NEURAL TROPOMODULIN - DEVELOPMENTAL EXPRESSION AND EFFECT OF SEIZURE ACTIVITY

Tropomodulin is a 40.6 kDa tropomyosin-binding protein associated with actin filaments in muscle and the membrane cytoskeleton in erythrocyt es. We have detected tropomodulin mRNA and protein in brains of rats b y northern and western blot analyses. In situ hybridization of rat bra in and spinal cord sections shows tropomodulin expression in the cereb ellum, neocortex, hippocampus, and anterior horn of the spinal cord. T ropomodulin expression is first observed around day 15 after birth and increases through day 24. The temporal and spatial changes in tropomo dulin expression during cerebellar development parallel those for brai n tropomyosin. Tropomodulin mRNA increases in the dentate gyrus of the hippocampus following prolonged seizure activity induced by kainic ac id administration; the increase is clearly evident 8 h after initiatio n of seizures and is still present 1 week later. However, Western blot analysis of tropomodulin protein level in the dentate gyrus before an d after seizure induction show only slight increases in tropomodulin p rotein concentration, suggesting tight regulation of tropomodulin expr ession at the translational level. The developmental expression of tro pomodulin, together with the induction of tropomodulin mRNA production in the dentate gyrus after kainic acid treatment, suggests a role for tropomodulin in neuronal organization and plasticity.