TRANSLATIONAL MACHINERY IN DENDRITES OF HIPPOCAMPAL-NEURONS IN CULTURE

In neurons, several mRNAs are selectively delivered to dendritic domai ns where they are presumably translated by local protein synthetic mac hinery. Although electron microscopy has identified polyribosomes in d endrites, in particular in postsynaptic dendritic compartments, the fu nctional composition of the local protein synthetic apparatus and the scope of its translational capacity have not been analyzed. To ascerta in the translational competence of dendrites, we have probed hippocamp al neurons in primary culture for various integral and associated fact ors of the translational apparatus. We report here that dendrites of s uch neurons are equipped with a spectrum of translational machinery co mponents, including ribosomes, tRNAs, initiation and elongation factor s, and elements of the cotranslational signal recognition mechanism. T hese components are differentially and nonuniformly distributed in den dritic arbors. Their dendritic location illustrates the soma-independe nt potential of dendrites to synthesize selected proteins in local dom ains.