ChK1 activation induces reactive astrogliosis through CIP2A/PP2A/STAT3 pathway in Alzheimer's disease.

Cancerous Inhibitor of PP2A (CIP2A), an endogenous PP2A inhibitor, is upregulated and causes reactive astrogliosis, synaptic degeneration, and cognitive deficits in Alzheimer's disease (AD). However, the mechanism underlying the increased CIP2A expression in AD brains remains unclear. We here demonstrated that the DNA damage-related Checkpoint kinase 1 (ChK1) is activated in AD human brains and 3xTg-AD mice. ChK1-mediated CIP2A overexpression drives inhibition of PP2A and activates STAT3, then leads to reactive astrogliosis and neurodegeneration in vitro. Infection of mouse brain with GFAP-ChK1-AAV induced AD-like cognitive deficits and exacerbated AD pathologies in vivo. In conclusion, we showed that ChK1 activation induces reactive astrogliosis, degeneration of neurons, and exacerbation of AD through the CIP2A-PP2A-STAT3 pathway, and inhibiting ChK1 may be a potential therapeutic approach for AD treatment.

miR-340-5p mediates the therapeutic effect of mesenchymal stem cells on corneal neovascularization.

BACKGROUND: Our previous study revealed that mesenchymal stem cells (MSCs) inhibited angiogenesis via miRNA-mediated repression of prospero homeobox 1 (PROX1). This study aimed to verify whether miR-340-5p participates in the therapeutic effect of MSCs on corneal neovascularization (CNV) via repressing PROX1 and epithelial membrane protein 2 (EMP2). MATERIALS AND METHODS: The rat CNV model was established by corneal alkali burn. The binding relationship between miR-340-5p and 3'-untranslational regions (3'UTRs) of EMP2 and PROX1 was confirmed using dual-luciferase reporter assay. After culturing corneal epithelial cells (CECs) using MSC supernatants, the vascular endothelial growth factor (VEGF) level in CEC supernatants and the CEC viability were detected. The role of miR-340-5p in the therapeutic effect of MSC on CNV was determined via lentivirus-mediated miR-340-5p intervention in vivo. RESULTS: The expression of miR-340-5p was reduced and EMP2 and PROX1 were increased in CNV corneal tissues. The lentivirus-mediated overexpression of miR-340-5p inhibited the expressions of EMP2 and PROX1. The dual-luciferase reporter assay confirmed that miR-340-5p could bind with the 3'UTRs of EMP2 and PROX1. miR-340-5p was enriched in MSC supernatants and the culture of CECs using MSC supernatants increased the miR-340-5p expression in CECs. After being cultured in miR-340-5p-knocking down MSC supernatants, the expressions of EMP2 and PROX1 were increased, and the VEGF level and CEC viability were restored. The in vivo experiments also indicated that the therapeutic effect of MSCs was mediated by miR-340-5p. CONCLUSIONS: miR-340-5p mediates the therapeutic effect of MSCs on CNV via binding and repressing the expressions of EMP2 and PROX1.

Aerobic Exercise Inhibited P2X7 Purinergic Receptors to Improve Cardiac Remodeling in Mice With Type 2 Diabetes.

Background: Diabetic cardiomyopathy (DCM), the main complication of diabetes mellitus, presents as cardiac dysfunction by ventricular remodeling. In addition, the inhibition of P2X7 purinergic receptors (P2X7R) alleviates cardiac fibrosis and apoptosis in Type 1 diabetes. However, whether exercise training improves cardiac remodeling by regulating P2X7R remains unknown. Methods: Db/db mice spontaneously induced with type 2 diabetes and high-fat diet (HFD) and mice with streptozotocin (STZ)-induced type 2 diabetes mice were treated by 12-week treadmill training. Cardiac functions were observed by two-dimensional echocardiography. Hematoxylin-eosin staining, Sirius red staining and transmission electron microscopy were respectively used to detect cardiac morphology, fibrosis and mitochondria. In addition, real-time polymerase chain reaction and Western Blot were used to detect mRNA and protein levels. Results: Studying the hearts of db/db mice and STZ-induced mice, we found that collagen deposition and the number of disordered cells significantly increased compared with the control group. However, exercise markedly reversed these changes, and the same tendency was observed in the expression of MMP9, COL-I, and TGF-ß, which indicated cardiac fibrotic and hypertrophic markers, including ANP and MyHC expression. In addition, the increased Caspase-3 level and the ratio of Bax/Bcl2 were reduced by exercise training, and similar results were observed in the TUNEL test. Notably, the expression of P2X7R was greatly upregulated in the hearts of db/db mice and HFD + STZ-induced DM mice and downregulated by aerobic exercise. Moreover, we indicated that P2X7R knock out significantly reduced the collagen deposition and disordered cells in the DM group. Furthermore, the apoptosis levels and TUNEL analysis were greatly inhibited by exercise or in the P2X7R-/- group in DM. We found significant differences between the P2X7R-/- + DM + EX group and DM + EX group in myocardial tissue apoptosis and fibrosis, in which the former is significantly milder. Moreover, compared with the P2X7R-/- + DM group, the P2X7R-/- + DM + EX group represented a lower level of cardiac fibrosis. The expression levels of TGF-ß at the protein level and TGF-ß and ANP at the genetic level were evidently decreased in the P2X7R-/- + DM + EX group. Conclusion: Aerobic exercise reversed cardiac remodeling in diabetic mice at least partly through inhibiting P2X7R expression in cardiomyocytes.