The TDP43 CFTS Affect Brain Endothelial Cell Functions by Regulating YAP and Tight Junction Proteins in Cerebral Ischemic Injury.
Abstract Background: As important components of the blood-brain barrier (BBB), brain endothelial cells (ECs) interact with pericytes, astrocytes, neurons, microglia and extracellular matrix in the neurovascular unit to maintain central nerve system (CNS) homeostasis and regulate neurological functions. Pathological changes in brain endothelium plays an important role in progression of ischemic stroke. The compromised BBB under ischemic stroke condition causes neuronal damage. However, the pathophysiological mechanisms of BBB in normal and under ischemic stroke condition has not been fully elucidated.Methods: C57bl/6 mice were subjected to 1-hour transient middle cerebral occlusion (tMCAO) model, and collected the brain samples after reperfusion for 24hours, 72hours and 1week. Lentivirus (YAP/TAZ shRNA), adenovirus (YAPS112A), TDP43 siRNA, TDP43-CTFS35 overexpression plasmid, Oxygen-glucose deprivation (OGD), and lipopolysaccharides (LPS) were applied to brain endothelial cells in vitro experiments. Brain endothelial cells (ECs) functions were tested by cell proliferation, migration and cell viability. Hippo signaling pathway was examined by immunofluorescence and western blotting.Results: The present study demonstrates that TDP43 is an essential gene to regulate brain ECs normal function, and knockdown of TDP43 reduces tight junction protein expression and inhibits brain ECs migration. Furthermore, ischemic injury and inflammation induce cytoplasmic TDP43-CTFS35 aggregation brain ECs, which weaken TDP43 full-length’s function leading to impairing tight junction (TJ) protein expression and cell migration. The expression of cytoplasmic TDP43-CTFS35 in brain ECs increased at 24 hours and 72 hours after MCAO, but disappeared at 1 week after MCAO. The expressions of TJ proteins, ZO-1 and claudin-5, and expression of P-YAP are associated with the dynamic changes of TDP43-CTFS35 expression in brain ECs after MCAO. The underlying mechanism of TDP43-CTFS35’s effects on brain ECs is that TDP43-CTFS35 turns off the Hippo signaling pathway by inhibition of PMST1/2 phosphorylation leading to de-phosphorylate YAP, and subsequently causes brain ECs functional changes.Conclusions: The present study provides new insight knowledge regarding the mechanisms of brain vascular ECs regulation and pathological change in the BBB after cerebral ischemic injury.