MCP‐induced protein 1 regulates dynamic equilibrium of stress granule and processing bodies under stress condition

The cytoplasmic stress granules (SGs) which contain non‐translating messenger ribonucleoproteins (mRNPs) are formed when translation initiation is inhibited in response to stresses such as heat shock, oxidative stress and ischemia. The dynamic SGs suggest that they are sites of mRNA triage, wherein individual mRNAs are dynamically sorted for storage, degradation or translation. The processing bodies (PBs) contain the components of the mRNA decay machinery and facility mRNA decay. The factors that determine the SGs and PBs assembly and disassembly are poorly understood. We have previously reported MCP‐induced protein 1 (MCPIP1), a CCCH‐type zinc finger containing protein, as a deubiquitinase to negatively regulate JNK and NFêB signaling. Here we found that intrinsic MCPIPI co‐localized with the stress granule marker G3BP and eIF4E in response to stress stimuli. Interestingly, the overexpression of MCPIP1 can inhibit the assembly of stress granules. Western blotting results confirmed that overexpression of the MCPIP1 downregulated the phosphorylation of eukaryotic initiate factor 2 á (eIF2 á) in response to arsenite treatment. Furthermore, overexpresssion of MCPIP1 significantly increased the size and number of PBs. These results suggest that MCPIP1 may regulate the dynamic equilibrium of RNA granules such as SGs and PBs. These works are supported by UMKC Start‐up Fund.