Glyoxylate Reductase Research Articles

A cytosolic glyoxylate shunt complements the canonical photorespiratory pathway in Arabidopsis

Photorespiration functions in part to support photosynthetic performance, especially under stress such as high light, yet the underlying mechanisms are poorly understood. To identify modulators of photorespiration under high light, we have isolated genetic suppressors of the photorespiratory mutant hpr1 (hydroxypyruvate reductase 1) from Arabidopsis. A suppressor that partially rescues hpr1 is mapped to GLYR1, which encodes the cytosolic glyoxylate reductase 1 that converts glyoxylate to glycolate. Independent glyr1 mutants also partially rescue hpr1 and another photorespiratory mutant, catalase 2. Our genetic, transcriptomic and metabolic profiling analyses together reveal a connection between cytosolic glyoxylate and a non-canonical photorespiratory route mediated by HPR2, which we name the photorespiratory glyoxylate shunt. This shunt complements the canonical photorespiratory pathway and is especially critical when high photorespiratory fluxes are required and when the major photorespiratory pathway is deficient. Our findings support the metabolic flexibility of photorespiration and may help to improve crop performance under stress.

Challenges in elucidating ethylene glycol metabolism in Saccharomyces cerevisiae.

Polyethylene terephthalate (PET) is one of the most used polymers in the packaging industry; enzymatic recycling is emerging as a sustainable strategy to deal with waste PET, producing the virgin monomers terephthalic acid and ethylene glycol (EG). These monomers can be feedstocks for further microbial transformations. While EG metabolism has been uncovered in bacteria, in yeast the pathway for the oxidation to glycolic acid (GA) has only been proposed, but never experimentally elucidated. In this work, we investigated in Saccharomyces cerevisiae the potential contribution to this metabolism of two endogenous genes, YLL056C (a putative alcohol dehydrogenase) and GOR1 (glyoxylate reductase). Secondly, the possible role of alcohol dehydrogenases (ADHs) was considered, too. Finally, two heterologous genes (gox0313 from Gluconobacter oxydans and AOX1 from Komagataella phaffii) were expressed with the intent to push EG oxidation toward GA. Our main findings revealed that (i) Gor1, Yll056c, and ADHs are not involved in EG oxidation and (ii) the bottleneck of the catabolism is the first step in the pathway, due to the endogenous mechanisms for aldehyde detoxification. Multiomics studies are required to completely elucidate the pathway for EG catabolism, while further engineering directed toward relieving the bottleneck is needed to fully unleash the potential of yeasts for the upcycling of EG to GA.

A novel engineered strain of Methylorubrum extorquens for methylotrophic production of glycolic acid

AbstractThe conversion of CO2 into methanol depicts one of the most promising emerging renewable routes for the chemical and biotech industry. Under this regard, native methylotrophs have a large potential for converting methanol into value-added products but require targeted engineering approaches to enhance their performances and to widen their product spectrum. Here we use a systems-based approach to analyze and engineer M. extorquens TK 0001 for production of glycolic acid. Application of constraint-based metabolic modeling reveals the great potential of M. extorquens for that purpose, which is not yet described in literature. In particular, a superior theoretical product yield of 1.0 C-molGlycolic acid C-molMethanol−1 is predicted by our model, surpassing theoretical yields of sugar fermentation. Following this approach, we show here that strain engineering is viable and present 1st generation strains producing glycolic acid via a heterologous NADPH-dependent glyoxylate reductase. It was found that lactic acid is a surprising by-product of glycolic acid formation in M. extorquens, most likely due to a surplus of available NADH upon glycolic acid synthesis. Finally, the best performing strain was tested in a fed-batch fermentation producing a mixture of up to total 1.2 g L−1 glycolic acid and lactic acid. Several key performance indicators of our glycolic acid producer strain are superior to state-of-the-art synthetic methylotrophs. The presented results open the door for further strain engineering of the native methylotroph M. extorquens and pave the way to produce two promising biopolymer building blocks from green methanol, i.e., glycolic acid and lactic acid.

