Expression of JAK3 Sensitive Na+ Coupled Glucose Carrier SGLT1 in Activated Cytotoxic T Lymphocytes.
BACKGROUND
Similar to tumor cells, activated T-lymphocytes generate ATP mainly by glycolytic degradation of glucose. Lymphocyte glucose uptake involves non-concentrative glucose carriers of the GLUT family. In contrast to GLUT isoforms, Na+-coupled glucose-carrier SGLT1 accumulates glucose against glucose gradients and is effective at low extracellular glucose concentrations. The present study explored expression and regulation of SGLT1 in activated murine splenic cytotoxic T cells (CTLs) and human Jurkat T cells.


METHODS
FACS analysis, immunofluorescence, confocal microscopy, chemiluminescence and Western blotting were employed to estimate SGLT1 expression, function and regulation in lymphocytes, as well as dual electrode voltage clamp in SGLT1 ± JAK3 expressing Xenopus oocytes to quantify the effect of janus kinase3 (JAK3) on SGLT1 function.


RESULTS
SGLT1 is expressed in murine CTLs and also in human Jurkat T cells. 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose uptake was significantly decreased by SGLT1-blocker phloridzin (0.2 mM) and by pharmacological inhibition of JAK3 with WHI-P131 (156 µM), WHI-P154 (11.2 µM) and JAK3 inhibitor VI (0.5 µM). Electrogenic glucose transport (Iglucose) in Xenopus oocytes expressing human SGLT1 was increased by additional expression of human wild type JAK3, active A568VJAK3 but not inactive K851AJAK3. Coexpression of JAK3 enhanced the maximal transport rate without significantly modifying affinity of the carrier. Iglucose in SGLT1+JAK3 expressing oocytes was significantly decreased by WHI-P154 (11.2 µM). JAK3 increased the SGLT1 protein abundance in the cell membrane. Inhibition of carrier insertion by brefeldin A (5 µM) in SGLT1+JAK3 expressing oocytes resulted in a decline of Iglucose, which was similar in presence and absence of JAK3.


CONCLUSIONS
SGLT1 is expressed in murine cytotoxic T cells and human Jurkat T cells and significantly contributes to glucose uptake in those cells post activation. JAK3 up-regulates SGLT1 activity by increasing the carrier protein abundance in the cell membrane, an effect enforcing cellular glucose uptake into activated lymphocytes and thus contributing to the immune response.
Department of Cardiology, Vascular Medicine and Physiology, University of Tuebingen, Tuebigen, Germany.
Shefalee K
SK
Bhavsar
Yogesh
Y
Singh
Piyush
P
Sharma
Vishal
V
Khairnar
Zohreh
Z
Hosseinzadeh
Shaqiu
S
Zhang
Monica
M
Palmada
Ivan
I
Sabolic
Hermann
H
Koepsell
Karl S
KS
Lang
Philipp A
PA
Lang
Florian
F
Lang
D009327:4-Chloro-7-nitrobenzofurazan / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D020126:Brefeldin A / Q000494:pharmacology; D018938:Caco-2 Cells; D003847:Deoxyglucose / Q000031:analogs & derivatives / Q000494:pharmacology; D005786:Gene Expression Regulation; D005947:Glucose / Q000276:immunology* / Q000494:pharmacology; D006801:Humans; D053616:Janus Kinase 3 / Q000235:genetics* / Q000276:immunology; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D051379:Mice; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010695:Phlorhizin / Q000494:pharmacology; D061251:Primary Cell Culture; D011799:Quinazolines / Q000494:pharmacology; D015398:Signal Transduction; D051269:Sodium-Glucose Transporter 1 / Q000235:genetics* / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D019076:Transgenes; D014982:Xenopus laevis
D011799:Quinazolines; C495674:SLC5A1 protein, human; D051269:Sodium-Glucose Transporter 1; C116180:WHI P131; C113888:WHI P154; D020126:Brefeldin A; D003847:Deoxyglucose; D010695:Phlorhizin; C507933:JAK3 protein, human; D053616:Janus Kinase 3; D009327:4-Chloro-7-nitrobenzofurazan; D005947:Glucose; C098340:2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose