College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Huazhong Agricultural University, Wuhan, 430070, China.
School of Biological Sciences, University of Hong Kong, Hong Kong, China.
Sci Rep. 2016 Oct 27;6:36102. doi: 10.1038/srep36102.
In our previous study, NKB/NK3R system has been shown to act at the pituitary level to up-regulate SLα synthesis and secretion in grass carp. However, whether NK3R expression can serve as a regulatory target at the pituitary level and contribute to NKB interactions with other SLα regulators is still unclear. In current study, using grass carp pituitary cells as a model, we have a novel finding that co-treatment of SLα/SLβ with carp TAC3 gene products, could induce a noticeable enhancement in SLα mRNA expression and these potentiating effects occurred with a parallel rise in NK3R transcript level after SLα/SLβ treatment. Interestingly, the stimulatory effects of SLα/SLβ on NK3R gene expression could be further potentiated by co-treatment with IGF-I/-II and simultaneous exposure of carp pituitary cells to SLα/SLβ and IGF-I/-II in the presence of TAC3 gene products was found to markedly elevated SLα mRNA expression (20 fold increase) and this synergistic stimulation was mediated by cAMP/PKA-, PLC/PKC- and Ca -dependent cascades functionally coupled with NK3R activation. These findings suggest that local release of SLα via functional interactions with IGF-I/-II and TAC3/NK3R system may constitute a potent stimulatory signal for SLα gene expression in the carp pituitary via up-regulation of NK3R expression.
在我们之前的研究中，已经表明 NKB/NK3R 系统在垂体水平起作用，以上调草鱼 SLα 的合成和分泌。然而，NK3R 表达是否可以作为垂体水平的调节靶点，并有助于 NKB 与其他 SLα 调节剂相互作用，目前尚不清楚。在本研究中，我们以草鱼垂体细胞为模型，有一个新的发现，即 SLα/SLβ 与鲤鱼 TAC3 基因产物共同处理，可以显著增强 SLα mRNA 的表达，并且这些增强作用伴随着 SLα/SLβ 处理后 NK3R 转录水平的平行上升。有趣的是，SLα/SLβ 对 NK3R 基因表达的刺激作用可以通过与 IGF-I/-II 共同处理进一步增强，并且同时暴露于鲤鱼垂体细胞 SLα/SLβ 和 IGF-I/-II 以及 TAC3 基因产物，发现 SLα mRNA 的表达明显升高（增加 20 倍），这种协同刺激作用是通过与 NK3R 激活功能偶联的 cAMP/PKA、PLC/PKC 和 Ca 依赖性级联介导的。这些发现表明，SLα 通过与 IGF-I/-II 和 TAC3/NK3R 系统的功能相互作用而局部释放，可能通过上调 NK3R 表达，构成草鱼垂体中 SLα 基因表达的有力刺激信号。
