FIGURE 12.

Hypothetical model of the role that ribosomal biogenesis plays in dendritic growth and maintenance. A, under normal conditions, neuronal maturation is associated with a relatively rapid expansion of ribosomes. Robust ribosome supply supports protein synthesis that is needed for the dendritic growth response to BDNF and dendritic maintenance. B, when ribosomal biogenesis is reduced, ribosome shortage impairs translation initiation resulting in formation of SGs and diminished protein synthesis. Such defects may be relatively selective for mRNAs whose translation requires optimal translation initiation rates to support synthesis of necessary pro-dendritic proteins. In consequence, dendritic growth and maintenance are impaired. Thus, ribosomal biogenesis is critical for maturation of post-mitotic neurons, and its impairment may contribute to disruption of neuronal connectivity in neurodevelopmental and/or neurodegenerative diseases that affect production of ribosomes (see text for more details).