C. Angulo et al., HEXOSE TRANSPORTER EXPRESSION AND FUNCTION IN MAMMALIAN SPERMATOZOA -CELLULAR-LOCALIZATION AND TRANSPORT OF HEXOSES AND VITAMIN-C, Journal of cellular biochemistry, 71(2), 1998, pp. 189-203
We analyzed the expression of hexose transporters in human testis and
in human, rat, and bull spermatozoa and studied the uptake of hexoses
and vitamin C in bull spermatozoa. Immunocytochemical and reverse tran
scription-polymerase chain reaction analyses demonstrated that adult h
uman testis expressed the hexose transporters GLUT1, GLUT2, GLUT3, GLU
T4, and GLUT5. Immunoblotting experiments demonstrated the presence of
proteins of about 50-70 kD reactive with anti-GLUT1, GLUT2, GLUT3, an
d GLUT5 in membranes prepared from human spermatozoa, but no proteins
reactive with GLUT4 antibodies were detected. Immunolocalization exper
iments confirmed the presence of GLUT1, GLUT2, GLUT3, GLUT5, and low l
evels of GLUT4 in human, rat, and bull spermatozoa. Each transporter i
soform showed a typical subcellular localization in the head and the s
perm tail. In the tail, GLUT3 and GLUT5 were present at the level of t
he middle piece in the three species examined, GLUT1 was present in th
e principal piece, and the localization of GLUT2 differed according of
the species examined. Bull spermatozoa transported deoxyglucose, fruc
tose, and the oxidized form of vitamin C, dehydroascorbic acid. Transp
ort of deoxyglucose and dehydroascorbic acid was inhibited by cytochal
asin B, indicating the direct participation of facilitative hexose tra
nsporters in the transport of both substrates by bull spermatozoa. Tra
nsport of fructose was not affected by cytochalasin B, which is consis
tent for an important role for GLUT5 in the transport of fructose in t
hese cells. The data show that human, rat, and bull spermatozoa expres
s several hexose transporter isoforms that allow for the efficient upt
ake of glucose fructose, and dehydroascorbic acid by these cells. J. C
ell. Biochem. 71 :189-203, 1998. (C) 1998 Wiley-Liss, Inc.