Hsp72 Enhances the Effect of Hu R to Regulate p21~(CIP1) Expression

RNA binding protein Hu R regulates m RNA stability and translation through binding to target m RNAs. However,factors influencing the RNA binding affinity of Hu R remain to be studied. In this study,we investigated whether the RNA binding affinity of Hu R could be influenced by protein-protein interaction. We found that Hsp72 interacted with Hu R in the cytoplasm. Interaction of Hsp72 with Hu R enhanced the binding of Hu R to the 3'UTR( 3'untranslated region) of p21( KIP1). He La cells exposed to heat shock exhibited elevated total and cytoplasmic protein levels of Hsp72,while the total and cytoplasmic protein levels of Hu R kept unchanged. The interaction of Hu R with p21 3' UTR and the expression of p21 increased with heat shock. In sum,Hsp72 enhances the binding of Hu R to p21 m RNA by interacting with Hu R. The Hsp72-Hu R-p21 regulatory process impacts on the upregulation of p21 by Hu R in heat shock. Our findings provide evidence for elucidating the mechanisms controlling the RNA binding affinity of Hu R.