RESUMO
Expression of myelin P0 protein by myelinating Schwann cells in vivo is dependent on axonal influences. This report describes P0 gene expression during development of rat sciatic nerve and spinal nerve roots using Northern blotting, in situ hybridization and immunohistochemistry. We demonstrate that: (1) the appearance of P0 mRNA and P0 protein in Schwann cells during nerve development in the rat begins prenatally, at day 18 post-fertilization (E18); (2) P0 mRNA and P0 protein have essentially identical developmental profiles, and are expressed in Schwann cells that are many days prior to myelin formation; (3) initial P0 gene expression is greatest in Schwann cells at the periphery of nerve bundles and in Schwann cells in contact with motor axons; (4) the decline in P0 expression with nerve maturation is accompanied by a sharp decline in P0 message levels in most Schwann cells, but a small subpopulation of these cells continue to synthesize very high levels of P0 mRNA. This study provides data on myelin P0 protein gene expression and distribution during PNS development and adds further insights into the axonal influences controlling Schwann cell behaviour during myelination of the rat PNS.
Assuntos
Envelhecimento/fisiologia , Desenvolvimento Embrionário e Fetal , Expressão Gênica , Proteínas da Mielina/biossíntese , Neurônios/metabolismo , RNA Mensageiro/biossíntese , Nervo Isquiático/metabolismo , Raízes Nervosas Espinhais/metabolismo , Animais , Northern Blotting , Moléculas de Adesão Celular Neuronais/biossíntese , Idade Gestacional , Hibridização In Situ , Proteína P0 da Mielina , Proteínas da Mielina/análise , Neurônios/citologia , Neurônios/fisiologia , RNA Mensageiro/análise , Ratos , Ratos Endogâmicos Lew , Nervo Isquiático/embriologia , Nervo Isquiático/crescimento & desenvolvimento , Raízes Nervosas Espinhais/embriologia , Raízes Nervosas Espinhais/crescimento & desenvolvimentoRESUMO
Fifty-nine percent of 49 patients with motor neuron disease and 25% of 91 control subjects had IgM antibodies to ganglioside GM1 but usually not to GD1b at titers less than 1:80. This suggests that antibodies to GM1 may be part of the normal human antibody repertoire. However, given the higher incidence of antibodies to GM1 in patients with motor neuron disease, there may be specific epitopes important in antiganglioside antibodies associated with motor neuron disease.