The Cloning and Expression of a Human Creatine Transporter

Sora, Ichiro; Richman, Jeremy G.; Santoro, G; Wei, Hongbing; Wang, Yu; Vanderah, Todd W.; Horvath, Rita; Nguyen, Mike; Waite, Sue; Roeske, William R.; Yamamura, Henry I.

doi:10.1006/bbrc.1994.2475

Cited by 120 publications

(91 citation statements)

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“…2C). This K m value is in good agreement with an apparent K m of 15 and 30 mol/L in human and rat CRT, respectively (Saltarelli et al, 1996;Sora et al, 1994), and is 17-fold lower than the plasma creatine concentration (272 mol/L) in the mouse (Marescau et al, 1992). This suggests that creatine transport is saturated by endogenous plasma creatine.…”

Section: Discussionsupporting

confidence: 80%

The Blood–Brain Barrier Creatine Transporter is a Major Pathway for Supplying Creatine to the Brain

Ohtsuki

Tachikawa

Takanaga

et al. 2002

J Cereb Blood Flow Metab

138

100

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Summary:Although creatine plays a pivotal role in the storage of phosphate-bound energy in the brain, the source of cerebral creatine is still unclear. The authors examined the contribution made by the creatine transporter (CRT) at the blood-brain barrier in supplying creatine to the brain from blood. An in vivo intravenous administration study suggested that creatine is continuously transported from the blood to the brain against the creatine concentration gradient that exists between brain and blood. Conditionally immortalized mouse brain capillary endothelial cells (TM-BBB) exhibited creatine uptake, which is Na + and Cl − dependent and inhibited by CRT inhibitors, such as ␤-guanidinopropionate and guanidinoacetate. Northern blot and immunoblot analyses demonstrated that CRT is expressed in TM-BBB cells and isolated mouse brain microvessels. Moreover, high expression of CRT was observed in the mouse brain capillaries by confocal immunofluorescent microscopy. These results suggest that CRT plays an important role in supplying creatine to the brain via the blood-brain barrier.

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Section: Discussionsupporting

confidence: 80%

The Blood–Brain Barrier Creatine Transporter is a Major Pathway for Supplying Creatine to the Brain

Ohtsuki

Tachikawa

Takanaga

et al. 2002

J Cereb Blood Flow Metab

138

100

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“…As expected, lung, testis, and intestine show lower levels of CRT expression. The tissue-specific expression of CRT mRNA by Northern blot hybridization has been investigated previously, and CRT mRNA expression was also detected in most tissues tested but most prominently in kidney, heart, and brain (21,42,52,59), in agreement with CRT protein expression in these tissues shown in Fig. 4A.…”

Section: Discussionsupporting

confidence: 59%

New creatine transporter assay and identification of distinct creatine transporter isoforms in muscle

