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Gajja S. Salomons - One of the best experts on this subject based on the ideXlab platform.

  • rna sequencing of creatine transporter SLC6A8 deficient fibroblasts reveals impairment of the extracellular matrix
    Human Mutation, 2014
    Co-Authors: Silvy J M Van Dooren, Benjamin Nota, Joseph Ndika, Jiddeke M Van De Kamp, Warsha A Kanhai, Mark A Van De Wiel, Gerard Pals, Gajja S. Salomons
    Abstract:

    Creatine transporter (SLC6A8) deficiency is the most common cause of cerebral creatine syndromes, and is characterized by depletion of creatine in the brain. Manifestations of this X-linked disorder include intellectual disability, speech/language impairment, behavior abnormalities, and seizures. At the moment, no effective treatment is available. In order to investigate the molecular pathophysiology of this disorder, we performed RNA sequencing on fibroblasts derived from patients. The transcriptomes of fibroblast cells from eight unrelated individuals with SLC6A8 deficiency and three wild-type controls were sequenced. SLC6A8 mutations with different effects on the protein product resulted in different gene expression profiles. Differential gene expression analysis followed by gene ontology term enrichment analysis revealed that especially the expression of genes encoding components of the extracellular matrix and cytoskeleton are altered in SLC6A8 deficiency, such as collagens, keratins, integrins, and cadherins. This suggests an important novel role for creatine in the structural development and maintenance of cells. It is likely that the (extracellular) structure of brain cells is also impaired in SLC6A8-deficient patients, and future studies are necessary to confirm this and to reveal the true functions of creatine in the brain.

  • functional and electrophysiological characterization of four non truncating mutations responsible for creatine transporter SLC6A8 deficiency syndrome
    Journal of Inherited Metabolic Disease, 2013
    Co-Authors: Vassili Valayannopoulos, Gajja S. Salomons, Naziha Bakouh, Michel Mazzuca, Luc Nonnenmacher, Laurence Hubert, Fatnalea Makaci, Allel Chabli, Caroline Mellotdraznieks
    Abstract:

    Intellectual disability coupled with epilepsy are clinical hallmarks of the creatine (Cr) transporter deficiency syndrome resulting from mutations in the SLC6A8 gene. So far characterization of pathogenic mutations of SLC6A8 has been limited to Cr uptake. The aim of our study was to characterize the electrogenic and pharmacological properties of non truncating SLC6A8 mutations identified in patients presenting variable clinical severity. Electrophysiological and pharmacological properties of four mutants (including two novel ones) were studied in X. laevis oocyte expression system. Creatine uptake was assessed with [14C]-Cr in X. laevis and patients’ fibroblasts. Subcellular localization was determined by immunofluorescence and western blot. All mutants were properly targeted to the plasma membrane in both systems. Mutations led to the complete loss of both electrogenic and transport activities in X. laevis and Cr uptake in patients’ fibroblasts. Among the Cr analogs tested, guanidinopropionate induced an electrogenic activity with the normal SLC6A8 transporter similar to creatine whereas a phosphocreatine derivative, PCr-Mg-CPLX, resulted in partial activity. SLC6A8 mutants displayed no electrogenic activity with all Cr analogs tested in X. laevis oocytes. Although the mutations altered various domains of SLC6A8 Cr uptake and electrogenic properties were completely inhibited and could not be dissociated. Besides the metabolic functions of Cr, the loss of SLC6A8 electrogenic activity, demonstrated here for the first time, may also play a role in the altered brain functions of the patients.

  • contiguous deletion of SLC6A8 and bap31 in a patient with severe dystonia and sensorineural deafness
    Molecular Genetics and Metabolism, 2012
    Co-Authors: Hitoshi Osaka, Gajja S. Salomons, Atsushi Takagi, Yu Tsuyusaki, Takahito Wada, Mizue Iai, Sumimasa Yamashita, Hiroko Shimbo, Hirotomo Saitsu, Cornelis Jakobs
    Abstract:

    We report here a 6-year-old boy exhibiting severe dystonia, profound intellectual and developmental disability with liver disease, and sensorineural deafness. A deficient creatine peak in brain (1)H-MR spectroscopy and high ratio of creatine/creatinine concentration in his urine lead us to suspect a creatine transporter (solute carrier family 6, member 8; SLC6A8) deficiency, which was confirmed by the inability to take up creatine into fibroblasts. We found a large ~19 kb deletion encompassing exons 5-13 of SLC6A8 and exons 5-8 of the B-cell receptor-associated protein (BAP31) gene. This case is the first report in which the SLC6A8 and BAP31 genes are both deleted. The phenotype of BAP31 mutations has been reported only as a part of Xq28 deletion syndrome or contiguous ATP-binding cassette, sub-family D, member 1 (ABCD1)/DXS1375E (BAP31) deletion syndrome [MIM ID #300475], where liver dysfunction and sensorineural deafness have been suggested to be attributed to the loss of function of BAP31. Our case supports the idea that the loss of BAP31 is related to liver dysfunction and hearing loss.

