OX2R activation induces PKC-mediated ERK and CREB phosphorylation.
OX2R activation induces PKC-mediated ERK and CREB phosphorylation.
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DOI：
10.1016/j.yexcr.2012.04.015
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发表时间：
2012-10-01
影响因子：
3.7
通讯作者：
Feng, Pingfu
中科院分区：
文献类型：
--
作者：
Guo, Yang;Feng, Pingfu
脑食欲素和丝裂原活化蛋白激酶（MAPK）信号通路成分的缺乏在人类抑郁症或抑郁症动物模型中都有报道。大脑对食欲素的管理会影响改善抑郁症状的行为。然而，关于食欲素受体激活与MAPK信号通路之间的内源性联系的文献仍然不足。在本研究中，我们报道了过表达OX2R的CHO细胞和小鼠下丘脑细胞系CLU172中食欲素2受体（OX2R）激活对细胞信号传导的影响。在过表达OX2R的CHO细胞中，观察到短期细胞外信号调节激酶（ERK）磷酸化和长期环磷酸腺苷（cAMP）反应元件结合蛋白（CREB）磷酸化，而在小鼠成年下丘脑神经元细胞系CLU172中，观察到20分钟的ERK磷酸化。在CHO细胞中，同样可以激活OX2R的Orexin A介导的ERK磷酸化与Orexin B相同。在CHO细胞中，MAPK抑制剂可消除ERK磷酸化，但不能消除CREB磷酸化。此外，ERK和CREB磷酸化不是由蛋白激酶A （PKA）或钙调蛋白激酶（CaMK）介导的。然而，GF 109203X对蛋白激酶C （PKC）的抑制消除了CHO细胞中ERK和CREB的磷酸化。在1 μM GF 109203X预处理下，ERK和CREB磷酸化显著降低，这表明PKC的传统和新型同工型在OX2R激活后负责CREB磷酸化。而1 μM的蛋白激酶C抑制剂不能抑制orexin B在CLU172细胞中诱导的ERK磷酸化。通过以上观察，我们得出结论：OX2R被食欲素B激活诱导ERK和CREB磷酸化，而食欲素A与食欲素B起着相同的作用。PKC的几种亚型可能参与了CREB磷酸化的延长。Orexin B诱导小鼠下丘脑神经元细胞ERK磷酸化与CHO细胞系不同，PKC抑制剂GF 109203X无法抑制。下丘脑神经元细胞可能通过不同的下行通路介导食欲素B诱导的ERK磷酸化。这一结果支持了食欲素可能具有抗抑郁作用的发现。
Deficiencies in brain orexins and components of mitogen activated protein kinase (MAPK) signaling pathway have been reported in either human depression or animal model of depression. Brain administration of orexins affects behaviors toward improvement of depressive symptoms. However, the documentation of endogenous linkage between orexin receptor activation and MAPK signaling pathway remains to be insufficient. In this study, we report the effects of orexin 2 receptor (OX2R) activation on cell signaling in CHO cells over-expressing OX2R and in mouse hypothalamus cell line CLU172. Short-term extracellular signal-regulated kinase (ERK) phosphorylation and long-term cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) phosphorylation were subsequently observed in CHO cells that over-express OX2R while 20 min of ERK phosphorylation was significantly detected in mouse adult hypothalamus neuron cell line CLU172. Orexin A, which can also activate OX2R, mediated ERK phosphorylation was as the same as orexin B in CHO cells. A MAPK inhibitor eliminated ERK phosphorylation but not CREB phosphorylation in CHO cells. Also, ERK and CREB phosphorylation was not mediated by protein kinase A (PKA) or calmodulin kinase (CaMK). However, inhibition of protein kinase C (PKC) by GF 109203X eliminated the phosphorylation of ERK and CREB in CHO cells. A significant decrease in ERK and CREB phosphorylation was observed with 1 μM GF 109203X pre-treatment indicating that the conventional and novel isoforms of PKC are responsible for CREB phosphorylation after OX2R activation. In contrast, ERK phosphorylation induced by orexin B in CLU172 cells cannot be inhibited by 1 μM of protein kinase C inhibitor. From above observation we conclude that OX2R activation by orexin B induces ERK and CREB phosphorylation and orexin A played the same role as orexin B. Several isoforms of PKC may be involved in prolonged CREB phosphorylation. Orexin B induced ERK phosphorylation in mouse hypothalamus neuron cells differs from CHO cell line and cannot be inhibited by PKC inhibitor GF 109203X. And hypothalamus neuron cells may use different downsteam pathway for orexin B induced ERK phosphorylation. This result supports findings that orexins might have anti-depressive roles.
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