Cytokine-induced Down-regulation of zfm1/Splicing Factor-1 Promotes Smooth Muscle Cell Proliferation

Marco Cattaruzza,Katrin Schäfer,Markus Hecker

doi:10.1074/jbc.m108283200

Marco Cattaruzza, Katrin Schäfer + Show 1 more

Open Access

https://doi.org/10.1074/jbc.m108283200

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Abstract

One hallmark of inflammation is the proliferation of bystander cells such as vascular smooth muscle cells (SMC), a process governed by growth factors and cytokines. Whereas cytokine induction of gene products promoting inflammation and proliferation is well characterized, little is known about the concomitant down-regulation of potentially counter-regulatory gene products in these cells. By employing the suppression subtractive hybridization-PCR technique, RNA isolated from rat aortic SMC treated with the cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) was subtracted from RNA of control cells. Eleven genes were identified, the expression of which fell by 44-77%. One, the transcriptional repressor splicing factor-1 or zfm1, was characterized further. Antisense oligonucleotide suppression of zfm1 protein synthesis mimicked the stimulatory effects of IL-1 beta and TNF alpha on SMC proliferation and expression of the chemokine MCP-1 and the vascular cell adhesion molecule-1. Moreover, in an in vivo mouse model of atherosclerosis, zfm1 abundance was decreased in proliferating arterial SMC. These findings suggest a role for zfm1 in controlling both proliferation and expression of pro-inflammatory gene products in SMC. Therefore, cytokine-induced down-regulation of zfm1 expression may contribute to the pathogenesis of hyperproliferative inflammatory diseases.

Highlights

Pro-inflammatory cytokines such as interleukin-1␤ (IL-1␤1) and tumor necrosis factor ␣ (TNF␣) play an important role both in acute and chronic inflammation
One hallmark of inflammation is the proliferation of bystander cells such as vascular smooth muscle cells (SMC), a process governed by growth factors and cytokines
Subtractive hybridization of cDNA derived from rat aortic cultured SMC, which were exposed to IL-1␤ plus TNF␣, against cDNA isolated from quiescent SMC combined with suppression PCR analysis [11] was performed, followed by cloning and sequencing of the differentially expressed gene products

Summary

Introduction

Pro-inflammatory cytokines such as interleukin-1␤ (IL-1␤1) and tumor necrosis factor ␣ (TNF␣) play an important role both in acute and chronic inflammation. The pro-inflammatory effect of these cytokines seems to involve the up-regulation of various gene products such as the chemokine monocyte chemoattractant protein-1 (MCP-1 [7]) or the vascular cell adhesion molecule-1 (VCAM-1 [8]), capable of recruiting circulating leukocytes to the site of inflammation. In addition to the many known genes induced by IL-1␤ plus TNF␣, it is important to identify gene products, which help to maintain the phenotype of bystander cells in inflamed tissue, but are down-regulated upon exposure to proinflammatory cytokines. To identify such gene products, cultured vascular SMC were used as a model system. Subtractive hybridization of cDNA derived from rat aortic cultured SMC, which were exposed to IL-1␤ plus TNF␣, against cDNA isolated from quiescent SMC combined with suppression PCR analysis [11] was performed, followed by cloning and sequencing of the differentially expressed gene products

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