Department of Animal Physiology and Development, Faculty of Biology, Adam Mickiewicz University, Poznań, ul. Uniwersytetu Poznańskiego 6, 61-614, Poznan, Poland.
J Comp Physiol B. 2020 Sep;190(5):669-679. doi: 10.1007/s00360-020-01300-6. Epub 2020 Aug 4.
Sulfakinins (SKs) are pleiotropic neuropeptides commonly found in insects, structurally and functionally homologous to the mammalian gastrin/cholecystokinin (CCK) neuropeptides. SKs together with sulfakinin receptors (SKRs) are involved in sulfakinin signaling responsible for variety of biological functions, including food intake or fatty acid metabolism. In the present study, we determined the distribution of SKRs in Tenebrio molitor larvae and characterized the impact of nonsulfated and sulfated SKs on carbohydrates and insulin-like peptides (ILPs) level in beetle hemolymph. Our results indicate the presence of both sulfakinin receptors, SKR1 and SKR2, in the nervous system of T. molitor. The distribution of SKR2 in peripheral tissues was more widespread than SKR1, and their transcripts have been found in fat body, gut and hemolymph. This is also the first evidence for SKRs presence in insect hemocytes indicating immunotropic activity of SKs. Moreover, in the present study, we have demonstrated that SKs regulate ILPs and carbohydrates level in insect hemolymph, and that sulfation is not crucial for peptides activity. Our study confirms the role of SKs in maintaining energy homeostasis in beetles.
Sulfakinins (SKs) 是一类在昆虫中广泛存在的多功能神经肽，在结构和功能上与哺乳动物的胃泌素/胆囊收缩素 (CCK) 神经肽同源。SKs 与 sulfakinin 受体 (SKRs) 一起参与了 sulfakinin 信号通路，该信号通路负责多种生物学功能，包括食物摄入或脂肪酸代谢。在本研究中，我们确定了 SKRs 在黄粉虫幼虫中的分布，并研究了非磺化和磺化 SKs 对甲虫血淋巴中碳水化合物和胰岛素样肽 (ILPs) 水平的影响。我们的结果表明，SKR1 和 SKR2 这两种磺酰基肽受体都存在于黄粉虫的神经系统中。SKR2 在周围组织中的分布比 SKR1 更为广泛，其转录本存在于脂肪体、肠道和血淋巴中。这也是 SKRs 在昆虫血细胞中存在的首次证据，表明 SKs 具有免疫调节活性。此外，在本研究中，我们证明了 SKs 可以调节昆虫血淋巴中的 ILPs 和碳水化合物水平，并且磺化对于肽的活性并非至关重要。我们的研究证实了 SKs 在维持甲虫体内能量平衡中的作用。
