Infliximab therapy reverses the increase of allograft inflammatory factor-1 in serum and colonic mucosa of rats with inflammatory bowel disease.

Objective: Our purpose was to study the molecular basis of infliximab (IFX) effect on colon mucosa in a colitis model and to identify new biomarkers of mucosal healing.

Methods: Healthy rats and rats which were subjected to experimental colitis induced by dextran sulfate sodium, with or without IFX treatment (in the short- and long-term), were studied along with forty-seven IBD patients. Colon mucosal integrity by periodic acid Schiff (PAS) staining, intestinal damage by immunohistochemistry (proliferating cell nuclear antigen, β-catenin, E-cadherin, phosphotyrosine, p-p38, allograft inflammatory factor-1 (AIF-1) and colonic mucosal apoptosis by TUNEL staining were evaluated in rats while serum and colon AIF-1 levels were determined in IBD patients.

RNAi-mediated silencing of insulin receptor substrate-4 enhances actinomycin D- and tumor necrosis factor-alpha-induced cell death in hepatocarcinoma cancer cell lines.

Insulin receptor substrate-4 (IRS-4) transmits signals from the insulin-like growth factor receptor (IGF-IR) and the insulin receptor (IR) to the PI3K/AKT and the ERK1/2 pathways. IRS-4 expression increases dramatically after partial hepatectomy and plays an important role in HepG2 hepatoblastoma cell line proliferation/differentiation. In human hepatocarcinoma, IRS-4 overexpression has been associated with tumor development.

Role of insulin receptor substrate-4 in IGF-I-stimulated HEPG2 proliferation.

Backgrounds/aims: Insulin receptor substrate-4 (IRS-4) is a scaffold protein that mediates the actions of insulin-like growth factor-I (IGF-I). Its expression increases dramatically after partial hepatectomy (a liver regeneration model). Herein, we report IRS-4 expression in a human hepatoblastoma cell line (HepG2) and IGF-I-dependent IRS-4 tyrosine phosphorylation.

Insulin receptor substrate-4 signaling in quiescent rat hepatocytes and in regenerating rat liver.

This study was designed to characterize insulin receptor substrate-4 (IRS-4) in isolated rat hepatocytes and to examine its role in liver regeneration. Subcellular fractionation revealed that 85% of IRS-4 is located at isolated hepatocyte plasma membranes. The distribution of IRS-4 among intracellular compartments remained unchanged in insulin-stimulated cells.

Pretreatment with FK506 up-regulates insulin receptors in regenerating rat liver.

This report examines the effect of FK506 pretreatment on liver insulin receptor expression in partially (70%) hepatectomized rats. FK506 pretreatment led to an increased insulin receptor number 24 hours after hepatectomy, detected by means of insulin binding and cross-linking procedures. This increase was related to enhanced insulin receptor expression determined by in vitro mRNA translation and Western blot techniques.