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http://dx.doi.org/10.12717/DR.2021.25.4.199

Specific Biological Activity of Equine Chorionic Gonadotropin (eCG) Glycosylation Sites in Cells Expressing Equine Luteinizing Hormone/CG (eLH/CG) Receptor  

Byambaragchaa, Munkhzaya (Institute of Genetic Engineering, Hankyong National University)
Cho, Seung-Hee (Animal Biotechnology, Hankyong National University)
Joo, Hyo-Eun (Dept. of Animal Life Science, Hankyong National University)
Kim, Sang-Gwon (Dept. of Animal Life Science, Hankyong National University)
Kim, Yean-Ji (Dept. of Animal Life Science, Hankyong National University)
Park, Gyeong-Eun (Dept. of Animal Life Science, Hankyong National University)
Kang, Myung-Hwa (Dept. of Food Science and Nutrition, Hoseo University)
Min, Kwan-Sik (Institute of Genetic Engineering, Hankyong National University)
Publication Information
Development and Reproduction / v.25, no.4, 2021 , pp. 199-211 More about this Journal
Abstract
Equine chorionic gonadotropin (eCG), produced by the endometrial cups of the placenta after the first trimester, is a specific glycoprotein that displays dual luteinizing hormone (LH)-like and follicle-stimulating hormone (FSH)-like effects in non-equid species. However, in equidaes, eCG exhibits only LH-like activity. To identify the specific biological functions of glycosylated sites in eCG, we constructed the following site mutants of N- and O-linked glycosylation: eCGβ/αΔ56, substitution of α-subunit56 N-linked glycosylation site; eCGβ-D/α, deletion of the O-linked glycosylation sites at the β-subunit, and eCGβ-D/αΔ56, double mutant. We produced recombinant eCG (rec-eCG) proteins in Chinese hamster ovary suspension (CHO-S) cells. We examined the biological activity of rec-eCG proteins in CHO-K1 cells expressing the eLH/CG receptor and found that signal transduction activities of deglycosylated mutants remarkably decreased. The EC50 levels of eCGβ/αΔ56, eCGβ-D/α, and eCGβ-D/αΔ56 mutants decreased by 2.1-, 5.6-, and 3.4-fold, respectively, compared to that of wild-type eCG. The Rmax values of the mutants were 56%-80% those of wild-type eCG (141.9 nmol/104 cells). Our results indicate that the biological activity of eCG is greatly affected by the removal of N- and O-linked glycosylation sites in cells expressing eLH/CGR. These results provide important information on rec-eCG in the regulation of specific glycosylation sites and improve our understanding of the specific biological activity of rec-eCG glycosylation sites in equidaes.
Keywords
rec-eCG; Glycosylation sites; Chinese hamster ovary suspension (CHO-S) cells; Biological activity; Equine luteinizing hormone/chorionic gonadotropin receptors (eLH/CGR);
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