Decreased nucleoside transport and hENT1 transporter expression in beta-thalassemia major.
OBJECTIVE
This study investigated nucleoside transport activity and transporter polypeptide expression in erythrocytes from beta-thalassemia major patients to determine if inhibition of transport activity is a sensitive indicator of oxidative membrane damage.


METHODS
Blood samples were obtained from 54 patients, diagnosed as having beta-thalassemia major prior to therapeutic transfusion, and 20 normal subjects. Uptake of (3)H-uridine into washed erythrocytes was measured at room temperature using short incubation periods (5 s) and a rapid inhibitor oil stop protocol. Erythrocyte membranes were analyzed by SDS-PAGE and nucleoside (hENT1) and glucose (GLUT-1) transporter polypeptides quantitated on immunoblots.


RESULTS
Uridine uptake was significantly lower in beta-thalassemic cells than in normal erythrocytes (20.03 +/- 1.08 pmol/10(8) cells/ 5 s, mean +/- SEM, n = 31, vs. 31.15 +/- 1.21 pmol/10(8) cells/5 s, n = 20; p < 0.0001). Expression of hENT1 was significantly lower in beta-thalassemic cells (23.90 +/- 1.01 arbitrary units, n = 54) than in controls (101.20 +/- 2.43 arbitrary units, n = 20; p < 0.001) but expression of GLUT-1 was not changed appreciably (101.80 +/- 2.43 arbitrary units, n = 54, for thalassemic cells; 102.60 +/- 3.02 arbitrary units, n = 20, for control cells; p = 0.87).


CONCLUSIONS
Erythrocytes from beta-thalassemia major patients showed decreased uridine transport which was associated with decreased nucleoside transporter expression. The process(es) mediating a selective decrease in hENT1 polypeptides in beta-thalassemia major was/were not determined.
Department of Biochemistry, Faculty of Medicine, Health Sciences Center, Kuwait University, Kuwait.
Arwa Lufti
AL
Al-Massaeid
James D
JD
Craik
D000241:Adenosine / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D001692:Biological Transport; D016022:Case-Control Studies; D004591:Electrophoresis, Polyacrylamide Gel; D033721:Equilibrative Nucleoside Transporter 1 / Q000097:blood*; D006801:Humans; D015151:Immunoblotting; D007730:Kuwait; D008875:Middle Aged; D033703:Nucleoside Transport Proteins / Q000097:blood* / Q000235:genetics; D018384:Oxidative Stress; D014529:Uridine / Q000378:metabolism*; D055815:Young Adult; D017086:beta-Thalassemia / Q000097:blood* / Q000235:genetics
D033721:Equilibrative Nucleoside Transporter 1; D033703:Nucleoside Transport Proteins; C438649:SLC29A1 protein, human; D000241:Adenosine; D014529:Uridine