NMDA induces post-transcriptional regulation of alpha2-guanylyl-cyclase-subunit expression in cerebellar granule...

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 alpha2 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 alpha2 mRNA is significantly prolonged in cells exposed to NMDA. The role of the 3' untranslated region of the alpha2 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 alpha2 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 alpha2 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.