  • detection of variants in SLC6A8 and functional analysis of unclassified missense variants
    Molecular Genetics and Metabolism, 2012
    Co-Authors: Ofir T. Betsalel, Efraim H. Rosenberg, Cornelis Jakobs, Ana Pop, Matilde Fernandezojeda, Gajja S. Salomons
    Abstract:

    Creatine transporter deficiency is an X-linked disorder caused by mutations in the SLC6A8 gene. Currently, 38 pathogenic, including 15 missense variants, are reported. In this study, we report 33 novel, including 6 missense variants. To classify all known missense variants, we transfected creatine deficient fibroblasts with the SLC6A8 ORF containing one of the unique variants and tested their ability to restore creatine uptake. This resulted in the definitive classification of 2 non-disease associated and 19 pathogenic variants of which 3 have residual activity. Furthermore, we report the development and validation of a novel DHPLC method for the detection of heterozygous SLC6A8 variants. The method was validated by analysis of DNAs that in total contained 67 unique variants of which 66 could be detected. Therefore, this rapid screening method may prove valuable for the analysis of large cohorts of females with mild intellectual disability of unknown etiology, since in this group heterozygous SLC6A8 mutations may be detected. DHPLC proved also to be important for the detection of somatic mosaicism in mothers of patients who have a pathogenic mutation in SLC6A8. All variants reported in the present and previous studies are included in the Leiden Open Source Variant Database (LOVD) of SLC6A8 (www.LOVD.nl/SLC6A8).

  • Treatment of intractable epilepsy in a female with SLC6A8 deficiency.
    Molecular genetics and metabolism, 2010
    Co-Authors: Saadet Mercimek-mahmutoglu, Mary B. Connolly, Kenneth J. Poskitt, Gabriella Horvath, Noel Lowry, Gajja S. Salomons, Brett Casey, Graham Sinclair, Cynthia Davis, Cornelis Jakobs
    Abstract:

    Abstract A female heterozygous for a novel, disease causing, missense mutation in the X-linked cerebral creatine transporter (SLC6A8) gene (c.1067G > T, p.Gly356Val) presented with intractable epilepsy, mild intellectual disability and moderately reduced cerebral creatine levels. Treatment with creatine monohydrate, to enhance cerebral creatine transport, combined with l -arginine and l -glycine, to enhance cerebral creatine synthesis, resulted in complete resolution of seizures. Heterozygous SLC6A8 deficiency is a potentially treatable condition and should be considered in females with intractable epilepsy and developmental delay/intellectual disability.

Vadivel Ganapathy - One of the best experts on this subject based on the ideXlab platform.

  • slc5a8 nuclear translocation and loss of expression are associated with poor outcome in pancreatic ductal adenocarcinoma
    Pancreas, 2012
    Co-Authors: James F Helm, Vadivel Ganapathy, Domenico Coppola, Mark C Lloyd, Barbara A Centeno, Dungtsa Chen, Mokenge P Malafa, Jong Y Park
    Abstract:

    Pancreatic cancer has the lowest long-term survival rate of any cancer, with no more than 5% of all pancreatic cancer patients surviving for 5 years.1 Most pancreatic cancers are ductal adenocarcinomas. The prognosis of patients with pancreatic ductal adenocarcinoma (PDA) has remained unchanged despite significant advances in our knowledge of the molecular biology and treatment of many other cancers. If the outcome of patients with pancreatic cancer is to improve, we need to identify new biomarkers for early diagnosis and prognosis, as well as molecular targets for treatment. Abnormal expression of the tumor suppressor gene SLC5A8 may be useful as a prognostic biomarker and is potentially of interest for the development of pancreatic cancer treatments. SLC5A8 belongs to the solute-linked carrier gene family 5 (SLC5), a family of 12 sodium-coupled transporters for a number of chemicals.2,3 SLC5A8 is a sodium-coupled transporter for nicotinate and analogs,4 lactate,5 and of particular interest, the short-chain fatty acids butyrate and pyruvate, which are known to induce tumor apoptosis through histone deacetylase (HDAC) inhibition.2,6,7 Evidence suggests that SLC5A8 functions as a tumor suppressor gene whose silencing may contribute to carcinogenesis and tumor progression.2,8 We and others have reported that loss of SLC5A8 expression resulting from DNA hypermethylation in the promoter region is associated with prognostic features in cancers of the brain,9 colon,8,10–12 thyroid,13–16 stomach,17 breast,7 lung,18 prostate,19 and head and neck,20 as well as acute myeloid leukemia.21 In a previous study, we showed by methylation-specific polymerase chain reaction that SLC5A8 CpG island methylation was infrequent in non–neoplastic pancreas (NNP) (11%) but common in pancreatic cancer (70%), a finding consistent with tumor-specific loss of SLC5A8 expression.22 Using bisulfite sequencing analysis, we also observed that pancreatic cancer cell lines that did not express SLC5A8 were densely methylated in the promoter region. SLC5A8 expression in these cell lines was restored by treatment with the demethylating agent 5-aza-deoxycytidine, implying that SLC5A8 expression is suppressed by aberrant DNA methylation in pancreatic cancer.22 In colon and thyroid cancer, hypermethylation in the promoter region of SLC5A8 has been found to be associated with disease progression features, including target tissue invasion, lymphangiogenesis, multifocality, and advanced stage.10,14 However, little is known about the prognostic significance of SLC5A8 expression in PDA. Our aim in this study was to characterize SLC5A8 expression in pancreatic cancer by immunohistochemistry and seek an association of abnormal expression with poor survival.

