RESUMO
Objective:To investigate the effect of the transcriptional coactivator Mediator 1 (Med1) on mouse hair regeneration, and to explore potential mechanisms.Methods:Med1 flox/flox C57BL/6J mice were mated with K14-Cre mice, and the mice with epidermis-specific knockout of Med1 gene, namely K14-Cre-expressing Med1 flox/flox mice (knockout group) , were obtained by using the Cre-Loxp system, while Med1 flox/flox mice without K14-Cre expression served as control group. Mice in the two groups (3 mice in each group) were raised together for 8 weeks followed by dorsal hair removal. Hair regeneration was observed for 12 consecutive days after hair removal. After 12 days, all mice in the two groups were sacrificed, their depilated and non-depilated dorsal skin tissues were resected, and total RNA was extracted from the tissues. Real-time quantitative PCR was performed to determine the mRNA expression of hair keratin genes, vitamin D receptor/β-catenin pathway-related genes, and genes associated with maintenance of hair follicle stem cell proliferation and quiescence. Paraffin-embedded sections of depilated and non-depilated mouse skin tissues were prepared, and immunofluorescence staining was conducted to determine the number of stem cells in the hair follicle bulge. Two-independent-sample t test was used for comparisons between two groups. Results:From days 0 to 12 after depilation, hair regeneration was delayed in the depilated skin area in the knockout group compared with the control group. Real-time quantitative PCR showed significantly decreased mRNA relative expression levels of hair keratin genes Ha1 and Krt2-16, vitamin D receptor/β-catenin pathway-related genes S100a3, Dlx3 and Tubb3, and genes associated with maintenance of hair follicle stem cell proliferation and quiescence including Lhx2, Sox9 and Nfatc1 in the depilated skin tissues in the knockout group (22.09 ± 12.32, 2.07 ± 0.20, 0.02 ± 0.01, 12.36 ± 2.12, 1.75 ± 0.46, 0.39 ± 0.02, 4.42 ± 0.76, 0.44 ± 0.07, respectively) compared with the control group (70.53 ± 9.46, 7.76 ± 0.49, 0.05 ± 0.01, 26.16 ± 2.96, 2.60 ± 0.14, 0.71 ± 0.09, 11.93 ± 0.42, 0.75 ± 0.04, respectively; t = 5.40, 18.64, 3.89, 6.57, 3.04, 6.10, 15.03, 6.18, respectively, all P < 0.05) . Immunofluorescence staining showed that the number of CD34 +K15 + hair follicle stem cells in the hair follicle bulge in both depilated and non-depilated skin tissues was significantly lower in the knockout group than in the control group. Conclusion:Med1 gene knockout may down-regulate the expression of downstream genes of the vitamin D receptor/β-catenin pathway and genes associated with maintenance of hair follicle stem cell proliferation and quiescence (Sox9, Nfatc1 and Lhx2) , and reduce the number of hair follicle stem cells, leading to hair follicle differentiation disorder and hair regeneration delay.
RESUMO
AIM:To construct AFT024-SCF cell line and HPC-Lhx2 cell line for confirming the biological function of AFT024-SCF.METHODS:The HPC-Lhx2 cell line, AFT024-SCF cell line and AFT024-GFP cell line were constructed by retro-viral infection.The expression of stem cell factor(SCF) in AFT024-SCF cells was detected by real-time PCR and Western blot.SCF in the supernatant of AFT024-SCF was detected with ELISA.The supernatant of AFT024-SCF and AFT024-GFP were collected and then diluted (1:10) with basic IMDM medium.So we made 4 culture medium:AFT024-SCF medium was used for experiment group, AFT024-GFP medium was used for endogenous negative control, IM-DM basic medium was used for exogenous negative control, and IMDM basic medium with SCF was used for positive con-trol.SCF-dependent HPC-Lhx2 cell line was cultured in these 4 different medium for 72 h.According to MTT method and colony forming experiment, the biological function of AFT024-SCF was confirmed by the proliferation ability of SCF-depend-ent HPC-Lhx2 cell line.RESULTS:SCF was highly expressed in AFT024-SCF cells.After cultured for 72 h, neither IM-DM basic medium nor GFP-AFT024 medium support HPC-Lhx2 cell line proliferation.However, AFT024-SCF medium supported HPC-Lhx2 cell line expansion as well as the positive control medium.CONCLUSION:AFT024-SCF cells ex-press SCF successfully and recombinant SCF can be replaced by the supernatant of AFT024-SCF culture medium for expan-ding HPC-Lhx2 cell line in vitro.