Oxalate exposure provokes HSP 70 response in LLC-PK1 cells, a line of renal epithelial cells: protective role of HSP 70 against oxalate toxicity
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We investigated the effects of oxalate on immediate early genes (IEGs) and stress protein HSP 70, commonly induced genes in response to a variety of stresses. LLC-PK1 cells were exposed to oxalate. Gene transcription and translation were monitored by Northern and Western blot analysis. RNA and DNA synthesis were assessed by [3H]-uridine and [3H]-thymidine incorporation, respectively. Oxalate exposure selectively increased the levels of mRNA encoding IEGs c-myc and c-jun as well as stress protein HSP 70. While expression of c-myc and c-jun was rapid (within 15 min to 2 h) and transient, HSP 70 expression was delayed (∼8 h) and stable. Furthermore, oxalate exposure resulted in delayed induction of generalized transcription by 18 h and reinitiation of the DNA synthesis by 24 h of oxalate exposure. Moreover, we show that prior induction of HSP 70 by mild hypertonic exposure protected the cells from oxalate toxicity. To the best of our knowledge this is the first study to demonstrate rapid IEG response and delayed heat-shock response to oxalate toxicity and protective role of HSP 70 against oxalate toxicity to renal epithelial cells. Oxalate, a metabolic end product, induces IEGs c-myc and c-jun and a delayed HSP 70 expression; While IEG expression may regulate additional genetic responses to oxalate, increased HSP 70 expression would serve an early protective role during oxalate stress.
KeywordsLLC-PK1 cells Immediate early genes Heat shock protein Nephrolithiasis Oxalate toxicity Gene expression
This work was supported in part by research grant to Dr. Koul from National Institutes of Health (NIH-DK-RO1-54084).
- 8.Chomczynski P, Sacchi N (1994) Guanidine methods for total RNA preparation. In: Ausubel FM, Brent R, Kingston RE, Moore DD, Seidman JG, Smith JA, Struhl K (eds) Current protocol in molecular biology. Wiley, New York, pp 4.2.1–4.2.2Google Scholar
- 14.Koul H, Huang M (2003) Oxalate exposure provokes the immediate early genes (c-myc and c-jun) and HSP70 response in LLC-PK1 cells, a line of renal epithelial cells. J Am Soc Nephrol 14:abstract# SO-PO760Google Scholar
- 25.Koul H, Menon M, Scheid C (1996) Oxalate and renal tubular cells: a complex interaction. Ital J Miner Electrolyte Metab 10:67–74Google Scholar
- 26.Koul H (1999) Idiopathic calcium oxalate urolithiasis: Y2K update. In: Proceedings of the international CME in urology, pp 89–97Google Scholar
- 39.Robertson WG, Peacock M, Heyburn PJ, Marshall RW, Rutherford A, Williams RE, Clark PB (1979) The significance of mild hyperoxaluria in calcium stone-formation. In: Rose GA, Robertson WG, Watts REW (eds) Oxalate in human biochemistry and clinical pathology. The Welcome Foundation Ltd, London, p 173Google Scholar