Transport of ketone bodies and lactate in the sheep ruminal epithelium by monocarboxylate transporter 1

2002 ◽  
Vol 283 (5) ◽  
pp. G1139-G1146 ◽  
Author(s):  
Frank Müller ◽  
Korinna Huber ◽  
Helga Pfannkuche ◽  
Jörg R. Aschenbach ◽  
Gerhard Breves ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cultured Cells ◽  
Ketone Bodies ◽  
Short Chain Fatty Acids ◽  
Monocarboxylate Transporter ◽  
Monocarboxylate Transporter 1 ◽  
Protein Levels ◽  
Ruminal Epithelium ◽  
Intracellular Metabolism ◽  
Acid Extrusion

Due to intensive intracellular metabolism of short-chain fatty acids, ruminal epithelial cells generate large amounts of d-β-hydroxybutyric acid, acetoacetic acid, and lactic acid. These acids have to be extruded from the cytosol to avoid disturbances of intracellular pH (pHi). To evaluate acid extrusion, pHi was studied in cultured ruminal epithelial cells of sheep using the pH-sensitive fluorescent dye 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. Extracellular addition of d-β-hydroxybutyrate, acetoacetate, or lactate (20 mM) resulted in intracellular acidification. Vice versa, removing extracellulard-β-hydroxybutyrate, acetoacetate, or lactate after preincubation with the respective monocarboxylate induced an increase of pHi. Initial rate of pHi decrease as well as of pHi recovery was strongly inhibited by pCMBS (400 μM) and phloretin (20 μM). Both cultured cells and intact ruminal epithelium were tested for the possible presence of proton-linked monocarboxylate transporter (MCT) on both the mRNA and protein levels. With the use of RT-PCR, mRNA encoding for MCT1 isoform was demonstrated in cultured ruminal epithelial cells and the ruminal epithelium. Immunostaining with MCT1 antibodies intensively labeled cultured ruminal epithelial cells and cells located in the stratum basale of the ruminal epithelium. In conclusion, our data indicate that MCT1 is expressed in the stratum basale of the ruminal epithelium and may function as a main mechanism for removing ketone bodies and lactate together with H+ from the cytosol into the blood.

miR-29a, b and c Regulate SLC5A8 Expression in Intestinal Epithelial Cells

2021 ◽  
Author(s):  
Arivarasu Natarajan Anbazhagan ◽  
Shubha Priyamvada ◽  
Anoop Kumar ◽  
Dulari Jayawardena ◽  
Alip Borthakur ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
In Silico Analysis ◽  
Short Chain Fatty Acids ◽  
Monocarboxylate Transporter ◽  
Luciferase Reporter ◽  
Intestinal Epithelial ◽  
Bacterial Fermentation ◽  
Monocarboxylate Transporter 1 ◽  
Beneficial Effects ◽  
And Function

Short chain fatty acids (SCFAs) produced by bacterial fermentation of dietary fiber exert myriad of beneficial effects including the amelioration of inflammation. SCFAs exist as anions at luminal pH, their entry into the cells depends on the expression and function of monocarboxylate transporters. In this regard, sodium-coupled monocarboxylate transporter-1 (SMCT-1) is one of the major proteins involved in the absorption of SCFA in the mammalian colon. However, very little is known about the mechanisms of regulation of SMCT-1 expression in health and disease. MicroRNAs (miRs) are known to play a key role in modulating gene expression. In silico analysis showed miR-29abc with highest context score and its binding region was conserved among mammals. The 3`-untranslated region (UTR) of human SMCT-1 gene was cloned into pmirGLO vector upstream of luciferase reporter and transiently transfected with miR-29a, b and c mimics into Caco-2 and/or T-84 cells. The presence of UTR of this gene significantly decreased luciferase activity compared to empty vector. Co-transfection with miR-29a, b or c resulted in further decrease in 3`UTR activity of SMCT-1 luciferase constructs. Mimic transfection significantly decreased SMCT-1 protein expression without altering mRNA expression. Further, the expression of miR-29a and c were significantly lower in mouse colon compared to small intestine, consistent with higher levels of SMCT-1 protein in the colon. Our studies demonstrated a novel finding in which miR-29a, b and c down-regulate SMCT-1 expression in colonic epithelial cells and may partly explain the differential expression of these transporters along the length of the GI tract.

