RESUMO
Tetraethylammonium (TEA) induces a form of long-term potentiation (LTP) that is independent on N-methyl-D-aspartate (NMDA) receptor activation (LTP(K)). LTP(K) may be a suitable chemical model to study molecular mechanisms underlying LTP. We monitored the phosphorylation state of two identified neural-specific protein kinase C (PKC) substrates (the presynaptic protein GAP-43/B-50 and postsynaptic protein RC3) after different chemical depolarisations. TEA induced a long-lasting increase in synaptic efficacy in the CA1 field of the hippocampus and increased the phosphorylation of both GAP-43/B-50 and RC3 (51 and 56.1%, respectively). These effects were blocked by the voltage-dependent calcium channel antagonist nifedipine, but not by the NMDA receptor antagonist AP5. These data show that in LTP(K) the in situ phosphorylation of pre-and postsynaptic PKC substrates is increased, indicating that NMDA receptor-dependent and NMDA receptor-independent LTP share common Ca(2+)-dependent expression mechanisms, including activation of pre- and postsynaptic PKC.
Assuntos
Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Potenciação de Longa Duração/efeitos dos fármacos , Potenciação de Longa Duração/fisiologia , Terminações Pré-Sinápticas/efeitos dos fármacos , Terminações Pré-Sinápticas/metabolismo , Proteína Quinase C/efeitos dos fármacos , Proteína Quinase C/metabolismo , Membranas Sinápticas/efeitos dos fármacos , Membranas Sinápticas/metabolismo , Tetraetilamônio/farmacologia , 2-Amino-5-fosfonovalerato/farmacologia , 4-Aminopiridina/farmacologia , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Proteínas de Ligação a Calmodulina/metabolismo , Antagonistas de Aminoácidos Excitatórios/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Proteína GAP-43/metabolismo , Hipocampo/citologia , Técnicas In Vitro , Proteínas do Tecido Nervoso/metabolismo , Neurogranina , Nifedipino/farmacologia , Fosforilação , Bloqueadores dos Canais de Potássio , Canais de Potássio/efeitos dos fármacos , Canais de Potássio/metabolismo , Terminações Pré-Sinápticas/ultraestrutura , Ratos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Membranas Sinápticas/ultraestrutura , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologiaRESUMO
Jak3, a member of the Janus tyrosine kinase family is an intracellular kinase functionally coupled to cytokine receptors that share a common gamma chain (gamma c). Defects in the gamma c or Jak3 result in T-B + severe combined immunodeficiency (SCID). In order to clarify discrepancies between earlier reported genomic organisations of human JAK3, the present study was undertaken to redefine its whole exon-intron structure. The genomic structure of human JAK3 consists of 23 exons and 22 introns, and shows strong homology with the organisation of the murine JAK3 locus. The exon-intron sequences provided in this report can be used to facilitate the identification of new Jak3-deficient SCID patients, including prenatal diagnosis.