Abstract-Monocyte chemoattractant protein-1 (MCP-1; CCL2)-mediated inflammation plays a critical role in the development of ischemic heart disease (IHD). However, the gene expression changes caused by signal transduction, triggered by MCP-1 binding to its receptor CCR2, and their possible role in the development of IHD are not understood. We present evidence that MCP-1 binding to CCR2 induces a novel transcription factor (MCP-induced protein [MCPIP]) that causes cell death. Gene microarray analysis showed that when expressed in hiuman embryonic kidney 293 cells, MCPIP induced apoptotic gene families before causing cell death. Mutagenesis studies showed that the structural features required for transcription factor-like activity were also required for causing cell death. Activation of caspase-3 was detected after MCPIP transfection and Z-VAD-fmk partially inhibited cell death. Cardiomyocyte-targeted expression of MCP-1 in mice caused death by heart failure at 6 months of age. MCPIP expression increased in parallel with the development of ventricular dysfunction. In situ hybridization showed the presence of MCPIP transcripts in the cardiomyocytes and immunohistochemistry showed that MCPIP was associated with the cardiomyocyte nuclei of apoptotic cardiomyocytes. CCR2 expression in cardiomyocytes increased with the development of IHD. MCPIP production induced by MCP-1 binding to CCR2 in the cardiomyocytes is probably involved in the development of IHD in this murine model. MCPIP transcript levels were much higher in the explanted human hearts with IHD than with nonischemic heart disease. These results provide a molecular insight into how chronic inflammation and exposure to MCP-1 contributes to heart failure and suggest that MCPIP could be a potential target for therapeutic intervention. nflammation is an important component of cardiovascular pathology associated with a number of types of heart diseases. However, the mechanism by which inflammation contributes to the development of cardiac dysfunction is poorly understood. 1-4 The recruitment and activation of monocytes/macrophages through monocyte chemoattractant protein-1 (MCP-1; CCL2) are thought to be important events that contribute to the initiation and pathophysiology of cardiovascular diseases. 5-7 MCP-1 is the main chemotactic factor for the migration of monocytes/macrophages and the pathogenesis of chronic inflammation. 8,9 Eliminating MCP-1 function or blockade of MCP-1/CCR2 pathway has been shown to decrease neointimal hyperplasia after injury and atherogenesis in mice 10 -14 and attenuate postischemic myocardial remodeling and heart failure. 15 In an attempt to mimic the inflammatory component implicated in the development of cardiovascular diseases, transgenic mice that express MCP-1 specifically in the heart were generated. Cardiactargeted expression of MCP-1 results in monocyte/macrophage infiltration into the heart, and the mice experience a thrombotic occlusive arteriolar vasculopathy that results in ischemia, interstitial fibrosis, ventricular cha...

MCP-1 (monocyte chemotactic protein-1) plays a critical role in the development of heart failure that is known to involve apoptosis. How MCP-1 contributes to cell death involved in the development of heart disease is not understood. In the present study we show that MCP-1 causes death in cardiac myoblasts, H9c2 cells, by inducing oxidative stress which causes ER stress leading to autophagy via a novel zinc-finger protein, MCPIP (MCP-1-induced protein). MCPIP expression caused cell death, and knockdown of MCPIP attenuated MCP-1-induced cell death. It caused induction of iNOS (inducible NO synthase), translocation of the NADPH oxidase subunit phox47 from the cytoplasm to the membrane, production of ROS (reactive oxygen species), and induction of ER (endoplasmic reticulum) stress markers HSP40 (heat-shock protein 40), PDI (protein disulfide-isomerase), GRP78 (guanine-nucleotide-releasing protein 78) and IRE1alpha (inositol-requiring enzyme 1alpha). It also caused autophagy, as indicated by beclin-1 induction, cleavage of LC3 (microtubule-associated protein 1 light chain 3) and autophagolysosome formation, and apoptosis, as indicated by caspase 3 activation and TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling) assay. Inhibitors of oxidative stress, including CeO2 nanoparticles, inhibited ROS formation, ER stress, autophagy and cell death. Specific inhibitors of ER stress inhibited autophagy and cell death as did knockdown of the ER stress signalling protein IRE1. Knockdown of beclin-1 and autophagy inhibitors prevented cell death. This cell death involved caspase 2 and caspase 12, as specific inhibitors of these caspases prevented MCPIP-induced cell death. Microarray analysis showed that MCPIP expression caused induction of a variety of genes known to be involved in cell death. MCPIP caused activation of JNK (c-Jun N-terminal kinase) and p38 and induction of p53 and PUMA (p53 up-regulated modulator of apoptosis). Taken together, these results suggest that MCPIP induces ROS/RNS (reactive nitrogen species) production that causes ER stress which leads to autophagy and apoptosis through caspase 2/12 and IRE1alpha-JNK/p38-p53-PUMA pathway. These results provide the first molecular insights into the mechanism by which elevated MCP-1 levels associated with chronic inflammation may contribute to the development of heart failure.

Glucose-induced cardiomyocyte death is mediated via MCP-1 production and MCPIP induction, which causes sequential events--ROS production, ER stress, autophagy, and cell death.

Younce CW, Burmeister MA, Ayala JE. Exendin-4 attenuates high glucose-induced cardiomyocyte apoptosis via inhibition of endoplasmic reticulum stress and activation of SERCA2a.

Obesity involves inflammation. MCP-1, an inflammatory chemokine, and MCP-1-induced protein (MCPIP) are known to induce adipogenesis that causes increase in the number of adipocytes. Here we elucidate the intermediate processes through which MCPIP induces adipogenesis. Forced expression of MCPIP in 3T3-L1 preadipocytes caused increased reactive oxygen/nitrogen species (ROS/RNS) production and inducible-nitric oxide synthase (iNOS) expression, endoplasmic reticulum stress (ER), as indicated by expression of ER chaperones and protein disulfide isomerase, and autophagy as indicated by expression of beclin-1 and cleavage of LC3. Treatment of ROS inhibitor, apocynin attenuated MCPIP induction of adipogenesis as measured by the induction of transcription factors involved in adipogenesis, adipocyte markers and lipid droplet accumulation. Inhibition of ER stress with taurursodeoxycholate or knockdown of inositol requiring enzyme 1 (IRE1) inhibited MCPIP induced autophagy and adipogenesis. Preadipocytes in adipogenesis-inducing cocktail manifested ER stress and autophagy. Knockdown of MCPIP attenuated these effects. MCPIP induced p38 activation and p38 inhibitor, SB203580, attenuated MCPIP-induced adipogenesis.