  • abstract 17 tumor suppressive function of slc5a8 in renal cancer cells
    Cancer Research, 2012
    Co-Authors: Veena Coothankandaswamy, Muthusamy Thangaraju, Vadivel Ganapathy, Selvakumar Elangovan, Elangovan Gopal, Joo Hee Kim, Keith D Robertson, Puttur D Prasad
    Abstract:

    SLC5A8, a Na+-coupled high-affinity transporter for monocarboxylates, and the closely related SLC5A12, a Na+-coupled low-affinity transporter for monocarboxylates, are both highly expressed in kidney, where they mediate the reuptake of lactate and pyruvate from the glomerular filtrate. Recent studies have shown that SLC5A8 is a tumor-suppressor that is silenced in many cancers by promoter hypermethylation. We investigated if SLC5A8 serves as a tumor suppressor in renal cancer cells (RCC). Comparison of the expression of SLC5A8 at the mRNA and protein levels in two RCC (A498 & 786-0) and two normal kidney cell lines (HK-2 & HEK-293) revealed that the expression of SLC5A8 was significantly lower in RCC. Analysis of methylation status of the CpG island in the regulatory region of SLC5A8 showed that the extent of methylation was significantly higher in the two RCC compared to the two normal cells. Culturing A498 cells in the presence of 5-aza-deoxycytidine resulted in re-expression of SLC5A8, confirming that the silencing of the gene is due to DNA methylation. Ectopic expression of SLC5A8 in A498 cells caused apoptosis when cultured in the presence of HDAC inhibitors butyrate and pyruvate. These data show that SLC5A8-mediated concentrative entry of HDAC inhibitors causes cell death in RCC. Interestingly, normal proximal tubular cells, which express SLC5A8 robustly and are exposed to pyruvate, do not undergo apoptosis; HDAC inhibitor-mediated apoptosis is specific to cancer cells. To investigate if HDAC isoforms play a role in this differential sensitivity of normal and RCC to pyruvate, we compared the expression of various HDAC isoforms in HK-2 and A498 cells by RT-PCR. The results indicated that the expression of HDAC1 and HDAC3 was higher in RCC compared to normal cells. The total HDAC enzyme activity was ∼2-3-fold higher in RCC compared to normal cells. If intracellular pyruvate is detrimental to the survival of tumor cells and the tumor cells silence SLC5A8 to prevent entry of extracellular pyruvate into cells, the levels of pyruvate inside tumor cells should be lower in RCC compared to normal cells. To confirm this, we measured pyruvate and lactate levels in normal cells and RCC and found that pyruvate levels were ∼4-fold lower while lactate was ∼2-fold higher in RCC cells compared to normal cells. Finally, to conclusively demonstrate the tumor-suppressive role for SLC5A8 in RCC, we performed mouse xenograft studies using control A498 & 786-0 cells, which do not express SLC5A8 constitutively, and A498 & 786-0 cells, which were made to express SLC5A8 by lentiviral mediated transfection of SLC5A8 cDNA. The growth of the tumor was significantly slower with SLC5A8-expressing cells than with SLC5A8-negative parent cells. These studies demonstrate that SLC5A8 is indeed a tumor suppressor in kidney, suggesting that pharmacological induction of the transporter expression in renal cancer might be a novel strategy for treatment of renal cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 17. doi:1538-7445.AM2012-17

  • abstract 2194 slc5a8 a novel transporter with tumor suppressor function mediates its effect through survivin depletion
    Cancer Research, 2011
    Co-Authors: Veena Coothankandaswamy, Muthusamy Thangaraju, Puttur D Prasad, Selvakumar Elangovan, Vadivel Ganapathy
    Abstract:

    Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Introduction: SLC5A8 is a Na+-coupled transporter for lactate, pyruvate, nicotinate and ketone bodies and is down-regulated in a wide variety of cancers. It is expressed in normal cells whereas tumor cells suppress its expression by methylation of CpG islands in its promoter. Studies from our laboratory have shown that (i) pyruvate (but not lactate) is a tumor suppressor through its ability to inhibit HDAC1/3, and that ectopic expression of SLC5A8 in breast cancer cells suppresses expression of the anti-apoptotic protein survivin. Apart from its role in protecting tumor cells from apoptosis, survivin also serves as an important determinant of chemoresistance. Based on these findings, we hypothesized that forced expression of SLC5A8 in breast cancer cells will deplete survivin and consequently enhance chemosensitivity. Methods: The estrogen receptor-positive human breast cancer cell line MCF7 does not express SLC5A8. These cells were engineered to express SLC5A8 by a doxycycline-inducible promoter. The expression of the transporter was monitored by Na+-coupled nicotinate uptake and by immunocytochemistry. The interaction between SLC5A8 and survivin was investigated by immunocytochemical analysis for co-localization. The chemosensitivity was studied by monitoring the cytotoxic effects of docetaxel in SLC5A8-negative control cells and SLC5A8-expressing cells. Results: MCF7 cells transfected with vector alone did not show Na+-coupled nicotinate uptake, indicating the absence of functional expression of SLC5A8. In contrast, MCF7 cells transfected with the SLC5A8 construct under a doxycycline-inducible promoter exhibited marked activity for Na+-coupled nicotinate uptake but only when exposed to doxycycline. This was complemented with immunocytochemical evidence of SLC5A8 protein expression in the plasma membrane. In SLC5A8-expressing control MCF7 cells, survivin was expressed robustly and the expression was restricted predominantly to the nucleus. In contrast, in SLC5A8-expressing MCF7 cells, the cellular levels of survivin were depleted. Furthermore, the location of survivin was shifted from the nucleus to the plasma membrane. Co-localization studies revealed merging of immuno-positive signals for SLC5A8 and survivin at the plasma membrane. Chemosensitivity studies showed that SLC5A8-expressing MCF7 cells were more susceptible to docetaxel than SLC5A8-negative control MCF7 cells. Conclusions: MCF7 cells are SLC5A8-negative, but express survivin with its localization found predominantly in the nucleus. Ectopic expression of SLC5A8 in these cells depletes survivin as well as changes the localization of survivin from the nucleus to the plasma membrane through interaction with SLC5A8. This is accompanied with a marked increase in chemosensitivity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2194. doi:10.1158/1538-7445.AM2011-2194

