Research On HDAC6 Intervention Mechanisms On Lung Endothelial Barrier Function

Endothelial barrier has important functions on kinds of physical process.Lung endothelial barrier is an semi-permeability membrane located between vascular luminal and underneath tissue,keep the balance of liquid endovascular and extravascular.Endothelial barrier dysfunction also shows in the early period of kinds of disease such as acute lung injury,and could increase mortality if not fix it.The compositions of barrier function had been reported in details.Simply include cell adherents(AJs,TJs and local gap junction)and cytoskeleton.Kinds of agonists could cause endothelial hyperpermeability like TNF?,LPS,including cell contraction,cell-cell adjunction rand cytoskeleton rearrangement subsequently followed with imbalance of water and other proteins.Here we focus on the mechanism of endothelial barrier dysfunction caused by TNF?,LPS and CLP model and protection of HDAC6 inhibitor.HDAC6 belongs to class IIB deacetylation protease,and could regulate substrates through deacetylation and ubiquitination.It has been universally accepted that ?-tubulin,HSP90,cortactin are the substrate of HDAC6.HDAC6 has been demonstrated amount of functions like antitumor,anti-inflammation so as a new drug target for these kinds of diseases.But less know about the molecular mechanism.In vitro TNF? challenged endothelial cell could cause hyperpermeability mainly because: 1.The damage of cell adherents junction complex.VE-cadherin and ?-catenin are the important elements of AJs and contact with each other compose of complex.This complex is critical for the AJs stability.TNF? disrupt this complex and cause the gap between the cells.TNF? could induce caspase3 activation which is also attributed cell-cell junction damage in endothelial cells.2.The rearrangement of cytoskeleton: microtubule and microfilament are the mainly components of cytoskeleton.MT has two globular protein ?-tubulin and ?-tubulin and also compose dimer polymerization and keep MT stable.TNF? could disrupt the polymerization which followed with the rearrangement of Factin and MLC phosphorylation.HDAC6 inhibitor or HDAC6 knockdown by small interferon RNA could reduce TNF? induced endothelial barrier function through acetylation of ?-tubulin and ?-catenin.The first part is in vitro experiments to recognize the molecular mechanisms of HDAC6 inhibitor protecting endothelial barrier function.TNF? challenged HPAEC and HMVEC induce hyperpermeability,we can observe the TNF? group had high permeability,VE-cadherin and ?-catenin discontinuous,increased stress fiber and the expression of P-MLC and caspase3.While pretreat with HDAC6 inhibitor(Tub A or CAY10603)6h could alleviate these reaction.And we found high expression of ace-?-tubulin and ace-?-catenin.We presume that HDAC6 could blunt the TNF? induced endothelial barrier dysfunction through acetylation of ?-tubulin and ?-catenin and block caspase3 activation.The second part we focus on the animal model.LPS intraperitoneal injection and CLP induced C57/B6 mice sepsis.We found LPS and CLP group mice showed increase W/D ratio while decrease ac-?-tubulin and ac-?-catenin expression.Compared with the LPS or CLP group,we observed that injected Tub A or CAY10603 intraperitoneal before LPS challenged or after surgery showed a decreased W/D ratio,c-caspase3 protein expression and increase ac-?-tubulin and ac-?-catenin expression which is more closely to the control group.Those results supported the hypothesis that HDAC6 inhibitor could protect endothelial barrier function mainly through increase ace-?-tubulin and ace-?-catenin and block caspase3 activation.Above all,we first present selective HDAC6 inhibitor or HDAC6 knock down could blunt TNF? induced endothelial hyperpermeability through acetylation its substrate ?-tubulin and ?-catenin and block caspase3 activation.