Knockdown of AMPKα2 Promotes Pulmonary Arterial Smooth Muscle Cells Proliferation via mTOR/Skp2/p27Kip1 Signaling Pathway

Abstract

It has been shown that activation of adenosine monophosphate-activated protein kinase (AMPK) suppresses proliferation of a variety of tumor cells as well as nonmalignant cells. In this study, we used post-transcriptional gene silencing with small interfering RNA (siRNA) to specifically examine the effect of AMPK on pulmonary arterial smooth muscle cells (PASMCs) proliferation and to further elucidate its underlying molecular mechanisms. Our results showed that knockdown of AMPKα2 promoted primary cultured PASMCs proliferation; this was accompanied with the elevation of phosphorylation of mammalian target of rapamycin (mTOR) and S-phase kinase-associated protein 2 (Skp2) protein level and reduction of p27Kip1. Importantly, prior silencing of mTOR with siRNA abolished AMPKα2 knockdown-induced Skp2 upregulation, p27Kip1 reduction as well as PASMCs proliferation. Furthermore, pre-depletion of Skp2 by siRNA also eliminated p27Kip1 downregulation and PASMCs proliferation caused by AMPKα2 knockdown. Taken together, our study indicates that AMPKα2 isoform plays an important role in regulation of PASMCs proliferation by modulating mTOR/Skp2/p27Kip1 axis, and suggests that activation of AMPKα2 might have potential value in the prevention and treatment of pulmonary arterial hypertension.

Tsantan Sumtang Alleviates Chronic Hypoxia-Induced Pulmonary Hypertension by Inhibiting Proliferation of Pulmonary Vascular Cells

“…p27Kip1, as the key CDK inhibitor, plays major roles in cell-cycle regulation. p27Kip1 binds cyclin-Cdk multiplexes and inhibits the hyperphosphorylation of the retinoblastoma protein, causes G 1 blockage, and limits cell proliferation [44, 45]. This result is in accordance with other studies and shows that p27Kip1 acted as a negative regulator of cell proliferation by downregulating the expression of CDK4 and cyclin D1 [16–18, 45, 46].…”

“…p27Kip1 binds cyclin-Cdk multiplexes and inhibits the hyperphosphorylation of the retinoblastoma protein, causes G 1 blockage, and limits cell proliferation [44, 45]. This result is in accordance with other studies and shows that p27Kip1 acted as a negative regulator of cell proliferation by downregulating the expression of CDK4 and cyclin D1 [16–18, 45, 46]. Compared with the hypoxia group, the CDK4 and cyclin D1 levels in the Tsantan Sumtang groups were distinctly decreased.…”

Egr-1 mediates leptin-induced PPARγ reduction and proliferation of pulmonary artery smooth muscle cells

“…Primary PASMC from pulmonary arteries were prepared from 40 male Sprague-Dawley rats (4-wk-old, 70–80 g) according to the method of our previous studies ( Wu et al ., 2014 ; Ke et al ., 2016 ). All animal care and experiments were performed in accordance with the Guide for the Care and Use of Laboratory Animals of the Xi’an Jiaotong University Animal Experiment Center.…”

All-Trans-Retinoic Acid Suppresses Neointimal Hyperplasia and Inhibits Vascular Smooth Muscle Cell Proliferation and Migration via Activation of AMPK Signaling Pathway

“…Therefore, targeting AMPK might be a good strategy for atherosclerosis management. A previous study has found that ATRA enhances the activity of AMPK in ovarian cancer, skeletal muscle cells and endothelial cells (Ke et al, 2016). Nevertheless, it remains unclear whether ATRA inhibit ligation-induced neointimal hyperplasia and VSMC proliferation via activation of AMPK.…”

“…Additionally, the significance of AMPK in vascular function is well-supported by anti-atherosclerosis agents, including statins, thiazolidinediones, leptin and rosiglitazone, which exhibit anti-atherosclerosis effects, at least partially, through the activation of AMPK (Zou and Wu, 2008). In addition, activation of AMPK further results in inhibition of mTOR signaling in a variety of cells, including VSMC (Ke et al, 2016). Therefore, targeting AMPK might be a good strategy for atherosclerosis management.…”