Differential gene expression of extracellular matrix components in dilated cardiomyopathy

Abstract

Extracellular matrix metalloproteinases (MMPs) are activated in dilated cardiomyopathic (DCM) hearts [Tyagi et al. (1996): Mol Cell Biochem 155:13-21]. To examine whether the MMP activation is occurring at the gene expression level, we performed differential display mRNA analysis on tissue from six dilated cardiomyopathy (DCM) explanted and five normal human hearts. Specifically, we identified three genes to be induced and several other genes to be repressed following DCM. Southern blot analysis of isolated cDNA using a collagenase cDNA probe indicated that one of the genes induced during DCM was interstitial collagenase (MMP-1). Northern blot analysis using MMP-1 cDNA probe indicated that MMP-1 was induced three- to fourfold in the DCM heart as compared to normal tissue. To analyze posttranslational expression of MMP and tissue inhibitor of matrix metalloproteinase (TIMP) we performed immunoblot, immunoassay, and substrate zymographic assays. TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue specimens (P < 0.01) and 2 +/- 1 ng/mg and 45 +/- 11 ng/mg in DCM tissue (P < 0.01), respectively. Zymographic analysis demonstrated lytic bands at 66 kDa and 54 kDa in DCM tissue as compared to one band at 66 kDa in normal tissue. Incubation of zymographic gel with metal chelator (phenanthroline) abolished both bands suggesting activation of neutral MMP in DCM heart tissue. TIMP-1 was repressed approximately twentyfold in DCM hearts when compared with normal heart tissue. In situ immunolabeling of MMP-1 indicated phenotypic differences in the fibroblast cells isolated from the DCM heart as compared to normal heart. These results suggest disruption in the balance of myopathic-fibroblast cell ECM-proteinase and antiproteinase in ECM remodeling which is followed by dilated cardiomyopathy.

Increased Matrix Metalloproteinase Activity and Selective Upregulation in LV Myocardium From Patients With End-Stage Dilated Cardiomyopathy

“…10,11,27 For example, Weber et al 10 reported alterations in the myocardial fibrillar collagen architecture in patients with DCM. Tyagi et al 15 reported increased collagen degradation products in DCM myocardial samples, providing evidence for increased collagen degradation. More recently, several studies have demonstrated increased myocardial MMP zymographic activity in patients with DCM.…”

“…[12][13][14][15] More importantly, MMPs have been shown to be upregulated in various disease states. [13][14][15][16][17]26 The relation between MMP activity and MMP and TIMP species abundance in LV myocardium in the setting of idiopathic DCM remained unexplored. Accordingly, this study examined MMP activity and MMP and TIMP abundance in normal and DCM human LV myocardium.…”

“…More recently, several studies have demonstrated increased myocardial MMP zymographic activity in patients with DCM. 11,15,16 Furthermore, experimental models of LV dilation and failure reported increased MMP zymographic activity with the development of severe LV pump dysfunction. 17,28 In the present study, increased LV myocardial MMP zymographic activity was observed with human end-stage DCM.…”

“…13,14 More importantly, increased myocardial MMP activity has been reported to occur in both clinical and experimental forms of DCM. 13,[15][16][17] However, the types of MMPs expressed within the normal and DCM human LV myocardium and the relation to MMP activity remain unexplored. MMP activity is tightly controlled in normal myocardium by a family of closely related inhibitors known as TIMPs.…”

“…MMP activity is tightly controlled in normal myocardium by a family of closely related inhibitors known as TIMPs. [12][13][14][15] Previous studies suggest that TIMP activity exists in normal myocardium 15,18 ; however, the abundance and types of TIMPs expressed in normal human LV myocardium and the balance between MMP and TIMP abundance in the setting of DCM have not been examined. Therefore, the goals of the present study were twofold.…”