  • sodium coupled electrogenic transport of pyroglutamate 5 oxoproline via slc5a8 a monocarboxylate transporter
    Biochimica et Biophysica Acta, 2010
    Co-Authors: Seiji Miyauchi, Vadivel Ganapathy, Yoshiyuki Kubo, Sonne R Srinivas, Ellappan Babu, Elangovan Gopal, Nagavedi S Umapathy, Santosh V Thakkar, Puttur D Prasad
    Abstract:

    Abstract Pyroglutamate, also known as 5-oxoproline, is a structural analog of proline. This amino acid derivative is a byproduct of glutathione metabolism, and is reabsorbed efficiently in kidney by Na+-coupled transport mechanisms. Previous studies have focused on potential participation of amino acid transport systems in renal reabsorption of this compound. Here we show that it is not the amino acid transport systems but instead the Na+-coupled monocarboxylate transporter SLC5A8 that plays a predominant role in this reabsorptive process. Expression of cloned human and mouse SLC5A8 in mammalian cells induces Na+-dependent transport of pyroglutamate that is inhibitable by various SLC5A8 substrates. SLC5A8-mediated transport of pyroglutamate is saturable with a Michaelis constant of 0.36 ± 0.04 mM. Na+-activation of the transport process exhibits sigmoidal kinetics with a Hill coefficient of 1.8 ± 0.4, indicating involvement of more than one Na+ in the activation process. Expression of SLC5A8 in Xenopuslaevis oocytes induces Na+-dependent inward currents in the presence of pyroglutamate under voltage-clamp conditions. The concentration of pyroglutamate necessary for induction of half-maximal current is 0.19 ± 0.01 mM. The Na+-activation kinetics is sigmoidal with a Hill coefficient of 2.3 ± 0.2. Ibuprofen, a blocker of SLC5A8, suppressed pyroglutamate-induced currents in SLC5A8-expressing oocytes; the concentration of the blocker necessary for causing half-maximal inhibition is 14 ± 1 μM. The involvement of SLC5A8 can be demonstrated in rabbit renal brush border membrane vesicles by showing that the Na+-dependent uptake of pyroglutamate in these vesicles is inhibitable by known substrates of SLC5A8. The Na+ gradient-driven pyroglutamate uptake was stimulated by an inside-negative K+ diffusion potential induced by valinomycin, showing that the uptake process is electrogenic.

  • sodium coupled transport of the short chain fatty acid butyrate by slc5a8 and its relevance to colon cancer
    Journal of Gastrointestinal Surgery, 2008
    Co-Authors: Muthusamy Thangaraju, Gail Cresci, Shiro Itagaki, John D Mellinger, Darren D Browning, Franklin G Berger, Puttur D Prasad, Vadivel Ganapathy
    Abstract:

    Introduction SLC5A8, expressed predominantly in the colon, is a Na+-coupled transporter for short-chain fatty acids. In this paper, we report on the characterization of butyrate transport by SLC5A8 and the relevance of SLC5A8-mediated butyrate transport to colon cancer.

Matthew R Skelton - One of the best experts on this subject based on the ideXlab platform.

  • creatine transporter knockout mice SLC6A8 show increases in serotonin related proteins and are resilient to learned helplessness
    Behavioural Brain Research, 2020
    Co-Authors: Zuhair I Abdulla, Jordan L Pennington, Arnold Gutierrez, Matthew R Skelton
    Abstract:

    Abstract Approximately 20% of adults in the U.S. will experience an affective disorder during their life. While it is well established that serotonin (5-HT) is a crucial factor in mood, impaired cellular bioenergetics are also implicated. Creatine (Cr), through the Cr/Phospho-Cr (PCr) shuttle, maintains high ATP concentrations in the neuron. This system may be implicated in the etiology of affective disorders, as reduced Cr, PCr, and ATP are often seen in the brains of affected patients. To address this issue, Cr transporter (Crt) deficient male mice (SLC6A8−/y) and female mice heterozygous for Crt expression (SLC6A8+/-) were used to evaluate how a Cr deficient system would alter affective-like behaviors. SLC6A8−/y and SLC6A8+/- mice had faster escape latencies in learned helplessness, indicating a potential resilience to behavioral despair. SLC6A8−/y had decrease latency to immobility in the tail-suspension test and SLC6A8+/- had increased open entries in elevated zero maze, but all other variables matched those of wildtype mice, however. SLC6A8−/y mice have increased 5-hydroxyindoleacetic acid content in the hippocampus and striatum and increased monoamine oxidase protein and tryptophan hydroxylase-2 protein content in the hippocampus, while 5-HT levels are unchanged. This indicates an alteration to the 5-HTergic system in Cr deficient mice. Our results indicate that Cr plays a complex role in affective disorders and 5-HT, warranting further investigation.

