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Glucose metabolism down‐regulates the uptake of 6‐(N‐(7‐nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yl)amino)‐2‐deoxyglucose (6‐ NBDG ) mediated by glucose transporter 1 isoform ( GLUT 1): theory and simulations using the symmetric four‐state carrier model
Author(s) -
DiNuzzo Mauro,
Giove Federico,
Maraviglia Bruno,
Mangia Silvia
Publication year - 2013
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/jnc.12164
Subject(s) - glucose transporter , glut1 , transporter , glucose uptake , glucose transporter type 1 , biophysics , carbohydrate metabolism , gene isoform , deoxyglucose , ligand (biochemistry) , intracellular , chemistry , biochemistry , metabolism , steady state (chemistry) , mediated transport , membrane transport , membrane transport protein , biology , receptor , membrane , endocrinology , insulin , gene
The non‐metabolizable fluorescent glucose analogue 6‐(N‐(7‐nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yl)amino)‐2‐deoxyglucose (6‐ NBDG ) is increasingly used to study cellular transport of glucose. Intracellular accumulation of exogenously applied 6‐ NBDG is assumed to reflect concurrent gradient‐driven glucose uptake by glucose transporters ( GLUT s). Here, theoretical considerations are provided that put this assumption into question. In particular, depending on the microscopic parameters of the carrier proteins, theory proves that changes in glucose transport can be accompanied by opposite changes in flow of 6‐ NBDG . Simulations were carried out applying the symmetric four‐state carrier model on the GLUT 1 isoform, which is the only isoform whose kinetic parameters are presently available. Results show that cellular 6‐ NBDG uptake decreases with increasing rate of glucose utilization under core‐model conditions, supported by literature, namely where the transporter is assumed to work in regime of slow reorientation of the free‐carrier compared with the ligand–carrier complex. To observe an increase of 6‐ NBDG uptake with increasing rate of glucose utilization, and thus interpret 6‐ NBDG increase as surrogate of glucose uptake, the transporter must be assumed to operate in regime of slow ligand–carrier binding, a condition that is currently not supported by literature. Our findings suggest that the interpretation of data obtained with NBDG derivatives is presently ambiguous and should be cautious because the underlying transport kinetics are not adequately established.