Evaluate the Molecluar Mechanims and Clinical Application on Atf3 Regulated microRNAs(3/3)

Our previous study showed that microRNA 494 (miR-494) can regulate the expression level of transcriptional factor, ATF3, in acute renal injury. In addition, recent reports also indicate that transcription factor can regulate microRNA (miR) expression resulting in the alteration of pathophysiological phenomena. The reciprocal modulation of transcription factors and miRs indicate that they play important pathophysiological roles. However, there are still no studies investigating the regulation of miRs by ATF3. Our previous data using microRNA array analysis revealed that many miRs, were up or down regulated when renal epithelium cells were treated under hypoxic/reoxygenation condition or overexpressed with ATF3 (Fig.1) indicating that the transcription factor, ATF3 can up or down-regulate miRs processing. We further observed that ATF3 overexpression resulted in the enhancement of miR-16 level in in vitro renal epithelium cells (Fig.2). These preliminary results suggest that not only miR-16 but other miRs may also be regulated by ATF3. We also propose that the altered expression of miRs may affect the pathophysiologic phenomenon in the kidneys after ischemia/reperfusion. In this three years proposal, we will evaluate which miRs in addition to miR-16 and down stream of miR-16 regulated genes may be regulated by ATF3, thereby affecting the function of the kidneys The goals to be completed for this 3-year proposal are as follows: 1. To characterize the miR-16 or the other miRs that will be regulated by ATF3 and to identify the molecular mechanisms involved in in vitro assay (First year). 2. To characterize the pathophysiological role of ATF3-regulated miRs (like miR-16) in the kidneys using in vivo assay, and to verify that the identified miRs can be used as a preclinical tool (Second year). Our previous studies demonstrated that mi-R494, 16 and ATF3 (exosome) (Fig.3) were all increased in the urine of patients with acute kidney injury. Furthermore, we also showed that miR-16 can be used as a urine biomarker of acute kidney injury patients (patented by Taipei Medical University). Therefore, based on the results from the first 2 years, we would like to learn further whether these ATF3-regulated miRs, besides miR-16, can also be used as biomarkers for monitoring patients suffering acute kidney injury. The goal of the 3rd year will be : 3. To confirm that ATF3-regulated miRs (like miR-16) can be used as biomarkers in patients with acute kidney injury (Third year). This study will provide not only a more detailed dissection of the relationship between transcriptional factor, ATF3, and miRs in kidney pathophysiology but may also provide these ATF3 regulated miRs as new therapeutic and diagnostic targets.