Dissertation Defense: Zinc Finger Protein MCPIP in Cell Death and Differentiation
BMS Trailer November 12, 2009
08:30 AM - 10:30 AM
Announcing the Final Examination of Mr. Craig W. Younce for the degree of Doctor of Philosophy in Biomedical Sciences.
Monocyte chemotactic protein-1 (MCP-1) plays a critical role in the development of cardiovascular diseases. How MCP-1 contributes to the development of heart disease is not understood. This study presents evidence that MCP-1 causes death in cardiac myoblasts, H9c2 by inducing oxidative stress, ER stress and autophagy via a novel Zn-finger protein, MCP-1 induced protein (MCPIP). MCPIP expression caused cell death and knockdown of MCPIP attenuated MCP-1 induced cell death. Expression of MCPIP resulted in induction of iNOS and production of reactive oxygen (ROS). It caused induction of NADPH oxidase subunit phox47 and its translocation to the cytoplasmic membrane. Oxidative stress led to the induction of ER stress markers HSP40, PDI, GRP78 and IRE1a. ER stress lead to autophagy as indicated by beclin-1 induction, cleavage of LC3 to LCII and autophagolysosome formation. Here, MCPIP-induced processes lead to apoptosis as indicated by caspase 3 activation and TUNEL assay. This cell death involved caspase 2 and caspase 12 as inhibition of these caspases prevented MCPIP-induced cell death. Inhibitors of oxidative stress inhibited ER stress, and cell death. Specific inhibitors of ER stress inhibited autophagy and cell death as did the knockdown of the ER stress signaling protein IRE1. Inhibition of autophagy inhibited cell death. MCPIP caused activation of JNK and p38 and induction of p53 and PUMA. These results collectively suggest that MCPIP induces ROS/RNS production that causes ER stress which leads to autophagy and apoptosis through caspase 2/12 and IRE1a –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.
A role for inflammation and MCP-1 in obesity and diabetes has been implicated. Adipogenesis is a key process involved in obesity and associated diseases such as type 2 diabetes. This process involves temporally regulated genes controlled by a set of transcription factors, C/EBPß, C/EBPd, C/EBPa, and PPAR?. Currently PPAR? is considered the master regulator of adipogenesis as no known factor can induce adipogenesis without PPAR?. We present evidence that a novel Zn-finger protein, MCPIP, can induce adipogenesis without PPAR?. Classical adipogenesis-inducing medium induces MCP-1 production and MCPIP expression in 3T3-L1 cells before the induction of the C/EBP family of transcription factors and PPAR?. Knockdown of MCPIP prevents their expression and adipogenesis. Treatment of 3T3-L1 cells with MCP-1 or forced expression of MCPIP induces expression of C/EBPß, C/EBPd, C/EBPa, PPAR? and adipogenesis without any other inducer. Forced expression of MCPIP induces adipogenesis in PPAR?-/- fibroblasts. Thus, MCPIP is a newly identified master controller that can induce adipogenesis without PPAR?.
Faculty and Staff 
Dissertation Defense: Zinc Finger Protein MCPIP in Cell Death and Differentiation
