Glucocorticoids promote CCL20 expression in keratinocytes.

BACKGROUND: Glucocorticoids (GCs) are generally envisioned as immunosuppressive, but in conditions such as rosacea and perioral dermatitis they can lead to increased skin inflammation. In lung epithelia, GCs promote expression of the proinflammatory cytokine CCL20, which contributes to steroid-resistant asthma. In the skin, CCL20 stimulates inflammation by recruiting T helper 17 T lymphocytes and dendritic cells, and is elevated in papulopustular rosacea. OBJECTIVES: To understand if, and how, GCs affect CCL20 expression in human keratinocytes. CCL20 expression was assessed by quantitative reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay. METHODS: Selective inhibition of candidate genes and signalling pathways was performed using RNA interference and chemical inhibitors. The binding of activated GC receptor to genomic DNA was determined by chromatin immunoprecipitation, and enhancer activity of genomic sequences was measured with a reporter assay. RESULTS: We found that GC treatment increased CCL20 expression in human keratinocytes and murine skin, both in the undisturbed state and with tumour necrosis factor-α stimulation. GC repressed proinflammatory signalling pathways, including nuclear factor kappa B and p38/mitogen-activated protein kinase, but these inhibitory effects were opposed by the direct binding of activated GC receptor to the CCL20 enhancer, promoting CCL20 expression. CONCLUSIONS: Viewed together, these findings demonstrate a mechanism by which GCs induce expression of CCL20 in keratinocytes, which may contribute to the inflammation seen in steroid-exacerbated skin conditions.

[Construction of transmembrane 6 superfamily member 2 E167K gene knock-in mouse model by using CRISPR/Cas9 technology].

Objective: To construct a transmembrane 6 superfamily member 2 (Tm6sf2) E167K gene knock-in mouse model. Methods: The plasmid was constructed to simultaneously express the single-stranded guide RNA Cas9 at a specific site of the mouse Tm6sf2 gene in the donor plasmid carrying the Tm6sf2 E167K fragment. The above two plasmids were injected into the mouse fertilized eggs together. The positive F0 generation mice were validated by PCR detection and sequencing. The number of F2 generation surviving mice in three genotypes of wild (Wt), heterozygous and knock-in (KI) were calculated. Wt and KI male mice (8 mice/ group) of F2 generation littermates were selected and given a normal diet for 8 weeks. The body weight of the mice was recorded every week, and the glucose metabolism and lipid metabolism indexes of the two mice were detected. The comparison between groups was performed with an independent sample t-test. Results: Genotype detection and sequencing results showed that the Tm6sf2 E167K gene knock-in mouse model was successfully established. KI mice had absence of homozygous lethal embryo phenotype. The body weight of KI mice was higher than that of Wt mice during lactation, and the difference between the two groups was statistically significant (P < 0.05).The fasting blood glucose of KI mice (9.50 ± 0.33)mmol/L was higher than that of Wt mice (7.80 ± 0.30)mmol/L, and the difference between the two groups was statistically significant (P < 0.05). During the oral glucose tolerance test, the 2-hour blood glucose level of KI mice (9.20 ± 0.51)mmol/L was higher than that of Wt mice (7.60 ± 0.18)mmol/L, and the difference between the two groups was statistically significant (P < 0.05). The liver triglyceride content of KI mice (8.40 ± 0.55)mg/g was higher than that of Wt mice (7.30 ± 0.63)mg/g, but the difference was not statistically significant (P > 0.05). There was no significant difference in plasma triglyceride levels between the two mice (P > 0.05). The Oil red O staining results showed that KI mice had more lipid accumulation in the centrilobular region of ​​liver than Wt mice. Conclusion: Tm6sf2 E167K gene knock-in mice were successfully constructed. Tm6sf2 E167K gene knock-in can cause abnormal glucose metabolism in mice and promote the occurrence of hepatic steatosis.

X-chromosome kiss and tell: how the Xs go their separate ways.

Loci associated with noncoding RNAs have important roles in X-chromosome inactivation (XCI), the dosage compensation mechanism by which one of two X chromosomes in female cells becomes transcriptionally silenced. The Xs start out as epigenetically equivalent chromosomes, but XCI requires a cell to treat two identical X chromosomes in completely different ways: One X chromosome must remain transcriptionally active while the other becomes repressed. In the embryo of eutherian mammals, the choice to inactivate the maternal or paternal X chromosome is random. The fact that the Xs always adopt opposite fates hints at the existence of a trans-sensing mechanism to ensure the mutually exclusive silencing of one of the two Xs. This paper highlights recent evidence supporting a model for mutually exclusive choice that involves homologous chromosome pairing and the placement of asymmetric chromatin marks on the two Xs.