Monocarboxylate transporters 1 and 4: expression and regulation by PPARα in ovine ruminal epithelial cells

2014 ◽  
Vol 307 (12) ◽  
pp. R1428-R1437 ◽  
Author(s):  
Franziska Benesch ◽  
Franziska Dengler ◽  
Franziska Masur ◽  
Helga Pfannkuche ◽  
Gotthold Gäbel
Keyword(s):  
Epithelial Cells ◽  
Intracellular Ph ◽  
Target Genes ◽  
Specific Inhibitor ◽  
Short Chain Fatty Acids ◽  
Monocarboxylate Transporter ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Selective Ligand

In the intact rumen epithelium, isoforms 1 and 4 of the monocarboxylate transporter (MCT1 and MCT4) are thought to play key roles in mediating transcellular and intracellular permeation of short-chain fatty acids and their metabolites and in maintaining intracellular pH. We examined whether both MCT1 and MCT4 are expressed at mRNA and protein levels in ovine ruminal epithelial cells (REC) maintained in primary culture and whether they are regulated by peroxisome proliferator-activated receptor-α (PPARα). Because both transporters have been characterized to function coupled to protons, the influence of PPARα on the recovery of intracellular pH after l-lactate exposure was evaluated by spectrofluorometry. MCT1 and MCT4 were detected using immunocytochemistry both at the cell margins and intracellularly in cultured REC. To test regulation by PPARα, cells were exposed to WY 14.643, a selective ligand of PPARα, for 48 h. The subsequent qPCR analysis resulted in a dose-dependent upregulation of MCT1 and PPARα target genes, whereas response of MCT4 was not uniform. Protein expression of MCT1 and MCT4 quantified by Western blot analysis was not altered by WY 14.643 treatment. l-Lactate-dependent proton export was blocked almost completely by pHMB, a specific inhibitor of MCT1 and MCT4. However, l-lactate-dependent, pHMB-inhibited proton export in WY 14.643-treated cells was not significantly altered compared with cells not treated with WY 14.643. These data suggest that PPARα is particularly regulating MCT1 but not MCT4 expression. Extent of lactate-coupled proton export indicates that MCT1 is already working on a high level even under unstimulated conditions.

scholarly journals The Hepatic Monocarboxylate Transporter 1 (MCT1) Contributes to the Regulation of Food Anticipation in Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Tomaz Martini ◽  
Jürgen A. Ripperger ◽  
Rohit Chavan ◽  
Michael Stumpe ◽  
Citlalli Netzahualcoyotzi ◽  
...  
Keyword(s):  
Food Restriction ◽  
Ketone Bodies ◽  
Cell Types ◽  
Time Of Day ◽  
Monocarboxylate Transporter ◽  
Monocarboxylate Transporter 1 ◽  
Circadian Timing System ◽  
Peripheral Clocks ◽  
Anticipatory Activity ◽  
Central Pacemaker

Daily recurring events can be predicted by animals based on their internal circadian timing system. However, independently from the suprachiasmatic nuclei (SCN), the central pacemaker of the circadian system in mammals, restriction of food access to a particular time of day elicits food anticipatory activity (FAA). This suggests an involvement of other central and/or peripheral clocks as well as metabolic signals in this behavior. One of the metabolic signals that is important for FAA under combined caloric and temporal food restriction is β-hydroxybutyrate (βOHB). Here we show that the monocarboxylate transporter 1 (Mct1), which transports ketone bodies such as βOHB across membranes of various cell types, is involved in FAA. In particular, we show that lack of the Mct1 gene in the liver, but not in neuronal or glial cells, reduces FAA in mice. This is associated with a reduction of βOHB levels in the blood. Our observations suggest an important role of ketone bodies and its transporter Mct1 in FAA under caloric and temporal food restriction.

scholarly journals Differential Response of Hippocampal and Cerebrocortical Autophagy and Ketone Body Metabolism to the Ketogenic Diet

2021 ◽  
Vol 15 ◽  
Author(s):  
Daniela Liśkiewicz ◽  
Arkadiusz Liśkiewicz ◽  
Marta M. Nowacka-Chmielewska ◽  
Mateusz Grabowski ◽  
Natalia Pondel ◽  
...  
Keyword(s):  
Frontal Cortex ◽  
Ketogenic Diet ◽  
Ketone Body ◽  
Brain Aging ◽  
Ketone Bodies ◽  
Monocarboxylate Transporter ◽  
Proper Function ◽  
Monocarboxylate Transporter 1 ◽  
Coa Transferase ◽  
Ketone Body Metabolism

