Koul Sweaty, Huang Meiyi, Bhat Sidarth, Maroni Paul, Meacham Randall B, Koul Hari K
Signal Transduction and Molecular Urology Laboratory, Program in Urosciences, Division of Urology, Department of Surgery, University of Colorado, School of Medicine, 4200 East Ninth Avenue, C-319, Denver, CO 80262, USA.
Urol Res. 2008 Feb;36(1):1-10. doi: 10.1007/s00240-007-0130-4. Epub 2008 Jan 3.
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 [(3)H]-uridine and [(3)H]-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 (approximately 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.
我们研究了草酸盐对即刻早期基因（IEGs）和应激蛋白HSP 70的影响，这两种蛋白是细胞对多种应激反应时常见的诱导基因。将LLC-PK1细胞暴露于草酸盐中。通过Northern和Western印迹分析监测基因转录和翻译情况。分别通过[³H]-尿苷和[³H]-胸苷掺入法评估RNA和DNA合成。草酸盐暴露选择性地增加了编码IEGs的c-myc和c-jun以及应激蛋白HSP 70的mRNA水平。虽然c-myc和c-jun的表达迅速（15分钟至2小时内）且短暂，但HSP 70的表达延迟（约8小时）且稳定。此外，草酸盐暴露导致广义转录延迟诱导18小时，并在草酸盐暴露24小时后重新启动DNA合成。而且，我们发现轻度高渗暴露预先诱导HSP 70可保护细胞免受草酸盐毒性。据我们所知，这是第一项证明肾上皮细胞对草酸盐毒性存在快速IEG反应和延迟热休克反应以及HSP 70对草酸盐毒性具有保护作用的研究。草酸盐作为一种代谢终产物，可诱导IEGs的c-myc和c-jun以及延迟的HSP 70表达；虽然IEG表达可能调节对草酸盐的其他遗传反应，但增加的HSP 70表达在草酸盐应激期间将起到早期保护作用。
