title: Protein disulfide isomerase externalization in endothelial cells follows classical and unconventional routes.
abstract: Extracellular protein disulfide isomerase (PDIA1) pool mediates thrombosis and vascular remodeling, however its externalization mechanisms remain unclear. We performed systematic pharmacological screening of secretory pathways affecting extracellular PDIA1 in endothelial cells (EC). We identified cell-surface (csPDIA1) and secreted non-particulated PDIA1 pools in EC. Such Golgi bypass also occurred for secreted PDIA1 in EC at baseline or after PMA, thrombin or ATP stimulation. Inhibitors of Type I, II and III unconventional routes, secretory lysosomes and recycling endosomes, including syntaxin-12 deletion, did not impair EC PDIA1 externalization. This suggests predominantly Golgi-independent unconventional secretory route(s), which were GRASP55-independent. Also, these data reinforce a vesicular-type traffic for PDIA1. We further showed that PDIA1 traffic is ATP-independent, while actin or tubulin cytoskeletal disruption markedly increased EC PDIA1 secretion. Clathrin inhibition enhanced extracellular soluble PDIA1, suggesting dynamic cycling. Externalized PDIA1 represents <2% of intracellular PDIA1. PDIA1 was robustly secreted by physiological levels of arterial laminar shear in EC and supported alpha 5 integrin thiol oxidation. Such results help clarify signaling and homeostatic mechanisms involved in multiple (patho)physiological extracellular PDIA1 functions.
authors.affiliation: Vascular Biology Laboratory, Heart Institute (InCor), University of São Paulo School of Medicine, São Paulo 05403-000, Brazil.
authors.forename: Thaís L S
authors.initials: TLS
authors.lastname: Araujo
authors.affiliation: Vascular Biology Laboratory, Heart Institute (InCor), University of São Paulo School of Medicine, São Paulo 05403-000, Brazil.
authors.forename: Julianna D
authors.initials: JD
authors.lastname: Zeidler
authors.affiliation: Vascular Biology Laboratory, Heart Institute (InCor), University of São Paulo School of Medicine, São Paulo 05403-000, Brazil.
authors.forename: Percíllia V S
authors.initials: PVS
authors.lastname: Oliveira
authors.affiliation: Instituto de Química, Universidade de São Paulo, Brazil; Laboratório Especial de Ciclo Celular (LECC), Center of Toxins, Immune-Response and Cell Signaling - CeTICS-Cepid, Instituto Butantan, Brazil.
authors.forename: Matheus H
authors.initials: MH
authors.lastname: Dias
authors.affiliation: Instituto de Química, Universidade de São Paulo, Brazil; Laboratório Especial de Ciclo Celular (LECC), Center of Toxins, Immune-Response and Cell Signaling - CeTICS-Cepid, Instituto Butantan, Brazil.
authors.forename: Hugo A
authors.initials: HA
authors.lastname: Armelin
authors.affiliation: Vascular Biology Laboratory, Heart Institute (InCor), University of São Paulo School of Medicine, São Paulo 05403-000, Brazil. Electronic address: francisco.laurindo@incor.usp.br.
authors.forename: Francisco R M
authors.initials: FRM
authors.lastname: Laurindo
mesh_terms: D001696:Biomechanical Phenomena; D002478:Cells, Cultured; D006056:Golgi Apparatus / Q000201:enzymology; D061307:Human Umbilical Vein Endothelial Cells / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D039482:Integrin alpha5 / Q000378:metabolism; D040542:Mechanotransduction, Cellular; D010084:Oxidation-Reduction; D011393:Procollagen-Proline Dioxygenase / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*; D021381:Protein Transport
chemical_list: D039482:Integrin alpha5; D011393:Procollagen-Proline Dioxygenase; C526497:P4HB protein, human; D019704:Protein Disulfide-Isomerases
keywords: Endothelial cell; Golgi bypass; Protein disulfide isomerase; Shear stress; Vascular smooth muscle