Maternal high-fat diet modifies epigenetic marks H3K27me3 and H3K27ac in bone to regulate offspring osteoblastogenesis in mice

ABSTRACT

Studies from both humans and animal models indicated that maternal chronic poor-quality diet, especially a high fat diet (HFD), is significantly associated with reduced bone density and childhood fractures in offspring. When previously studied in a rat model, our data suggested that maternal HFD changes epigenetic marks such as DNA methylation and histone modifications to control osteoblast metabolism. In mouse embryonic and postnatal offspring bone samples, a ChIP-sequencing (ChIP-Seq)-based genome-wide method was used to locate the repressive histone mark H3K27me3 (mediated via the polycomb histone methyltransferase, Ezh2) and expressive histone mark H3K27ac (p300/CBP mediated) throughout the genome. Using isolated mouse embryonic cells from foetal calvaria (osteoblast-like cells), H3K27me3 ChIP-Seq showed that 147 gene bodies and 26 gene promoters in HFD embryotic samples had a greater than twofold increase in H3K27me peaks compared to controls. Among the HFD samples, Pthlh and Col2a1 that are important genes playing roles during chondro- and osteogenesis had significantly enriched levels of H3K27me3. Their decreased mRNA expression was confirmed by real-time PCR and standard ChIP analysis, indicating a strong association with Ezh2 mediated H3K27me3 epigenetic changes. Using embryonic calvaria osteoblastic cells and offspring bone samples, H3K27ac ChIP-Seq analysis showed that osteoblast inhibitor genes Tnfaip3 and Twist1 had significantly enriched peaks of H3K27ac in HFD samples compared to controls. Their increased gene expression and association with H3K27ac were also confirmed by real-time PCR and standard ChIP analysis. These findings indicate that chronic maternal HFD changes histone trimethylation and acetylation epigenetic marks to regulate expression of genes controlling osteoblastogenesis.

KEYWORDS:

• High fat diet
• maternal obesity
• histone modification
• osteoblast

Acknowledgement

This work was supported by the United States Department of Agriculture (USDA)/Agricultural Research Service (ARS), project number # USDA-ARS project 6026-51,000-010-05S, to the Arkansas Children’s Nutrition Center. We would like to thank the following people for their technical assistance: Matt Ferguson, Hoy Pittman, and Bobby Fay.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Jin-Ran Chen designed and performed the study, and wrote the paper; Haijun Zhao and Oxana P. Lazarenko performed cell, biochemical and molecular experiments, and in vivo sample analysis; Michael Blackburn helped to perform ChIP analysis, and Kartik Shankar contributed to the performance of experiments and study designs.

Study limitations

We have used mouse embryonic cells isolated from foetal calvaria (osteoblast-like cells) and postnatal offspring bone samples, and a ChIP-sequencing (ChIP-Seq)-based genome-wide method was used to locate the repressive histone mark H3K27me3 (mediated via the polycomb histone methyltransferase, Ezh2) and expressive histone mark H3K27ac (p300/CBP mediated) throughout the genome. We determined that chronic maternal HFD changes histone trimethylation and acetylation epigenetic marks to regulate expression of genes controlling osteoblastogenesis. There are study limitations if those identified genes are truly associated with maternal HFD. Future and additional works are needed to prove that increased DNA acetylation or trimethylation of those genes during embryonic stages are associated with persistent defects of bone development in postnatal offspring.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15592294.2022.2111759

Additional information

Funding

This study is supported by USDA-ARS Project 6026-51000-010-05S. We confirm that all methods/animal experiments were carried out in accordance with relevant guidelines and regulations.