Structural insights into the mechanism underlying the dual cofactor specificity of glyoxylate reductase from Acetobacter aceti in the β-hydroxyacid dehydrogenase family

Structural insights into the mechanism underlying the dual cofactor specificity of glyoxylate reductase from Acetobacter aceti in the β-hydroxyacid dehydrogenase family

Comparative studies on substrate specificity of succinic semialdehyde reductase from Gluconobacter oxydans and glyoxylate reductase from Acetobacter aceti.

Gluconobacter oxydans succinic semialdehyde reductase (GoxSSAR) and Acetobacter aceti glyoxylate reductase (AacGR) represent a novel class in the β-hydroxyacid dehydrogenases superfamily. Kinetic analyses revealed GoxSSAR's activity with both glyoxylate and succinic semialdehyde, while AacGR is glyoxylate specific. GoxSSAR K167A lost activity with succinic semialdehyde but retained some with glyoxylate, whereas AacGR K175A lost activity. These findings elucidate differences between these homologous enzymes.

GRHPR gene variations in Iraqi patients infected with calcium oxalate kidney stones

حصى الكلى هو مرض شديد الخطورة له تهديد خطير لكل من الصحة والاقتصاد العالميين. توجد عدة أنواع مختلفة من الحصى، ولكن حصوات أكسالات الكالسيوم هي الأكثر انتشارًا في العراق. لم يتم دراسة التغيرات في تركيزات اختزال الجليوكسيلات واختزال هيدروكسي البيروفات في المصل والتغيرات الجينية المرتبطة بحصوات أكسالات الكالسيوم في المرضى العراقيين سابقًا لذا تهدف هذه الدراسة إلى التركيز على هذه النقاط. اشتملت هذه الدراسة على 80 شخص, كانو 50 مريضاً مصابا بحصى أكسالات الكالسيوم مقارنة بـ 30 لمجموعة السيطرة. تم اجراء بعض الاختبارات البيوكيميائية لوظائف الكلى (الكرياتينين واليوريا وحمض البوليك) في مصل كلا المجموعتين، فضلا عن تحاليل تعداد الدم الكامل، وسكر الدم العشوائي، واختبارات فصائل الدم. كما تم جمع البول من أجل الفحص العام للبول، لتأكيد رؤية بلورات الأكسالات في بول المريض. بالإضافة إلى قياس تركيز إنزيم اختزال الجليوكسيلات واختزال هيدروكسي البيروفات في المصل كلا المجموعتين بطريقة الايلايزا. و تم استخلاص الدنا من الدم الكامل وتم التحري عن الطفرات الممرضة c.295C>T (rs119490108) وc.165G>A (rs180177314) و rs180177322في مورث GRHPRعن طريق تضخيم الحمض النووي المستهدف عن طريق تفاعل البلمرة المتسلسل وتحري التعاقبات المباشر للمنتجات ثم تم تحليل النتائج. وجدت هذه الدراسة أن تركيز الإنزيم في مجموعة السيطرة (4.78 ± 1.06 مجم / ديسيلتر) كان أعلى بكثير من تركيزه في مجموعة المرضى (0.411 ± 0.02 مجم / ديسيلتر). لم تظهر الطفرات الممرضة في كلا المجموعتين، ولكن وجد بان عدة مواقع ضمن القطع المدروسة كانت ذات تعدد بالأشكال: في اكسون 4: rs2768659 (A>G) و rs1294628807 (G>A)و rs2736664 (C>A)و اكسون 6: c.494-68A>G rs309459 (A>G)و rs309458 (A>G) واكسون 9 : .rs1057507 (A>G) و كأستنتاج وجد بان تكوين حصى اوكزالات الكالسيوم ارتبط بانخفاض انزيم اختزال الجليوكسيلات واختزال هيدروكسي البيروفات في المرضى مقارنة بمجموعة السيطرة والتي ربما حدثت بسبب الطفرات او الوراثة الفوقية الكابحة للتعبير الجيني.

