Li Jingjing, Zhu Zidan, Bi Jingxiu, Feng Qili, Beerntsen Brenda T, Song Qisheng
Division of Plant Science and Technology, University of Missouri, Columbia, MO, United States.
Guangdong Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology and School of Life Sciences, South China Normal University, Guangzhou, China.
Front Physiol. 2021 Oct 21;12:717437. doi: 10.3389/fphys.2021.717437. eCollection 2021.
Bursicon is a neuropeptide belonging to the cystine knot family and is composed of burs and partner of burs (pburs) subunits. It can form heterodimers or homodimers to execute different biological functions. Bursicon heterodimers regulate cuticle sclerotization and wing maturation, whereas bursicon homodimers mediate innate immunity and midgut stem cell proliferation. A recent study has shown that bursicon potentially induces the expression of vitellogenin (Vg) in the black tiger shrimp ; however, the underlying mechanism remains unknown. In this study, we investigated the role of bursicon in the reproductive physiology of the red flour beetle, . The knockdown of burs, pburs, or its receptor in 2-day pupae significantly downregulated the expression levels of Vg1, Vg2, and Vg receptor (VgR) genes in females 3- and 5-day post-adult emergence, leading to abnormal oocytes with limited Vg content. The silencing of burs repressed the number of eggs laid and completely inhibited egg hatch, whereas the silencing of pburs dramatically decreased the number of eggs laid, hatch rate, and offspring larval size, and this RNA interference (RNAi) effects persisted to the next generation. Furthermore, the knockdown of burs or pburs downregulated the expression of the insulin/insulin-like signaling/target of rapamycin (TOR) signaling genes encoding insulin receptor (InR), protein kinase B (Akt), TOR, and ribosomal protein S6 kinase (S6K). Most importantly, the injection of recombinant pburs (r-pburs) protein was able to upregulate the expression of (), (), and () in normal females and rescue the expression of and in pburs RNAi females but failed to rescue and in Tcrk knockdown females. We infer that bursicon homodimers influence expression the receptor Tcrk, possibly by mediating the expression of the juvenile hormone (JH) and IIS/TOR pathway genes, thereby regulating reproduction in . .
bursicon是一种属于胱氨酸结家族的神经肽，由burs和burs的伙伴（pburs）亚基组成。它可以形成异源二聚体或同源二聚体来执行不同的生物学功能。bursicon异源二聚体调节表皮硬化和翅膀成熟，而bursicon同源二聚体介导先天免疫和中肠干细胞增殖。最近的一项研究表明，bursicon可能诱导黑虎虾中卵黄蛋白原（Vg）的表达；然而，其潜在机制仍不清楚。在本研究中，我们调查了bursicon在赤拟谷盗生殖生理学中的作用。在2日龄蛹期敲低burs、pburs或其受体，显著下调了成虫羽化后3天和5天雌性中Vg1、Vg2和Vg受体（VgR）基因的表达水平，导致卵母细胞异常，Vg含量有限。敲低burs抑制了产卵数量并完全抑制了卵孵化，而敲低pburs显著降低了产卵数量、孵化率和后代幼虫大小，并且这种RNA干扰（RNAi）效应持续到下一代。此外，敲低burs或pburs下调了编码胰岛素受体（InR）、蛋白激酶B（Akt）、雷帕霉素靶蛋白（TOR）和核糖体蛋白S6激酶（S6K）的胰岛素/胰岛素样信号/TOR信号基因的表达。最重要的是，注射重组pburs（r-pburs）蛋白能够上调正常雌性中（）、（）和（）的表达，并挽救pburs RNAi雌性中（）和（）的表达，但未能挽救Tcrk敲低雌性中（）和（）的表达。我们推断，bursicon同源二聚体可能通过介导保幼激素（JH）和IIS/TOR途径基因的表达来影响受体Tcrk的表达，从而调节赤拟谷盗的繁殖。
