Molecular mechanisms of Fyn-tyrosine kinase for regulating mammalian behaviors and ethanol sensitivity

Abstract

Mice lacking Fyn, a Src-related non-receptor tyrosine kinase, show impairment of various behaviors, such as spatial learning, suckling, emotional behaviors, and ethanol sensitivity. These mice also display both morphological defects and impairment of synaptic function. Fyn is highly expressed in the mammalian CNS from embryonic day 8.5 to adulthood. Pharmacological and electrophysiological analyses of mice lacking Fyn reveal gamma-aminobutyric acid and glutamatergic defects. We propose here the hypothesis that these defects are caused separately by developmental disorganization and impairment of synapse function by a deficit in Fyn. Regarding the glutamatergic defect, in particular, after ethanol administration the N-methyl-D-aspartate (NMDA)-dependent function is recovered by Fyn, paralleled with tyrosine phosphorylation of NMDA receptor 2B subtype. Thus, modulation of the NMDA receptor function by Fyn may have a significant role in building and regulating sophisticated neural circuits and behavior. In addition, the cadherin-related neural receptor (CNR) family is isolated by binding activity for Fyn. The CNR-Fyn complex will also open a new angle for gaining insight into the molecular mechanisms for regulating mammalian behavior.