Using ion exchange chromatography for the purification of glyoxylate reductase from corn leaves and studying its characteristics

The purpose of this study was to obtain a purified preparation of the studied enzyme from corn leaves and to study its characteristics. In this work, kinetic and regulatory parameters of glyoxylate reductase were calculated for leaves of 14-day-old corn (Zea mays) seedlings grown hydroponically at 25°C. The following methods were used during the study: sample homogenisation, four-step purification including ammonium sulphate for desalting, gel filtration on G-25 columns, and ion exchange chromatography using DEAE-sephacel, as well as electrophoresis on polyacrylamide gels and quantitative analysis of protein. To study the properties of the enzyme, we used electrophoretically homogenous preparations. The influence of pH, substrate concentration, and cofactor on the rate of the enzymatic reaction was determined by a series of measurements with different values of the enzymatic reaction rate. As a result of four-stage purification, we obtained a homogeneous preparation with a specific activity of167 E/mg of protein. Ion exchange chromatography was important for purification; we obtained 1 peak of enzyme activity upon desorption in 104 mM sodium chloride. Studying the properties of glyoxylate reductase showed a significant dependence of activity on pH. The optimal pH value was 6.5 units.

The miR-23b-3p from adipose-derived stem cell exosomes alleviate inflammation in mice experiencing kainic acid-induced epileptic seizures.

Epilepsy is a common neurologic disorder. While a good clinical solution is still missing, studies have confirmed that exosomes (Exos) derived from adipose-derived stem cells (ADSCs) had a therapeutic effect on various diseases, including neurological diseases. Therefore, this study aimed to reveal whether ADSC-Exo treatment could improve kainic acid (KA)-induced seizures in epileptic mice. ADSCs and Exos were isolated. Mice were generated with KA-induced epileptic seizures. ELISA was used to detect inflammatory factor expression. Luciferase reporter analysis detection showed a relationship among miR-23b-3p, STAT1, and glyoxylate reductase 1 (GlyR1). ADSC-Exos had a protective effect on KA-induced seizures by inhibiting inflammatory factor expression and the M1 microglia phenotype. The result showed that miR-23b-3p played an important role in the Exo-mediated protective effect in KA-induced seizures in epileptic mice by regulating STAT1 and GlyR1. Luciferase reporter analysis confirmed that miR-23b-3p interacted with the 3'-UTR of STAT1 and GlyR1. The miR-23b-3p inhibited M1 microglia-mediated inflammatory factor expression in microglial cells by regulating STAT1 and GlyR1. The downregulation of miR-23b-3p decreased the protective effect of ADSC-Exos on KA-induced seizures in epileptic mice. The miR-23b-3p from ADSC-Exos alleviated inflammation in mice with KA-induced epileptic seizures.

GLYR1 transcriptionally regulates PER3 expression to promote the proliferation and migration of multiple myeloma

GLYR1 transcriptionally regulates PER3 expression to promote the proliferation and migration of multiple myeloma

Fine-Tuning the Expression of the Glycolate Biosynthetic Pathway in Escherichia coli Using Synthetic Promoters

Glycolate plays an important role as a platform chemical in both polymeric material and cosmetic industries. However, the microbial production of glycolate often encounters challenges associated with unbalanced metabolic flux, leading to a notably low titer. Additionally, the use of expensive inducers, such as IPTG, contributes to an increase in the overall production cost. To address these issues, the key enzymes involved in the glycolate biosynthetic route, including citrate synthase (gltA), isocitrate lyase (aceA), isocitrate dehydrogenase kinase/phosphatase (aceK) and glyoxylate reductase (ycdW), were overexpressed in E. coli under the control of inducible promoters with varying strengths in order to determine the optimal combination. Subsequently, the glycolate pathway was further modulated by replacing inducible promoters with various constitutive synthetic promoters. Through this systematic optimization, the best strain, named Mgly4T1562, produced 3.02 g/L glycolate with 97.32% theoretical yield in shake-flask cultivation. The titer further increased to 15.53 g/L in a fed-batch experiment. Notably, this study marks the first successful utilization of synthetic promoters in tuning the glycolate biosynthetic pathway for glycolate biosynthesis. The strategy presented in this research holds significant promise for facilitating the cost-effective and industrially viable production of glycolate without the need for expensive inducers.

