RRM
2010 Rustbelt RNA Meeting
RRM
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Poster abstracts
Abstract:
HuR is an RNA binding protein that plays a protective role during cellular stress. The aims of our present study are to evaluate the regulation of HuR expression and mechanisms of transcriptional control. Previous studies in our lab demonstrated that HuR is expressed in two different forms, one of which contains an approximately 20 base 5’UTR sequence, and one that contains a 150 base G+C rich 5’UTR that is inhibitory to translation. Recovery of renal epithelia from cellular stress induced increased expression of the shorter, more translatable transcript and decreased expression of the longer form. Analysis of HuR upstream regions revealed regulatory sequences for the shorter mRNA. Within the long G+C rich 5’UTR exists multiple copies of the alternate Smad 1/5/8 binding motif, GCCGnCGC. During recovery following the stress ATP depletion, Smad 1/5/8 levels increased. The ability of these Smads to bind relevant motifs in the 5’UTR was confirmed by ChIP and gel shift assays. Transfection of low amounts of exogenous Smad1 increased HuR mRNA expression. Our preliminary data with transcriptional co-activators of Smads such as Sp1 and Sp3 revealed that they are involved in a regulatory role of HuR expression in renal proximal tubule cells. We also demonstrate that the long AU-rich 3’UTR of HuR contains potential regulatory sequences controlling stability of HuR mRNA. Further studies involving auto-regulation and possible micro RNA target binding sites at the level of 3’UTR need to be evaluated. These data suggest that HuR, an RNA-binding protein, is under strong transcriptional regulation and elucidating these mechanisms will help us understand its protective role in renal ischemia- reperfusion injury, ischemic pre-conditioning and other models of cellular stress.
Keywords: HuR, RNA binding proteins, Ischemia
