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Cancer is caused by uncontrolled cell division and is a leading cause of mortality worldwide. Oenothera odorata (O. odorata) extract is used in herbal medicine to inhibit inflammation, but its potential anti-tumor properties have not been fully evaluated. Here, we demonstrated that O. odorata extract inhibits the proliferation of lung adenocarcinoma and melanoma cell lines In Vitro, and also inhibits the growth of melanoma cells In Vivo. After partitioning the extract with n-hexane, chloroform, ethyl acetate, and n-butanol, it was found that the butanol-soluble (OOB) and water-soluble (OOW) fractions of O. odorata extract are effective at inhibiting tumor cell growth In Vivo although OOW is more effective than OOB. Interestingly, these fractions did not inhibit the growth of non-cancerous cells. The anti-proliferative effects of the OOW fraction were found to be mediated by inhibition of glycolysis and cellular respiration. UPLC of both fractions showed two major common peaks, which were predicted to be hydrolyzable tannin-related compounds. Taken together, these data suggest that O. odorata extract has anti-tumor properties, and the molecular mechanism involves metabolic alterations and inhibition of cell proliferation. O. odorata extract therefore holds promise as a novel natural product for the treatment of cancer.

Sophora flavescens is used as a traditional herbal medicine to modulate inflammatory responses. However, little is known about the impact of (‐)‐maackiain, a compound derived from S. flavescens, on the activation of inflammasome/caspase‐1, a key factor in interleukin‐1β (IL‐1β) processing. Here, we report that (‐)‐maackiain potently amplified caspase‐1 cleavage in macrophages in response to nigericin (Nig). In macrophages primed with either lipopolysaccharide or monophosphoryl lipid A, Nig‐mediated caspase‐1 cleavage was also markedly promoted by (‐)‐maackiain. Notably, (‐)‐maackiain induced the production of vimentin, an essential mediator for the activation of the NOD‐, LRR‐, and pyrin domain‐containing protein 3 inflammasome, thereby contributing to promotion of the formation of the inflammasome complex to activate caspase‐1. Taken together, our data suggest that (‐)‐maackiain exerts an immunostimulatory effect by promoting IL‐1β production via activation of the inflammasome/caspase‐1 pathway. Thus, the potent inflammasome‐activating effect of (‐)‐maackiain may be clinically useful as an acute immune‐stimulating agent., Proinflammatory cytokine interleukin‐1β (IL‐1β) plays critical roles in defending against infections. Sophora flavescens‐derived (‐)‐maackiain potently amplifies caspase‐1 cleavage in response to nigericin. Notably, (‐)‐maackiain promotes caspase‐1 cleavage and IL‐1β production even in monophosphoryl lipid A‐primed macrophages. The potent inflammasome‐activating effect of (‐)‐maackiain may be clinically useful as an acute immune‐stimulating agent.

Objective: Interleukin-6 (IL-6) is a T cell-derived B cell stimulating factor which plays an important role in inflammatory diseases. In this study, the pharmacokinetic properties of LMT-28 including physicochemical property, in vitro liver microsomal stability and an in vivo pharmacokinetic study using BALB/c mice were characterized.Methods: LMT-28 has been synthesized and is being developed as a novel therapeutic IL-6 inhibitor. The physicochemical properties and in vitro pharmacokinetic profiles such as liver microsomal stability and Madin-Darby canine kidney (MDCK) cell permeability assay were examined. For in vivo pharmacokinetic studies, pharmacokinetic parameters using BALB/c mice were calculated.Results: The logarithm of the partition coefficient value (LogP; 3.65) and the apparent permeability coefficient values (Papp; 9.7×10–6 cm/s) showed that LMT-28 possesses a moderate-high cell permeability property across MDCK cell monolayers. The plasma protein binding rate of LMT-28 was 92.4% and mostly bound to serum albumin. The metabolic half-life (t1/2) values of LMT-28 were 15.3 min for rat and 21.9 min for human at the concentration 1 μM. The area under the plasma drug concentration-time curve and Cmax after oral administration (5 mg/kg) of LMT-28 were 302±209 h∙ng/mL and 137±100 ng/mL, respectively.Conclusion: These data suggest that LMT-28 may have good physicochemical and pharmacokinetic properties and may be a novel oral drug candidate as the first synthetic IL-6 inhibitor to ameliorate mammalian inflammation.

