Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom 73170, Thailand.
Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom 73170, Thailand; Department of Biochemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand.
Comp Biochem Physiol A Mol Integr Physiol. 2020 May;243:110682. doi: 10.1016/j.cbpa.2020.110682. Epub 2020 Feb 22.
Vitellogenesis is a principal process during ovarian maturation in crustaceans. This process is negatively regulated by gonad-inhibiting hormone (GIH), a neuronal peptide hormone from eyestalks. However, the detailed mechanism through which GIH regulates Vg expression is still ambiguous. In this study, suppression subtractive hybridization (SSH) under specific GIH-knockdown condition was utilized to determine the expression of genes in the ovary that may act downstream of GIH to control vitellogenin synthesis in Penaeus monodon. The total of 102 and 82 positive clones of up-regulated and down-regulated genes in GIH- knockdown shrimp were identified from the forward and reverse SSH libraries, respectively. Determination of the expression profiles of these reproduction-related genes during ovarian development revealed that the expression of calreticulin (CALR) was significantly reduced in vitellogenic ovary suggesting its role in vitellogenesis. Suppression of CALR by specific dsRNA showed elevated vitellogenin (Vg) transcript level in the ovary at day 7 post-dsRNA injection. Since CALR can bind to steroid hormone receptors and prevents the binding of the receptor to its responsive element to regulate gene expression, it is possible that CALR is an inhibitory mediator of vitellogenin synthesis via steroidal pathway. Our results posted a possible novel pathway of GIH signaling that might interfere the steroid signaling cascade to mediate Vg synthesis in the shrimp.
卵黄发生是甲壳动物卵巢成熟过程中的一个主要过程。这个过程受到性腺抑制激素（GIH）的负调控，GIH 是一种来自眼柄的神经肽激素。然而，GIH 调节 Vg 表达的详细机制仍然不清楚。在这项研究中，利用特定 GIH 敲低条件下的抑制性消减杂交（SSH）来确定卵巢中可能作为 GIH 下游的基因表达，以控制斑节对虾的卵黄蛋白原合成。从正向和反向 SSH 文库中分别鉴定出 GIH 敲低虾中上调和下调基因的 102 个和 82 个阳性克隆。在卵巢发育过程中这些与生殖相关基因的表达谱的测定表明，钙网蛋白（CALR）的表达在卵黄发生期卵巢中显著降低，提示其在卵黄发生中的作用。特异性 dsRNA 抑制 CALR 显示，dsRNA 注射后 7 天卵巢中卵黄蛋白原（Vg）转录本水平升高。由于 CALR 可以结合甾体激素受体，并防止受体与其反应元件结合以调节基因表达，因此，CALR 可能通过甾体途径作为卵黄蛋白原合成的抑制性介质。我们的结果提出了 GIH 信号的一个可能的新途径，它可能干扰甾体信号级联反应来调节虾中的 Vg 合成。
