Chemical stimulation of synaptosomes modulates alpha-Ca2+/calmodulin-dependent protein kinase II mRNA association to polysomes

The presence of specific mRNAs in dendrites and at synapses is well establi shed, but a direct and reliable demonstration that they are associated with polysomes is still missing. To address this point we analyzed the polysoma l association of the mRNAs for the alpha-subunit of Ca2+/calmodulin-depende nt protein kinase II (alpha-CaMKII), for type 1 inositol 1,4,5-trisphosphat e receptor (InsP3R1) and for the activity-regulated cytoskeleton-associated protein (Arc) in a synaptosomal preparation devoid of contaminating materi al from neuronal and glial perikarya. We show that a fraction of alpha-CaMK II, InsP3R1, and Arc mRNAs present in synaptosomes is indeed associated wit h polysomes. Moreover, we show that polysomal association of alpha-CaMKII m RNA, but not InsP3R1 and Arc mRNAs, increases with depolarization of the sy naptosomal membrane. Finally, we show that the synthesis of alpha-CaMKII pr otein increases with stimulation. Dendritic mRNA recruitment onto polysomes in response to synaptic stimulation might represent one of the mechanisms underlying the processes of learning and memory.