Identification of a microRNA signature of renal ischemia reperfusion injury

Abstract

Renal ischemia reperfusion injury (IRI) is associated with significant morbidity and mortality. Given the importance of microRNAs (miRNAs) in regulating gene expression, we examined expression profiles of miRNAs following renal IRI. Global miRNA expression profiling on samples prepared from the kidneys of C57BL/6 mice that underwent unilateral warm ischemia revealed nine miRNAs (miR-21, miR-20a, miR-146a, miR-199a-3p, miR-214, miR-192, miR-187, miR-805, and miR-194) that are differentially expressed following IRI when compared with sham controls. These miRNAs were also differently expressed following IRI in immunodeficient RAG-2/ common γ-chain double-knockout mice, suggesting that the changes in expression observed are not significantly influenced by lymphocyte infiltration and therefore define a lymphocyte-independent signature of renal IRI. In vitro studies revealed that miR-21 is expressed in proliferating tubular epithelial cells (TEC) and up-regulated by both cell-intrinsic and -extrinsic mechanisms resulting from ischemia and TGF-β signaling, respectively. In vitro, knockdown of miR-21 in TEC resulted in increased cell death, whereas overexpression prevented cell death. However, overexpression of miR-21 alone was not sufficient to prevent TEC death following ischemia. Our findings therefore define a molecular fingerprint of renal injury and suggest miR-21 may play a role in protecting TEC from death.kidney | miR-21 | tubular epithelial cells | programmed cell death protein 4 I schemic injury followed by reperfusion results in the clinical syndrome of acute kidney injury, a common clinical problem (1-4). The initial nonimmune hypoxic injury and subsequent reperfusion leads to activation of innate and adaptive immune responses, resulting in tissue damage (5). Following injury, a repair process involving cellular proliferation must take place to regain renal function (6). Ischemia reperfusion injury (IRI) is also inevitable in kidney transplantation and contributes to delayed graft function and long-term changes in kidney transplants that affect outcome (7-9). Although IRI is clearly a major clinical problem in native kidneys and in the setting of renal transplantation, the pathogenesis of renal IRI is not fully understood.MicroRNAs (miRNAs) are a class of small, noncoding RNAs ≈21-22 nucleotides in length that regulate gene expression and many disease processes (10, 11). A role for miRNAs in kidney disease is rapidly emerging (12). Numerous hallmarks of IRI (9), such as apoptosis (13), fibrosis (14), epithelial-mesenchymal transition (15), and TLR signaling (16), are regulated by miRNAs in other settings. Recent work has also revealed a role for miRNAs in the regulation of cardiac (13) and hepatic IRI (17).We hypothesized that miRNA expression patterns may serve as a biomarker of kidney injury. To test this hypothesis we reasoned that it would be necessary to examine miRNA expression patterns in an unbiased manner and examine whether differences in miRNA expression patterns were the result of lymphocyte in...

MicroRNA-21 in the pathogenesis of acute kidney injury

“…Ischemia markedly initiates injury of both the renal tubular epithelium and renal microvasculature, which is exacerbated upon reperfusion by an increase in oxidative stress, infl ammation, apoptosis, and necrosis (Bonventre and Weinberg, 2003;Devarajan, 2006). MiR-21 down-regulated apoptosis and necrosis of renal TECs, which promoted cellular proliferation and played a protective role in the response to stress and infl ammation in renal IRI (Lindsay, 2008;Thum et al, 2008a;Godwin et al, 2010). As shown in a previous animal study, knockdown of miR-21 increased cell death.…”

“…As shown in a previous animal study, knockdown of miR-21 increased cell death. However, a confl icting result was also noted in vitro: over-expression of miR-21 did not prevent cell death following simulated ischemia (Godwin et al, 2010). These results indicated the role of miR-21 is a two sided sword in renal IRI: neither under-nor over-expression led to adverse consequences (Fig.…”

“…Surviving TECs then dedifferentiate and proliferate to reconstitute a functioning nephron . MiR-21 has been reported to promote such proliferation and act as a strong anti-apoptotic factor to inhibit cell death (Chan et al, 2005;Cheng et al, 2010;Godwin et al, 2010). Recent fi ndings have also shown that up-regulation of miR-21 contributed to a reduction in renal cell apoptosis and it also consistently shows protective effects against renal IRI after ischemic preconditioning (IPC) (Xu et al, 2012).…”

MicroRNA-494 Reduces ATF3 Expression and Promotes AKI

“…AKI microarray data also showed that several miRNAs (miR-21, miR-20a, miR-146a, miR-199a-3p, miR-214, miR-192, miR-187, miR-805, and miR-194) are differentially expressed. 26 These miRNAs are defined as the lymphocyte-independent signature of ischemic renal injury. However, in several tissues, including the kidneys, ATF3 acted as an early inducible transcriptional repressor 27 and inhibited lymphocytedependent ischemic renal injury.…”

A Comprehensive Profile of Mature MicroRNA in the Pig

“…The miRNAs may be ideal candidates as biomarkers of disease [82][83][84][85][86]. Several factors (the relatively consistent changes seen in diseases, reliable analysis methods, tissue-specific expression patterns, less complexity than mRNAs, no post-processing modification, and amplifiable signals) contribute to making miRNAs ideal candidates, especially in the cancer diagnostic field [87][88][89][90][91].…”