This application is submitted in response to RFA-HL-10-027. As indicated in the RFA announcement, "The goals of this RFA are to elucidate, in animal models, the cellular and molecular mechanisms that underlie large artery stiffening and determine the role of arterial stiffening in the etiology of hypertension". Klotho is a recently-discovered anti-aging gene. Genetic mutation of klotho results in multiple premature aging phenotypes while overexpression of klotho extends lifespan. Cardiovascular disease is associated with aging. In humans, the prevalence of arterial stiffening and hypertension increases with age while the level of circulating klotho decreases with age. It is not known, however, if klotho is involved in the maintenance of normal arterial compliance. Whether klotho gene deficiency causes arterial stiffening has never been determined. Chronic kidney disorders are associated with arterial stiffening. Our new preliminary studies showed that conditional kidney- specific knockout of klotho gene (KL-KO) caused arterial stiffening and systolic hypertension. The objective of the proposed research is to determine the role of kidney-derived klotho in the maintenance of arterial compliance and the molecular mechanisms that mediate klotho deficiency-induced arterial stiffening and its relationship to the development of hypertension. This objective will be achieved by pursuing three coherent specific aims using a combination of experimental approaches including conditional kidney-specific gene knockout, in vivo gene delivery, and real-time monitoring of blood pressure (telemetry). (1) Determine the contribution of impaired endothelial function (down-regulation of eNOS) and oxidative stress (up-regulation of NADPH oxidase p47phox) to the KL-KO-induced arterial stiffening and systolic hypertension. (2) Determine the role of the up-regulation of MMP-9, TGF-21, and runt-related transcription factor-2 (RUNX-2) in SMCs and their relationship in KL-KO- induced elastin degradation, osteoblastic transition, calcification (elastocalcinosis), and arterial stiffening and systolic hypertension. (3) Determine the effects of therapeutic prevention of a decline in the circulating klotho on the development of arterial stiffening and systolic hypertension in senescence-accelerated mice P1 (SAMP1). The proposed studies are significant as they will reveal, for the first time, an important role of klotho deficiency in the pathogenesis of arterial stiffening. These studies will also demonstrate that arterial stiffening could be an important etiological factor in the development of systolic hypertension. Completion of the project may provide new insights into the therapeutic strategies for the control of arterial stiffening and related cardiovascular complications.
Arterial stiffening and related cardiovascular disease is associated with aging and diabetes and is the major cause of death in the US. Indeed, the prevalence of arterial stiffening and hypertension increases with age. The purpose of the proposed research is to determine the role of klotho, a recently-discovered anti-aging gene, in the pathogenesis of large, conduit artery stiffening and its relationship to development of systolic hypertension. The results will provide novel information regarding the molecular mechanism of large artery stiffening in klotho-deficient animals. Completion of the project may offer a new therapeutic approach for large artery stiffening and related cardiovascular disorders. The finding will benefit the US population which has a high prevalence of cardiovascular disease.
|Gao, Diansa; Zuo, Zhong; Tian, Jing et al. (2016) Activation of SIRT1 Attenuates Klotho Deficiency-Induced Arterial Stiffness and Hypertension by Enhancing AMP-Activated Protein Kinase Activity. Hypertension 68:1191-1199|
|Lin, Yi; Chen, Jianglei; Sun, Zhongjie (2016) Antiaging Gene Klotho Deficiency Promoted High-Fat Diet-Induced Arterial Stiffening via Inactivation of AMP-Activated Protein Kinase. Hypertension 67:564-73|
|Varshney, Rohan; Ali, Quaisar; Wu, Chengxiang et al. (2016) Monocrotaline-Induced Pulmonary Hypertension Involves Downregulation of Antiaging Protein Klotho and eNOS Activity. Hypertension 68:1255-1263|
|Chen, Kai; Zhou, Xiaoli; Sun, Zhongjie (2015) Haplodeficiency of Klotho Gene Causes Arterial Stiffening via Upregulation of Scleraxis Expression and Induction of Autophagy. Hypertension 66:1006-13|
|Lin, Yi; Sun, Zhongjie (2015) Antiaging Gene Klotho Attenuates Pancreatic Î²-Cell Apoptosis in Type 1 Diabetes. Diabetes 64:4298-311|
|Xu, Yuechi; Sun, Zhongjie (2015) Molecular basis of Klotho: from gene to function in aging. Endocr Rev 36:174-93|
|Lin, Yi; Sun, Zhongjie (2015) In vivo pancreatic Î²-cell-specific expression of antiaging gene Klotho: a novel approach for preserving Î²-cells in type 2 diabetes. Diabetes 64:1444-58|
|Sun, Zhongjie (2015) Aging, arterial stiffness, and hypertension. Hypertension 65:252-6|
|Zhou, Xiaoli; Chen, Kai; Lei, Han et al. (2015) Klotho gene deficiency causes salt-sensitive hypertension via monocyte chemotactic protein-1/CC chemokine receptor 2-mediated inflammation. J Am Soc Nephrol 26:121-32|
|Wang, Yuhong; Sun, Zhongjie (2014) Antiaging gene Klotho regulates endothelin-1 levels and endothelin receptor subtype B expression in kidneys of spontaneously hypertensive rats. J Hypertens 32:1629-36; discussion 1636|
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