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Disruption of membrane trafficking underlies the reduction in Kv1.3 channel surface expression in T lymphocytes during hypoxia
Author(s) -
Chimote Ameet,
Vergamini Sue,
Filipovich Alexandra,
Conforti Laura
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.861.14
Subject(s) - endocytosis , microbiology and biotechnology , brefeldin a , downregulation and upregulation , chemistry , clathrin , endosome , bafilomycin , golgi apparatus , biology , cell , biochemistry , apoptosis , intracellular , autophagy , endoplasmic reticulum , gene
Hypoxia (H) in solid tumors contributes to decreased immunosurveillance via Kv1.3 channel downregulation and inhibition of T cell function. However, the mechanisms responsible for Kv1.3 downregulation are not understood. We tested the hypothesis that chronic H (CH) reduces Kv1.3 surface expression via alterations in membrane trafficking. Jurkat T cells were maintained either in normoxia (21% O 2 ) or H (1% O 2 ) for 24h and Kv1.3 surface expression was quantified by in‐cell western blot analysis and flow cytometry using a specific Kv1.3 antibody against an extracellular epitope. CH decreased Kv1.3 surface expression in T cells by 25%. To study the involvement of endocytosis, endosome formation was blocked with Bafilomycin A1 (BAF). Comparable inhibition of Kv1.3 surface expression in CH was observed in BAF (27±4%) and control (ctr) (25±3%) cells. On the contrary, inhibition of the Golgi apparatus by Brefeldin A (BFE) prevented Kv1.3 surface expression reduction in CH (ctr 25±2% and BFE −4±3%). Furthermore, blockade of clathrin‐coated vesicle formation in the Golgi by dynasore (DYN), a selective dynamin inhibitor, prevented Kv1.3 surface expression decrease in CH (ctr 23±0.5% and DYN 0.93±1%). Our data suggest that CH disrupts forward trafficking of Kv1.3 protein from the G olgi to the plasma membrane thus contributing to the decrease in Kv1.3 surface expression in T lymphocytes. (NIH 2R01CA095286)