Walzel

Speer

Boehm

et al. 2002

American Journal of Physiology-Endocrinology and Metabolism

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. New creatine transporter assay and identification of distinct creatine transporter isoforms in muscle. Am J Physiol Endocrinol Metab 283: E390-E401, 2002. First published February 26, 2002 10.1152/ajpendo.00428.2001.-Despite the pivotal role of creatine (Cr) and phosphocreatine (PCr) in muscle metabolism, relatively little is known about sarcolemmal creatine transport, creatine transporter (CRT) isoforms, and subcellular localization of the CRT proteins. To be able to quantify creatine transport across the sarcolemma, we have developed a new in vitro assay using rat sarcolemmal giant vesicles. The rat giant sarcolemmal vesicle assay reveals the presence of a specific high-affinity and saturable transport system for Cr in the sarcolemma (Michaelis-Menten constant 52.4 Ϯ 9.4 M and maximal velocity value 17.3 Ϯ 3.1 pmol ⅐ min Ϫ1 ⅐ mg vesicle protein Ϫ1 ), which cotransports Cr into skeletal muscle together with Na ϩ and Cl Ϫ ions. The regulation of Cr transport in giant vesicles by substrates, analogs, and inhibitors, as well as by phorbol 12-myristate 13-acetate and insulin, was studied. Two antibodies raised against COOH-and NH 2-terminal synthetic peptides of CRT sequences both recognize two major polypeptides on Western blots with apparent molecular masses of 70 and 55 kDa, respectively. The highest CRT expression occurs in heart, brain, and kidney, and although creatine kinase is absent in liver cells, CRT is also found in this tissue. Surprisingly, immunofluorescence staining of cultured adult rat heart cardiomyocytes with specific anti-CRT antibodies, as well as cell fractionation and cell surface biotinylation studies, revealed that only a minor CRT species with an intermediate molecular mass of ϳ58 kDa is present in the sarcolemma, whereas the previously identified major CRT-related protein species of 70 and 55 kDa are specifically located in mitochondria. Our studies indicate that mitochondria may represent a major compartment of CRT localization, thus providing a new aspect to the current debate about the existence and whereabouts of intracellular Cr and PCr compartments that have been inferred from [ 14 C]PCr/Cr measurements in vivo as well as from recent in vivo NMR studies.

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“…These numbers indicate a preferential uptake of cyCr into the tumour tissue. The role of a specific sodium-dependent transporter of Cr and cyCr (Guimbal et al, 1993;Sora et al, 1994) remains to be determined. This transport molecule may have a higher affinity for cyCr than Cr.…”

Section: Growth Inhibition By Cr and Cycrmentioning

confidence: 99%

Creatine and cyclocreatine treatment of human colon adenocarcinoma xenografts: 31P and 1H magnetic resonance spectroscopic studies

et al. 1998

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Summary Creatine (Cr) and cyclocreatine (cyCr) have been shown to inhibit the growth of a variety of human and murine tumours. The purpose of this study was to evaluate the anti-tumour effect of these molecules in relation to drug accumulation, energy metabolism, tumour water accumulation and toxicity. Nude mice carrying a human colon adenocarcinoma (LS174T) with a creatine kinase (CK) activity of 2.12 units mg -1 protein were fed Cr (2.5% or 5%) or cyCr (0.025%, 0.1% or 0.5%) for 2 weeks and compared with controls fed standard diet. Cr concentrations of 2.5% and 5% significantly inhibited tumour growth, as did 0.1% and 0.5% cyCr. In vivo 31 P magnetic resonance spectroscopy (MRS) after 2 weeks of treatment showed an increase in [phosphocreatine (PCr)+phosphocyclocreatine (PcyCr)]/nucleoside triphosphate (NTP) with increasing concentrations of dietary Cr and cyCr, without changes in absolute NTP contents. The antiproliferative effect of the substrates of CK was not related to energy deficiency but was associated with acidosis. Intratumoral substrate concentrations (measured by 1 H-MRS) of 4.8 µmol g -1 wet weight Cr (mice fed 2.5% Cr) and 6.2 µmol g -1 cyCr (mice fed 0.1% cyCr) induced a similar decrease in growth rate, indicating that both substrates were equally potent in tumour growth inhibition. The best correlant of growth inhibition was the total Cr or (cyCr+Cr) concentrations in the tissue. In vivo, these agents did not induce excessive water accumulation and had no systemic effects on the mice (weight loss, hypoglycaemia) that may have caused growth inhibition.

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The Cloning and Expression of a Human Creatine Transporter

Cited by 120 publications

References 0 publications

The Blood–Brain Barrier Creatine Transporter is a Major Pathway for Supplying Creatine to the Brain

The Blood–Brain Barrier Creatine Transporter is a Major Pathway for Supplying Creatine to the Brain

New creatine transporter assay and identification of distinct creatine transporter isoforms in muscle

Creatine and cyclocreatine treatment of human colon adenocarcinoma xenografts: 31P and 1H magnetic resonance spectroscopic studies

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