The value-added products in livestock industry is one of the key issues in order to maximize the revenue and to create a new business model. Numerous studies have suggested application of herbal plants as feed additives to increase health, productivity, and/or high-quality product in livestock. In this study, the first experiment was designed to develop in vitro evaluation system by using primary chicken myoblast (pCM) cells isolated from pectoralis major of 10-day-old male embryos. Subsequently, to evaluate effects of Korean Danggui Angelica gigas Nakai (AGN), we optimized the concentration of AGN root extract for treatment of primary pCM cells. After the treatment of AGN root extract, we compared proliferation and differentiation capacity, and also examined the gene expression. In the second experiment, the next generation sequencing analysis was performed to compare the different patterns of the global gene expression in pCM cells treated with AGN extract. Three up-regulated (pancreas beta cells, fatty acid metabolism and glycolysis) and one down-regulated (adipogenesis) gene sets were characterized suggesting that the AGN extract affected the metabolic pathways for the utilization of fat and glucose in chicken muscle cells. Furthermore, we validated the expression patterns of the up-regulated genes (GCLC, PTPN6, ISL1, SLC25A13, TGFBI, and YWHAH) in the AGN-treated pCM cells by quantitative RT-PCR. These results demonstrated that the treatment of AGN extract decreased proliferation and differentiation of pCM cells, and affected the metabolic pathways of glucose and fatty acids. Moreover, AGN extract derived from byproducts such as stem and leaf also showed the reduced proliferation patterns on AGN-treated pCM cells. Taken together, pCM cell-based in vitro assay system could be primarily and efficiently applied for evaluating the biofunctional efficacy of various feed additive candidates.

Glycogen storage disease type Ib (GSD-Ib), caused by a deficiency in glucose-6-phosphate transporter (G6PT), is characterized by disrupted glucose homeostasis, inflammatory bowel disease, neutropenia, and neutrophil dysfunction. The purpose of this study was to investigate the role of G6PT on macrophage functions and metabolism. Peritoneal macrophages of G6pt-/- mice were lower in number and their effector functions including migration, superoxide production, and phagocytosis were impaired. To investigate the underlying mechanisms of macrophage dysfunction, the G6PT gene was mutated in porcine alveolar macrophage 3D4/31 cells using the CRISPR/Cas9 technology. The G6PT-deficient macrophages exhibited significant decline in cell growth, bactericidal activity, and antiviral response. These phenotypes are associated with the impaired glycolysis and mitochondrial oxidative phosphorylation. We therefore propose that the G6PT-mediated metabolism is essential for effector functions of macrophage, the immune deficiencies observed in GSD-Ib extend beyond neutropenia and neutrophil dysfunction, and future therapeutic targets aimed both the neutrophils and macrophages may be necessary.

Ferritin (FT), a cage-protein composed of 24 subunits, may carry small molecules inside the core of cage. To enhance the potential of FT as a more functional drug carrier, FT genetically-fused with silaffin R5 peptide at N-terminus (R5FT) and silica-enveloped cage protein (SiO2/R5FT) were developed. Doxorubicin (Dox) can be loaded into cage interior by re-assembly of R5FT. The release of Dox loaded in internal cages was retarded by the silica-coated matrix and showed the pH-controlled behavior, in which the release amount is larger in acidic environments than neutral. R5FT provides a biocompatible and eco-friendly manufacturing process for the drug-laden silica nanoparticles over conventional production methods.

Hafnium-aluminum zinc oxide (HAZO) films as an active layer of oxide-transistors with different hafnium (Hf) contents were deposited via co-sputtering of separate targets. The effects of the sputtering power during co-sputtering on the structural, optical, electrical, and chemical properties of the HAZO films were examined. As the sputtering power increased, the structure of the HAZO films changed from polycrystalline to amorphous, and the Hf O bonds in the HAZO films increased, but the Zn O bonds decreased. Also, a bottom-gate-type thin-film transistor (TFT) using the HAZO film as its channel layer was fabricated and characterized. The TFTs using HAZO layer at room temperature as channel layer exhibited the device characteristics, such as a field effect mobility of 0.45 cm2/V·s, a threshold voltage of 17.18 V, a subthreshold swing of 0.85 V/decade, an on/off current ratio of 3.68 × 107, and a visible transmittance of 82.7%. It was discovered that the changes of the electrical characteristics of the HAZO TFTs were closely related to the changes of the Zn O/Hf O bonding ratio.

