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α-Tocopherol transfer protein does not regulate the cellular uptake and intracellular distribution of α- and γ-tocopherols and -tocotrienols in cultured liver cells
- Source :
- Redox Biology, Vol 19, Iss, Pp 28-36 (2018), Redox Biology
- Publication Year :
- 2018
- Publisher :
- Elsevier, 2018.
-
Abstract
- Liver cells express a cytosolic α-tocopherol transfer protein (αTTP) with high binding affinity for α-tocopherol (αT) and much lower affinities for the non-αT congeners. The role of αTTP in the intracellular distribution of the different vitamin E forms is currently unknown. We therefore investigated the intracellular localization of αT, γ-tocopherol (γT), α-tocotrienol (αT3), and γ-tocotrienol (γT3) in cultured hepatic cells with and without stable expression of αTTP. We first determined cellular uptake of the four congeners and found the methylation of the chromanol ring and saturation of the sidechain to be important factors, with tocotrienols being taken up more efficiently than tocopherols and the γ-congeners more than the α-congeners, irrespective of the expression of αTTP. This, however, could perhaps also be due to an observed higher stability of tocotrienols, compared to tocopherols, in culture media rather than a higher absorption. We then incubated HepG2 cells and αTTP-expressing HepG2 cells with αT, γT, αT3, or γT3, isolated organelle fractions by density gradient centrifugation, and determined the concentrations of the congeners in the subcellular fractions. All four congeners were primarily associated with the lysosomes, endoplasmic reticulum, and plasma membrane, whereas only αT correlated with mitochondria. Neither the chromanol ring methylation or sidechain saturation, nor the expression of αTTP were important factors for the intracellular distribution of vitamin E. In conclusion, αTTP does not appear to regulate the uptake and intracellular localization of different vitamin E congeners in cultured liver cells.<br />Graphical abstract fx1<br />Highlights • We studied how αTTP affects intracellular distribution of αT, γT, αT3, γT3 in HepG2 cells. • All congeners associated with lysosomes, endoplasmic reticulum and the plasma membrane. • Only αT significantly correlated with mitochondria. • Neither the chemical structure, nor αTTP were important for intracellular localization.
- Subjects :
- 0301 basic medicine
medicine.medical_treatment
alpha-Tocopherol
Clinical Biochemistry
AUC, are under the concentration-time curve
Mitochondrion
Biochemistry
0302 clinical medicine
α-Tocopherol transfer protein
Vitamin E
Tocopherol
lcsh:QH301-705.5
lcsh:R5-920
Trafficking
Chemistry
Tocotrienols
αT, α-tocopherol
γT, γ-tocopherol
Hep G2 Cells
Mitochondria
Intracellular localization
030220 oncology & carcinogenesis
HepG2 liver cells
lcsh:Medicine (General)
Intracellular
Research Paper
Plasma membrane
HepG2-TTP, HepG2 cell line expressing the human TTP cDNA
αTTP, α-tocopherol transfer protein
03 medical and health sciences
αT3, α-tocotrienol
HepG2-EV, HepG2 cell line transfected with the antibiotic resistance gene
medicine
Humans
Differential centrifugation
gamma-Tocopherol
HepG2, human hepatoma cultured cell
Endoplasmic reticulum
Cell Membrane
Organic Chemistry
Biological Transport
Cytosol
030104 developmental biology
lcsh:Biology (General)
Hepatocytes
Hepatic stellate cell
Carrier Proteins
Lysosomes
γT3, γ-tocotrienol
Subjects
Details
- Language :
- English
- ISSN :
- 22132317
- Volume :
- 19
- Database :
- OpenAIRE
- Journal :
- Redox Biology
- Accession number :
- edsair.doi.dedup.....0b9c34a1b403b10d046c5c46ab0b9bdf