scholarly journals Human umbilical vein endothelial cells secrete transcobalamin II

Blood ◽  
1990 ◽  
Vol 75 (1) ◽  
pp. 251-254 ◽  
Author(s):  
R Carmel ◽  
SM Neely ◽  
RB Jr Francis

Abstract Transcobalamin II (TC II) is essential for cellular uptake of cobalamin. However, the origin of this transport protein is controversial and many organ sources have been suggested. We studied human umbilical vein endothelial cells cultured in vitro. The cells contained TC II (2.3 pmol/10(8) cells) and released progressively increasing amounts of the protein into the surrounding medium during the 3-day incubation period. This release exceeded the starting intracellular content of TC II. In contrast, endothelial cells did not contain or elaborate R binder, the other major circulating binding protein for cobalamin, Cycloheximide inhibited the elaboration of TC II, suggesting that the endothelial cells synthesize the protein. Thrombin, which stimulates tissue plasminogen activator release, did not enhance TC II release, and neither did endotoxin or mellitin. However, thrombin did appear to partially protect TC II release from inhibition by cycloheximide. Among other cells studied, human fibroblasts also released TC II into the incubation medium, while K562 human leukemia cells, ARH-77 and HS Sultan human plasma cell lines, and Raji strain lymphoblasts did not. The data suggest that endothelial cells are an important source of the metabolically crucial TC II.

Blood ◽  
1990 ◽  
Vol 75 (1) ◽  
pp. 251-254
Author(s):  
R Carmel ◽  
SM Neely ◽  
RB Jr Francis

Transcobalamin II (TC II) is essential for cellular uptake of cobalamin. However, the origin of this transport protein is controversial and many organ sources have been suggested. We studied human umbilical vein endothelial cells cultured in vitro. The cells contained TC II (2.3 pmol/10(8) cells) and released progressively increasing amounts of the protein into the surrounding medium during the 3-day incubation period. This release exceeded the starting intracellular content of TC II. In contrast, endothelial cells did not contain or elaborate R binder, the other major circulating binding protein for cobalamin, Cycloheximide inhibited the elaboration of TC II, suggesting that the endothelial cells synthesize the protein. Thrombin, which stimulates tissue plasminogen activator release, did not enhance TC II release, and neither did endotoxin or mellitin. However, thrombin did appear to partially protect TC II release from inhibition by cycloheximide. Among other cells studied, human fibroblasts also released TC II into the incubation medium, while K562 human leukemia cells, ARH-77 and HS Sultan human plasma cell lines, and Raji strain lymphoblasts did not. The data suggest that endothelial cells are an important source of the metabolically crucial TC II.


1989 ◽  
Vol 256 (2) ◽  
pp. C296-C303 ◽  
Author(s):  
E. V. Quadros ◽  
S. P. Rothenberg ◽  
E. A. Jaffe

Transcobalamin II (TCII) is a cobalamin (Cbl) binding protein in the plasma that mediates the cellular uptake of Cbl. Although the synthesis of TCII by a variety of cultured mammalian cells and by some isolated perfused organs has been reported, no single tissue has been identified as the source of TCII in vivo. In this study, we demonstrate that cultured human umbilical vein endothelial cells secrete a protein that binds CN[57Co]Cbl, elutes from a Sephacryl S-200 column in the same position as TCII, and precipitates with an antiserum to purified human TCII. The biosynthesis of TCII by these cells was confirmed by demonstrating the incorporation of [35S]methionine into a nascent protein that immunoprecipitated with anti-TCII and which, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) had an Mr of 43,000, the same as human TCII. This secreted protein also had the functional properties of TCII because it facilitated the uptake of CN[57Co]Cbl by the same endothelial cells that secreted it as well as other cell lines that express the membrane receptor for TCII. We also present evidence that the venous endothelium could be the source of TCII in vivo by showing that an intact umbilical vein in an isolated umbilical cord, when perfused with medium containing [35S]methionine, secretes a radiolabeled nascent protein with the same immunoreactive and electrophoretic properties as human TCII. These studies demonstrate that the endothelial cell, which has been shown to secrete a number of plasma proteins, also synthesizes and secretes TCII both in vitro and as an intact endothelium in situ, and therefore, could be the source of circulating TCII in vivo.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zaipul I. Md Dom ◽  
Caterina Pipino ◽  
Bozena Krolewski ◽  
Kristina O’Neil ◽  
Eiichiro Satake ◽  
...  

AbstractWe recently identified a kidney risk inflammatory signature (KRIS), comprising 6 TNF receptors (including TNFR1 and TNFR2) and 11 inflammatory proteins. Elevated levels of these proteins in circulation were strongly associated with risk of the development of end-stage kidney disease (ESKD) during 10-year follow-up. It has been hypothesized that elevated levels of these proteins in circulation might reflect (be markers of) systemic exposure to TNFα. In this in vitro study, we examined intracellular and extracellular levels of these proteins in human umbilical vein endothelial cells (HUVECs) exposed to TNFα in the presence of hyperglycemia. KRIS proteins as well as 1300 other proteins were measured using the SOMAscan proteomics platform. Four KRIS proteins (including TNFR1) were down-regulated and only 1 protein (IL18R1) was up-regulated in the extracellular fraction of TNFα-stimulated HUVECs. In the intracellular fraction, one KRIS protein was down-regulated (CCL14) and 1 protein was up-regulated (IL18R1). The levels of other KRIS proteins were not affected by exposure to TNFα. HUVECs exposed to a hyperglycemic and inflammatory environment also showed significant up-regulation of a distinct set of 53 proteins (mainly in extracellular fraction). In our previous study, circulating levels of these proteins were not associated with progression to ESKD in diabetes.


Immunobiology ◽  
2006 ◽  
Vol 211 (5) ◽  
pp. 351-357 ◽  
Author(s):  
Jong-Seo Yoon ◽  
Hyun-Hee Kim ◽  
Ji-Whan Han ◽  
Yoon Lee ◽  
Joon-Sung Lee

2017 ◽  
Vol 33 (9) ◽  
pp. 592-599 ◽  
Author(s):  
Francesca Felice ◽  
Ester Belardinelli ◽  
Alessandro Frullini ◽  
Tatiana Santoni ◽  
Egidio Imbalzano ◽  
...  

Objectives Aminaphtone, a naphtohydrochinone used in the treatment of capillary disorders, may affect oedema in chronic venous insufficiency. Aim of study is to investigate the effect of aminaphtone on vascular endothelial permeability in vitro and its effects on three-dimensional capillary-like structures formed by human umbilical vein endothelial cells. Method Human umbilical vein endothelial cells were treated with 50 ng/ml VEGF for 2 h and aminaphtone for 6 h. Permeability assay, VE-cadherin expression and Matrigel assay were performed. Results VEGF-induced permeability was significantly decreased by aminaphtone in a range concentration of 1–20 µg/ml. Aminaphtone restored VE-cadherin expression. Finally, 6 h pre-treatment with aminaphtone significantly preserved capillary-like structures formed by human umbilical vein endothelial cells on Matrigel up to 48 h compared to untreated cells. Conclusions Aminaphtone significantly protects endothelium permeability and stabilises endothelial cells organised in capillary-like structures, modulating VE-cadherin expression. These data might explain the clinical benefit of aminaphtone on chronic venous insufficiency.


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