  • deletion of the creatine transporter SLC6A8 in dopaminergic neurons leads to hyperactivity in mice
    Journal of Molecular Neuroscience, 2020
    Co-Authors: Zuhair I Abdulla, Bahar Pahlevani, Kerstin H Lundgren, Jordan L Pennington, Kenea C Udobi, Kim B Seroogy, Matthew R Skelton
    Abstract:

    The lack of cerebral creatine (Cr) causes intellectual disability and epilepsy. In addition, a significant portion of individuals with Cr transporter (Crt) deficiency (CTD), the leading cause of cerebral Cr deficiency syndromes (CCDS), are diagnosed with attention-deficit hyperactivity disorder. While the neurological effects of CTD are clear, the mechanisms that underlie these deficits are unknown. Part of this is due to the heterogenous nature of the brain and the unique metabolic demands of specific neuronal systems. Of particular interest related to Cr physiology are dopaminergic neurons, as many CCDS patients have ADHD and Cr has been implicated in dopamine-associated neurodegenerative disorders, such as Parkinson’s and Huntington’s diseases. The purpose of this study was to examine the effect of a loss of the SLC6A8 (Crt) gene in dopamine transporter (Slc6a3; DAT) expressing cells on locomotor activity and motor function as the mice age. Floxed SLC6A8 (SLC6A8flox) mice were mated to DATIREScre expressing mice to generate DAT-specific SLC6A8 knockouts (dCrt−/y). Locomotor activity, spontaneous activity, and performance in the challenging beam test were evaluated monthly in dCrt−/y and control (SLC6A8flox) mice from 3 to 12 months of age. dCrt−/y mice were hyperactive compared with controls throughout testing. In addition, dCrt−/y mice showed increased rearing and hindlimb steps in the spontaneous activity test. Latency to cross the narrow bridge was increased in dCrt−/y mice while foot slips were unchanged. Taken together, these data suggest that the lack of Cr in dopaminergic neurons causes hyperactivity while sparing motor function.

  • creatine transporter knockout mice SLC6A8 show increases in serotonin related proteins and are resilient to learned helplessness
    bioRxiv, 2019
    Co-Authors: Zuhair I Abdulla, Jordan L Pennington, Arnold Gutierrez, Matthew R Skelton
    Abstract:

    Abstract Approximately 20% of adults in the U.S. will experience an affective disorder during their life. While it is well established that serotonin (5-HT) is a crucial factor in mood, impaired cellular bioenergetics are also implicated. Creatine (Cr), through the Cr/Phospho-Cr (PCr) shuttle, maintains high ATP concentrations in the neuron. This system may be implicated in the etiology of affective disorders, as reduced Cr, PCr, and ATP are often seen in the brains of affected patients. To address this issue, Cr transporter (Crt) deficient male mice (SLC6A8−/y) and female mice heterozygous for Crt expression (SLC6A8+/−) were used to evaluate how a Cr deficient system would alter affective-like behaviors. SLC6A8−/y and SLC6A8+/− mice had more escapes and faster escape latencies in learned helplessness, indicating a potential resilience to behavioral despair. Elevated zero maze and tail-suspension test performance matched that of wildtype mice, however. SLC6A8−/y mice have increased 5-hydroxyindoleacetic acid content in the hippocampus and striatum and increased monoamine oxidase protein and tryptophan hydroxylase-2 protein content in the hippocampus, while serotonin levels are unchanged. This indicates an increase in 5-HT turnover. Our results indicate that Cr plays a complex role in affective disorders and 5-HT neurotransmission, warranting further investigation.

  • cognitive deficits and increases in creatine precursors in a brain specific knockout of the creatine transporter gene SLC6A8
    Genes Brain and Behavior, 2018
    Co-Authors: Kenea C Udobi, Amanda N Kokenge, Emily R Hautman, Gabriela Ullo, Julie Coene, Michael T Williams, Charles V Vorhees, Aloise Mabondzo, Matthew R Skelton
    Abstract:

    Creatine transporter (CrT; SLC6A8) deficiency (CTD) is an X-linked disorder characterized by severe cognitive deficits, impairments in language and an absence of brain creatine (Cr). In a previous study, we generated floxed SLC6A8 (SLC6A8 flox ) mice to create ubiquitous SLC6A8 knockout (SLC6A8-/y ) mice. SLC6A8-/y mice lacked whole body Cr and exhibited cognitive deficits. While SLC6A8-/y mice have a similar biochemical phenotype to CTD patients, they also showed a reduction in size and reductions in swim speed that may have contributed to the observed deficits. To address this, we created brain-specific SLC6A8 knockout (bKO) mice by crossing SLC6A8flox mice with Nestin-cre mice. bKO mice had reduced cerebral Cr levels while maintaining normal Cr levels in peripheral tissue. Interestingly, brain concentrations of the Cr synthesis precursor guanidinoacetic acid were increased in bKO mice. bKO mice had longer latencies and path lengths in the Morris water maze, without reductions in swim speed. In accordance with data from SLC6A8 -/y mice, bKO mice showed deficits in novel object recognition as well as contextual and cued fear conditioning. bKO mice were also hyperactive, in contrast with data from the SLC6A8 -/y mice. The results show that the loss of cerebral Cr is responsible for the learning and memory deficits seen in ubiquitous SLC6A8-/y mice.

