Ischemic acute renal failure induces differential expression of small heat shock proteins

• Published in: Journal of the American Society of Nephrology Vol. 11; no. 2; pp. 211 - 221
• Main Authors: SMOYER, W. E, RANSOM, R, HARRIS, R. C, WELSH, M. J, LUTSCH, G, BENNDORF, R
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01-02-2000
• Subjects: Acute Kidney Injury - etiology; Acute Kidney Injury - metabolism; Animals; Biological and medical sciences; Crystallins - metabolism; Heat-Shock Proteins - chemistry; Heat-Shock Proteins - metabolism; HSP27 Heat-Shock Proteins; HSP70 Heat-Shock Proteins - metabolism; Ischemia - complications; Kidney - metabolism; Medical sciences; Neoplasm Proteins - metabolism; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; Phosphorylation; Rats; Renal Circulation; Renal failure; Kidney disease; Immunohistochemistry; Urinary system disease; Pathophysiology; Acute; Cardiovascular disease; Exploration; Kidney; Pathology; Ischemia; Animal; Renal failure; Heat shock protein
• ISSN: 1046-6673; 1533-3450
• DOI: 10.1681/ASN.V112211

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.