CAT-1 as a novel CAM stabilizes endothelial integrity and mediates the protective actions of L-Arg via a NO-independent mechanism.
Interendothelial junctions play an important role in the maintenance of endothelial integrity and the regulation of vascular functions. We report here that cationic amino acid transporter-1 (CAT-1) is a novel interendothelial cell adhesion molecule (CAM). We identified that CAT-1 protein localized at cell-cell adhesive junctions, similar to the classic CAM of VE-cadherin, and knockdown of CAT-1 with siRNA led to an increase in endothelial permeability. In addition, CAT-1 formed a cis-homo-dimer and showed Ca(2+)-dependent trans-homo-interaction to cause homophilic cell-cell adhesion. Co-immunoprecipitation assays showed that CAT-1 can associate with β-catenin. Furthermore, we found that the sub-cellular localization and function of CAT-1 are associated with cell confluency, in sub-confluent ECs CAT-1 proteins distribute on the entire surface and function as L-Arg transporters, but most of the CAT-1 in the confluent ECs are localized at interendothelial junctions and serve as CAMs. Further functional characterization has disclosed that extracellular L-Arg exposure stabilizes endothelial integrity via abating the cell junction disassembly of CAT-1 and blocking the cellular membrane CAT-1 internalization, which provides the new mechanisms for L-Arg paradox and trans-stimulation of cationic amino acid transport system (CAAT). These results suggest that CAT-1 is a novel CAM that directly regulates endothelial integrity and mediates the protective actions of L-Arg to endothelium via a NO-independent mechanism.
Shandong University Qilu Hospital Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital of Shandong University, Jinan 250012, China.
Lu
L
Guo
Shandong University Qilu Hospital Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital of Shandong University, Jinan 250012, China.
Shuang
S
Tian
Department of Emergency, Qilu Hospital of Shandong University, Jinan 250012, China.
Yuguo
Y
Chen
Shandong University Qilu Hospital Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital of Shandong University, Jinan 250012, China.
Yun
Y
Mao
Department of Emergency, Qilu Hospital of Shandong University, Jinan 250012, China.
Sumei
S
Cui
Center of Applied Genomics, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA 19104, USA.
Aihua
A
Hu
Department of Medicine, University of FL, Gainesville, FL 32608, USA.
Jianliang
J
Zhang
Department of Medicine, University of FL, Gainesville, FL 32608, USA.
Shen-Ling
SL
Xia
Department of Medicine, University of FL, Gainesville, FL 32608, USA.
Yunchao
Y
Su
Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
Jie
J
Du
Department of Medicine, University of FL, Gainesville, FL 32608, USA.
Edward R
ER
Block
Shandong University Qilu Hospital Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital of Shandong University, Jinan 250012, China; Division of Cardiothoracic Surgery, The Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX, USA. Electronic address: xingliwang@sdu.edu.cn.
Xing Li
XL
Wang
Shandong University Qilu Hospital Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital of Shandong University, Jinan 250012, China. Electronic address: zcui@sdu.edu.cn.
Zhaoqiang
Z
Cui
D000818:Animals; D001120:Arginine / Q000378:metabolism; D002199:Capillary Permeability / Q000235:genetics*; D027201:Cationic Amino Acid Transporter 1 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000235:genetics*; D017629:Gap Junctions / Q000235:genetics / Q000473:pathology; D005786:Gene Expression Regulation / Q000235:genetics; D055785:Gene Knockdown Techniques; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism; D013552:Swine; D051176:beta Catenin / Q000378:metabolism
D027201:Cationic Amino Acid Transporter 1; C420825:SLC7A1 protein, human; D051176:beta Catenin; D009569:Nitric Oxide; D001120:Arginine
CAT-1; Cell adhesion molecule; Vascular permeability; l-arginine paradox; trans-stimulation