The Hepatic Monocarboxylate Transporter 1 (MCT1) Contributes to the Regulation of Food Anticipation in Mice.
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ABSTRACT:
SUBMITTER: Martini T
PROVIDER: S-EPMC8079775 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Membrane monocarboxylate transporter 1 (SLC16A1/MCT1) plays an important role in hepatocyte homeostasis, as well as drug handling. However, there is no available information about the impact of liver pathology on the transporter levels and function. The study was aimed to quantify SLC16A1 mRNA (qRT-PCR) and MCT1 protein abundance (liquid chromatography-tandem mass spectrometry (LC---MS/MS)) in the livers of patients diagnosed, according to the standard clinical criteria, with hepatitis C, primary biliary cirrhosis, primary sclerosing hepatitis, alcoholic liver disease (ALD), and autoimmune hepatitis. The stage of liver dysfunction was classified according to Child-Pugh score. Downregulation of SLC16A1/MCT1 levels was observed in all liver pathology states, significantly for ALD. The progression of liver dysfunction, from Child-Pugh class A to C, involved the gradual decline in SLC16A1 mRNA and MCT1 protein abundance, reaching a clinically significant decrease in class C livers. Reduced levels of MCT1 were associated with significant intracellular lactate accumulation. The MCT1 transcript and protein did not demonstrate significant correlations regardless of the liver pathology analyzed, as well as the disease stage, suggesting posttranscriptional regulation, and several microRNAs were found as potential regulators of MCT1 abundance. MCT1 membrane immunolocalization without cytoplasmic retention was observed in all studied liver pathologies. Overall, the study demonstrates that SLC16A1/MCT1 is involved in liver pathology, especially in ALD.
| S-EPMC7084425 | biostudies-literature
Project description:Diabetic peripheral neuropathy (DPN) is one of the most common complications in diabetic patients. Though the exact mechanism for DPN is unknown, it clearly involves metabolic dysfunction and energy failure in multiple cells within the peripheral nervous system. Lactate is an alternate source of metabolic energy that is increasingly recognized for its role in supporting neurons. The primary transporter for lactate in the nervous system, monocarboxylate transporter-1 (MCT1), has been shown to be critical for peripheral nerve regeneration and metabolic support to neurons/axons. In this study, MCT1 was reduced in both sciatic nerve and dorsal root ganglia in wild-type mice treated with streptozotocin (STZ), a common model of type-1 diabetes. Heterozygous MCT1 null mice that developed hyperglycemia following STZ treatment developed a more severe DPN compared to wild-type mice, as measured by greater axonal demyelination, decreased peripheral nerve function, and increased numbness to innocuous low-threshold mechanical stimulation. Given that MCT1 inhibitors are being developed as both immunosuppressive and chemotherapeutic medications, our results suggest that clinical development in patients with diabetes should proceed with caution. Collectively, our findings uncover an important role for MCT1 in DPN and provide a potential lead toward developing novel treatments for this currently untreatable disease.
| S-EPMC7502508 | biostudies-literature
Project description:PurposeSuccinate is exported by the retina and imported by eyecup tissue. The transporters mediating this process have not yet been identified. Recent studies showed that monocarboxylate transporter 1 (MCT1) can transport succinate across plasma membranes in cardiac and skeletal muscle. Retina and retinal pigment epithelium (RPE) both express multiple MCT isoforms including MCT1. We tested the hypothesis that MCTs facilitate retinal succinate export and RPE succinate import.MethodsWe assessed retinal succinate export and eyecup succinate import in short-term ex vivo culture using gas chromatography-mass spectrometry. We tested the dependence of succinate export and import on pH, proton ionophores, conventional MCT substrates, and the MCT inhibitors AZD3965, AR-C155858, and diclofenac.ResultsSuccinate exits retinal tissue through MCT1 but does not enter the RPE through MCT1 or any other MCT. Intracellular succinate levels are a contributing factor that determines if an MCT1-expressing tissue will export succinate.ConclusionsMCT1 facilitates export of succinate from retinas. An unidentified, non-MCT transporter facilitates import of succinate into RPE.
