Translational Health Sciences, University of Bristol, Research Floor Level 7, Bristol Royal Infirmary, Bristol, BS2 8HW, UK.
School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
Sci Rep. 2018 Mar 20;8(1):4904. doi: 10.1038/s41598-018-23199-4.
Vascular smooth muscle cell (VSMC) proliferation has been implicated in the development of restenosis after angioplasty, vein graft intimal thickening and atherogenesis. We investigated the mechanisms underlying positive and negative regulation of VSMC proliferation by the transcription factor cyclic AMP response element binding protein (CREB). Incubation with the cAMP elevating stimuli, adenosine, prostacyclin mimetics or low levels of forksolin activated CREB without changing CREB phosphorylation on serine-133 but induced nuclear translocation of the CREB co-factors CRTC-2 and CRTC-3. Overexpression of CRTC-2 or -3 significantly increased CREB activity and inhibited VSMC proliferation, whereas CRTC-2/3 silencing inhibited CREB activity and reversed the anti-mitogenic effects of adenosine A2B receptor agonists. By contrast, stimulation with serum or PDGF significantly increased CREB activity, dependent on increased CREB phosphorylation at serine-133 but not on CRTC-2/3 activation. CREB silencing significantly inhibited basal and PDGF induced proliferation. These data demonstrate that cAMP activation of CREB, which is CRTC2/3 dependent and serine-133 independent, is anti-mitogenic. Growth factor activation of CREB, which is serine-133-dependent and CRTC2/3 independent, is pro-mitogenic. Hence, CREB plays a dual role in the regulation of VSMC proliferation with the mode of activation determining its pro- or anti-mitogenic function.
血管平滑肌细胞（VSMC）增殖被认为与血管成形术后再狭窄、静脉移植物内膜增厚和动脉粥样硬化的发生有关。我们研究了转录因子环磷酸腺苷反应元件结合蛋白（CREB）对 VSMC 增殖的正向和负向调节的机制。用 cAMP 升高刺激物腺苷、前列环素模拟物或低水平佛司可林孵育，不改变丝氨酸 133 上的 CREB 磷酸化，但诱导 CREB 共因子 CRTC-2 和 CRTC-3 的核转位。CRTC-2 或 -3 的过表达显著增加了 CREB 活性并抑制了 VSMC 增殖，而 CRTC-2/3 沉默抑制了 CREB 活性并逆转了腺苷 A2B 受体激动剂的抗有丝分裂作用。相比之下，血清或 PDGF 的刺激显著增加了 CREB 活性，这依赖于丝氨酸 133 上 CREB 磷酸化的增加，但不依赖于 CRTC-2/3 的激活。CREB 沉默显著抑制了基础和 PDGF 诱导的增殖。这些数据表明，cAMP 激活 CREB，这是依赖于 CRTC2/3 和不依赖于丝氨酸 133 的，是抗有丝分裂的。生长因子激活 CREB，这是依赖于丝氨酸 133 和不依赖于 CRTC2/3 的，是促有丝分裂的。因此，CREB 在调节 VSMC 增殖中发挥双重作用，其激活方式决定其促有丝分裂或抗有丝分裂功能。
