GAS7 - A GENE EXPRESSED PREFERENTIALLY IN GROWTH-ARRESTED FIBROBLASTSAND TERMINALLY DIFFERENTIATED PURKINJE NEURONS AFFECTS NEURITE FORMATION

Growth arrest-specific (gas) genes are er,pressed preferentially in ce lls that enter a quiescent state. gas7, which we identified in serum-s tarved murine fibroblasts, is reported here to be expressed in vivo se lectively in neuronal cells of the mature cerebral cortex, hippocampus , and cerebellum. gas7 transcripts encode a 48-kDa protein containing a structural domain that resembles sequences of OCT2, a POU transcript ion factor implicated in neuronal development, and synapsins, which ha ve a role in modulating neurotransmitter release. Using iii situ hybri dization and immunocytochemical analysis, we show that GAS7 expression occurs prominently in cerebellar Purkinje cells and that inhibition o f production in terminally differentiating cultures of embryonic murin e cerebellum impedes neurite outgrowth from maturing Purkinje cells, C onversely, GAS7 overexpression in undifferentiated neuroblastoma cell cultures dramatically promotes neurite-like outgrowth. Collectively, o ur results provide evidence for an association between expression of t his gas gene and neuronal development.