Mechanism Of PARP1 Regulating The Expression RNA Binding Protein HuB

Poly ADP ribosylation,PARylation,is an ancient post-translational modification of proteins found in viruses,bacteria,and most eukaryotes.Covalently attached to the target molecule by N-,O-,and S-glycosidic linkages.Can participate in a variety of biological events in cells,such as apoptosis,gene expression regulation.In recent years,people have gradually discovered the non-covalent interaction of free PAR and protein produced during PAR modification,which is an important supplement to PAR function.Although PARP1,which mainly catalyzes the PAR-modification,is localized in the nucleus,it can still regulate extracellular proteins by producing free PAR.Studies have reported that PAR can affect DNA damage repair,participate in ATP synthesis in the nucleus,and recruit ubiquitinated proteins to mediate degradation of target proteins through non-covalent interactions with proteins.Previous studies in our laboratory found that PARP1 regulates gene expression at the post-transcriptional level.The regulation of mRNA stability is critical for post-transcriptional regulation of gene expression,where cis-acting elements can affect the stability of mRNA and thus the expression of target proteins.The RNA binding protein is capable of binding to an ARE element in the 3' untranslated region of the mRNA,regulating the stability of the target mRNA.Some RNA-binding proteins can promote the degradation of mRNA,such as TTP,and the Hu family proteins studied in our laboratory can stabilize the target mRNA.That is,PARP1 is involved in the regulation of gene expression at the post-transcriptional level(by regulation of mRNA stability)through PAR-modification of the RNA-binding protein Hu R.Our previous results showed that in RAW cells,the expression of HuB was up-regulated under the stimulation of LPS,and the addition of PARPs inhibitors could inhibit the expression of HuB,but the mechanism by which PARP1 regulates HuB expression was not elucidated,which prompted us to think To further explore the specific mechanism by which PARP1 regulates HuB expression.Our study found that free PAR can bind to the RNA binding protein HuB and affect the regulation of HuB protein stability to target mRNA.In our experimental system,1)He La cells were stimulated with bleomycin(BLM),and the expression of the RNA-binding protein HuB was up-regulated,and the expression of HuB protein was regulated by PARP1.2)Through double reporter experiments,it was found that PARP1 does not regulate the expression of HuB at the transcriptional level.3)HuB is involved in the regulation of self-expression at the post-transcriptional level.4)Free PAR is able to bind to HuB,and the interaction between the two is mediated by the RRM2 domain of HuB.5)free PAR is capable of promoting the binding of HuB to the target mRNA.This study proposes a new mechanism by which free PAR binds to the RNA-binding protein HuB and affects the regulation of HuB protein stability to itself and other target mRNAs.PARP1 can be non-covalently bound to the RNA-binding protein HuB by generating free PAR.HuB itself and its associated target mRNA participate in a series of downstream biological events.