Abstract: Objective To investigate the post-transcriptional regulation of dual-specificity phosphatase-1 (DUSP1) by the RNAbinding
protein HuR in heat shock. Methods The recombinant plasmids carrying wild-type (WT) HuR or its mutants at
threonine 118 were constructed and transiently transfected into NIH 3T3 cells via liposome, and the changes in the expressions
of DUSP1 mRNA and protein were detected by quantitative real-time PCR and Western blotting, respectively. Results Heat
shock caused significantly enhanced phosphorylation of HuR at the residue T118. In 3T3 cells transfected with the plasmids
carrying wild-type HuR for its over-expression showed significantly up-regulated DUSP1 mRNA and protein expressions at 24
h after transfection. Over-expression of HuR(T118A) down-regulated DUSP1 mRNA and protein expressions in cells challenged
with heat shock, while HuR(T118E) over-expression significantly increased DISP1 expression at both mRNA and protein levels.
After heat shock, HuR(WT) translocated from the cell nucleus to the cytoplasm to form particles. HuR(T118E) was diffusely
distributed in the cytoplasm before heat shock and formed particles after heat shock. HuR(T118A) did not undergo such
translocation in response to heat shock challenge. Conclusion HuR regulates DUSP1 mRNA and protein expression at the
post-transcriptional level to increase its expression after heat shock by enhancing the phosphorylation HuR T118.