Bioinformatics analysis of time-series genes profiling to explore key genes affected by age in fracture healing

The present study was aimed to explore possible key genes and bioprocess affected by age during fracture healing. GSE589, GSE592 and GSE1371 were downloaded from gene expression omnibus database. The time-series genes of three age levels rats were firstly identified with hclust function in R. Then functional and pathway enrichment analysis for selected time-series genes were performed. Finally, the VennDiagram package of R language was used to screen overlapping n time-series genes. The expression changes of time-series genes in the rats of three age levels were classified into two types: one was higher expressed at 0 day, decreased at 3 day to 2 week, and increased from 4 to 6 week; the other was the opposite. Functional and pathways enrichment analysis showed that 12 time-series genes of adult and old rats were significantly involved in ECM-receptor interaction pathway. The expression changes of 11 genes were consistent with time axis, 10 genes were up-regulated at 3 days after fracture, and increased slowly in 6 week, while Itga2b was down-regulated. The functions of 106 overlapping genes were all associated with growth and development of bone after fracture. The key genes in ECM-receptor interaction pathway including Spp1, Ibsp, Tnn and Col3a1 have been reported to be related to fracture in literatures. The difference during fracture healing in three age levels rats is mainly related to age. The Spp1, Ibsp, Tnn and Col3a1 are possible potential age-related genes and ECM-receptor interaction pathway is the potential age-related process during fracture healing.