Experimental and clinical data support the neuroprotective properties of the ketogenic diet and ketone bodies, but there is still a lot to discover to comprehensively understand the underlying mechanisms. Autophagy is a key mechanism for maintaining cell homeostasis, and therefore its proper function is necessary for preventing accelerated brain aging and neurodegeneration. Due to many potential interconnections, it is possible that the stimulation of autophagy may be one of the mediators of the neuroprotection afforded by the ketogenic diet. Recent studies point to possible interconnections between ketone body metabolism and autophagy. It has been shown that autophagy is essential for hepatic and renal ketogenesis in starvation. On the other hand, exogenous ketone bodies modulate autophagy both in vitro and in vivo. Many regional differences occur between brain structures which concern i.e., metabolic responses and autophagy dynamics. The aim of the present study was to evaluate the influence of the ketogenic diet on autophagic markers and the ketone body utilizing and transporting proteins in the hippocampus and frontal cortex. C57BL/6N male mice were fed with two ketogenic chows composed of fat of either animal or plant origins for 4 weeks. Markers of autophagosome formation as well as proteins associated with ketolysis (BDH1—3-hydroxybutyrate dehydrogenase 1, SCOT/OXCT1—succinyl CoA:3-oxoacid CoA transferase), ketone transport (MCT1—monocarboxylate transporter 1) and ketogenesis (HMGCL, HMGCS2) were measured. The hippocampus showed a robust response to nutritional ketosis in both changes in the markers of autophagy as well as the levels of ketone body utilizing and transporting proteins, which was also accompanied by increased concentrations of ketone bodies in this brain structure, while subtle changes were observed in the frontal cortex. The magnitude of the effects was dependent on the type of ketogenic diet used, suggesting that plant fats may exert a more profound effect on the orchestrated upregulation of autophagy and ketone body metabolism markers. The study provides a foundation for a deeper understanding of the possible interconnections between autophagy and the neuroprotective efficacy of nutritional ketosis.

scholarly journals Monocarboxylate transporter 1 (MCT1) plays a direct role in short-chain fatty acids absorption in caprine rumen

2006 ◽  
Vol 576 (2) ◽  
pp. 635-647 ◽  
Author(s):  
Doaa Kirat ◽  
Junji Masuoka ◽  
Hideaki Hayashi ◽  
Hidetomo Iwano ◽  
Hiroshi Yokota ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Short Chain Fatty Acids ◽  
Short Chain ◽  
Monocarboxylate Transporter ◽  
Direct Role ◽  
Monocarboxylate Transporter 1 ◽  
Chain Fatty Acids

scholarly journals Physiological concentrations of short-chain fatty acids immediately suppress colonic epithelial permeability

2008 ◽  
Vol 100 (2) ◽  
pp. 297-305 ◽  
Author(s):  
Takuya Suzuki ◽  
Shoko Yoshida ◽  
Hiroshi Hara
Keyword(s):  
Barrier Function ◽  
Lucifer Yellow ◽  
Short Chain Fatty Acids ◽  
Monocarboxylate Transporter ◽  
Phosphatidylinositol 3 Kinase ◽  
Fermentation Products ◽  
Epithelial Barrier Function ◽  
Monocarboxylate Transporter 1 ◽  
Promotive Effect ◽  
Anaesthetized Rats

Colonic fermentation products, SCFA, have various effects on colonic functions. Here, we found that physiological concentrations of SCFA immediately promote epithelial barrier function in the large intestine. Solutions of mixed and individual SCFA were applied to the caecal walls mounted on Ussing-type chambers. Transepithelial electrical resistance (TER) increased rapidly and reached a peak 35 % higher than that in the control specimen within 10 min post application of the SCFA mixture (80 acetate, 40 propionate, 20 butyrate (mmol/l)). The Lucifer yellow permeability, a paracellular transport marker, was dose-dependently reduced by the mixed SCFA, acetate and propionate solutions. Inhibition of monocarboxylate transporter-1 did not influence the increase in TER with acetate; however, lowering the pH (from 7·5 to 5·5) clearly enhanced the effect of acetate. Non-metabolizable, bromo and chloro derivatives of SCFA also increased TER. These results suggest that passive diffusion of SCFA is dominant and the metabolism of SCFA is not required for the promotive effect of SCFA on barrier function. We also observed that individual SCFA dose-dependently increased TER in T84 and Caco-2 cells, which indicates that SCFA directly stimulate epithelial cells. Depletion of membrane cholesterol and inhibitors of phosphatidylinositol-3 kinase and Gq protein attenuated the acetate-mediated promotive effect. Finally, we found that the mucosal application of the SCFA mixture dose-dependently suppressed [3H] mannitol transport from the caecal lumen to the mesenteric blood in the anaesthetized rats. We conclude that physiological concentrations of SCFA immediately enhance barrier function of the colonic epithelium through cholesterol-rich microdomain in the plasma membrane.