  • cognitive deficits and increases in creatine precursors in a brain specific knockout of the creatine transporter gene SLC6A8
    bioRxiv, 2017
    Co-Authors: Kenea C Udobi, Amanda N Kokenge, Emily R Hautman, Gabriela Ullo, Julie Coene, Michael T Williams, Charles V Vorhees, Aloise Mabondzo, Matthew R Skelton
    Abstract:

    Creatine transporter (CrT; SLC6A8) deficiency (CTD) is an X-linked disorder characterized by severe cognitive deficits, impairments in language, and an absence of brain creatine (Cr). In a previous study, we generated floxed SLC6A8 (SLC6A8flox) mice to create ubiquitous SLC6A8 knockout (SLC6A8-/y) mice. SLC6A8-/y mice lacked whole body Cr and exhibited cognitive deficits. While SLC6A8-/y mice have a similar biochemical phenotype to CTD patients, they also showed a reduction in size and reductions in swim speed that may have contributed to the observed deficits. To address this, we created brain-specific SLC6A8 knockout (bKO) mice by crossing SLC6A8Flox mice with Nestin-cre mice. bKO mice had reduced cerebral Cr levels while maintaining normal Cr levels in peripheral tissue. Interestingly, brain concentrations of the Cr synthesis precursor guanidinoacetic acid were increased in bKO mice. bKO mice had longer latencies and path lengths in the Morris water maze, without reductions in swim speed. In accordance with data from SLC6A8-/y mice, bKO mice showed deficits in novel object recognition as well as contextual and cued fear conditioning. bKO mice were also hyperactive, in contrast with data from the SLC6A8-/y mice. The results demonstrate that the loss of cerebral Cr is responsible for the learning and memory deficits seen in ubiquitous SLC6A8-/y mice.

Cornelis Jakobs - One of the best experts on this subject based on the ideXlab platform.

  • contiguous deletion of SLC6A8 and bap31 in a patient with severe dystonia and sensorineural deafness
    Molecular Genetics and Metabolism, 2012
    Co-Authors: Hitoshi Osaka, Gajja S. Salomons, Atsushi Takagi, Yu Tsuyusaki, Takahito Wada, Mizue Iai, Sumimasa Yamashita, Hiroko Shimbo, Hirotomo Saitsu, Cornelis Jakobs
    Abstract:

    We report here a 6-year-old boy exhibiting severe dystonia, profound intellectual and developmental disability with liver disease, and sensorineural deafness. A deficient creatine peak in brain (1)H-MR spectroscopy and high ratio of creatine/creatinine concentration in his urine lead us to suspect a creatine transporter (solute carrier family 6, member 8; SLC6A8) deficiency, which was confirmed by the inability to take up creatine into fibroblasts. We found a large ~19 kb deletion encompassing exons 5-13 of SLC6A8 and exons 5-8 of the B-cell receptor-associated protein (BAP31) gene. This case is the first report in which the SLC6A8 and BAP31 genes are both deleted. The phenotype of BAP31 mutations has been reported only as a part of Xq28 deletion syndrome or contiguous ATP-binding cassette, sub-family D, member 1 (ABCD1)/DXS1375E (BAP31) deletion syndrome [MIM ID #300475], where liver dysfunction and sensorineural deafness have been suggested to be attributed to the loss of function of BAP31. Our case supports the idea that the loss of BAP31 is related to liver dysfunction and hearing loss.

  • detection of variants in SLC6A8 and functional analysis of unclassified missense variants
    Molecular Genetics and Metabolism, 2012
    Co-Authors: Ofir T. Betsalel, Efraim H. Rosenberg, Cornelis Jakobs, Ana Pop, Matilde Fernandezojeda, Gajja S. Salomons
    Abstract:

    Creatine transporter deficiency is an X-linked disorder caused by mutations in the SLC6A8 gene. Currently, 38 pathogenic, including 15 missense variants, are reported. In this study, we report 33 novel, including 6 missense variants. To classify all known missense variants, we transfected creatine deficient fibroblasts with the SLC6A8 ORF containing one of the unique variants and tested their ability to restore creatine uptake. This resulted in the definitive classification of 2 non-disease associated and 19 pathogenic variants of which 3 have residual activity. Furthermore, we report the development and validation of a novel DHPLC method for the detection of heterozygous SLC6A8 variants. The method was validated by analysis of DNAs that in total contained 67 unique variants of which 66 could be detected. Therefore, this rapid screening method may prove valuable for the analysis of large cohorts of females with mild intellectual disability of unknown etiology, since in this group heterozygous SLC6A8 mutations may be detected. DHPLC proved also to be important for the detection of somatic mosaicism in mothers of patients who have a pathogenic mutation in SLC6A8. All variants reported in the present and previous studies are included in the Leiden Open Source Variant Database (LOVD) of SLC6A8 (www.LOVD.nl/SLC6A8).

