At the dawn of an age when RNA molecules are being used as therapeutics, we identified a novel RNA-based mechanism in the regulation of endothelin-1 (ET-1). The ET-1 hormone signaling pathway is an emerging target for the treatment of age-related pathologies such as chronic kidney disease (CKD). Excessive renal ET-1 expression occurs at all stages of CKD. Moreover, ET-1 plays a central role in CKD-related cell proliferation, inflammation and fibrosis. Existing pharmacological strategies targeting the ET-1 signaling pathway are fraught with serious and unacceptable side effects. An RNA-based therapeutic represents a fundamentally different approach for controlling ET-1 action. We discovered a novel long noncoding antisense RNA (EDN1-AS) originating from within the human ET-1 locus. EDN1-AS is expressed in male and female mouse kidney, in human breast, lung, and renal cell lines and in human adult kidney tissue. We propose to define the regulation and function of EDN1-AS in a model of CKD. Typically, antisense RNAs down-regulate expression of a gene in a highly specific manner. Our preliminary data demonstrate that EDN1-AS is expressed in a circadian manner and that the circadian clock protein Per1 interacts with the EDN1-AS promoter. Together these findings demonstrate the existence of a novel long noncoding RNA with the potential to provide an entirely new approach for targeting ET-1 in CKD and other age-related disease states. The strength of our investigative team is the ability to link physiological observations to the underlying molecular mechanisms. Together we have made numerous contributions to the understanding of ET-1 regulation, expression, and function. The scope of our combined approach ranges from analysis of chromatin structure, to discovery of mineralocorticoid receptor induction of EDN1 gene activity, to characterization of circadian clock regulation of EDN1, to detection of miRNA action on ET-1 synthesis. Thus, we are well-suited to perform the proposed studies to characterize a novel mechanism of endothelin regulation. Our long term goal is to demonstrate that manipulation of ET-1 levels using an EDN1-AS approach will result in therapeutic benefits for CKD patients by decreasing cell proliferation and fibrosis in the renal proximal tubule. Since EDN1-AS is a newly discovered antisense RNA, the goals of this proposal are to characterize EDN1-AS, determine its mode of action, and define its regulation by the circadian clock in a model of CKD. Our central hypothesis is that EDN1-AS represents a novel regulatory mechanism governing endothelin signaling with implications for treating age-related disease states focusing on CKD. These studies are absolutely necessary to lay the groundwork for development of therapeutic strategies.
The peptide hormone Endothelin-1 is a treatment target in age-related chronic kidney disease but drugs that block Endothelin-1 activity have caused unacceptable negative side effects. We discovered a novel regulatory Endothelin-1 antisense RNA that is expressed in human kidney cells, a cell type that is critically affected in chronic kidney disease. Antisense RNAs can down-regulate expression of a gene in a highly specific manner; the proposed studies will test the hypothesis that this antisense RNA represents a new way to control Endothelin-1 expression and activity in aging and chronic kidney disease.