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Sci Signal. 2015 May 12;8(376):ra44. doi: 10.1126/scisignal.2005482.

Phosphorylation of GATA-6 is required for vascular smooth muscle cell differentiation after mTORC1 inhibition.

Author information

1
Yale Cardiovascular Research Center, Vascular Biology and Therapeutics Program, and Departments of Medicine and Pharmacology, Yale University School of Medicine, New Haven, CT 06511, USA.
2
Department of Pharmacology and Toxicology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA. Department of Surgery, Section of Vascular Surgery, The Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA.
3
Yale Cardiovascular Research Center, Vascular Biology and Therapeutics Program, and Departments of Medicine and Pharmacology, Yale University School of Medicine, New Haven, CT 06511, USA. Department of Pharmacology and Toxicology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA. Department of Surgery, Section of Vascular Surgery, The Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA.
4
Department of Surgery, Section of Vascular Surgery, The Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA.
5
Institute for Diabetes, Obesity and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
6
Department of Biology, University of Vermont, Burlington, VT 05405, USA.
7
Department of Biostatistics, Yale School of Public Health, New Haven, CT 06510, USA.
8
Yale Cardiovascular Research Center, Vascular Biology and Therapeutics Program, and Departments of Medicine and Pharmacology, Yale University School of Medicine, New Haven, CT 06511, USA. Department of Pharmacology and Toxicology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
9
Yale Cardiovascular Research Center, Vascular Biology and Therapeutics Program, and Departments of Medicine and Pharmacology, Yale University School of Medicine, New Haven, CT 06511, USA. Department of Pharmacology and Toxicology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA. Department of Surgery, Section of Vascular Surgery, The Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA. kathleen.martin@yale.edu.

Abstract

Vascular smooth muscle cells (VSMCs) undergo transcriptionally regulated reversible differentiation in growing and injured blood vessels. This dedifferentiation also contributes to VSMC hyperplasia after vascular injury, including that caused by angioplasty and stenting. Stents provide mechanical support and can contain and release rapamycin, an inhibitor of the mechanistic target of rapamycin complex 1 (mTORC1). Rapamycin suppresses VSMC hyperplasia and promotes VSMC differentiation. We report that rapamycin-induced differentiation of VSMCs required the transcription factor GATA-6. Inhibition of mTORC1 stabilized GATA-6 and promoted the nuclear accumulation of GATA-6, its binding to DNA, its transactivation of promoters encoding contractile proteins, and its inhibition of proliferation. These effects were mediated by phosphorylation of GATA-6 at Ser(290), potentially by Akt2, a kinase that is activated in VSMCs when mTORC1 is inhibited. Rapamycin induced phosphorylation of GATA-6 in wild-type mice, but not in Akt2(-/-) mice. Intimal hyperplasia after arterial injury was greater in Akt2(-/-) mice than in wild-type mice, and the exacerbated response in Akt2(-/-) mice was rescued to a greater extent by local overexpression of the wild-type or phosphomimetic (S290D) mutant GATA-6 than by that of the phosphorylation-deficient (S290A) mutant. Our data indicated that GATA-6 and Akt2 are involved in the mTORC1-mediated regulation of VSMC proliferation and differentiation. Identifying the downstream transcriptional targets of mTORC1 may provide cell type-specific drug targets to combat cardiovascular diseases associated with excessive proliferation of VSMCs.

PMID:
25969542
PMCID:
PMC4560350
DOI:
10.1126/scisignal.2005482
[Indexed for MEDLINE]
Free PMC Article

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