo G Kazanietz, Koichi Oshima, Minoru Shigemori
• Journal: International journal of molecular medicine (Int J Mol Med) Vol. 17 Issue 4 Pg. 559-66 (Apr 2006) ISSN: 1107-3756 [Print] Greece
• PMID: 16525710 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• GTPase-Activating Proteins
• Indoles
• Maleimides
• Mitogens
• Neoplasm Proteins
• Platelet-Derived Growth Factor
• beta-chimaerin
• Protein Kinase C
• bisindolylmaleimide I
• Tetradecanoylphorbol Acetate

Topics

• Animals
• Blotting, Western
• Cell Line
• Cell Line, Tumor
• Cell Movement (physiology)
• Cell Proliferation
• Cells, Cultured
• GTPase-Activating Proteins (genetics, metabolism, physiology)
• Gene Expression (drug effects)
• Humans
• Immunohistochemistry
• Indoles (pharmacology)
• Infant, Newborn
• Maleimides (pharmacology)
• Mitogens (pharmacology)
• Muscle, Smooth, Vascular (cytology, drug effects, metabolism)
• Neoplasm Proteins (genetics, metabolism, physiology)
• Platelet-Derived Growth Factor (pharmacology)
• Protein Kinase C (antagonists & inhibitors)
• Rats
• Reverse Transcriptase Polymerase Chain Reaction
• Tetradecanoylphorbol Acetate (pharmacology)