Glyoxylate reductase: Definitive identification in human liver mitochondria, its importance for the compartment-specific detoxification of glyoxylate.

Glyoxylate is a key metabolite generated from various precursor substrates in different subcellular compartments including mitochondria, peroxisomes, and the cytosol. The fact that glyoxylate is a good substrate for the ubiquitously expressed enzyme lactate dehydrogenase (LDH) requires the presence of efficient glyoxylate detoxification systems to avoid the formation of oxalate. Furthermore, this detoxification needs to be compartment-specific since LDH is actively present in multiple subcellular compartments including peroxisomes, mitochondria, and the cytosol. Whereas the identity of these protection systems has been established for both peroxisomes and the cytosol as concluded from the deficiency of alanine glyoxylate aminotransferase (AGT) in primary hyperoxaluria type 1 (PH1) and glyoxylate reductase (GR) in PH2, the glyoxylate protection system in mitochondria has remained less well defined. In this manuscript, we show that the enzyme glyoxylate reductase has a bimodal distribution in human embryonic kidney (HEK293), hepatocellular carcinoma (HepG2), and cervical carcinoma (HeLa) cells and more importantly, in human liver, and is actively present in both the mitochondrial and cytosolic compartments. We conclude that the metabolism of glyoxylate in humans requires the complicated interaction between different subcellular compartments within the cell and discuss the implications for the different primary hyperoxalurias.

Cytogenetic Infractions of Latex Extract of the Floristic Dumbcane (Dieffenbachia amoena) on Mitotic Chromosomes of Onion (Allium cepa)

Background: Diffenbachia amoena commonly called dumb cane is a houseplant found in homes, offices, banks and landscape premises as ornamental plants. This family of plants has shown high levels of acute and chronic toxicities with high cytogenic, mutagenic, carcinogenic, genotoxic potentials. Several studies had implicated some phytochemicals contained in the whitish latex sap including saponins, glycosides, tannins and oxalates to be responsible for the toxicity of this houseplant to plant cells and proteins. Methods: Cytological investigation protocol was used to determine cytogenetic infractions such as chromosome stickiness, lagging chromosomes, bridged chromosomes, deletions and chromosomal aberrations. The phytochemicals contained in the latex were determined using high performance liquid chromatography while computational biology approach was used to determine the latex phytochemicals interactions with the onion plant proteins using SIB stitch of expasy.org. Result: Cytogenetic studies reveals that Dumb cane causes significant effect and infractions in the cytogenetics of onion cells ranging from chromatid-type breakage-fusion-bridge, chromosome stickiness, lagging chromosomes, bridged chromosomes, deletions and chromosomal aberrations. The latex sap from the stem contains oxalates, saponins, glycosides, tannins, alkaloids to varying degree which impairs photosynthetic and biochemical processes in the plant system. Phytochemicals-proteins interactions revealed that oxalates impairs and inhibits the formation and functionality of alanine glycoxylatetransferase (GRHPR), Chromobox homolog 5 chromosome (CBX5), alpha ketaglutarate dehydrogenase (AGXT) and glyoxylate reductase (OGDH) genes. Hence, there is need for enlightenment of the public on the dangers and toxicity of this houseplant in rural community households, urban cities, offices, recreational parks, business centers where the use of this deadly plant as ornamental is still very predominant.

Macrophage mitochondrial bioenergetics and tissue invasion are boosted by an Atossa‐Porthos axis in Drosophila

Cellular metabolism must adapt to changing demands to enable homeostasis. During immune responses or cancer metastasis, cells leading migration into challenging environments require an energy boost, but what controls this capacity is unclear. Here, we study a previously uncharacterized nuclear protein, Atossa (encoded by CG9005), which supports macrophage invasion into the germband of Drosophila by controlling cellular metabolism. First, nuclear Atossa increases mRNA levels of Porthos, a DEAD‐box protein, and of two metabolic enzymes, lysine‐α‐ketoglutarate reductase (LKR/SDH) and NADPH glyoxylate reductase (GR/HPR), thus enhancing mitochondrial bioenergetics. Then Porthos supports ribosome assembly and thereby raises the translational efficiency of a subset of mRNAs, including those affecting mitochondrial functions, the electron transport chain, and metabolism. Mitochondrial respiration measurements, metabolomics, and live imaging indicate that Atossa and Porthos power up OxPhos and energy production to promote the forging of a path into tissues by leading macrophages. Since many crucial physiological responses require increases in mitochondrial energy output, this previously undescribed genetic program may modulate a wide range of cellular behaviors.