  • Treatment of intractable epilepsy in a female with SLC6A8 deficiency.
    Molecular genetics and metabolism, 2010
    Co-Authors: Saadet Mercimek-mahmutoglu, Mary B. Connolly, Kenneth J. Poskitt, Gabriella Horvath, Noel Lowry, Gajja S. Salomons, Brett Casey, Graham Sinclair, Cynthia Davis, Cornelis Jakobs
    Abstract:

    Abstract A female heterozygous for a novel, disease causing, missense mutation in the X-linked cerebral creatine transporter (SLC6A8) gene (c.1067G > T, p.Gly356Val) presented with intractable epilepsy, mild intellectual disability and moderately reduced cerebral creatine levels. Treatment with creatine monohydrate, to enhance cerebral creatine transport, combined with l -arginine and l -glycine, to enhance cerebral creatine synthesis, resulted in complete resolution of seizures. Heterozygous SLC6A8 deficiency is a potentially treatable condition and should be considered in females with intractable epilepsy and developmental delay/intellectual disability.

  • screening for x linked creatine transporter SLC6A8 deficiency via simultaneous determination of urinary creatine to creatinine ratio by tandem mass spectrometry
    Molecular Genetics and Metabolism, 2009
    Co-Authors: Saadet Mercimekmahmutoglu, Gajja S. Salomons, Cornelis Jakobs, Adolf Muehl, Birgit Neophytou, Dorothea Moeslinger, Eduard A Struys, Olaf Bodamer, Sylvia Stockleripsiroglu
    Abstract:

    Abstract High urinary creatine to creatinine ratio (U-CrCrtR) is a potential diagnostic marker of X-linked creatine transporter (SLC6A8) deficiency. We developed a tandem mass-spectrometry method to simultaneously determine urinary creatine and creatinine in 975 individuals (0–18 years). U-CrCrtR increased up to 8 years and decreased thereafter. U-CrCrtR was 2.29 and 2.12 (99th percentile: 1.87) in two males with subsequently confirmed SLC6A8 mutations. The frequency of SLC6A8 deficiency was 2.3% in 157 males at risk.

  • functional characterization of missense variants in the creatine transporter gene SLC6A8 improved diagnostic application
    Human Mutation, 2007
    Co-Authors: Efraim H. Rosenberg, Ofir T. Betsalel, Tjitske Kleefstra, Charles E. Schwartz, Ton J Degrauw, Cornelis Jakobs, Cristina Martinez Munoz, Silvy J M Van Dooren, Matilde Fernandez, Gajja S. Salomons
    Abstract:

    Creatine transporter deficiency is an X-linked mental retardation disorder caused by mutations in the creatine transporter gene (SLC6A8). So far, 20 mutations in the SLC6A8 gene have been described. We have developed a diagnostic assay to test creatine uptake in fibroblasts. Additionally, we expanded the assay to characterize novel SLC6A8 missense variants. A total of 13 variants were introduced in the SLC6A8 cDNA by site-directed mutagenesis. All variants were transiently transfected in SLC6A8-deficient fibroblasts and tested for restoration of creatine uptake in deficient primary fibroblasts. Thus, we proved that nine variants (p.Gly87Arg, p.Phe107del, p.Tyr317X, p.Asn336del, p.Cys337Trp, p.Ile347del, p.Pro390Leu, p.Arg391Trp, and p.Pro554Leu) are pathogenic mutations and four variants (p.Lys4Arg, p.Gly26Arg, p.Met560Val, and p.Val629Ile) are nonpathogenic. The present study provides an improved diagnostic tool to classify sequence variants of unknown significance.

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  • down regulation of the na cl coupled creatine transporter creat SLC6A8 by glycogen synthase kinase gsk3s
    Cellular Physiology and Biochemistry, 2016
    Co-Authors: Myriam Fezai, Mohamed Jemaa, Hajar Fakhri, Hong Chen, Bhaeldin Elsir, Lisann Pelzl, Florian Lang
    Abstract:

    Background: The Na+,Cl- coupled creatine transporter CreaT (SLC6A8) is expressed in a variety of tissues including the brain. Genetic defect

  • Upregulation of the creatine transporter SLC6A8 by Klotho.
    Kidney & blood pressure research, 2014
    Co-Authors: Ahmad Almilaji, Mentor Sopjani, Miribane Dërmaku-sopjani, Bernat Elvira, Jose Borras, Carlos Munoz, Jamshed Warsi, Undine E. Lang, Florian Lang
    Abstract:

