RESUMO
Insulin resistance is a key feature of obesity and type 2 diabetes mellitus (T2DM). Interaction of insulin with the insulin receptor (IR) leads to both its auto-phosphorylation and phosphorylation of tyrosine residues on the IR substrate (IRS) proteins, initiating the activation of intracellular signaling cascades. The metabolic effects of IRS are known to be mediated through pathways involving phosphatidyl-inositol 3-kinase (PI-3K), which result in the activation of Akt signaling. The C-terminal region of the IR ectodomain is required to facilitate the conformational changes that are required for high-affinity binding to insulin. Furthermore, the CH2 and CH3 domains in the Fc fragments of immunoglobulins are responsible for their binding to the Fc receptor, which triggers transcytosis. In this study, we created a fusion peptide of the C-terminal end of the human IR ectodomain with the IgG4 Fc fragment, including an intervening polyG fragment to ensure enough space for insulin binding. We named this new peptide "Yiminsu", meaning an insulin sensitizer. The results of our analyses show that Yiminsu significantly facilitates insulin signaling via the activation of Akt in hepatocytes in a dose- and time-dependent manner. Further studies are required to determine whether Yiminsu can act as an insulin sensitizer.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Fragmentos Fab das Imunoglobulinas/farmacologia , Imunoglobulina G/farmacologia , Insulina/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Recombinantes de Fusão/farmacologia , Animais , Células CHO , Linhagem Celular , Clonagem Molecular/métodos , Cricetulus , Diabetes Mellitus Tipo 2/metabolismo , Relação Dose-Resposta a Droga , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Fragmentos Fab das Imunoglobulinas/química , Fragmentos Fab das Imunoglobulinas/genética , Imunoglobulina G/química , Imunoglobulina G/genética , Resistência à Insulina , Fosfatidilinositol 3-Quinase/metabolismo , Fosforilação/efeitos dos fármacos , Engenharia de Proteínas , Estrutura Terciária de Proteína , Receptor de Insulina/metabolismo , Receptores Fc/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Transdução de Sinais/efeitos dos fármacos , Tirosina/metabolismoRESUMO
Dual graft liver transplantation has been demonstrated to be feasible as well as effective in increasing the donor pool and in preventing the potential for small-for-size syndrome. However, little is known about the pathophysiological and immune processes following dual graft liver transplantation due to the lack of appropriate animal models. The aim of this study, therefore, was to establish an improved rat model of dual graft liver transplantation, with long-term survival. Male inbred rats were used as both donors and recipients. One middle lobe together with another right middle lobe from the livers of two different donors were used as the dual grafts. The "basin-shaped anastomosis" technique was used to connect the suprahepatic inferior vena cava; "Y-shaped bridge" and "three-cuff" techniques were adopted for the anastomosis of the portal veins; and the "two-stent" technique was used for the anastomosis of the bile ducts. Six of the ten recipients survived for more than 100 days after dual graft liver transplantation. There was no difference in graft survival between dual and whole liver transplantation. The long-term survivors with dual grafts from two different donors had unobstructed portal vein flow, unobstructed biliary tract dilatation, normal graft function, and well-preserved hepatic structure. Therefore, this improved model will be potentially useful for evaluating the pathophysiological processes, immune responses between dual grafts and recipient, and mechanisms underlying the liver regeneration in dual grafts after dual graft liver transplantation.