Establishment of cell-lines stably expressing recombinant Japanese eel follicle-stimulating hormone and luteinizing hormone using CHO-DG44 cells: fully induced ovarian development at different modes

Yukinori Kazeto; Risa Ito; Toshiomi Tanaka; Hiroshi Suzuki; Yuichi Ozaki; Koichi Okuzawa; Koichiro Gen

doi:10.3389/fendo.2023.1201250

Establishment of cell-lines stably expressing recombinant Japanese eel follicle-stimulating hormone and luteinizing hormone using CHO-DG44 cells: fully induced ovarian development at different modes

Front Endocrinol (Lausanne). 2023 Aug 25:14:1201250. doi: 10.3389/fendo.2023.1201250. eCollection 2023.

Authors

Yukinori Kazeto¹, Risa Ito², Toshiomi Tanaka³, Hiroshi Suzuki⁴, Yuichi Ozaki², Koichi Okuzawa², Koichiro Gen⁵

Affiliations

¹ Fisheries Technology Institute, Minamiizu Field Station, Japan Fisheries Research and Education Agency, Minamiizu, Shizuoka, Japan.
² Fisheries Technology Institute, Tamaki Field Station, Japan Fisheries Research and Education Agency, Tamaki, Mie, Japan.
³ Hamanako Branch, Shizuoka Prefectural Research Institute of Fishery and Ocean, Hamamatsu, Shizuoka, Japan.
⁴ Fisheries Technology Institute, Shibushi Field Station, Japan Fisheries Research and Education Agency, Shibushi, Kagoshima, Japan.
⁵ Fisheries Technology Institute, Nagasaki Station, Japan Fisheries Research and Education Agency, Nagasaki, Japan.

Abstract

The gonadotropins (Gth), follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh), play central roles in gametogenesis in vertebrates. However, available information on their differential actions in teleost, especially in vivo, is insufficient. In this study, we established stable CHO-DG44 cell lines expressing long-lasting recombinant Japanese eel Fsh and Lh with extra O-glycosylation sites (Fsh-hCTP and Lh-hCTP), which were produced in abundance. Immature female eels received weekly intraperitoneal injections of Gths. Fsh-hCTP induced the entire ovarian development by 8 weeks from the beginning of injection; thus, the ovaries of most fish were at the migratory nucleus stage while the same stage was observed in eels after 4 weeks in the Lh-hCTP-treated group. In contrast, all pretreated and saline-injected eels were in the pre-vitellogenic stage. Gonadosomatic indices in the Fsh-hCTP-treated group were significantly higher than those in the Lh-hCTP group at the migratory nucleus stage because of the significantly higher frequency of advanced ovarian follicles. Ovarian mRNA levels of genes related to E2 production (cyp11a1, cyp17a1, cyp19a1, hsd3b, fshr, and lhr) were measured using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). All genes were induced by both Fsh-hCTP and Lh-hCTP, with a peak at either the mid- or late vitellogenic stages. Transcript abundance of cyp19a1 and fshr in the Lh-hCTP group were significantly higher than those in the Fsh-hCTP group, whereas no difference in the expression of other genes was observed between the groups. Fluctuations in serum levels of sex steroid hormones (estradiol-17β, 11-ketotestosterone, and testosterone) in female eels were comparable in the Fsh-hCTP and Lh-hCTP groups, thus increasing toward the maturational phase. Furthermore, the fecundity of the eels induced to mature by Fsh-hCTP was significantly higher than that induced by Lh-hCTP. These findings indicate that Fsh and Lh can induce ovarian development in distinctively different modes in the Japanese eel.

Keywords: Japanese eel; fecundity; ovarian development; recombinant follicle-stimulating hormone; recombinant luteinizing hormone.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
CHO Cells
Cricetinae
Eels / genetics
Female
Follicle Stimulating Hormone, Human*
Gametogenesis
Luteinizing Hormone*

Substances

Luteinizing Hormone
Follicle Stimulating Hormone, Human

Grants and funding

This work was supported by a Grant-in-Aid (Development of Sustainable Aquaculture Technology Independent of Wild Fishery Resources) from the Ministry of Agriculture, Forestry, and Fisheries, Government of Japan.