NMDA induces post-transcriptional regulation of α2-guanylyl-cyclase-subunit expression in cerebellar granule cells

Activation of N-methyl-D-aspartate (NMDA) glutamate receptors commonly affects gene expression in different neurons. We reported previously that chronic treatment of rat cerebellar granule cells with NMDA ( 24 hours) upregulates the expression of mRNA encoding the alpha(2) subunit of the nitric-oxide-sensitive guanylyl cyclase. However, the molecular mechanisms involved in this process remained to be elucidated. Here, we have performed mRNA-decay experiments using the transcriptional inhibitor actinomycin D, providing evidence that the half-life of alpha(2) mRNA is significantly prolonged in cells exposed to NMDA. The role of the 3' untranslated region of the alpha(2) transcripts in NMDA-induced mRNA stabilisation was examined and an association between the RNA-binding proteins AUF1 and ELAV-like protein 1 (HuR/HuA), and endogenous alpha(2) mRNA was demonstrated in vivo, as revealed by coimmunoprecipitation experiments with specific antibodies against AUF1 and HuR. Further studies indicated that stimulation of the NMDA receptor induces a downregulation in AUF1 levels stabilising the alpha(2) mRNA transcripts. These events are triggered through a mechanism that depends on formation of nitric oxide, and on the subsequent activation of guanylyl cyclase and cGMP dependent protein kinases.