    Background/Aims: The transmembrane Klotho protein contributes to inhibition of 1,25(OH) 2 D 3 formation. The extracellular domain of Klotho protein could function as an enzyme with e.g. β-glucuronidase activity, be cleaved off and be released into blood and cerebrospinal fluid. Klotho regulates several cellular transporters. Klotho protein deficiency accelerates the appearance of age related disorders including neurodegeneration and muscle wasting and eventually leads to premature death. The main site of Klotho protein expression is the kidney. Klotho protein is also appreciably expressed in other tissues including chorioid plexus. The present study explored the effect of Klotho protein on the creatine transporter CreaT (SLC6A8), which participates in the maintenance of neuronal function and survival. Methods: To this end cRNA encoding SLC6A8 was injected into Xenopus oocytes with and without additional injection of cRNA encoding Klotho protein. Creatine transporter CreaT (SLC6A8) activity was estimated from creatine induced current determined by two-electrode voltage-clamp. Results: Coexpression of Klotho protein significantly increased creatine-induced current in SLC6A8 expressing Xenopus oocytes. Coexpression of Klotho protein delayed the decline of creatine induced current following inhibition of carrier insertion into the cell membrane by brefeldin A (5 µM). The increase of creatine induced current by coexpression of Klotho protein in SLC6A8 expressing Xenopus oocytes was reversed by β-glucuronidase inhibitor (DSAL). Similarly, treatment of SLC6A8 expressing Xenopus oocytes with recombinant human alpha Klotho protein significantly increased creatine induced current. Conclusion: Klotho protein up-regulates

  • negative regulation of the creatine transporter SLC6A8 by spak and osr1
    Kidney & Blood Pressure Research, 2014
    Co-Authors: Myriam Fezai, Bernat Elvira, Jose Borras, Zohreh Hoseinzadeh, Mossadok Benattia, Florian Lang
    Abstract:

    Background/Aims: Transport regulation involves several kinases including SPAK (SPS1-related proline/alanine-rich kinase) and OSR1 (oxidative stress-responsive kinase 1), which are under control of WNK (with-no-K[Lys]) kinases. The present study explored whether SPAK and/or OSR1 participate in the regulation of the creatine transporter CreaT (SLC6A8), which accomplishes Na+ coupled cellular uptake of creatine in several tissues including kidney, intestine, heart, skeletal muscle and brain. Methods: cRNA encoding SLC6A8 was injected into Xenopus laevis oocytes with or without additional injection of cRNA encoding wild-type SPAK, constitutively active T233ESPAK, WNK insensitive T233ASPAK, catalytically inactive D212ASPAK, wild-type OSR1, constitutively active T185EOSR1, WNK insensitive T185AOSR1 and catalytically inactive D164AOSR1. Transporter activity was determined from creatine (1 mM) induced current utilizing dual electrode voltage clamp. Results: Coexpression of wild-type SPAK and of T233ESPAK, but not of T233ASPAK or of D212ASPAK was followed by a significant decrease of creatine induced current in SLC6A8 expressing oocytes. Coexpression of SPAK significantly decreased maximal transport rate. Coexpression of wild-type OSR1, T185EOSR1 and T185AOSR1 but not of D164AOSR1 significantly negatively regulated SLC6A8 activity. OSR1 again decreased significantly maximal transport rate. Conclusions: Both, SPAK and OSR1, are negative regulators of the creatine transporter SLC6A8.

  • Downregulation of the Creatine Transporter SLC6A8 by JAK2
    The Journal of Membrane Biology, 2012
    Co-Authors: Manzar Shojaiefard, Zohreh Hosseinzadeh, Shefalee K. Bhavsar, Florian Lang
    Abstract:

    Janus-activated kinase-2 (JAK2) participates in the regulation of the Na^+-coupled glucose transporter SGLT1 and the Na^+-coupled amino acid transporter SLC6A19. Concentrative cellular creatine uptake is similarly accomplished by Na^+-coupled transport. The carrier involved is SLC6A8 (CreaT). The present study thus explored whether JAK2 regulates the activity of SLC6A8. To this end, cRNA encoding SLC6A8 was injected into Xenopus oocytes with or without cRNA encoding wild-type JAK2, constitutively active ^V617FJAK2 or inactive ^K882EJAK2. Electrogenic creatine transport was determined in those oocytes by dual-electrode voltage-clamp experiments. In oocytes injected with cRNA encoding SLC6A8 but not in oocytes injected with water or with cRNA encoding JAK2 alone, addition of 1 mM creatine to the extracellular bath generated an inward current ( I _crea). In SLC6A8 expressing oocytes I _crea was significantly decreased by coexpression of JAK2 or ^V617FJAK2 but not by coexpression of ^K882EJAK2. According to kinetic analysis, coexpression of JAK2 decreased the maximal transport rate without significantly modifying the affinity of the carrier. In oocytes expressing SLC6A8 and ^V617FJAK2 I _crea was gradually increased by the JAK2 inhibitor AG490 (40 μM). In SLC6A8 and JAK2 coexpressing oocytes the decline of I _crea following disruption of carrier insertion with brefeldin A (5 μM) was similar in the absence and presence of JAK2. In conclusion, JAK2 is a novel regulator of the creatine transporter SLC6A8, which downregulates the carrier, presumably by interference with carrier protein insertion into the cell membrane.

  • pikfyve in the sgk1 mediated regulation of the creatine transporter SLC6A8
    Cellular Physiology and Biochemistry, 2007
    Co-Authors: Nathalie Strutzseebohm, Manzar Shojaiefard, David L Christie, Jeremy M Tavare, Guiscard Seebohm, Florian Lang
    Abstract:

    The Na2+,Cl--,creatine transporter CreaT (SLC6A8) mediates concentrative cellular uptake of creatine into a wide variety of cells. Previous observations disclosed that SLC6A8 tra