scholarly journals SCFA transport in rat duodenum

2015 ◽  
Vol 308 (3) ◽  
pp. G188-G197 ◽  
Author(s):  
Izumi Kaji ◽  
Toshihiko Iwanaga ◽  
Masahiko Watanabe ◽  
Paul H. Guth ◽  
Eli Engel ◽  
...  
Keyword(s):  
Bacterial Colonization ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Bacterial Overgrowth ◽  
Short Circuit Current ◽  
Short Chain Fatty Acids ◽  
Duodenal Mucosa ◽  
Monocarboxylate Transporter ◽  
Monocarboxylate Transporter 1 ◽  
Rat Duodenum

Bacterial or ingested food-derived short-chain fatty acids (SCFAs) are present in the duodenal lumen. Acetate, the most abundant SCFA in the foregut lumen, is absorbed immediately after ingestion, although the mechanism by which this absorption occurs is not fully understood. We investigated the distribution and function of candidate SCFA transporters in rat duodenum. The Na+-coupled monocarboxylate transporter-1 (SMCT1) was localized to the brush border, whereas the pH-dependent monocarboxylate transporter (MCT) 1 and MCT4 were localized to the duodenocyte basolateral membrane. In Ussing chambered duodenal mucosa, luminal acetate dose-dependently increased short-circuit current ( Isc) in the presence of serosal bumetanide and indomethacin by a luminal Na+-dependent, ouabain-sensitive mechanism. The Isc response was inhibited dose-dependently by the SMCT1 nonsubstrate inhibitor ibuprofen, consistent with net electrogenic absorption of acetate via SMCT1. Other SCFAs and lactate also increased Isc. Furthermore, duodenal loop perfusion of acetate increased portal venous acetate concentration, inhibited by coperfusion of ibuprofen or a MCT inhibitor. Luminal acetate perfusion increased duodenal HCO3− secretion via capsaicin-sensitive afferent nerve activation and cyclooxygenase activity, consistent with absorption-mediated HCO3− secretion. These results suggest that absorption of luminal SCFA via SMCT1 and MCTs increases duodenal HCO3− secretion. In addition to SCFA sensing via free fatty acid receptors, the presence of rapid duodenal SCFA absorption may be important for the suppression of luminal bacterial colonization and implicated in the generation of functional dyspepsia due to bacterial overgrowth.

scholarly journals Keratin 8 absence down-regulates colonocyte HMGCS2 and modulates colonic ketogenesis and energy metabolism

2015 ◽  
Vol 26 (12) ◽  
pp. 2298-2310 ◽  
Author(s):  
Terhi O. Helenius ◽  
Julia O. Misiorek ◽  
Joel H. Nyström ◽  
Lina E. Fortelius ◽  
Aida Habtezion ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Mechanical Stability ◽  
Short Chain Fatty Acids ◽  
Monocarboxylate Transporter ◽  
Simple Type ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Intermediate Filament Proteins ◽  
Monocarboxylate Transporter 1 ◽  
Keratin 8

Simple-type epithelial keratins are intermediate filament proteins important for mechanical stability and stress protection. Keratin mutations predispose to human liver disorders, whereas their roles in intestinal diseases are unclear. Absence of keratin 8 (K8) in mice leads to colitis, decreased Na/Cl uptake, protein mistargeting, and longer crypts, suggesting that keratins contribute to intestinal homeostasis. We describe the rate-limiting enzyme of the ketogenic energy metabolism pathway, mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), as a major down-regulated protein in the K8-knockout (K8−/−) colon. K8 absence leads to decreased quantity and activity of HMGCS2, and the down-regulation is not dependent on the inflammatory state, since HMGCS2 is not decreased in dextran sulfate sodium-induced colitis. Peroxisome proliferator–activated receptor α, a transcriptional activator of HMGCS2, is similarly down-regulated. Ketogenic conditions—starvation or ketogenic diet—increase K8+/+ HMGCS2, whereas this response is blunted in the K8−/− colon. Microbiota-produced short-chain fatty acids (SCFAs), substrates in the colonic ketone body pathway, are increased in stool, which correlates with decreased levels of their main transporter, monocarboxylate transporter 1 (MCT1). Microbial populations, including the main SCFA-butyrate producers in the colon, were not altered in the K8−/−. In summary, the regulation of the SCFA-MCT1-HMGCS2 axis is disrupted in K8−/− colonocytes, suggesting a role for keratins in colonocyte energy metabolism and homeostasis.

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