Effects of oocyte vitrification on gene expression in the liver and kidney tissues of adult offspring

Abstract

Oocyte vitrification is an important assisted reproductive technology (ART) that preserves the fertility of unmarried patients with malignant tumors, and promotes the development of the oocyte donation program. In recent years, the effects of ART, including the vitrification of oocytes and embryos on the health of offspring, have attracted much attention; however, it is difficult to conduct long-term follow-up and biochemical evaluation in humans. In this study, we detected the effect of oocyte vitrification on gene expression in the organs of adult mice offspring by RNA sequencing for the first time. Our results showed that only a small amount of gene expression was significantly affected. Seven genes (Tpm3, Hspe1-rs1, Ntrk2, Cyp4a31, Asic5, Cyp4a14, Retsat) were abnormally expressed in the liver, and ten genes (Lbp, Hspe1-rs1, Prxl2b, Pfn3, Gm9008, Bglap3, Col8a1, Hmgcr, Ero1lb, Ifi44l) were abnormal in the kidney. Several genes were related to metabolism and disease occurrence in the liver or kidney. Besides, we paid special attention to the expression of known imprinted genes and DNA methylation-related genes in adult organs, which are susceptible to oocyte cryopreservation in the preimplantation stage. As a result, some of these transcripts were detected in adult organs, but they were not affected by oocyte vitrification. In conclusion, we first report that oocyte vitrification did not significantly change the global gene expression in offspring organs; nonetheless, it can still influence the transcription of a few functional genes. The potential adverse effects caused by oocyte vitrification need attention and further study.

Keywords: Assisted reproduction; DNA methylation; Imprinted genes; Offspring health; Oocyte vitrification.

Fig. 1

Sequencing data and sample correlation analysis. A Venn diagram based on the detected transcripts in each sample. B Violin plot showing the distribution of gene expression in different samples. C PCA result of all samples obtained by the R program. LC, liver samples from control; LT, liver samples from vitrified oocytes; KC, kidney samples from control; KT, kidney samples from vitrified oocytes. Each group contains 3 ~ 4 biological replicates

Fig. 2

The differentially expressed genes (DEGs) in the organs of offspring from vitrified oocytes. DEGs were screened by standard difference analysis of gene expression (FDR < 0.05, FC > 2). A Heatmap illustration indicating DEGs in the liver. B Heatmap illustration indicating DEGs in the kidney. LC, liver samples from control; LT, liver samples from vitrified oocytes; KC, kidney samples from control; KT, kidney samples from vitrified oocytes. Each group contains 3 ~ 4 biological replicates. C, D Interaction analysis between DEGs in the liver and kidney, respectively. They were made by the String online tool. The lines between spheres represent a potential interaction

Fig. 3

Enrichment of genes affected by oocyte vitrification in offspring liver. The differential genes were identified by relaxed screening criteria (p < 0.01, FC > 1.5). A, B Bar plots showing GO and KEGG enrichment of differential genes in the liver, respectively. A q value < 0.05 was considered significantly enriched. The smaller the q value, the higher the enrichment degree

Fig. 4

The detection of imprinted genes and DNA methylation–related gene expression in organs of offspring from control and vitrified oocytes. A, B Heatmap illustration showing the expression of imprinted genes in liver and kidney, respectively. C, D Heatmap illustration showing the expression of DNA methylation–related genes in the liver and kidney, respectively. LC, liver samples from control; LT, liver samples from vitrified oocytes; KC, kidney samples from control; KT, kidney samples from vitrified oocytes. Each group contains 3 ~ 4 biological replicates