The vine stem of Spatholobus suberectus Dunn (SS) is used as a traditional herbal medicine in China. Chinese herbal medicines are well known as natural bioactive compounds that can be used as new medicines, and their antioxidant and anticancer effects have also been reported. This study aimed to examine the anticancer effect of a high-pressure hot-water SS extract on rat C6 glioma cells. The SS extract effectively suppressed the viability and proliferation of C6 glioma cells through an antioxidant effect. Reactive oxygen species (ROS) levels in cancer cells are higher than that in normal cells. If the ROS level falls below that required for the growth of cancer cells, their rapid proliferation and growth can be suppressed. We also measured the induction of mitochondrial membrane depolarization and cell cycle arrest effect caused by the SS extract in C6 glioma cells through a FACS analysis. In addition, we observed an increase in STAT3, p53, E2F1, and p21 mRNA expression and a decrease in Bcl-2 mRNA expression by quantitative PCR. An increase in p21 protein expression of over 83% was observed through western blot analysis. All these data support the fact that the high-pressure hot-water SS extract has the potential to be used for glioma treatment.

Gliomas are one of the most common types of primary brain tumors, characterized by rapid proliferation and infiltration into normal brain tissue. Corncob is the most plentiful byproducts of Zea mays L., of which anti-cancer effect has not been reported. Therefore, we aimed to examine the anti-proliferative effect of a high-pressure hot-water extract of corncob on glioma cells and elucidated the underlying mechanism. The high-pressure hot-water corncob extract contained approximately 94.8 mg/g and 1.82 μg/g of total phenol and catechin, respectively. Glioma cell treated with different concentrations of high-pressure hot-water corncob extract was shown to be suppressed in growth during three days of culture. In parallel, corncob extract reduced the glioma cell viability and induced cell cycle arrest in G0/G1 phase by upregulating the expression level of cyclin-dependent kinase inhibitor p21. Decreased proliferation and viability in glioma cells treated with corncob extract can be attributed to reduced reactive oxygen species (ROS), antiapoptotic Bcl-2 protein, and a lactate transporter monocarboxylate transporter 1 of which levels are higher than those in normal cells. Based on its inhibitory effects on proliferation and viability of C6 glioma cells, a high-pressure hot-water corncob extract has the potential to be used for glioma treatment.

Pravastatin is a lipid-lowering agent that attenuates atherosclerosis. However, the multifactorial pathogenesis of atherosclerosis requires other drugs with different anti-atherogenic mechanisms. We chose sarpogrelate as an anti-platelet agent and a novel component of a complex drug with pravastatin due to its high potential but little information on its beneficial effects on atherosclerosis. Low-density lipoprotein receptor-knockout mice were fed a high-fat, high-cholesterol diet and treated with pravastatin alone, sarpogrelate alone, or a combination of both drugs. Although sarpogrelate alone did not significantly reduce atherosclerotic plaque areas, co-treatment with pravastatin significantly decreased aortic lesions compared to those of the pravastatin alone treated group. The combined therapy was markedly more effective than that of the single therapies in terms of foam cell formation, smooth muscle cell proliferation, and inflammatory cytokine levels. These results suggest that pravastatin and sarpogrelate combined therapy may provide a new therapeutic strategy for treating atherosclerosis.

Glycogen storage disease type Ib (GSD-Ib) is caused by a deficiency in the glucose-6-phosphate (G6P) transporter (G6PT) that works with a liver/kidney/intestine–restricted glucose-6-phosphatase-α (G6Pase-α) to maintain glucose homeostasis between meals. Clinically, GSD-Ib patients manifest disturbed glucose homeostasis and neutrophil dysfunctions but the cause of the latter is unclear. Neutrophils express the ubiquitously expressed G6PT and G6Pase-β that together transport G6P into the endoplasmic reticulum (ER) lumen and hydrolyze it to glucose. Because we expected G6PT-deficient neutrophils to be unable to produce endogenous glucose, we hypothesized this would lead to ER stress and increased apoptosis. Using GSD-Ib mice, we showed that GSD-Ib neutrophils exhibited increased production of ER chaperones and oxidative stress, consistent with ER stress, increased annexin V binding and caspase-3 activation, consistent with an increased rate of apoptosis. Bax activation, mitochondrial release of proapoptotic effectors, and caspase-9 activation demonstrated the involvement of the intrinsic mitochondrial pathway in these processes. The results demonstrate that G6P translocation and hydrolysis are required for normal neutrophil functions and support the hypothesis that neutrophil dysfunction in GSD-Ib is due, at least in part, to ER stress and increased apoptosis.

