Activation profiles of HSPA5 during the glomerular mesangial cell stress response to chemical injury.
Environmental injury has been associated with endoplasmic reticulum (ER) stress, a response characterized by activation of the unfolded protein response, proteasomal degradation of proteins, and induction of HSPA5, also known as GRP78 or BiP. Although HSPA5 has been implicated in the stress response to environmental injury in several cell types, its role in the glomerular ER stress response is unknown. In this study, we evaluated HSPA5 activation profiles in rat glomerular mesangial cells (rGMCs) challenged with heavy metals (HgCl2 or Pb2+ acetate) or polycyclic aromatic hydrocarbons (PAHs, ie, benzo(a)pyrene [BaP]). Challenge of rGMCs with 1 or 10 microM HgCl2 or Pb2+ acetate increased HSPA5 mRNA and protein levels. The induction response was sensitive to transcriptional and translational inhibition by actinomycin D (AD) and cyclohexamide, respectively. HSPA5 mRNA was induced by 3 microM BaP in an AD-sensitive manner, but this response was unaffected by the presence of heavy metals. A promoter construct containing sequences that mediate thapsigargin (TH) inducibility of the HSPA5 promoter was refractory to both heavy metals and BaP. The HSPA5 induction response in rGMCs is conserved because it was reproduced with fidelity in immunolocalization experiments of HSPA5 protein in M15 and HEK293 cells in embryonic lines of murine and human origin, respectively. Collectively, these findings identify HSPA5 in the stress response of rGMCs and implicate regulatory mechanisms that are distinct from those involved in TH inducibility.
Falahatpisheh
Hadi
H
Department of Biochemistry and Molecular Biology and Center for Genetics and Molecular Medicine, University of Louisville, Louisville, KY 40292, USA.
Nanez
Adrian
A
Montoya-Durango
Diego
D
Qian
Yongchang
Y
Tiffany-Castiglioni
Evelyn
E
Ramos
Kenneth S
KS
D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008627:Mercuric Chloride / Q000633:toxicity*; D050527:Mesangial Cells / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D009942:Organometallic Compounds / Q000633:toxicity*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013312:Stress, Physiological / Q000235:genetics / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
D000091342:Endoplasmic Reticulum Chaperone BiP; C051684:GRP78 protein, rat; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D018832:Molecular Chaperones; D019384:Nucleic Acid Synthesis Inhibitors; D009942:Organometallic Compounds; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D003609:Dactinomycin; D001564:Benzo(a)pyrene; D008627:Mercuric Chloride; D019284:Thapsigargin; D003513:Cycloheximide; C008261:lead acetate