Laboratory of Aquaculture Biology, Graduate School of Agricultural Science, Tohoku University, 468-1Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-0845, Japan.
Pesticide Action Network of North America, 1611 Telegraph Ave, Suite 1200, Oakland, CA 94612, USA.
J Steroid Biochem Mol Biol. 2023 Jul;231:106302. doi: 10.1016/j.jsbmb.2023.106302. Epub 2023 Mar 27.
Estrogen receptors (ERs) were known as estrogen-activated transcription factors and function as major reproduction regulators in vertebrates. The presence of er genes had been reported in Molluscan cephalopods and gastropods. However, they were considered as constitutive activators with unknown biological functions since reporter assays for these ERs did not show a specific response to estrogens. In this study, we tried characterization of ER orthologues from the Yesso scallop, Patinopecten yessoensis, in which estrogens had been proven to be produced in the gonads and involved in the spermatogenesis and vitellogenesis. Identified ER and estrogen related receptor (ERR) of Yesso scallops, designated as py-ER and py-ERR, conserved specific domain structures for a nuclear receptor. Their DNA binding domains showed high similarities to those of vertebrate ER orthologues, while ligand binding domains had low similarities with them. Both the py-er and py-err expression levels decreased in the ovary at the mature stage while py-vitellogenin expression increased in the ovary by quantitative real-time RT-PCR. Also, the py-er and py-err showed higher expressions in the testis than ovary during the developing and mature period, suggesting both genes might function in the spermatogenesis and testis development. The py-ER showed binding affinities to vertebrate estradiol-17β (E). However, the intensity was weaker than the vertebrate ER, indicating scallops might exist endogenous estrogens with a different structure. On the other hand, the binding property of py-ERR to E was not confirmed in this assay, speculating that py-ERR was a constitutive activator as other vertebrate ERRs. Further, the py-er was localized in the spermatogonia in the testis and in the auxiliary cells in the ovary by in situ hybridization, indicating its potential roles in promoting spermatogenesis and vitellogenesis. Taken together, the present study demonstrated that py-ER was an authentic E receptor in the Yesso scallop and might have functions for the spermatogonia proliferation and vitellogenesis, while py-ERR was involved in the reproduction by undiscovered manners.
雌激素受体（ERs）被认为是雌激素激活的转录因子，在脊椎动物中作为主要的生殖调节剂发挥作用。在头足类和腹足类软体动物中已经报道了 ER 基因的存在。然而，由于这些 ER 的报告基因检测没有显示出对雌激素的特异性反应，因此它们被认为是组成型激活剂，具有未知的生物学功能。在这项研究中，我们试图从 Yesso 扇贝（Patinopecten yessoensis）中鉴定 ER 直系同源物，因为已经证明雌激素在性腺中产生，并参与精子发生和卵黄发生。鉴定出的 Yesso 扇贝的 ER 和雌激素相关受体（ERR），分别命名为 py-ER 和 py-ERR，具有核受体的特定结构域。它们的 DNA 结合结构域与脊椎动物 ER 直系同源物高度相似，而配体结合结构域与它们的相似性较低。通过定量实时 RT-PCR 发现，py-er 和 py-err 的表达水平在卵巢成熟阶段下降，而 py-卵黄原蛋白在卵巢中表达增加。此外，py-er 和 py-err 在发育和成熟期间在睾丸中的表达水平高于卵巢，表明这两个基因可能在精子发生和睾丸发育中发挥作用。py-ER 对脊椎动物雌二醇-17β（E）表现出结合亲和力。然而，其强度弱于脊椎动物 ER，表明扇贝可能存在结构不同的内源性雌激素。另一方面，在该测定中，py-ERR 与 E 的结合特性未得到证实，推测 py-ERR 像其他脊椎动物 ERR 一样是组成型激活剂。此外，通过原位杂交，py-er 在睾丸的精原细胞和卵巢的辅助细胞中定位，表明其在促进精子发生和卵黄发生方面具有潜在作用。总之，本研究表明，py-ER 是 Yesso 扇贝中的一种真正的 E 受体，可能具有促进精原细胞增殖和卵黄发生的功能，而 py-ERR 则以未发现的方式参与生殖。