| S-EPMC8976921 | biostudies-literature
Project description:Peripheral nerve regeneration following injury occurs spontaneously, but many of the processes require metabolic energy. The mechanism of energy supply to axons has not previously been determined. In the central nervous system, monocarboxylate transporter 1 (MCT1), expressed in oligodendroglia, is critical for supplying lactate or other energy metabolites to axons. In the current study, MCT1 is shown to localize within the peripheral nervous system to perineurial cells, dorsal root ganglion neurons, and Schwann cells by MCT1 immunofluorescence in wild-type mice and tdTomato fluorescence in MCT1 BAC reporter mice. To investigate whether MCT1 is necessary for peripheral nerve regeneration, sciatic nerves of MCT1 heterozygous null mice are crushed and peripheral nerve regeneration was quantified electrophysiologically and anatomically. Compound muscle action potential (CMAP) recovery is delayed from a median of 21 days in wild-type mice to greater than 38 days in MCT1 heterozygote null mice. In fact, half of the MCT1 heterozygote null mice have no recovery of CMAP at 42 days, while all of the wild-type mice recovered. In addition, muscle fibers remain 40% more atrophic and neuromuscular junctions 40% more denervated at 42 days post-crush in the MCT1 heterozygote null mice than wild-type mice. The delay in nerve regeneration is not only in motor axons, as the number of regenerated axons in the sural sensory nerve of MCT1 heterozygote null mice at 4 weeks and tibial mixed sensory and motor nerve at 3 weeks is also significantly reduced compared to wild-type mice. This delay in regeneration may be partly due to failed Schwann cell function, as there is reduced early phagocytosis of myelin debris and remyelination of axon segments. These data for the first time demonstrate that MCT1 is critical for regeneration of both sensory and motor axons in mice following sciatic nerve crush.
| S-EPMC4292924 | biostudies-literature
Project description:Amplification of the MYCN oncogene occurs in ~25% of primary neuroblastomas and is the single most powerful biological marker of poor prognosis in this disease. MYCN transcriptionally regulates a range of biological processes important for cancer, including cell metabolism. The MYCN-regulated metabolic gene SLC16A1, encoding the lactate transporter monocarboxylate transporter 1 (MCT1), is a potential therapeutic target. Treatment of neuroblastoma cells with the MCT1 inhibitor SR13800 increased intracellular lactate levels, disrupted the nicotinamide adenine dinucleotide (NADH/NAD+) ratio, and decreased intracellular glutathione levels. Metabolite tracing with 13C-glucose and 13C-glutamine following MCT1 inhibitor treatment revealed increased quantities of tricarboxylic acid (TCA) cycle intermediates and increased oxygen consumption rate. MCT1 inhibition was highly synergistic with vincristine and LDHA inhibition under cell culture conditions, but this combination was ineffective against neuroblastoma xenografts. Posttreatment xenograft tumors had increased synthesis of the MCT1 homolog MCT4/SLC16A, a known resistance factor to MCT1 inhibition. We found that MCT4 was negatively regulated by MYCN in luciferase reporter assays and its synthesis in neuroblastoma cells was increased under hypoxic conditions and following hypoxia-inducible factor (HIF1) induction, suggesting that MCT4 may contribute to resistance to MCT1 inhibitor treatment in hypoxic neuroblastoma tumors. Co-treatment of neuroblastoma cells with inhibitors of MCT1 and LDHA, the enzyme responsible for lactate production, resulted in a large increase in intracellular pyruvate and was highly synergistic in decreasing neuroblastoma cell viability. These results highlight the potential of targeting MCT1 in neuroblastoma in conjunction with strategies that involve disruption of pyruvate homeostasis and indicate possible resistance mechanisms.
| S-EPMC7970707 | biostudies-literature
Project description:We describe two half-siblings with monocarboxylate transporter 1 (MCT1, SLC16A1) deficiency, a defect on ketone body utilization, that has only recently been identified (van Hasselt et al., N Engl J Med, 371:1900-1907, 2014) as a cause for recurrent ketoacidoses. Our index patient is a boy with non-consanguineous parents who had presented acutely with impaired consciousness and severe metabolic ketoacidosis following a 3-day history of gastroenteritis at age 5 years. A 12.5-year-old half-brother who shared the proband's mother also had a previous history of recurrent ketoacidoses. Results of mutation and enzyme activity analyses in proband samples advocated against methylacetoacetyl-coenzyme A thiolase ("beta-ketothiolase") and succinyl-coenzyme A: 3-oxoacyl coenzyme A transferase (SCOT) deficiencies. A single heterozygous c.982C>T transition in the SLC16A1 gene resulting in a stop mutation (p.Arg328Ter) was detected in both boys. It was shared by their healthy mother and by the proband's half-sister, but was absent in the proband's father. MCT1 deficiency may be more prevalent than is apparent, as clinical manifestations can occur both in individuals with bi- and monoallelic mutations. It may be an important differential diagnosis in recurrent ketoacidosis with or without hypoglycemia, particularly in the absence of any specific metabolic profiles in blood and urine. Early diagnosis may enable improved disease management. Careful identification of potential triggers of metabolic decompensations in individuals even with single heterozygous mutations in the SLC16A1 gene is indicated.
