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Ca2+/calmodulin-dependent protein kinase kinase β phosphorylation of Sirtuin 1 in endothelium is atheroprotective

  1. John Y.-J. Shyyb,f,1
  1. aDepartment of Physiology and Pathophysiology, Peking University Health Sciences Center, Beijing 100191, China;
  2. bDivision of Biomedical Sciences and
  3. cDepartment of Chemistry, University of California, Riverside, CA 92521;
  4. dDepartment of Kinesiology and Health Sciences, California State University, San Bernardino, CA 92407; and
  5. Departments of eBioengineering and
  6. fMedicine, University of California, San Diego, La Jolla, CA 92093

  1. Contributed by Shu Chien, May 16, 2013 (sent for review March 3, 2013)

Significance

Different flow patterns in the arterial tree determine the severity and topographic distribution of atherosclerosis. Atheroprotective flow exerts anti-inflammatory and antioxidative effects on vascular endothelial cells, and the underlying mechanism involves the flow-induced upregulation of Sirtuin (SIRT)1. This study reveals that athero-protective flow activates Ca2+/calmodulin-dependent protein kinase kinase (CaMKK)β, which, in turn, phosphorylates SIRT1 at Ser-27 and Ser-47 to increase the stability and activity of SIRT1. The mechanosensitive CaMKKβ-SIRT1 pathway alleviates inflammatory and redox status in the endothelium. Such a conclusion is evident from the drastically increased atherosclerosis in mice lacking CaMKKβ or endothelial SIRT1.

Abstract

Atheroprotective flow exerts antioxidative and anti-inflammatory effects on vascular endothelial cells (ECs), in part through the induction of Sirtuin 1 (SIRT1), a class III histone deacetylase. The role of Ca2+/calmodulin-dependent protein kinase kinase (CaMKK)β in flow induction of SIRT1 both in vitro and in vivo was investigated. Pulsatile shear stress mimicking atheroprotective flow increased the level of SIRT1 in cultured ECs by enhancing its stability, and this effect was abolished by inhibition or knockdown of CaMKKβ. Flow-enhanced SIRT1 stability was primarily mediated by CaMKKβ phosphorylation of SIRT1 at Ser-27 and Ser-47, as evidenced by in vitro kinase assay, mass spectrometry, and experiments using loss- or gain-of-function SIRT1 mutants. Flow-induced CaMKKβ phosphorylation of SIRT1 Ser-27 and Ser-47 increased antioxidative and anti-inflammatory capacities. Ablation of CaMKKβ or SIRT1 in mice with an apolipoprotein E-null background showed increased atherosclerosis both in athero-prone and in athero-protective areas. The results suggest that the CaMKKβ-SIRT1 axis in ECs is mechanosensitive, antioxidative, and anti-inflammatory.

Footnotes

  • ↵1To whom correspondence may be addressed. E-mail: yizhuucr{at}yahoo.com, shuchien{at}ucsd.edu, or jshyy{at}ucsd.edu.

  • Author contributions: L.W., Z.C., D.A.J., Y.Z., S.C., and J.Y.-J.S. designed research; L.W., Z.C., F.Z., X.C., W.S., G.G.G., and Y.W. performed research; L.W., Y.Z., and J.Y.-J.S. analyzed data; and L.W., D.A.J., Y.Z., S.C., and J.Y.-J.S. wrote the paper.

  • The authors declare no conflict of interest.

  • This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1309354110/-/DCSupplemental.

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