Noradrenergic regulation of period1 expression in spinal astrocytes is involved in protein kinase A, c-Jun N-terminal kinase and extracellular signal-regulated kinase activation mediated by α1- and β2-adrenoceptors.

Our recent data suggest that noradrenaline (NA) regulates expression of Per1 mRNA in rat C6 cells, as a model of brain astrocytes, by two distinct NA-mediating pathways. Although C6 cells possess potential astrocyte-type characteristics, we hypothesize that astrocytes located in a distinct tissue or organ play specific roles consistent with their own unique functions in response to the surrounding environment. We have herein found in primary rat spinal astrocytes using real-time RT-PCR that NA induced robust transient increases in Per1, Cry1, Cry2 and Bmal1 mRNA expression. Cry1, Cry2 and Bmal1 expressions induced by NA were attenuated by transfection of Per1 small interference RNA (siRNA). The effect of NA on Per1 expression was partially blocked by either prazosin (a selective antagonist of α1-adrenoceptor) or ICI118551 (a selective antagonist of β2-adrenoceptor), and completely blocked by the combination of both antagonists. Treatment with H89 (a protein kinase A [PKA] inhibitor), SP600125 (a c-Jun N-terminal kinase [JNK] inhibitor), or PD98059 (an extracellular signal-regulated kinase [ERK] inhibitor), partially inhibited NA-induced Per1 mRNA expression, and the combination of these three inhibitors inhibited expression to nearly a non-stimulated level. Furthermore, NA phosphorylated not only ERK but also JNK1, an effect that was detected by western blotting. These actions were inhibited only by prazosin, and not by ICI118551. In addition, we found that NA induced phosphorylation of transcription-related proteins such as cAMP response element binding protein (CREB) and c-Jun. These phosphorylation processes were regulated through distinct pathways: CREB phosphorylation was dependent on the PKA and JNK pathways but c-Jun phosphorylation was mediated by the ERK and JNK pathways. These results suggest that Per1 plays a key role in noradrenergic regulation on clock gene expression in spinal astrocytes and activation of α1 and β2 adrenoceptors are of importance in regulation of Per1 mRNA expression via PKA/JNK-CREB and ERK/JNK-c-Jun cascades.

Sugimoto T ，Morioka N ，Sato K ，Hisaoka K ，Nakata Y ... -  《-》

Noradrenaline reduces the ATP-stimulated phosphorylation of p38 MAP kinase via beta-adrenergic receptors-cAMP-protein kinase A-dependent mechanism in cultured rat spinal microglia.

Morioka N ，Tanabe H ，Inoue A ，Dohi T ，Nakata Y ... -  《-》

The induction of Per1 expression by the combined treatment with glutamate, 5-hydroxytriptamine and dopamine initiates a ripple effect on Bmal1 and Cry1 mRNA expression via the ERK signaling pathway in cultured rat spinal astrocytes.

Clock genes contribute to the regulation of spinal cord astrocytic function. Although it was previously found that noradrenaline has a pivotal role in the regulation of clock genes expression in cultured rat spinal astrocytes, it is still unknown whether other neurotransmitters might affect clock gene expression. Thus, the effect of spinal neurotransmitters glutamate (Glu), 5-hydroxytriptamine (5-HT) and dopamine (DA) on clock genes expression was examined in cultured rat spinal astrocytes. Simultaneous treatment with Glu (100 μM), 5-HT (10 μM) and DA (10 μM) led to a transient induction of Per1 expression, and a delayed increase of Bmal1 expression and a decrease of Cry1 expression. By contrast, treatment with either Glu, 5-HT or DA alone increased only Per1 expression. The increase in Per1 mRNA by simultaneous treatment with Glu, 5-HT and DA was dependent on extracellular signal-regulated kinase (ERK) activation, since pretreatment with ERK inhibitor U0126 (3 μM) blocked Per1 expression. Second messengers p38 and c-jun N-terminal kinase were not involved in the neurotransmitter effect on Per1 expression, since pretreatment with SB202190 (3 μM) and SP600125 (10 μM), a p38 inhibitor and c-jun N-terminal kinase inhibitor, respectively, had no effect. Blockade of ERK signaling also prevented changes in Bmal1 and Cry1 mRNA expression induced by co-treatment with Glu, 5-HT and DA. In addition to modulating clock gene expression, co-treatment with Glu, 5-HT and DA significantly increased ERK1/2 phosphorylation. Per1 expression itself modulates the expression of other clock gene as knockdown of Per1 expression by using short interference RNA significantly blocked the increase of Bmal1 mRNA expression and the decrease of Cry1 mRNA expression. Thus, neurotransmitters Glu, 5-HT and DA regulate spinal astrocytic clock genes mRNA expression through the ERK pathway and Per1 is a key clock gene that likely modulates the oscillation of clock genes thereby regulating astrocytic function.

Morioka N ，Sugimoto T ，Sato K ，Okazaki S ，Saeki M ，Hisaoka-Nakashima K ，Nakata Y ... -  《-》

Noradrenaline induces clock gene Per1 mRNA expression in C6 glioma cells through beta(2)-adrenergic receptor coupled with protein kinase A - cAMP response element binding protein (PKA-CREB) and Src-tyrosine kinase - glycogen synthase kinase-3beta (Src-GSK

Morioka N ，Sugimoto T ，Tokuhara M ，Dohi T ，Nakata Y ... -  《-》

IL-1beta induces MMP-9 expression via a Ca2+-dependent CaMKII/JNK/c-JUN cascade in rat brain astrocytes.

Wu CY ，Hsieh HL ，Sun CC ，Yang CM ... -  《-》