RESUMO
Treating patients with kidney failure by organ transplantation has been extraordinarily successful. Although, current immunosuppressants have improved short-term allograft survival, most transplants are eventually lost due to chronic allograft nephropathy (CAN). The molecular mechanisms underlying CAN are poorly understood. Smooth muscle cells (SMC) play a major role in the pathogenesis of CAN by contributing to the thickening of the intima and narrowing of the lumen of blood vessels. We show that selenium-binding protein-1 (SBP-1), a protein implicated in protein trafficking and secretion, is localized primarily to SMC in vivo. SBP-1 was heavily tyrosine-phosphorylated in vivo. Remarkably, SBP-1 was absent or strongly downregulated in vascular SMC in monkey kidney allografts with CAN. In contrast, the SMC alpha-actin was strongly expressed in the vascular SMC of the same allografts, indicating that the decrease in SBP-1 was not due to a global decrease in SMC proteins. Out of four growth factors implicated in the pathogenesis of CAN, only TGF-beta blocked the expression of SBP-1; thus, TGF-beta could regulate the expression of SBP-1 in CAN. These results show that SBP-1 localizes primarily to SMC in vivo and implicate this phosphoprotein in the effects of TGF-beta on SMC and in the process of CAN.
Assuntos
Proteínas de Transporte/biossíntese , Regulação para Baixo , Imunossupressores/farmacologia , Músculo Liso/citologia , Nefrite/metabolismo , Actinas/metabolismo , Animais , Linhagem Celular , Vasos Coronários/metabolismo , Detergentes/farmacologia , Modelos Animais de Doenças , Eletroforese em Gel Bidimensional , Feminino , Humanos , Imuno-Histoquímica , Rim/metabolismo , Nefropatias/metabolismo , Macaca mulatta , Espectrometria de Massas , Fosfoproteínas/química , Fosforilação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteínas de Ligação a Selênio , Fator de Crescimento Transformador beta/metabolismo , Tirosina/metabolismo , Útero/metabolismoRESUMO
Neurotrophic factors have been shown to potentiate necrotic neuronal death in cortical cultures. In this study we characterized the death induced by various oxidative insults and tested the effects of neurotrophic factors on that death. Treatment with fibroblast growth factor-2, neurotrophin-4, or insulin-like growth factor-1 potentiated neuronal cell death induced by iron-citrate (Fe) or buthionine sulfoximine (BSO), but not ethacrynic acid (EA). Neuronal death induced by each insult was blocked by the free radical scavenger, trolox. An analysis of the death indicated that Fe and BSO induced necrotic cell death, while EA induced apoptotic cell death. BSO and EA caused decreased cellular glutathione levels, whereas Fe had no effect on glutathione levels. Neurotrophic factors had no effect on the changes in glutathione. The results indicate that oxidative insults can induce either apoptotic or necrotic death and that the effects of neurotrophic factors are dependent on the type of cell death.