Multiple strategies for metabolic engineering of Escherichia coli for efficient production of glycolate.

Glycolate is a bulk chemical with wide applications in the textile, food processing, and pharmaceutical industries. Glycolate can be produced from glucose via the glycolysis and glyoxylate shunt pathways, followed by reduction to glycolate. However, two problems limit the productivity and yield of glycolate when using glucose as the sole carbon source. The first is a cofactor imbalance in the production of glycolate from glucose via the glycolysis pathway, since NADPH is required for glycolate production, while glycolysis generates NADH. To rectify this imbalance, the NADP+ -dependent glyceraldehyde 3-phosphate dehydrogenase GapC from Clostridium acetobutylicum was introduced to generate NADPH instead of NADH in the oxidation of glyceraldehyde 3-phosphate during glycolysis. The soluble transhydrogenase SthA was further eliminated to conserve NADPH by blocking its conversion into NADH. The second problem is an unfavorable carbon flux distribution between the tricarboxylic acid cycle and the glyoxylate shunt. To solve this problem, isocitrate dehydrogenase (ICDH) was eliminated to increase the carbon flux of glyoxylate and thereby improve the glycolate titer. After engineering through the integration of gapC, combined with the inactivation of ICDH, SthA, and by-product pathways, as well as the upregulation of the two key enzymes isocitrate lyase (encoding by aceA), and glyoxylate reductase (encoding by ycdW), the glycolate titer increased to 5.3 g/L with a yield of 1.89 mol/mol glucose. Moreover, an optimized fed-batch fermentation reached a titer of 41 g/L with a yield of 1.87 mol/mol glucose after 60 h.

Identification and Characterization of Genes Encoding the Hydroxypyruvate Reductases in Chlamydomonas Reveal Their Distinct Roles in Photorespiration.

Photorespiration plays an important role in maintaining normal physiological metabolism in higher plants and other oxygenic organisms, such as algae. The unicellular eukaryotic organism Chlamydomonas is reported to have a photorespiration system different from that in higher plants, and only two out of nine genes encoding photorespiratory enzymes have been experimentally characterized. Hydroxypyruvate reductase (HPR), which is responsible for the conversion of hydroxypyruvate into glycerate, is poorly understood and not yet explored in Chlamydomonas. To identify the candidate genes encoding hydroxypyruvate reductases in Chlamydomonas (CrHPR) and uncover their elusive functions, we performed sequence comparison, enzyme activity measurement, subcellular localization, and analysis of knockout/knockdown strains. Together, we identify five proteins to be good candidates for CrHPRs, all of which are detected with the activity of hydroxypyruvate reductase. CrHPR1, a nicotinamide adenine dinucleotide (NADH)-dependent enzyme in mitochondria, may function as the major component of photorespiration. Its deletion causes severe photorespiratory defects. CrHPR2 takes part in the cytosolic bypass of photorespiration as the compensatory pathway of CrHPR1 for the reduction of hydroxypyruvate. CrHPR4, with NADH as the cofactor, may participate in photorespiration by acting as the chloroplastidial glyoxylate reductase in glycolate-quinone oxidoreductase system. Therefore, the results reveal that CrHPRs are far more complex than previously recognized and provide a greatly expanded knowledge base for studies to understand how CrHPRs perform their functions in photorespiration. These will facilitate both modification of photorespiration and genetic engineering for crop improvement by synthetic biology.

Characterization of a novel class of glyoxylate reductase belonging to the β-hydroxyacid dehydrogenase family in Acetobacter aceti.

