title: Src family kinases regulate renal epithelial dedifferentiation through activation of EGFR/PI3K signaling.
abstract: Dedifferentiation, a process by which differentiated cells become mesenchymal-like proliferating cells, is the first step in renal epithelium repair and occurs in vivo after acute kidney injury and in vitro in primary culture. However, the underlying mechanism remains poorly understood. In this report, we studied the signaling events that mediate dedifferentiation of proximal renal tubular cells (RPTC) in primary culture. RPTC dedifferentiation characterized by increased expression of vimentin concurrent with decreased expression of cytokeratin-18 was observed at 24 h after the initial plating of freshly isolated proximal tubules and persisted for 72 h. At 96 h, RPTC started to redifferentiate as revealed by reciprocal expression of cytokeratin-18 and vimentin and completed at 120 h. Phosphorylation levels of Src, epidermal growth factor receptor (EGFR), AKT (a target of phosphoinositide-3-kinase (PI3K)), and ERK1/2 were increased in the early time course of culture (<72 h). Inhibition of Src family kinases (SFKs) with PP1 blocked EGFR, AKT, and ERK1/2 phosphorylation, as well as RPTC dedifferentiation. Inhibition of EGFR with AG1478 also blocked AKT and ERK1/2 phosphorylation and RPTC dedifferentiation. Although inactivation of the PI3K/AKT pathway with LY294002 inhibited RPTC dedifferentiation, blocking the ERK1/2 pathway with U0126 did not show such an effect. Moreover, inhibition of SFKs, EGFR, PI3K/AKT, but not ERK1/2 pathways abrogated RPTC outgrowth and SFK inhibition decreased RPTC proliferation and migration. These findings demonstrate a critical role of SFKs in mediating RPTC dedifferentiation through activation of the EGFR/PI3K signaling pathway.
authors.affiliation: Department of Nephrology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China. szhuang@lifespan.org
authors.forename: Shougang
authors.initials: S
authors.lastname: Zhuang
authors.forename: Meili
authors.initials: M
authors.lastname: Duan
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
mesh_terms: D000818:Animals; D054337:Cell Dedifferentiation / Q000502:physiology*; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology*; D066246:ErbB Receptors / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000502:physiology; D051379:Mice; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D066246:ErbB Receptors; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases