Renal mass reduction results in accumulation of lipids and dysregulation of lipid regulatory proteins in the remnant kidney.
A significant reduction of renal mass results in proteinuria, glomerulosclerosis, and tubulointerstitial injury, culminating in end-stage chronic renal failure (CRF). The accumulation of lipids in the kidney can cause renal disease. Uptake of oxidized lipoproteins via scavenger receptors, reabsorption of filtered protein-bound lipids via the megalin-cubilin complex, and increased glucose load per nephron can promote lipid accumulation in glomerular, tubular, and interstitial cells in CRF. Cellular lipid homeostasis is regulated by lipid influx, synthesis, catabolism, and efflux. We examined lipid-regulatory factors in the remnant kidney of rats 11 wk after nephrectomy (CRF) or sham operation. CRF resulted in azotemia, proteinuria, lipid accumulation in the kidney, upregulation of megalin, cubilin, mediators of lipid influx (scavenger receptor class A and lectin-like oxidized receptor-1), lipid efflux (liver X receptor alpha/beta and ATP-binding cassette transporter), and fatty acid biosynthesis (carbohydrate-response element binding protein, fatty acid synthase, and acetyl-CoA carboxylase). However, factors involved in cholesterol biosynthesis (sterol regulatory element binding protein, 3-hydroxy-3-methylglutaryl coenzyme A reductase, SCAP, Insig-1, and Insig-2) and fatty acid oxidation (peroxisome proliferator-activated receptor, acyl-CoA oxidase, and liver-type fatty acid binding protein) were reduced in the remnant kidney. Thus CRF results in heavy lipid accumulation in the remnant kidney, which is mediated by upregulation of pathways involved in tubular reabsorption of filtered protein-bound lipids, influx of oxidized lipoproteins and synthesis of fatty acids, and downregulation of pathways involved in fatty acid catabolism.
Division of Nephrology and Hypertension, University of California, 101 The City Dr., Bldg. 53, Rm. 125, Rt. 81, Orange, CA 92868, USA.
Hyun Ju
HJ
Kim
Hamid
H
Moradi
Jun
J
Yuan
Keith
K
Norris
Nosratola D
ND
Vaziri
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000473:pathology; D050356:Lipid Metabolism / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins