[A transcriptomic study of osteoporosis induced by ketogenic diet in mice]

To investigate the molecular mechanism of osteoporosis caused by ketogenic diet (KD) using transcriptomic analysis.

Sixteen 8-week-old female C57BL/6J mice were divided into KD group and sham group for feeding with KD and normal diet for 3 months, respectively. Body weight, blood glucose and blood ketone levels of the mice were measured every two weeks. Microstructure of the cancellous bone in the distal femur was observed with Micro-CT. Total RNA was extracted from bone marrow cells for transcriptomic analysis and bioinformatics analysis. RT-qPCR was used to verify the expression levels of the genes with significant differential expression between the groups.

KD obviously weakened the microstructure of the cancellous bone in mice. Compared with those in the sham group, the mice in KD group showed 165 differentially expressed genes (94 up-regulated and 71 down-regulated ones), including Acot1, Mpig6b, Gp9, Ppbp, Slc2a9, etc. KEGG pathway enrichment analysis showed obvious enrichment of the Apelin signaling pathway, PI3K- Akt signaling pathway and ECM-receptor interaction signal transduction pathway with greater number of differential genes. RTqPCR results showed that the 5 differential genes screened by transcriptomics were significantly upregulated in KD group, among which Acot1, Mpig6b and Ppbp were upregulated by over two folds (2.49 ± 0.665, 2.58 ± 0.470, and 2.59 ± 0.611, respectively), suggesting their involvement in KD-induced osteoporosis.

The differentially expressed genes and enriched pathways identified in the mouse models provide new clues for studying the molecular mechanism and prevention of KD-induced osteoporosis.