Receptor protein tyrosine phosphatase micro regulates the paracellular pathway in human lung microvascular endothelia.
The pulmonary vascular endothelial paracellular pathway and zonula adherens (ZA) integrity are regulated, in part, through protein tyrosine phosphorylation. ZA-associated protein tyrosine phosphatase (PTP)s are thought to counterregulate tyrosine phosphorylation events within the ZA multiprotein complex. One such receptor PTP, PTPmu, is highly expressed in lung tissue and is almost exclusively restricted to the endothelium. We therefore studied whether PTPmu, in pulmonary vascular endothelia, associates with and/or regulates both the tyrosine phosphorylation state of vascular endothelial (VE)-cadherin and the paracellular pathway. PTPmu was expressed in postconfluent human pulmonary artery and lung microvascular endothelial cells (ECs) where it was almost exclusively restricted to EC-EC boundaries. In human lung microvascular ECs, knockdown of PTPmu through RNA interference dramatically impaired barrier function. In immortalized human microvascular ECs, overexpression of wild-type PTPmu enhanced barrier function. PTPmu-VE-cadherin interactions were demonstrated through reciprocal co-immunoprecipitation assays and co-localization with double-label fluorescence microscopy. When glutathione S-transferase-PTPmu was incubated with purified recombinant VE-cadherin, and when glutathione S-transferase-VE-cadherin was incubated with purified recombinant PTPmu, PTPmu directly bound to VE-cadherin. Overexpression of wild-type PTPmu decreased tyrosine phosphorylation of VE-cadherin. Therefore, PTPmu is expressed in human pulmonary vascular endothelia where it directly binds to VE-cadherin and regulates both the tyrosine phosphorylation state of VE-cadherin and barrier integrity.
Sui
Xiu Fen
XF
Department of Medicine and Pathology, Division of Infectious Diseases and Pulmonary Medicine, Mucosal Biology Research Center, University of Maryland School of Medicine, 22 Penn St., Baltimore, MD 21201, USA.
Kiser
Timothy D
TD
Hyun
Sang Won
SW
Angelini
Daniel J
DJ
Del Vecchio
Robert L
RL
Young
Bradford A
BA
Hasday
Jeffrey D
JD
Romer
Lewis H
LH
Passaniti
Antonino
A
Tonks
Nicholas K
NK
Goldblum
Simeon E
SE
D015824:Blood-Air Barrier / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism; D002199:Capillary Permeability / Q000502:physiology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008168:Lung / Q000098:blood supply*; D008833:Microcirculation / Q000378:metabolism; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011651:Pulmonary Artery / Q000378:metabolism; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D020133:Reverse Transcriptase Polymerase Chain Reaction
D015820:Cadherins; C502403:FAT1 protein, human; D005982:Glutathione Transferase; C516859:PTPRM protein, human; D017027:Protein Tyrosine Phosphatases; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2