The mechanical stress-activated serum-, glucocorticoid-regulated kinase 1 contributes to neointima formation in vein grafts

Jizhong Cheng, Ying Wang, Yewei Ma, Bonita Tak Yee Chan, Min Yang, Anlin Liang, Liping Zhang, Huihua Li, Jie Du

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Rationale: Mechanical stress plays an important role in proliferation of venous smooth muscle cells (SMCs) in neointima, a process of formation that contributes to failure of vein grafts. However, it is unknown what intracellular growth signal leads to proliferation of venous SMCs. Objective: The objective of this study is to identify mechanisms of mechanical stretch on neointima formation. Methods and results: By a microarray analysis, we found that mechanical cyclic stretch (15% elongation) stimulated the transcription of SGK-1 (serum-, glucocorticoid-regulated kinase-1). Mechanical stretch-induced SGK-1 mRNA expression was blocked by actinomycin D. The mechanism for the SGK-1 expression involved MEK1 but not p38 or JNK signaling pathway. SGK-1 activation in response to stretch is blocked by insulin-like growth factor (IGF)-1 receptor inhibitor and mammalian target of rapamycin complex (mTORC)2 inhibitor (Ku-0063794) but not mTORC1 inhibitor (rapamycin). Mechanical stretch-induced bromodeoxyuridine incorporation was reduced by 83.5% in venous SMCs isolated from SGK-1 knockout mice. In contrast, inhibition of Akt, another downstream signal of PI3K resulted in only partial inhibition of mechanical stretch-induced proliferation of venous SMCs. Mechanical stretch also induced phosphorylation and nuclear exportation of p27, whereas knockout of SGK-1 attenuated this effect of mechanical stretch on p27. In vivo, we found that placement of a vein graft into artery increased SGK-1 expression. Knockout of SGK-1 effectively prevented neointima formation in vein graft. There is significant lower level of p27 located in the nucleus of neointima cells in SGK-1 knockout mice compared with that of wild-type vein graft. In addition, we also found that wire injury of artery or growth factors in vitro increased expression of SGK-1. Conclusions: These results suggest that SGK-1 is an injury-responsive kinase that could mediate mechanical stretch-induced proliferation of vascular cells in vein graft, leading to neointima formation.

Original languageEnglish (US)
Pages (from-to)1265-1274
Number of pages10
JournalCirculation research
Volume107
Issue number10
DOIs
StatePublished - Nov 12 2010

Keywords

  • mTORC
  • mammalian target of rapamycin complex
  • mechanical stretch
  • neointima formation
  • serum-, glucocorticoid-regulated kinase-1

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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