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Human umbilical vein endothelial cells secrete transcobalamin II
R Carmel1, S M Neely, R B Francis
1Department of Medicine, University of Southern California School of Medicine, Los Angeles 90033.
Blood
|January 1, 1990
Summary
Human endothelial cells synthesize and release transcobalamin II (TC II), a protein vital for cobalamin uptake. This finding identifies a key source for this essential nutrient transport protein.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- Transcobalamin II (TC II) is crucial for cellular cobalamin uptake.
- The primary organ source of TC II remains debated.
- Endothelial cells are investigated as a potential source of TC II.
Purpose of the Study:
- To investigate the origin and synthesis of Transcobalamin II (TC II).
- To determine if human umbilical vein endothelial cells produce and release TC II.
- To explore other cell types' capacity to elaborate TC II.
Main Methods:
- Culturing human umbilical vein endothelial cells in vitro.
- Quantifying intracellular and released TC II over 72 hours.
- Utilizing cycloheximide to assess protein synthesis and thrombin to evaluate release modulation.
- Testing TC II release from fibroblasts and various human cell lines.
Main Results:
- Endothelial cells contained and released TC II, with release exceeding initial intracellular levels.
- Cycloheximide inhibited TC II release, indicating endothelial cell synthesis.
- Thrombin showed a partial protective effect against cycloheximide inhibition.
- Human fibroblasts released TC II, unlike leukemia, plasma cell, and lymphoblast lines.
Conclusions:
- Human endothelial cells are a significant source of the essential cobalamin-binding protein, TC II.
- This study provides evidence for endothelial cells synthesizing and secreting TC II.
- The findings contribute to understanding cobalamin transport and TC II metabolism.