ABSTRACT
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.
ABSTRACT
Objective:To evaluate the effect of nitric oxide on epidermal hyperplasia in mice with impaired barrier function.Methods:Fifteen SKH1 hairless mice were divided into 4 groups by using a random number table: normal control group (3 mice) , S-nitroso-N-acetyl-DL-penicillamine (SNAP) group (4 mice) , barrier-impaired group (4 mice) , SNAP-treated barrier-impaired group (4 mice) . Fifteen C57BL/6J mice were randomly and equally divided into 3 groups: normal control group, barrier-impaired group and sodium nitroprusside (SNP) -treated barrier-impaired group. Mice in the two normal control groups were both topically treated with propylene glycol-ethanol mixtures on the back; those in the SNAP group were topically treated with SNAP solution alone; those in the two barrier-impaired groups were both treated with repeated tape peeling followed by topical application of propylene glycol-ethanol mixtures on the back twice a day; those in the SNAP-or SNP-treated barrier-impaired group were treated with repeated tape peeling followed by topical application of 10-mmol/L SNAP or SNP solution on the back twice a day. After 4 consecutive days of treatment, all the mice were sacrificed on day 5, and skin tissues were resected from the back of mice followed by preparation of paraffin sections. Hematoxylin-eosin (HE) staining was performed to measure the epidermal thickness, and proliferating cell nuclear antigen (PCNA) staining was conducted to detect proliferating cells in the epidermis. Two-way analysis of variance and one-way analysis of variance were used for comparisons among groups, and least significant difference- t test was used for multiple comparisons. Results:No significant difference in the epidermal thickness or number of PCNA-positive cells was observed between the SNAP group and normal control group ( t=0.33, 1.25, P=0.748, 0.246, respectively) . Compared with the corresponding normal control groups, the barrier-impaired groups showed significantly increased epidermal thickness and number of PCNA-positive cells (all P < 0.01) . Compared with the corresponding barrier-impaired groups, SNAP-treated barrier-impaired group and SNP-treated barrier-impaired group both showed significantly increased epidermal thickness (SKH1: 127.5 ± 12.0 μm vs. 50.4 ± 5.4 μm; C57BL/6J: 78.1 ± 7.6 μm vs. 45.9 ± 3.7 μm; both P < 0.001) and number of PCNA-positive cells (SKH1: 120.0 ± 5.0 cells/mm vs. 87.3 ± 3.8 cells/mm; C57BL/6J: 285.0 ± 15.0 cells/mm vs. 232.0 ± 19.3 cells/mm; both P < 0.01) . Conclusion:Topical nitric oxide donors did not affect normal epidermis, but could aggravate epidermal hyperplasia in barrier-impaired skin, suggesting that skin condition affects the effect of topical nitric oxide donors on epidermal hyperplasia.
ABSTRACT
Aging-associated disorders include cardiovascular diseases, type 2 diabetes, Alzheimer′s disease and so on. Recent studies have demonstrated that aging-associated, low-grade inflammation, also termed inflammaging, contributes to the development of these disorders. However, the origin of inflammaging is still unclear. Some studies indicate that epidermal dysfunction may be the cause of inflammaging in the elderly. Compared with the young, the elderly show reduced water content of the stratum corneum, elevated skin surface pH and compromised epidermal permeability barrier homeostasis, which can all provoke cutaneous inflammation. Pruritus commonly occurs in the elderly, and pruritus-induced scratching can further perturb epidermal permeability barrier function and induce cutaneous inflammation. Sustained mild inflammation in the skin may lead to systemic inflammation. Recent studies in aged mice and humans have demonstrated that improvements in epidermal function can decrease inflammatory cytokine levels in peripheral blood, suggesting a pathogenic role of epidermal dysfunction in inflammaging in the elderly. Thus, improvements in epidermal function may be helpful for the prevention and remission of aging-associated disorders.
ABSTRACT
After the characteristics and necessity of medical informatics experimental course were analyzed, the application of three-stage case teaching in medical informatics experimental course was described, and its steps and methods were explained with the teaching contents of hospital system module used in experimental course as an example. This teaching method can strengthen the knowledge the students have learned.