Abstract
Matrix metalloproteinases (MMPs), a family of endoproteinases, are implicated in cardiac remodeling. Interleukin-1beta (IL-1beta), which is increased in the heart following myocardial infarction, increases expression and activity of MMP-2 (gelatinase A) and -9 (gelatinase B) in cardiac fibroblasts. Previously, we have shown that IL-1beta activates ERK1/2, JNKs, and protein kinase C (PKC). However, signaling pathways involved in the regulation of MMP-2 and -9 expression and activity are not yet well understood. Using adult rat cardiac fibroblasts, we show that inhibition of ERK1/2 and JNKs inhibits IL-1beta-stimulated increases in MMP-9, not MMP-2, expression and activity. Chelerythrine, an inhibitor of PKC, inhibited activation of ERK1/2 and JNKs and expression and activity of both MMPs. Selective inhibition of PKC-alpha/beta1 using Gö6976 inhibited JNKs activation and the expression and activity of MMP-9, not MMP-2. Inhibition of PKC-theta and PKC-zeta using pseudosubstrates inhibited IL-1beta-stimulated activation of ERK1/2 and JNKs and the expression and activity of MMP-2 and -9. Inhibition of PKC-epsilon had no effect. IL-1beta activated NF-kappaB pathway as measured by increased phosphorylation of IKKalpha/beta and IkappaB-alpha. Inhibition of ERK1/2, JNKs, and PKC-alpha/beta1 had no effect on NF-kappaB activation, whereas inhibition of PKC-theta and PKC-zeta inhibited IL-1beta-stimulated activation of NF-kappaB. SN50, NF-kappaB inhibitor peptide, inhibited IL-1beta-stimulated increases in MMP-2 and -9 expression and activity. These observations suggest that 1) activation of ERK1/2 and JNKs plays a critical role in the regulation of MMP-9, not MMP-2, expression and activity; 2) PKC-alpha/beta1 act upstream of JNKs, not ERK1/2; 3) PKC-zeta and -theta, not PKC-epsilon, act upstream of JNKs, ERK1/2, and NF-kappaB; and 4) activation of NF-kappaB stimulates expression and activity of MMP-2 and -9.
Highlights
Teins, and play a fundamental role in tissue remodeling [1,2,3,4,5,6]
Using adult rat cardiac fibroblasts, we show that inhibition of ERK1/2 and JNKs inhibits IL-1-stimulated increases in Matrix metalloproteinases (MMPs)-9, not MMP-2, expression and activity
SN50, NF-B inhibitor peptide, inhibited IL-1-stimulated increases in MMP-2 and -9 expression and activity. These observations suggest that 1) activation of ERK1/2 and JNKs plays a critical role in the regulation of MMP-9, not MMP-2, expression and activity; 2) PKC-␣/1 act upstream of JNKs, not ERK1/2; 3) PKC- and -, not PKC-⑀, act upstream of JNKs, ERK1/2, and NF-B; and 4) activation of NF-B stimulates expression and activity of MMP-2 and -9
Summary
Teins, and play a fundamental role in tissue remodeling [1,2,3,4,5,6]. MMPs are implicated in the remodeling processes of the heart during chronic heart failure and following myocardial infarction (6 –10). Inflammatory cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor-␣, increase expression of MMP-2 and -9 [12, 13] Both MMP-2 and -9 are activated in the heart during myocardial remodeling, the temporal changes in the expression of these enzymes are different [14]. These observations suggest differential regulation of MMP-2 and -9 in the heart Inflammatory cytokines such as IL-1 and tumor necrosis factor-␣ are increased during chronic heart failure [15] and following myocardial infarction [16, 17]. The present study was undertaken to investigate the signaling pathways, including MAPKs (ERK1/2 and JNKs), PKC (␣, 1,, , and ⑀), and NF-B, involved in the expression and activity of MMP-2 and -9 in response to IL-1 in adult rat cardiac fibroblasts. The data presented here suggest that different isoforms of PKC differentially activate ERK1/2, JNKs, and NF-B and that activation of ERK1/2, JNKs, and NF-B differentially modulates the expression and activity of MMP-2 and -9
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