Comparative analysis of binding of intact glucose-grownFibrobacter succinogenesstrain S85 cells and adhesion-defective mutants AD1 and AD4 to crystalline and acid-swollen (amorphous) cellulose showed that strain S85 bound efficiently to both forms of cellulose while mutant Ad1 bound to acid-swollen cellulose, but not to crystalline cellulose, and mutant Ad4 did not bind to either. One- and two-dimensional electrophoresis (2-DE) of outer membrane cellulose binding proteins and of outer membranes, respectively, of strain S85 and adhesion-defective mutant strains in conjunction with mass spectrometry analysis of tryptic peptides was used to identify proteins with roles in adhesion to and digestion of cellulose. Examination of the binding to cellulose of detergent-solubilized outer membrane proteins from S85 and mutant strains revealed six proteins in S85 that bound to crystalline cellulose that were absent from the mutants and five proteins in Ad1 that bound to acid-swollen cellulose that were absent from Ad4. Twenty-five proteins from the outer membrane fraction of cellulose-grownF. succinogeneswere identified by 2-DE, and 16 of these were up-regulated by growth on cellulose compared to results with growth on glucose. A protein identified as a Cl-stimulated cellobiosidase was repressed in S85 cells growing on glucose and further repressed in the mutants, while a cellulose-binding protein identified as pilin was unchanged in S85 grown on glucose but was not produced by the mutants. The candidate differential cellulose binding proteins of S85 and the mutants and the proteins induced by growth of S85 on cellulose provide the basis for dissecting essential components of the cellulase system ofF. succinogenes.

Batten disease (BD; also known as juvenile neuronal ceroid lipofuscinosis) is a genetic disorder inherited as an autosomal recessive trait and is characterized by blindness, seizures, cognitive decline, and early death resulting from the inherited mutation of the CLN3 gene. Mitochondrial oxidative stress, endoplasmic reticulum (ER) stress, disrupted autophagy, and enhanced apoptosis have been suggested to play a role in BD pathogenesis. Fibrates, a class of lipid-lowering drugs that induce peroxisome proliferator-activated receptor-α (PPAR-α) activation, are the most commonly used PPAR agonists. Assuming that fibrates have a neuroprotective effect, we studied the effects of fibrates, fenofibrate, bezafibrate, and gemfibrozil on apoptosis, depolarization of mitochondrial membrane, and defective autophagy in BD lymphoblast cells. The viability of fibrate-treated BD lymphoblast cells increased to levels of normal lymphoblast cells. In addition, treatment with fibrates inhibited depolarization of mitochondrial membrane potential in BD lymphoblast cells. Defective autophagy in BD lymphoblast cells was normalized when treated with fibrates as indicated by increased acridine orange staining. The recovery of autophagy in BD lymphoblast cells is most likely attributed to the upregulation of autophagy proteins, lysosomal-associated membrane protein 1 (LAMP1), and LC3 I/II, after treatment with fibrates. This study therefore suggests that fibrates may have a therapeutic potential against BD.

Acetylxylan esterase genes axe6A and axe6B located adjacent to one another on a Fibrobacter succinogenes chromosome have been separately cloned and their properties characterized. The corresponding esterases contained an N-terminal carbohydrate esterase family 6 catalytic domain (CD) and a C-terminal family 6 carbohydrate-binding module (CBM). The amino acid sequences of the CDs and CBMs were found to exhibit 52% and 40% amino acid similarity, respectively. The CDs of the two esterases exhibited the highest similarity to CDs of acetylxylan esterases: AxeA from the ruminal fungi Orpinomyces sp. and BnaA from Neocallimastix patriciarum. Axe6A and Axe6B were optimally active at neutral pH and had low Kmvalues of 0.084 and 0.056 mmol·L–1, respectively. Axe6A and Axe6B were shown to bind to insoluble cellulose and xylan and to soluble arabinoxylan. Axe6A deacetylated acetylated xylan at the same initial rate in the presence and absence of added Xyn10E xylanase from F. succinogenes, but the action of the xylanase on acetylated xylan was dependent upon the initial activity of Axe6A. The capacity of acetylxylan esterases to bind to plant cell wall polymers and to independently deacetylate xylan enabling xylanase to release xylooligo saccharides, documents the central role these enzymes have to improve access of F. succinogenes to cellulose.Key words: Fibrobacter succinogenes S85, acetylxylan esterase, xylanase, synergy.

