Single Cell Glucose Uptake Assays: A Cautionary Tale

Area of Science:

• Immunology
• Cellular Metabolism
• Biochemistry

Background:

• Assays for single-cell immune cell metabolic state and nutrient uptake are crucial.
• 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose (2-NBDG) is a fluorescent glucose analog used to study glucose uptake.
• 2-NBDG is validated for Glut2 but its selectivity for T cell glucose transporters (Glut1, Glut3) and non-transporter binding is unexplored.

Purpose of the Study:

• To investigate the specificity of 2-NBDG labeling as a readout for glucose transport in T lymphocytes.
• To assess whether 2-NBDG uptake accurately reflects glucose transport capacity in T cells.
• To determine if 2-NBDG binds to T cells independently of glucose transporters.

Main Methods:

• Comparison of flow cytometric 2-NBDG staining with radiolabeled glucose transport assays in murine T cells.
• Assessment of 2-NBDG uptake inhibition by competitive substrates and glucose transporter inhibitors.
• Evaluation of 2-NBDG's ability to competitively inhibit glucose uptake.

Main Results:

• Significant discordance observed between glucose transport capacity and 2-NBDG labeling in T cells.
• 2-NBDG uptake in murine T cells was not inhibited by known glucose transport inhibitors or competitive substrates.
• 2-NBDG did not competitively block glucose uptake in T cells.

Conclusions:

• 2-NBDG uptake alone is not a reliable tool for assessing cellular glucose transport capacity in T lymphocytes.
• The mechanism of 2-NBDG uptake in T cells may not involve canonical glucose transporters.
• Further research is needed to validate alternative methods for measuring T cell glucose uptake.