| S-EPMC5059203 | biostudies-literature
Project description:Treatment of locally advanced, unresectable head and neck squamous cell carcinoma (HNSCC) often yields only modest results with radiochemotherapy (RCT) as standard of care. Prognostic features related to outcome upon RCT might be highly valuable to improve treatment. Monocarboxylate transporters-1 and -4 (MCT1/MCT4) were evaluated as potential biomarkers. A cohort of HNSCC patients without signs for distant metastases was assessed eliciting 82 individuals eligible whereof 90% were diagnosed with locally advanced stage IV. Tumor specimens were stained for MCT1 and MCT4 in the cell membrane by immunohistochemistry. Obtained data were evaluated with respect to overall (OS) and progression-free survival (PFS). Protein expression of MCT1 and MCT4 in cell membrane was detected in 16% and 85% of the tumors, respectively. Expression of both transporters was not statistically different according to the human papilloma virus (HPV) status. Positive staining for MCT1 (n = 13, negative in n = 69) strongly worsened PFS with a hazard ratio (HR) of 3.1 (95%-confidence interval 1.6-5.7, p < 0.001). OS was likewise affected with a HR of 3.8 (2.0-7.3, p < 0.001). Multivariable Cox regression confirmed these findings. We propose MCT1 as a promising biomarker in HNSCC treated by primary RCT.
| S-EPMC7907348 | biostudies-literature
Project description:Inhibition of the monocarboxylate transporter MCT1 by AZD3965 results in an increase in glycolysis in human tumor cell lines and xenografts. This is indicated by changes in the levels of specific glycolytic metabolites and in changes in glycolytic enzyme kinetics. These drug-induced metabolic changes translate into an inhibition of tumor growth in vivo. Thus, we combined AZD3965 with fractionated radiation to treat small cell lung cancer (SCLC) xenografts and showed that the combination provided a significantly greater therapeutic effect than the use of either modality alone. These results strongly support the notion of combining MCT1 inhibition with radiotherapy in the treatment of SCLC and other solid tumors.
| S-EPMC4258406 | biostudies-literature
Project description:The effect of a cellular prion protein (PrPc) deficiency on neuroenergetics was primarily analyzed via surveying the expression of genes specifically involved in lactate/pyruvate metabolism, such as monocarboxylate transporters (MCT1, MCT2, MCT4). The aim of the present study was to elucidate a potential involvement of PrPc in the regulation of energy metabolism in different brain regions. By using quantitative real-time polymerase chain reaction (qRT-PCR), we observed a marked reduction in MCT1 mRNA expression in the cortex of symptomatic Zürich I Prnp-/- mice, as compared to their wild-type (WT) counterparts. MCT1 downregulation in the cortex was accompanied with significantly decreased expression of the MCT1 functional interplayer, the Na+/K+ ATPase α2 subunit. Conversely, the MCT1 mRNA level was significantly raised in the cerebellum of Prnp-/- vs. WT control group, without a substantial change in the Na+/K+ ATPase α2 subunit expression. To validate the observed mRNA findings, we confirmed the observed change in MCT1 mRNA expression level in the cortex at the protein level. MCT4, highly expressed in tissues that rely on glycolysis as an energy source, exhibited a significant reduction in the hippocampus of Prnp-/- vs. WT mice. The present study demonstrates that a lack of PrPc leads to altered MCT1 and MCT4 mRNA/protein expression in different brain regions of Prnp-/- vs. WT mice. Our findings provide evidence that PrPc might affect the monocarboxylate intercellular transport, which needs to be confirmed in further studies.
| S-EPMC7913939 | biostudies-literature
Project description:Fasting is increasingly recognized as a potential therapeutic intervention in the field of neurology and psychiatry. However, its impact upon the blood-brain barrier (BBB), which strictly regulates the cerebral uptake of a wide range of endogenous compounds and drugs, is unknown. In this study we used a combination of in vivo and in vitro experiments to assess the response of the brain endothelium in rats that were fed ad libitum or fasted for one to three days. Fasting did not change the expression of the main drug efflux ATP-binding cassette transporters or P-glycoprotein activity at the BBB but modulated a restrictive set of solute carrier transporters. These included the monocarboxylate transporter Mct1, which is pivotal for the cerebral uptake of ketone bodies and thus for brain adaptation to fasting. Transcriptional profiling of freshly isolated brain endothelial cells showed that Ppar δ, a major lipid sensor, was selectively activated in response to fasting. In primary cultured rat brain endothelial cells, pharmacological agonists and free fatty acids selectively activated Ppar δ, resulting in the upregulation of Mct1 expression at the transcriptional and protein level. This was confirmed in vivo, by showing that dosing rats with a specific Ppar δ antagonist blocked the upregulation of Mct1 expression and activity induced by fasting. Altogether, our study describes for the first time a selective adaptive response of the brain vasculature to fasting and opens new perspectives for the metabolic manipulation of the BBB in the healthy or diseased brain.
2024-04-24 | GSE241803 | GEO