The increasing demands of renewable energy have led to the critical emphasis on novel enzymes to enhance cellulose biodegradation for biomass conversion. To identify new cellulases in the ruminal bacterium Fibrobacter succinogenes , a cell extract of cellulose-grown cells was separated by ion-exchange chromatography and cellulases were located by zymogram analysis and identified by peptide mass fingerprinting. An atypical family 9 glycoside hydrolase (GH9), Cel9D, with less than 20% identity to typical GH9 cellulases, was identified. Purified recombinant Cel9D enhanced the production of reducing sugar from acid swollen cellulose (ASC) and Avicel by 1.5- to 4-fold when mixed separately with each of four other glucanases, although it had low activity on these substrates. Cel9D degraded ASC and cellodextrins with a degree of polymerization higher than 2 to glucose with no apparent endoglucanase activity, and its activity was restricted to β-1→4-linked glucose residues. It catalyzed the hydrolysis of cellulose by an inverting mode of reaction, releasing glucose from the nonreducing end. Unlike many GH9 cellulases, calcium ions were not required for its function. Cel9D had increased k cat /K m values for cello-oligosaccharides with higher degrees of polymerization. The k cat /K m value for cellohexaose was 2,300 times higher than that on cellobiose. This result indicates that Cel9D is a 1,4-β- d -glucan glucohydrolase (EC 3.2.1.74) in the GH9 family. Site-directed mutagenesis of Cel9D identified Asp166 and Glu612 as the candidate catalytic residues, while Ser168, which is not present in typical GH9 cellulases, has a crucial structural role. This enzyme has an important role in crystalline cellulose digestion by releasing glucose from accessible cello-oligosaccharides.

The objectives of this study were to characterize Fibrobacter succinogenes glycoside hydrolases from different glycoside hydrolase families and to study their synergistic interactions. The gene encoding a major endoglucanase (endoglucanase 1) of F. succinogenes S85 was identified as cel9B from the genome sequence by reference to internal amino acid sequences of the purified native enzyme. Cel9B and two other glucanases from different families, Cel5H and Cel8B, were cloned and overexpressed, and the proteins were purified and characterized. These proteins in conjunction with two predominant cellulases, Cel10A, a chloride-stimulated cellobiosidase, and Cel51A, formerly known as endoglucanase 2 (or CelF), were assayed in various combinations to assess their synergistic interactions using ball-milled cellulose. The degree of synergism ranged from 0.6 to 3.7. The two predominant endoglucanases produced by F. succinogenes , Cel9B and Cel51A, were shown to have a synergistic effect of up to 1.67. Cel10A showed little synergy in combination with Cel9B and Cel51A. Mixtures containing all the enzymes gave a higher degree of synergism than those containing two or three enzymes, which reflected the complementarity in their modes of action as well as substrate specificities.

Neutropenia and neutrophil dysfunction are common in many diseases, although their etiology is often unclear. Previous views held that there was a single ER enzyme, glucose-6-phosphatase-alpha (G6Pase-alpha), whose activity--limited to the liver, kidney, and intestine--was solely responsible for the final stages of gluconeogenesis and glycogenolysis, in which glucose-6-phosphate (G6P) is hydrolyzed to glucose for release to the blood. Recently, we characterized a second G6Pase activity, that of G6Pase-beta (also known as G6PC), which is also capable of hydrolyzing G6P to glucose but is ubiquitously expressed and not implicated in interprandial blood glucose homeostasis. We now report that the absence of G6Pase-beta led to neutropenia; defects in neutrophil respiratory burst, chemotaxis, and calcium flux; and increased susceptibility to bacterial infection. Consistent with this, G6Pase-beta-deficient (G6pc3-/-) mice with experimental peritonitis exhibited increased expression of the glucose-regulated proteins upregulated during ER stress in their neutrophils and bone marrow, and the G6pc3-/- neutrophils exhibited an enhanced rate of apoptosis. Our results define a molecular pathway to neutropenia and neutrophil dysfunction of previously unknown etiology, providing a potential model for the treatment of these conditions.

