Ischemic acute renal failure induces differential expression of small heat shock proteins.
AlphaB-crystallin and heat shock protein (hsp) 25 are structurally and functionally related small stress proteins induced by a variety of insults, including heat and ischemia. Cytoprotection by these two hsp is thought to result from molecular chaperoning and/or cytoskeletal stabilization. Because renal ischemia is characterized by disruption of the renal tubular cell actin cytoskeleton, this study was conducted to determine the localization and quantify the expression and phosphorylation of both hsp in renal cortex, isolated glomeruli, outer medulla, and inner medulla of rats after bilateral renal ischemia. Sham-operated kidneys had similarly small amounts of hsp25 and alphaB-crystallin in cortex and glomeruli, with substantially greater amounts of alphaB-crystallin versus hsp25 in outer and inner medulla. Ischemia resulted in significantly increased hsp25 (and hsp70i) but variable alphaB-crystallin levels in cortex and outer medulla, and progressively decreased glomerular hsp25 phosphorylation. In sham-operated kidneys, hsp25 localized to glomeruli, vessels, and collecting ducts, with alphaB-crystallin primarily in medullary thin limbs and collecting ducts. After ischemia, hsp25 accumulated in proximal tubules in cortex and outer medulla, while alphaB-crystallin labeling became nonhomogeneous in outer medulla, and increased in Bowman's capsule. It is concluded that: (1) There is striking differential expression of hsp25 and alphaB-crystallin in various renal compartments; and (2) Renal ischemia results in differential accumulation of hsp25 and alphaB-crystallin, with hsp25 part of a generalized stress response in renal proximal tubular cells, which may play a role in recovery from ischemia-induced actin filament disruption.
Smoyer
William E
WE
Department of Pediatrics University of Michigan, Ann Arbor, Michigan.
Ransom
Richard
R
Department of Pediatrics University of Michigan, Ann Arbor, Michigan.
Harris
Raymond C
RC
Department of Medicine, Vanderbilt University, Nashville, Tennessee.
Welsh
Michael J
MJ
Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan.
Lutsch
Gudrun
G
Max Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
Benndorf
Rainer
R
Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan.
D058186:Acute Kidney Injury / Q000209:etiology* / Q000378:metabolism; D000818:Animals; D003459:Crystallins / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D007511:Ischemia / Q000150:complications*; D007668:Kidney / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D012079:Renal Circulation
D003459:Crystallins; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins