BACKGROUND: It has been proven that phenotype shifting, from the contractile phenotype to the synthetic phenotype, of vascular smooth muscle cells (VSMCs), plays an important role in vascular diseases such as atherosclerosis, restenosis, and hypertension. Recently, accumulating evidence suggests that Klotho is associated with many cardiovascular diseases or damage. Through the estimation of the proliferation and migration of Ang II-induced VSMCs and the related intracellular signal transduction pathways, we researched the effects of Klotho on phenotype modulation in this study.

MATERIAL AND METHODS: A rat vascular smooth muscle cell line was grown in vitro with or without Ang II or Klotho, and cell proliferation and migration were evaluated.

RESULTS: The dose-dependent inhibition of Ang II-induced proliferation and migration by Klotho was shown in VSMCs. The phenotype modulation was inhibited by Klotho co-treatment; this co-treatment promoted the expression of contractile phenotype marker proteins, including SM22α, and also the proliferation phenotype marker protein PCNA compared with Ang II alone, which was suppressed, and activated VSMCs. Furthermore, by reducing the expression of G0/G1-specific regulatory proteins such as cyclin D1, cyclin-dependent kinase (CDK) 4, cyclin E, and CDK2, cell cycle arrest was induced by Klotho at G0/G1 phase. Although Ang II strongly stimulated NF-κB, p65, Akt, and ERK phosphorylation, these activation events were diminished by co-treatment with Ang II and Klotho.

CONCLUSIONS: Phenotype modulation of Ang II-induced VSMCs and stimulation of the NF-κB, p65, Akt, and ERK signaling pathways were inhibited by Klotho, which suggests that Klotho may play an important role in the phenotype modulation of VSMCs.

Keywords: Emigration and Immigration