磷酸腺苷激活的蛋白激酶参与调节细胞外信号调节激酶1/2活化发挥对血管平滑肌细胞胰岛素样生长因子-1信号的抑制作用

AMP-activated protein kinase inhibits insulin-like growth factor-1 signaling in vascular smooth muscle cells via regulating activation of extracellular signalre-gulated kinases 1/2

目的进一步证实在猪主动脉平滑肌细胞中磷酸腺苷激活的蛋白激酶(AMP-activated protein kinase,AMPK)抑制胰岛素样生长因子-1(insulin-like growth factor-1,IGF-1)刺激引起的细胞增生,以及探讨其可能的机制。方法使用AMPK活化剂二甲双胍增强细胞内AMPK的活化(表现为AMPK第172位苏氨酸磷酸化增高);采用定点突变获得组成性激活型AMPK突变体,设计短发卡RNA (short hairpin,shRNA)序列构建AMPK干扰载体,并分别包装产生组成性激活型AMPK和AMPK敲低慢病毒。分别采用AMPK活化剂二甲双胍处理、组成性激活型AMPK慢病毒感染和AMPK敲低慢病毒感染猪主动脉平滑肌细胞,观察AMPK活性对猪主动脉平滑肌细胞中IGF-1刺激引起的细胞外信号调节激酶1/2(extracellular signal-regulated kinases 1/2,ERK1/2)活性(表现为202位苏氨酸和204位酪氨酸的磷酸化)及其下游细胞增生的影响。结果二甲双胍明显增强AMPK的活性(表现为172位苏氨酸磷酸化增高),并明显抑制IGF-1刺激引起的ERK1/2活化(表现为202位苏氨酸和204位酪氨酸的磷酸化受到抑制);组成性激活型AMPK表达能明显抑制IGF-1刺激引起的ERK1/2活化以及下游的细胞增生;在AMPK敲低细胞中,IGF-1能引起更强的ERK1/2活化。结论 AMPK能通过抑制ERK1/2活化抑制血管平滑肌细胞IGF-1信号,并能抑制IGF-1刺激引起的血管平滑肌细胞增生。

Objective To further demonstrate AMP-activated protein kinase( AMPK) inhibiting IGF-1-stimulated cell proliferation and determine its potential mechanism in porcine aorta vascular smooth muscle cells( p VSMCs). Methods Metformine was utilized to enhance activation of AMPK( shown as increasing phosphorylation level of AMPK at threonine 172). Site-directed mutagenesis was utilized to construct constitutively active AMPK. Short hairpins RNA( shRNA) for AMPK were designed to construct AMPK silencing vectors. AMPK activator metformine,Lenti-virus-mediated expression of constitutively active forms of AMPK and Lenti-virus-mediated AMPK knocking-down were utilized to observe influence of AMPK activity on IGF-1-stimulated activation of extracellular signal – regulated kinases 1/2( ERK1/2,phospnorylation of ERK1/2 at threonine 202 and tyrosine 204) as well as subsequential cell proliferation in porcine aorta vascular smooth muscle cells. Results The AMPK activator metformine significantly increased phosphorylation of AMPK at thr172 and inhibited IGF-1-stimulated phosphorylation of ERK1/2 at threonine 202 and tyrosine 204( T202/Y204). Constitutively active forms of AMPK were expressed in pVSMCs and suppressed IGF-1-stimulated phosphorylation of ERK1/2 at T202/Y204 and cell proliferation. AMPK expression was significantly decreased in pVSMCs infected with AMPK silencing Lenti-virus. AMPK knocking-down induced higher phosphorylation of ERK1/2 at T202/Y204 upon IGF-1 stimulation in porcine aorta vascular smooth muscle cells. Conclusion AMPK induces inhibition of IGF-1 signaling through suppressing activation of ERK1/2 in porcine aorta vascular smooth muscle cells.