CL-27c

Methylene blue (MB) has a protective effect on cognitive decline caused by chronic hypoperfusion, but the specific mechanism is not clear. This article aims to determine whether MB protects vascular neurons through PI3K/Akt and plays a role in improving cognitive impairment. Molecular biological methods, the hippocampal neuronal density test, the hippocampal vascular network density test, and dynamic enhanced magnetic resonance imaging (MRI) were used to detect the blood-brain barrier permeability and Evans blue leakage rate in the hippocampus. We also observed and evaluated the changes in the above results after administration of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway protein inhibitor LY294002. There were significant differences for cerebral blood flow (CBF) between the chronic cerebral hypoperfusion (CCH) + MB group (100 ml/100 g/min) and the CCH group (60 ml/100 g/min, P < 0.05). After using LY294002, the CBF of the CCH + MB + LY294002 group dropped to 82 ml/100 g/min. The vascular density in the CCH + MB group was 23%, which is significantly higher than that in the CCH group (15.1%) (P < 0.05). The vascular density (17.5%) in the CCH + MB + LY294002 group was significantly higher than that in the CCH group but lower than that in the CCH + MB group. Western blotting results showed that one week after intraperitoneal injection of MB, the expression of t-Akt and p-Akt in the CCH + MB group was increased after CCH, and LY294002 partially blocked this up-regulation effect (CCH + MB + LY294002 group). MB is a potential therapy for the relief of mild cognitive impairment associated with CCH, vascular dementia, and Alzheimer's disease.

Terminally differentiated stratified squamous epithelial cells play an important role in barrier protection of the skin. The integrity of epidermal cells is maintained by tight regulation of proliferation and differentiation. The aim of this study was to investigate the role of epigenetic regulator H3K4me3 and its demethylase Jarid1b in the control of epithelial cell differentiation.

RT‐qPCR, Western blotting and IHC were used to detect mRNA and protein levels. We analysed cell proliferation by CCK8 assay and cell migration by wound healing assay. ChIP was used to measure H3K4me3 enrichment. A chamber graft model was established for epidermal development.

Our studies showed that H3K4me3 was decreased during epidermal differentiation. The H3K4me3 demethylase Jarid1b positively controlled epidermal cell differentiation in vitro and in vivo. Mechanistically, we found that Jarid1b substantially increased the expression of mesenchymal‐epithelial transition (MET)‐related genes, among which Ovol1 positively regulated differentiation gene expression. In addition, Ovol1 expression was repressed by PI3K‐AKT pathway inhibitors and overexpression (O/E) of the PI3K‐AKT pathway suppressor Ship1. Knockdown (KD) of Ship1 activated downstream PI3K‐AKT pathway and enhanced Ovol1 expression in HaCaT. Importantly, we found that Jarid1b negatively regulated Ship1 expression, but not that of Pten, by directly binding to its promoter to modulate H3K4me3 enrichment.

Our results identify an essential role of Jarid1b in the regulation of the Ship1/AKT/Ovol1 pathway to promote epithelial cell differentiation.