title: Phosphorylation of eIF2α via the general control kinase, GCN2, modulates the ability of renal medullary cells to survive high urea stress.
abstract: The phosphorylation of the α-subunit of the eukaryotic translation initiation factor 2 (eIF2α) occurs under many stress conditions in mammalian cells and is mediated by one of four eIF2α kinases: PERK, PKR, GCN2, and HRI. Cells of the renal medulla are regularly exposed to fluctuating concentrations of urea and sodium, the extracellular solutes responsible for the high osmolality in the renal medulla, and thus the kidneys ability to concentrate the urine in times of dehydration. Urea stress is known to initiate molecular responses that diverge from those seen in response to hypertonic stress (NaCl). We show that urea-inducible GCN2 activation initiates the phosphorylation of eIF2α and the downstream increase of activating transcription factor 3 (ATF3). Loss of GCN2 sensitized cells to urea stress, increasing the expression of activated caspase-3 and decreasing cell survival. Loss of GCN2 ablated urea-induced phosphorylation of eIF2α and reduced the expression of ATF3.
authors: Dept. of Physiology, College of Medicine, University of Arizona, 1656 E. Mabel St., Tucson, AZ 85724, USA.
authors: Qi
authors: Q
authors: Cai
authors: Heddwen L
authors: HL
authors: Brooks
mesh_terms: D051700:Activating Transcription Factor 3 / Q000096:biosynthesis; D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D007679:Kidney Medulla / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D013312:Stress, Physiological; D014508:Urea / Q000009:adverse effects* / Q000378:metabolism*
chemical_list: D051700:Activating Transcription Factor 3; C103002:Atf3 protein, mouse; D015852:Eukaryotic Initiation Factor-2; D014508:Urea; C070634:Eif2ak4 protein, mouse; D017346:Protein Serine-Threonine Kinases