Glucose-6-phosphatase-β (G6Pase-β or G6PC3) is a ubiquitously expressed glucose-6-phosphate (G6P) hydrolase that catalyzes the hydrolysis of G6P to glucose and phosphate. It is a key enzyme for intracellular glucose production in non-gluconeogenic organs. Mutations in G6Pase-β underlie severe congenital neutropenia syndrome type 4 (SCN4, MIM612541), an autosomal recessive disease characterized by neutropenia and neutrophil dysfunction. A mouse model for G6Pase-β deficiency (G6pc3-/-) established by gene targeting manifests both neutropenia and neutrophil dysfunction, mimicking the human disorder. Recent studies have shown that in G6Pase-β deficiency enhanced neutrophil apoptosis leads to neutropenia while disrupted energy homeostasis underlies neutrophil dysfunction. The patients of G6Pase-β deficiency also present with non-haematological defects, including prominent superficial venous pattern, congenital cardiac anomaly, myopathy, disrupted bone remodeling, and genital anomalies, suggesting that G6Pase-β deficiency leads to a broader cell dysfunction. We now hypothesize that these non-haematological defects may reflect loss of glucose metabolism within mesenchymal stem cells (MSC) that require levels of glucose beyond those supplied by the blood. MSC are multipotent stem cells that are capable of differentiating into all connective tissue types including bone, cartilage, myocytes, and adipocytes. Studies have shown that MSC cultured in reduced glucose concentrations exhibit increased proliferative ability and reduced replicative senescence. Using MSC isolated from the compact bones, we show that G6pc3-/- MSC grow at a significantly faster rate than those of wild type MSC under both normoxia and hypoxia conditions. Consistently, the colony-forming unit-fibroblastic counts in G6pc3-/- MSC are 2-fold higher than those in wild type MSC, suggesting that G6pc3-/- MSC contain higher numbers of progenitors. Differentiation of MSC involves metabolic shifts between glycolysis and mitochondrial oxidative phosphorylation. An increase in the ratio of lactate to pyruvate correlates with increased glycolysis and an increase in oxygen consumption measures increased mitochondrial oxidative phosphorylation. Adipogenesis and osteogenesis of MSC have been shown to be associated with increased oxygen consumption, while chondrogenesis of MSC is associated with increased glycolysis. We now show that cellular levels of lactate and ATP in G6pc3-/- MSC are 4.5- and 2-fold higher, respectively than those in wide type MSC. Moreover, G6pc3-/- MSC exhibit a 2.5-fold increase in the ratio of lactate to pyruvate but a decrease in oxygen consumption, compared to wild type MSC, suggesting that G6Pase-β-deficient MSC exhibit enhanced glycolysis along with impaired mitochondrial respiration activity. This also suggests that adipogenesis and osteogenesis of MSC may be impaired in G6pc3-/- MSC. Adipogenic differentiation of MSC from mice was then evaluated by morphological alterations and lipid accumulation. MSC from wild type mice, cultured for 3 days in adipogenic differentiation medium, changed from fibroblast-like cells to round-shaped adipocyte-like cells, while G6pc3-/- MSC cultured under the same conditions did not show any morphological changes. Wild type MSC, cultured for 5 days in adipogenic differentiation medium, yielded many adipocytes containing lipid droplets and staining positive by Oil red O, while adipocytes were rarely seen in G6pc3-/- MSC cultured under similar conditions, confirming the impaired adipogenic differentiation of G6pc3-/- MSC. In conclusion, the non-hematological defects associated with G6Pase-β deficiency may result from altered energy homeostasis in G6pc3-/- MSC, leading to enhanced glycolysis along with impaired mitochondrial respiration activity, that impacts MSC differentiation. Disclosures No relevant conflicts of interest to declare.

Blood glucose homeostasis between meals depends upon production of glucose within the endoplasmic reticulum (ER) of the liver and kidney by hydrolysis of glucose-6-phosphate (G6P) into glucose and phosphate (P(i)). This reaction depends on coupling the G6P transporter (G6PT) with glucose-6-phosphatase-α (G6Pase-α). Only one G6PT, also known as SLC37A4, has been characterized, and it acts as a P(i)-linked G6P antiporter. The other three SLC37 family members, predicted to be sugar-phosphate:P(i) exchangers, have not been characterized functionally. Using reconstituted proteoliposomes, we examine the antiporter activity of the other SLC37 members along with their ability to couple with G6Pase-α. G6PT- and mock-proteoliposomes are used as positive and negative controls, respectively. We show that SLC37A1 and SLC37A2 are ER-associated, P(i)-linked antiporters, that can transport G6P. Unlike G6PT, neither is sensitive to chlorogenic acid, a competitive inhibitor of physiological ER G6P transport, and neither couples to G6Pase-α. We conclude that three of the four SLC37 family members are functional sugar-phosphate antiporters. However, only G6PT/SLC37A4 matches the characteristics of the physiological ER G6P transporter, suggesting the other SLC37 proteins have roles independent of blood glucose homeostasis.