RESUMEN
Semaphorin 3A (Sema3A), originally identified as a potent growth cone collapsing factor in developing sensory neurons, is now recognized as a key player in immune, cardiovascular, bone metabolism and neurological systems. Here we established an anti-Sema3A monoclonal antibody that neutralizes the effects of Sema3A both in vitro and in vivo. The anti-Sema3A neutralization chick IgM antibodies were screened by combining an autonomously diversifying library selection system and an in vitro growth cone collapse assay. We further developed function-blocking chick-mouse chimeric and humanized anti-Sema3A antibodies. We found that our anti-Sema3A antibodies were effective for improving the survival rate in lipopolysaccharide-induced sepsis in mice. Our antibody is a potential therapeutic agent that may prevent the onset of or alleviate symptoms of human diseases associated with Sema3A.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/inmunología , Lipopolisacáridos/inmunología , Semaforina-3A/inmunología , Sepsis/inmunología , Animales , Células COS , Línea Celular , Pollos , Chlorocebus aethiops , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Proteínas Recombinantes/inmunologíaRESUMEN
Alzheimer's disease (AD) is characterized by amyloid-ß (Aß) protein and tau deposition in the brain. Numerous studies have reported a central role of Aß in the development of AD, but the pathogenesis is not well understood. Collapsin response mediator protein 2 (CRMP2), an intracellular protein mediating a repulsive axon guidance molecule, Semaphorin3A, is also accumulated in neurofibrillary tangles in AD brains. To gain insight into the role of CRMP2 phosphorylation in AD pathogenesis, we investigated the effects of Aß neurotoxicity in CRMP2 phosphorylation-deficient knock-in (crmp2(ki/ki)) mice, in which the serine residue at 522 was replaced with alanine. Intracerebroventricular (i.c.v.) injection of Aß25â35 peptide, a neurotoxic fragment of Aß protein, to wild-type (wt) mice increased hippocampal phosphorylation of CRMP2. Behavioral assessment revealed that i.c.v. injection of Aß25â35 peptide caused impairment of novel object recognition in wt mice, while the same peptide did not in crmp2(ki/ki) mice. In electrophysiological recording, wt and crmp2(ki/ki) mice have similar input-output basal synaptic transmission and paired-pulse ratios. However, long-term potentiation was impaired in hippocampal slices of Aß25â35 peptide-treated wt but not those of crmp2(ki/ki). Our findings indicate that CRMP2 phosphorylation is required for Aß-induced impairment of cognitive memory and synaptic plasticity.