Differential temporal expression of matrix metalloproteinases following sciatic nerve crush

We previously performed transcriptome sequencing and found that genes for matrix metalloproteinases (MMPs), such as MMP7 and 12, seem to be highly upregulated following peripheral nerve injury, and may be involved in nerve repair. In the present study, we systematically determined the expression levels of MMPs and their regulators at 1, 4, 7 and 14 days after sciatic nerve crush injury. The number of differentially expressed genes was elevated at 4 and 7 days after injury, but decreased at 14 days after injury. Among the differentially expressed genes, those most up-regulated showed fold changes of more than 214, while those most down-regulated exhibited fold changes of more than 2-10. Gene sequencing showed that, at all time points after injury, a variety of MMP genes in the "Inhibition of MMPs" pathway were up-regulated, and their inhibitor genes were down-regulated. Expression of key up- and down-regulated genes was verified by quantitative real-time polymerase chain reaction analysis and found to be consistent with transcriptome sequencing. These results suggest that MMP-related genes are strongly involved in the process of peripheral nerve regeneration.