Volume 11, Issue 3 pp. 410-417

Klotho gene delivery suppresses Nox2 expression and attenuates oxidative stress in rat aortic smooth muscle cells via the cAMP-PKA pathway

Yuhong Wang

Yuhong Wang

Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA

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Makoto Kuro-o

Makoto Kuro-o

Department of Pathology, University of Texas Southwestern Medical School, Dallas, TX 75390, USA

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Zhongjie Sun

Zhongjie Sun

Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA

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First published: 19 January 2012
Citations: 105
Zhongjie Sun, MD, PhD, FAHA, Professor of Physiology, Director, The Robert & Mary Cade Laboratory, BMSB 662A, Box 26901, Department of Physiology, BMSB 662A, College of Medicine, University of Oklahoma Health Sciences Center (OUHSC), 940 S.L. Young Blvd., Oklahoma City, OK 73126-0901, USA. Tel.: 405 271 2226 ext. 56237; fax: 405 271 3181; e-mail:[email protected]

Summary

Klotho is a recently discovered anti-aging gene. The purpose of this study was to investigate whether klotho gene transfer attenuates superoxide production and oxidative stress in rat aorta smooth muscle (RASM) cells. RASM cells were transfected with AAV plasmids carrying mouse klotho full-length cDNA (mKL) or LacZ as a control. Klotho gene transfer increased klotho expression in RASM cells. Notably, klotho gene expression decreased Nox2 NADPH oxidase protein expression but did not affect Nox2 mRNA expression, suggesting that the inhibition may occur at the posttranscriptional level. Klotho gene transfer decreased intracellular superoxide production and oxidative stress in RASM cells. Klotho gene expression also significantly attenuated the angiotensin II (AngII)-induced superoxide production, oxidative damage, and apoptosis. Interestingly, klotho gene delivery dose dependently increased the intracellular cAMP level and PKA activity in RASM cells. Rp-cAMP, a competitive inhibitor of cAMP, abolished the klotho-induced increase in PKA activity, indicating that klotho activated PKA via cAMP. Notably, inhibition of cAMP-dependent PKA activity by RP-cAMP abolished klotho-induced inhibition of Nox2 protein expression, suggesting an important role of cAMP-dependent PKA in this process. This finding revealed a previously unidentified role of klotho in regulating Nox2 protein expression in RASM cells. Klotho not only downregulated Nox2 protein expression and intracellular superoxide production but also attenuated AngII-induced superoxide production, oxidative damage, and apoptosis. The klotho-induced suppression of Nox2 protein expression may be mediated by the cAMP–PKA pathway.

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