Comparative gene expression profiling of mouse ovaries upon stimulation with natural equine chorionic gonadotropin (N-eC

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RESEARCH ARTICLE

Open Access

Comparative gene expression profiling of mouse ovaries upon stimulation with natural equine chorionic gonadotropin (NeCG) and tethered recombinant-eCG (ReCG) Kwan-Sik Min1,2* , Jong-Ju Park1, So-Yun Lee1, Munkhzaya Byambaragchaa1 and Myung-Hwa Kang3

Abstract Background: Equine chorionic gonadotropin (eCG) induces super-ovulation in laboratory animals. Notwithstanding its extensive usage, limited information is available regarding the differences between the in vivo effects of natural eCG (N-eCG) and recombinant eCG (R-eCG). This study aimed to investigate the gene expression profiles of mouse ovaries upon stimulation with N-eCG and R-eCG produced from CHO-suspension (CHO-S) cells. R-eCG gene was constructed and transfected into CHO-S cells and quantified. Subsequently, we determined the metabolic clearance rate (MCR) of N-eCG and R-eCG up to 24 h after intravenous administration through the mice tail vein and identified differentially expressed genes in both ovarian tissues, via quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC). Results: R-eCG was markedly expressed initially after transfection and maintained until recovery on day 9. Glycan chains were substantially modified in R-eCG protein produced from CHO-S cells and eliminated through PNGase F treatment. The MCR was higher for R-eCG than for N-eCG, and no significant difference was observed after 60 min. Notwithstanding their low concentrations, R-eCG and N-eCG were detected in the blood at 24 h post-injection. Microarray analysis of ovarian tissue revealed that 20 of 12,816 genes assessed therein were significantly up-regulated and 43 genes were down-regulated by > 2-fold in the group that received R-eCG (63 [0.49%] differentially regulated genes in total). The microarray results were concurrent with and hence validated by those of RT-PCR, qRT-PCR, and IHC analyses. Conclusions: The present results indicate that R-eCG can be adequately produced through a cell-based expression system through post-translational modification of eCG and can induce ovulation in vivo. These results provide novel insights into the molecular mechanisms underlying the up- or down-regulation of specific ovarian genes and the production of R-eCG with enhanced biological activity in vivo. Keywords: R-eCG, CHO-S cells, MCR, Microarray, qRT-PCR, Immunohistochemistry

* Correspondence: [email protected] 1 Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University, Ansung 17579, South Korea 2 School of Animal Life Convergence Science, Institute of Genetic Engineering, Hankyong National University, Ansung 17579, South Korea Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link t