Padanilam B J, Martin D R, Hammerman M R
George M. O'Brien Kidney and Urological Diseases Center, Renal Division, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Endocrinology. 1996 May;137(5):2133-40. doi: 10.1210/endo.137.5.8612558.
Pretreatment of rats with insulin-like growth factor I (IGF-I) ameliorates the course of acute ischemic renal injury. Differential display PCR was used to identify genes that are expressed in kidney after induction of acute ischemic renal injury in rats pretreated with vehicle or IGF-I. One amplification product that showed enhanced expression in kidneys of rats rendered ischemic compared to kidneys of sham-operated rats was identified as osteopontin. Sequence analysis of full-length complementary DNAs revealed a single species. Renal tissue was obtained for study 12 h and 1, 2, 3, 5, 7, 14, and 28 days postinjury. Levels of whole kidney osteopontin messenger RNA (mRNA) in rats rendered ischemic 1 day previously were elevated approximately 18-fold compared to levels measured in sham-operated controls, as determined by Northern analysis. No differences were noted 12 h postinjury. Levels of osteopontin mRNA remained elevated for 14 days after ischemia, but were no longer elevated at 28 days. IGF-I pretreatment resulted in enhanced levels of osteopontin mRNA 12 h, 1 day, and 5 days postinjury. In situ hybridization demonstrated that the elevated expression of osteopontin 1 day postinjury was localized predominantly to cells in the distal tubule and medullary thick ascending limb of Henle's loop. Immunostaining showed an identical localization for elevated protein expression. Five days postinjury, osteopontin peptide and mRNA were clearly detected in regenerating proximal tubules in addition to distal tubule and medullary thick ascending limb. We propose that endogenous osteopontin serves to promote tissue regeneration and tissue remodeling within 1 day after acute ischemic injury of kidney. IGF-I enhanced expression of osteopontin at an earlier time postischemia may ameliorate the course of injury.
用胰岛素样生长因子I（IGF-I）预处理大鼠可改善急性缺血性肾损伤的病程。采用差异显示PCR技术来鉴定在用赋形剂或IGF-I预处理的大鼠中诱导急性缺血性肾损伤后肾脏中表达的基因。与假手术大鼠的肾脏相比，在缺血大鼠的肾脏中显示出增强表达的一个扩增产物被鉴定为骨桥蛋白。全长互补DNA的序列分析揭示了单一物种。在损伤后12小时以及1、2、3、5、7、14和28天获取肾组织用于研究。通过Northern分析确定，与假手术对照组相比，1天前缺血的大鼠全肾骨桥蛋白信使核糖核酸（mRNA）水平升高了约18倍。损伤后12小时未观察到差异。骨桥蛋白mRNA水平在缺血后14天内一直升高，但在28天时不再升高。IGF-I预处理导致损伤后12小时、1天和5天骨桥蛋白mRNA水平升高。原位杂交表明，损伤后1天骨桥蛋白的表达升高主要定位于远端小管和髓袢升支粗段的细胞。免疫染色显示蛋白表达升高的定位相同。损伤后5天，除了远端小管和髓袢升支粗段外，在再生的近端小管中也清楚地检测到骨桥蛋白肽和mRNA。我们提出，内源性骨桥蛋白在肾脏急性缺血性损伤后1天内有助于促进组织再生和组织重塑。IGF-I在缺血后更早时间增强骨桥蛋白的表达可能改善损伤病程。
