A Novel Mode Of Cell Death Caused By Persistent Activation Of P38δ

Mitogen activated protein kinases(MAPKs)are a large group of serine/threonine protein kinases that can be activated by diverse extracellular stimuli and in turn regulate many cellular behaviors.p38 is an important class of proteins in the MAPK family that serves as a nexus for signal transduction and plays important roles in numerous biological processes.In this paper,we found that stimulated HeLa cells,in which the p3 8 protein-p3 8δis expressed,with PMA to activate p388,the cells would change from irregular polygon to circle,and then die.This mode of cell death is p388 specific,and activation of other members of the p38 family in HeLa cells cannot cause this death.Although this mode of death will appear to form apoptotic body-like structures similar to apoptosis in the later stage,the use of the caspase inhibitor Z-VAD-FMK cannot inhibit this cell death.The most striking feature of this mode of cell death is that the cells in the early stage will become round,which is similar to normal cells that entering the cell division phase in the cell cycle process.But during this death process,when the cell becomes a round shape,the DNA content in the cells is normal,and unlike normal cells entering the cell division phase,the DNA content is doubled.Therefore,the change in cell morphology is not caused by blocking the normal progress of the cell cycle.In order to explore the specific molecular mechanism underlying this cell death process,we used CRISPR-Cas9 gene editing technology to screen the gene gRNA library in HeLa cells stably expressing p38δ(HeLa-2#cells).Through screening,we found that the CARD10-BCL10-MALT1 complex(CBM)plays an essential role in this cell death process.Knockout of any one of the CARD10-BCL10-MALT1 complex in Hela-2#cells,stimulated the cell with PMA,the cell would not die.Whereas in knockout cell lines complementing the corresponding protein,activation of p38δ with PMA caused the cells to die again.We further proved that PMA can activate PKC,the activated PKC persistent activates p38δ through the CARD 10-BCL10-MALT1 complex,then leads to cell death.In brief,we found a new way of cell death different from apoptosis in HeLa cells,which is specifically dependent on the persistent activation of p38δ.