Synchronous and regulated expression of two AU-binding proteins, AUF1 and HuR, throughout murine development

The AUF1 (hnRNPD) and HuR (ELAV-like) proteins, potential trans-acting fact ors for regulated mRNA decay, bind in vitro to A+U-rich elements (AREs) fou nd in the 3' untranslated region (3' UTR) of many labile transcripts. In an effort to determine whether these trans-acting factors are likely to play a role in embryogenesis, we have analysed their expression during mouse dev elopment both at the mRNA and protein levels. We show that AUF1 and HuR are expressed at all the developmental stages analysed from day 8.5 of embryon ic development to adulthood. Expression levels are dynamic, varying between tissues and developmental stages. However, a strong positive correlation b etween AUF1 and HuR protein levels was observed in all examined tissues. Fi nally, we compared AUF1 and HuR expression with accumulation of one common target mRNA, c-myc. The similar spatio-temporal distribution of these prote ins and of c-myc mRNA is in agreement with a potential concerted role in AR E-mediated control of mRNA stability.