Abstract: Objective: To investigate the changesof DNA methylation in histone deacetylases 4 gene (HDAC4) and its effectduring the trans-differentiation process of human mesenchymal stem cells (hMSCs) into sweat gland like cells (SGLCs). Methods: Selected cell lines of human mesenchymal stem cells (hMSCs) were cultured and expended in vitro, the third generation ofhMSCs and heat-shocked sweat gland cells were picked up, and were co-culturedwith adding inducible factor in the transwell chamber. The sweat gland like cells (SGLCs)in experiment group and the hMSCs in control group were collected, the changes of DNA methylation degree of CpG dinucleotide sitesin histone deacetylases 4 gene (HDAC4) promotor were detected by methylation specific PCR (MSP)andMaldi-TOF Mass Array. And then, the hMSCs in experiment group were treated with 5-aza-CdR (5-aza-2-deoxycytidine, 10 μmol/L), while the hMSCsin control group were culturedwith PBS at the same time. ThemRNA expressions of HDAC4 gene and carcino-embryonic antigen (CEA)gene in the two groups were measured by RT-PCR. Results: The methylation of HDAC4gene in hMSCs was in high level before induction, the methylation degreeof CpG dinucleotide sites located in cg2463009 was 0.901, and the methylation degree of HDAC4gene in SGLCs was markedly decreased by 37% after induction, which was 0.531. The methylationlevel of CpG dinucleotide sites located in cg14823429was changed from 0.687to 0.386 after induction. The mRNA expression of HDAC4 gene was upregulated in test group after treated with 5-aza-CdR for 48 hours, the mRNA expression of CEA gene related with transdifferentiation was enhanced too at the same term, there was significantly statistic difference compared with control group (P<0.05). Conclusion: Methylation of HDAC4 gene participates in the regulation of the trans-differentiation of hMSCs into sweet gland like cells.

Key words: human mesenchymal stem cells, sweet gland like cells, histonedeacetylases 4 gene, DNAmethylation