Retinoids and binding proteins in the cerebellum during lifetime.

The vertebrate nervous system is one of the main sites where retinoids and related binding proteins play their critical roles. The cerebellum is subjected to the effects of retinoids over its lifetime. The retinoid binding proteins are differently expressed during life: CRBP I, expressed in the adult cerebellum, is possibly involved in plasticity during memory processes. CRABP I, expressed in the embryonic cerebellum, is involved in the development of the organ and in cellular differentiation. In particular, since the expression of CRABP I coincides with earliest cerebellar differentiation, it is probably involved in this critical step, participating in a complex network of regulatory genes expressed in the mes/methencephalon such as Fgf8, Wnt1, En1/2, Pax2/5, Otx2 and Gbx2. Finally, the way for metabolic synchronization of isthmic cell populations and the putative existence of alternative pathways for CRABP I to regulate RA are discussed.