Acquisition of the contractile phenotype by murine arterial smooth muscle cells depends on the Mir143/145 gene cluster
Thomas Boettger, Nadine Beetz, Sawa Kostin, Johanna Schneider, Marcus Krüger, Lutz Hein, Thomas Braun
Thomas Boettger, Nadine Beetz, Sawa Kostin, Johanna Schneider, Marcus Krüger, Lutz Hein, Thomas Braun
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Research Article

Acquisition of the contractile phenotype by murine arterial smooth muscle cells depends on the Mir143/145 gene cluster

Abstract

VSMCs respond to changes in the local environment by adjusting their phenotype from contractile to synthetic, a phenomenon known as phenotypic modulation or switching. Failure of VSMCs to acquire and maintain the contractile phenotype plays a key role in a number of major human diseases, including arteriosclerosis. Although several regulatory circuits that control differentiation of SMCs have been identified, the decisive mechanisms that govern phenotypic modulation remain unknown. Here, we demonstrate that the mouse miR-143/145 cluster, expression of which is confined to SMCs during development, is required for VSMC acquisition of the contractile phenotype. VSMCs from miR-143/145–deficient mice were locked in the synthetic state, which incapacitated their contractile abilities and favored neointimal lesion development. Unbiased high-throughput, quantitative, mass spectrometry–based proteomics using reference mice labeled with stable isotopes allowed identification of miR-143/145 targets; these included angiotensin-converting enzyme (ACE), which might affect both the synthetic phenotype and contractile functions of VSMCs. Pharmacological inhibition of either ACE or the AT1 receptor partially reversed vascular dysfunction and normalized gene expression in miR-143/145–deficient mice. We conclude that manipulation of miR-143/145 expression may offer a new approach for influencing vascular repair and attenuating arteriosclerotic pathogenesis.

Authors

Thomas Boettger, Nadine Beetz, Sawa Kostin, Johanna Schneider, Marcus Krüger, Lutz Hein, Thomas Braun

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Figure 3

SMCs of Mir143/145-KO mice show a shift from a contractile to a synthetic phenotype and reduced media thickness.

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SMCs of Mir143/145-KO mice show a shift from a contractile to a syntheti...
(A and B) Ultrastructural features of contractile and synthetic SMCs. (A) Typical contractile SMCs from WT animals show numerous focal adhesions (arrows) and intracellular dense bodies (arrowheads). (B) In contrast, synthetic SMCs from mutant mice only rarely display focal adhesions (arrow) and intracellular dense bodies and are rich in rough ER (rER). (C) Relative numbers of synthetic and contractile VSMCs in aorta and femoral artery. The number of synthetic SMCs is increased in the aorta and femoral arteries of KO mice. *P < 0.05; 300 cells per genotype were analyzed. (D–G) Quantification of markers of contractile SMCs (D–F) and synthetic SMCs (G). *P < 0.05 in D, E, and G; n = 3 WT, n = 3 KO mutant. *P < 0.0001 in F, n = 8 WT, n = 7 KO mutant. (H and I) EM pictures of cross sections through the femoral artery. Note the presence of contractile and synthetic SMCs in WT and mutant vessel walls, respectively. (J) Quantification of media thicknesses. *P < 0.05, n = WT, n = 3 KO mutant. Error bars indicate ± SEM.