Chen G, Bridenbaugh E A, Akintola A D, Catania J M, Vaidya V S, Bonventre J V, Dearman A C, Sampson H W, Zawieja D C, Burghardt R C, Parrish A R
Department of Systems Biology and Translational Medicine, College of Medicine, Texas A&M University System Health Science Center, College Station, TX 77843-1114, USA.
Am J Physiol Renal Physiol. 2007 Oct;293(4):F1272-81. doi: 10.1152/ajprenal.00138.2007. Epub 2007 Aug 1.
Aging is associated with an increased incidence and severity of acute renal failure. However, the molecular mechanism underlying the increased susceptibility to injury remains undefined. These experiments were designed to investigate the influence of age on the response of the kidney to ischemic injury and to identify candidate genes that may mediate this response. Renal slices prepared from young (5 mo), aged ad libitum (aged-AL; 24 mo), and aged caloric-restricted (aged-CR; 24 mo) male Fischer 344 rats were subjected to ischemic stress (100% N(2)) for 0-60 min. As assessed by biochemical and histological evaluation, slices from aged-AL rats were more susceptible to injury than young counterparts. Importantly, caloric restriction attenuated the increased susceptibility to injury. In an attempt to identify the molecular pathway(s) underlying this response, microarray analysis was performed on tissue harvested from the same animals used for the viability experiments. RNA was isolated and the corresponding cDNA was hybridized to CodeLink Rat Whole Genome Bioarray slides. Subsequent gene expression analysis was performed using GeneSpring software. Using two-sample t-tests and a twofold cut-off, the expression of 92 genes was changed during aging and attenuated by caloric restriction, including claudin-7, kidney injury molecule-1 (Kim-1), and matrix metalloproteinase-7 (MMP-7). Claudin-7 gene expression peaked at 18 mo; however, increased protein expression in certain tubular epithelial cells was seen at 24 mo. Kim-1 gene expression was not elevated at 8 or 12 mo but was at 18 and 24 mo. However, changes in Kim-1 protein expression were only seen at 24 mo and corresponded to increased urinary levels. Importantly, these changes were attenuated by caloric restriction. MMP-7 gene expression was decreased at 8 mo, but an age-dependent increase was seen at 24 mo. Increased MMP-7 protein expression in tubular epithelial cells at 24 mo was correlated with the gene expression pattern. In summary, we identified genes changed by aging and changes attenuated by caloric restriction. This will facilitate investigation into the molecular mechanism mediating the age-related increase in susceptibility to injury.
衰老与急性肾衰竭的发病率和严重程度增加相关。然而，易感性增加背后的分子机制仍不明确。这些实验旨在研究年龄对肾脏缺血性损伤反应的影响，并确定可能介导这种反应的候选基因。从年轻（5个月）、随意进食的老年（老年-AL；24个月）和热量限制的老年（老年-CR；24个月）雄性Fischer 344大鼠制备的肾切片，接受缺血应激（100% N₂）0至60分钟。通过生化和组织学评估，老年-AL大鼠的切片比年轻大鼠的切片更易受损伤。重要的是，热量限制减弱了易感性的增加。为了确定这种反应背后的分子途径，对用于活力实验的相同动物采集的组织进行了微阵列分析。分离RNA并将相应的cDNA与CodeLink大鼠全基因组生物阵列载玻片杂交。随后使用GeneSpring软件进行基因表达分析。使用双样本t检验和两倍截止值，92个基因的表达在衰老过程中发生变化并被热量限制减弱，包括紧密连接蛋白-7、肾损伤分子-1（Kim-1）和基质金属蛋白酶-7（MMP-7）。紧密连接蛋白-7基因表达在18个月时达到峰值；然而，在24个月时在某些肾小管上皮细胞中可见蛋白表达增加。Kim-1基因表达在8或12个月时未升高，但在18和24个月时升高。然而，Kim-1蛋白表达变化仅在24个月时可见，且与尿中水平升高相对应。重要的是，这些变化被热量限制减弱。MMP-7基因表达在8个月时降低，但在24个月时出现年龄依赖性增加。24个月时肾小管上皮细胞中MMP-7蛋白表达增加与基因表达模式相关。总之，我们确定了因衰老而改变且被热量限制减弱的基因。这将有助于研究介导与年龄相关的易感性增加的分子机制。
