Cardiovascular Research Advance Access first published online on September 8, 2008
This version [Corrected Proof] published online on October 1, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn242
Inhibition of allograft inflammatory factor-1 expression reduces development of neointimal hyperplasia and p38 kinase activity
,*
Department of Physiology, Independence Blue Cross Cardiovascular Research Center, Temple University School of Medicine, 810, MRB, 3420 North Broad Street, Philadelphia, PA 19140, USA
* Corresponding author. Tel: +1 215 707 1751; fax: +1 215 707 5737. E-mail address: mautieri{at}temple.edu
Aims: Allograft inflammatory factor-1 (AIF-1) is a calcium-binding, scaffold-signalling protein expressed in vascular smooth muscle cells (VSMCs) in response to injury. The effects of AIF-1 attenuation on development of intimal hyperplasia are unknown, and the molecular mechanisms of these effects remain uncharacterized. The goals of the present study were to determine whether AIF-1 knockdown reduced VSMC proliferation, migration, and intimal hyperplasia, and determine AIF-1 effects on signal transduction in VSMCs.
Methods and results: Balloon angioplasty-injured rat carotid arteries transduced with adenovirus to overexpress AIF-1 (AdAIF-1) significantly increased, and adenovirus to knock down AIF-1 (AdsiRNA) expression significantly decreased neointimal formation compared with green fluorescent protein (AdGFP) and Adscrambled controls (P < 0.05 and P < 0.01, n = 6). Primary rat VSMCs transduced with AdAIF-1 displayed a significant increase in proliferation, and AdsiRNA-transduced VSMCs proliferated significantly more slowly than controls (P < 0.05). VSMCs transduced with AdAIF-1 show increased migration when compared with control VSMCs (P < 0.01). Rat VSMCs transduced with AdAIF-1 showed constitutive and prolonged activation of the mitogen-activated protein kinase p38, whereas AdsiRNA-treated VSMCs showed decreased p38 activation compared with AdGFP (P < 0.05). Immunohistochemical analysis of AdAIF-1-transduced carotid arteries showed increased staining with a phospho-specific p38 antibody compared with AdGFP-transduced arteries. A specific p38 inhibitor abrogated AIF-1-induced VSMC proliferation, but not AIF-1-induced migration.
Conclusion: Taken together, AIF-1 expression plays a key role in the development of neointimal hyperplasia. AIF-1 expression enhances the activation of p38 MAP kinase. AIF-1-enhanced proliferation is p38 kinase dependent, but AIF-1-enhanced VSMC migration is p38 independent.
KEYWORDS AIF-1; Smooth muscle cell; Balloon angioplasty; p38; Proliferation; Migration
Time for primary review: 15 days
These authors contributed equally to this work.