MicroRNA In Diabetic Nephropathy

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PROJECT SUMMARY/ABSTRACT We are witnessing a paradigmatic shift in the practice of medicine whereby the concept of targeting RNAs as diagnostic and therapeutic strategies are rapidly evolving. Lon noncoding RNAs (lncRNAs) are a highly heterogeneous group of non-coding transcripts that participate in the regulation of almost every stage of gene expression, as well as being involved in a variety of disease states. Dysregulation of several lncRNAs have also been implicated in progression of diabetic nephropathy (DN) and because of the tissue-specific characteristics of lncRNAs, they are considered as the next generation of biomarkers and promising therapeutic targets for DN progression In the last funding cycle, our lab provided strong evidence that lncRNATug1 is down regulated in several experimental models of DN and in patients with Type 2 diabetes (Long, et al. JCI, 2016). Importantly, conditional overexpression of Tug1 in podocytes mitigated progression of DN. We also published our findings demonstrating that Tug1-mediated renoprotection in DN is accomplished through a PGC1a-dependent mechanisms on mitochondrial function. Thus, we proposed that Tug1 serves as a novel therapeutic target in DN progression. Our work over the last five years suggests that Tug1 has two major effects on mitochondrial function: 1) Tug1 impacts mitochondrial function indirectly through a PGC1a-dependent mechanism in the nucleus, and 2) we now provide preliminary data suggesting that Tug1 is also translocated from the nucleus to mitochondria. However, the impact of mitochondrial-associated Tug1 (mitoTug1) remains unknown. We also provide preliminary data that Tug1 transcripts localized to the cytoplasm is translated into micropeptides. Several lncRNAs have been shown to hide small open reading frames (sORFs) encoding for small functional peptides termed micropeptides. Our preliminary findings suggest a direct effect of Tug1 encoded micropeptide on mitochondrial function. However, its role on mitochondrial homeostasis and progression of DN is unknown. In this application, we propose a convergent model of Tug1-mediated impact on mitochondrial remodeling in DN. Two fundamental questions will be addressed: 1) First, elucidating the subcellular distribution and function of mitochondrial-associated Tug1 (mitoTug1) on mitochondrial homeostasis and progression of DN, and 2) Second, identifying the biological and pathological role of a Tug1-encoded micropepetide on mitochondrial function and DN progression. We will describe the various techniques and strategies to study the potential role of Tug1 on mitochondrial remodeling, the challenges to these approaches, and our published and preliminary data. The successful completion of our application will place high priority on developing strategies to target Tug1 as a potential candidate in future clinical studies, and open a rich field for investigation on the interorganelle communication and mitochondrial metabolism in the pathogenesis of DN.