GLUT9 Is Differentially Expressed and Targeted in the Preimplantation Embryo

Carayannopoulos, Mary O.; Schlein, A. L.; Wyman, Amanda; Chi, Maggie; Keembiyehetty, Chithra N.; Moley, Kelle H.

doi:10.1210/en.2003-1264

Cited by 46 publications

(37 citation statements)

References 32 publications

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“…Functionally, Glut9 was initially reported to be a glucose (88) and/or fructose (89) transporter that, in contrast to other members of the Glut family, could not be inhibited by cytochalasin B. However, the glucose and fructose transport activity reported in these publications was very low and could not be observed in other studies (90,91).…”

Section: Other Genes Identified By Genetic Association Studiesmentioning

confidence: 99%

Uric acid transport and disease

Thorens²

2010

J. Clin. Invest.

692

496

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Uric acid is the metabolic end product of purine metabolism in humans. It has antioxidant properties that may be protective but can also be pro-oxidant, depending on its chemical microenvironment. Hyperuricemia predisposes to disease through the formation of urate crystals that cause gout, but hyperuricemia, independent of crystal formation, has also been linked with hypertension, atherosclerosis, insulin resistance, and diabetes. We discuss here the biology of urate metabolism and its role in disease. We also cover the genetics of urate transport, including URAT1, and recent studies identifying SLC2A9, which encodes the glucose transporter family isoform Glut9, as a major determinant of plasma uric acid levels and of gout development.Conflict of interest: Alexander So has acted as a consultant and advisor for Novartis.Citation for this article:

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Section: Other Genes Identified By Genetic Association Studiesmentioning

confidence: 99%

Uric acid transport and disease

Thorens²

2010

J. Clin. Invest.

692

496

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“…The first was raised in rabbits against a C-terminal peptide common to both hGLUT9a and hGLUT9b protein, and this antibody has been used and characterized previously. 9,16 The other 2 GLUT9 polyclonal antibodies were raised against N-terminal peptides in rabbits. The GLUT9a antibody was raised against DTSHARPPGPGRAL-LEC, and the GLUT9b was raised against KSRGEDEESD-SAKKC.…”

Section: Reagents and Antibodiesmentioning

confidence: 99%

Asymmetric Syncytial Expression of GLUT9 Splice Variants in Human Term Placenta and Alterations in Diabetic Pregnancies

2011

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Glucose transport from the maternal to fetal side of the placenta is critical for fetal growth and development due to the absence of fetal gluconeogenesis. Human GLUT9, existing as 2 isoforms, is a novel member of the transporter family. This study investigated the localization and relative expression levels of these isoforms in the human term placenta from both control and diabetic patients. Placenta samples were collected from normal pregnancies and those complicated by maternal diabetes (White classifications A1, A2, and B). Antibodies specific for the different isoforms were used to detect expression. Both forms of the protein are expressed in syncytiotrophoblast cells. Subcellular fractionation revealed an asymmetrical expression pattern with GLUT9a on basal membranes, whereas GLUT9b localizes to microvillus membranes. Expression of both isoforms is significantly increased in placental tissue from diabetic pregnancies. Altered expression of GLUT9 in the placenta may play a role in the fetal pathophysiology associated with diabetes-complicated pregnancies.

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“…In mice (7,18) as well as in humans (2), several splice variants of GLUT9 Fig. 1 have been described.…”

Section: Mouse Glut9 Mediates Urate But Not Glucose Transportmentioning

confidence: 99%

“…One family member, SLC2A9 (GLUT9), has been identified as a class II sugar transport facilitator with high sequence similarity to GLUT5 and GLUT11 (2). Although glucose transport activity has been reported for GLUT9 (2,7), it does not seem to be as efficient as for the classic glucose transporter GLUT2. Several recent reports have associated GLUT9 polymorphisms and uric acid levels and have identified GLUT9 as an important genetic determinant of serum uric acid levels (5,8,9,11,19,28,31,32).…”

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confidence: 99%

Mouse GLUT9: evidences for a urate uniporter

Bibert¹,

Hess²,

Firsov³

et al. 2009

American Journal of Physiology-Renal Physiology

106

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GLUT9 (SLC2A9) is a newly described urate transporter whose function, characteristics, and localization have just started to be elucidated. Some transport properties of human GLUT9 have been studied in the Xenopus laevis oocyte expression system, but the type of transport (uniport, coupled transport system, stoichiometry … .) is still largely unknown. We used the same experimental system to characterize in more detail the transport properties of mouse GLUT9, its sensitivity to several uricosuric drugs, and the specificities of two splice variants, mGLUT9a and mGLUT9b. [14C]urate uptake measurements show that both splice variants are high-capacity urate transporters and have a Km of ∼650 μM. The well-known uricosuric agents benzbromarone (500 μM) and losartan (1 mM) inhibit GLUT9-mediated urate uptake by 90 and 50%, respectively. Surprisingly, phloretin, a glucose-transporter blocker, inhibits [14C]urate uptake by ∼50% at 1 mM. Electrophysiological measurements suggest that urate transport by mouse GLUT9 is electrogenic and voltage dependent, but independent of the Na+ and Cl− transmembrane gradients. Taken together, our results suggest that GLUT9 works as a urate (anion) uniporter. Finally, we show by RT-PCR performed on RNA from mouse kidney microdissected tubules that GLUT9a is expressed at low levels in proximal tubules, while GLUT9b is specifically expressed in distal convoluted and connecting tubules. Expression of mouse GLUT9 in the kidney differs from that of human GLUT9, which could account for species differences in urate handling.

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GLUT9 Is Differentially Expressed and Targeted in the Preimplantation Embryo

Cited by 46 publications

References 32 publications

Uric acid transport and disease

Uric acid transport and disease

Asymmetric Syncytial Expression of GLUT9 Splice Variants in Human Term Placenta and Alterations in Diabetic Pregnancies

Mouse GLUT9: evidences for a urate uniporter

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