Disruption of endothelial adherens junctions by high glucose is mediated by protein kinase C-β-dependent vascular endothelial cadherin tyrosine phosphorylation.
BACKGROUND
Hyperglycemia has been recognized as a primary factor in endothelial barrier dysfunction and in the development of micro- and macrovascular diseases associated with diabetes, but the underlying biochemical mechanisms remain elusive. Tyrosine phosphorylation of vascular endothelial cadherin (VE-cad) leads to the disruption of endothelial adherens junctions and increases the transendothelial migration (TEM) of leukocytes.


METHODS
VE-cad tyrosine phosphorylation, adherens junction integrity and TEM of monocytes in human umbilical vein endothelial cells (HUVECs) treated with high-concentration glucose were evaluated. The role of protein kinase C (PKC) in induction of endothelial cells adherence junction disruption by exposure of HUVECs to high concentration of glucose was explored.


RESULTS
The treatment of HUVEC with high-concentration glucose increased VE-cad tyrosine phosphorylation, whereas mannitol or 3-O-methyl-D-glucose had no effect. In addition, high-concentration glucose increased the dissociation of the VE-cad-β-catenin complex, activation of the Wnt/β-catenin pathway, and the TEM of monocytes. These alterations were accompanied by the activation of endothelial PKC and increased phosphorylation of ERK and myosin light chain (MLC). High-concentration glucose-induced tyrosine phosphorylation of VE-cad was attenuated by: 1- the inhibition of PKC-β by overexpression of dominant-negative PKC-β 2- inhibition of MLC phosphorylation by overexpression of a nonphosphorylatable dominant-negative form of MLC, 3- the inhibition of actin polymerization by cytochalasin D and 4- the treatment of HUVECs with forskolin (an activator of adenylate cyclase).


CONCLUSIONS
Our findings show that the high-concentration glucose-induced disruption of endothelial adherens junctions is mediated by tyrosine phosphorylation of VE-cad through PKC-β and MLC phosphorylation.
Department of Internal Medicine, Division of Cardiology, The University of Texas Medical School at Houston, 77030, Houston, TX, USA. Mehran.Haidari@uth.tmc.edu.|Texas Heart Institute at St. Luke's Episcopal Hospital, PO Box 20345 C1000, 77030, Houston, TX, USA. Mehran.Haidari@uth.tmc.edu.
Mehran
M
Haidari
Texas Heart Institute at St. Luke's Episcopal Hospital, PO Box 20345 C1000, 77030, Houston, TX, USA. wzhang@heart.thi.tmc.edu.
Wei
W
Zhang
Department of Internal Medicine, Division of Cardiology, The University of Texas Medical School at Houston, 77030, Houston, TX, USA. JWillerson@texasheart.org.|Texas Heart Institute at St. Luke's Episcopal Hospital, PO Box 20345 C1000, 77030, Houston, TX, USA. JWillerson@texasheart.org.
James T
JT
Willerson
Texas Heart Institute at St. Luke's Episcopal Hospital, PO Box 20345 C1000, 77030, Houston, TX, USA. RDixon@heart.thi.tmc.edu.
Richard Af
RA
Dixon
D022005:Adherens Junctions / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology; D004730:Endothelium, Vascular / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism; D006801:Humans; D009000:Monocytes / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D010766:Phosphorylation; D064546:Protein Kinase C beta / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
C495270:CTNNB1 protein, human; D015820:Cadherins; D018994:Myosin Light Chains; D051176:beta Catenin; D014443:Tyrosine; D064546:Protein Kinase C beta; D005947:Glucose