Enzymes related to β-hydroxyacid dehydrogenases/3-hydroxyisobutyrate dehydrogenases are ubiquitous, but most of them have not been characterized. An uncharacterized protein with moderate sequence similarities to Gluconobacter oxydans succinic semialdehyde reductase and plant glyoxylate reductases/succinic semialdehyde reductases was found in the genome of Acetobacter aceti JCM20276. The corresponding gene was cloned and expressed in Escherichia coli. The gene product was purified and identified as a glyoxylate reductase that exclusively catalyzed the NAD(P)H-dependent reduction of glyoxylate to glycolate. The strict substrate specificity of this enzyme to glyoxylate, the diverged sequence motifs for its binding sites with cofactors and substrates, and its phylogenetic relationship to homologous enzymes suggested that this enzyme represents a novel class of enzymes in the β-hydroxyacid dehydrogenase family. This study may provide an important clue to clarify the metabolism of glyoxylate in bacteria. Abbreviations: GR: glyoxylate reductase; GRHPR: glyoxylate reductase/hydroxypyruvate reductase; HIBADH: 3-hydroxyisobutyrate dehydrogenase; SSA: succinic semialdehyde; SSAR: succinic semialdehyde reductase.

Two glyoxylate reductase isoforms are functionally redundant but required under high photorespiration conditions in rice

BackgroundThe glyoxylate reductase (GR) multigene family has been described in various plant species, their isoforms show different biochemical features in plants. However, few studies have addressed the biological roles of GR isozymes, especially for rice.ResultsHere, we report a detailed analysis of the enzymatic properties and physiological roles of OsGR1 and OsGR2 in rice. The results showed that both enzymes prefer NADPH to NADH as cofactor, and the NADPH-dependent glyoxylate reducing activity represents the major GR activity in various tissues and at different growth stages; and OsGR1 proteins were more abundant than OsGR2, which is also a major contributor to total GR activities. By generating and characterizing various OsGR-genetically modified rice lines, including overexpression, single and double-knockout lines, we found that no phenotypic differences occur among the various transgenic lines under normal growth conditions, while a dwarfish growth phenotype was noticed under photorespiration-promoted conditions.ConclusionOur results suggest that OsGR1 and OsGR2, with distinct enzymatic characteristics, function redundantly in detoxifying glyoxylate in rice plants under normal growth conditions, whereas both are simultaneously required under high photorespiration conditions.

PD04-05 TARGETING HYDROXYPROLINE DEHYDROGENASE AS A POTENTIAL THERAPY FOR TYPE 2 PRIMARY HYPEROXALURIA

PD04-05 TARGETING HYDROXYPROLINE DEHYDROGENASE AS A POTENTIAL THERAPY FOR TYPE 2 PRIMARY HYPEROXALURIA

A Genetic Screen To Identify Genes Influencing the Secondary Redox Couple NADPH/NADP+ in the Yeast Saccharomyces cerevisiae.

NADPH is an important cofactor in the cell. In addition to its role in the biosynthesis of critical metabolites, it plays crucial roles in the regeneration of the reduced forms of glutathione, thioredoxins and peroxiredoxins. The enzymes and pathways that regulate NADPH are thus extremely important to understand, and yet are only partially understood. We have been interested in understanding how NADPH fluxes are altered in the cell. We describe here both an assay and a genetic screen that allows one to discern changes in NADPH levels. The screen exploits the secondary redox property of NADPH. At low levels of glutathione we show that the redox contributions of NADPH become critical for growth, and we have used this to develop a genetic screen for genes affecting NADPH homeostasis. The screen was validated in pathways that both directly (pentose phosphate pathway) and indirectly (glycolytic pathway) affect NADPH levels, and was then exploited to identify mitochondrial genes that affect NADPH homeostasis. A total of 239 mitochondrial gene knockouts were assayed using this screen. Among these, several genes were predicted to play a role in NADPH homeostasis. This included several new genes of unknown function, and others of poorly defined function. We examined two of these genes, FMP40 which encodes a protein required during oxidative stress and GOR1, glyoxylate reductase. Our studies throw new light on these proteins that appear to be major consumers of NADPH in the cell. The genetic screen is thus predicted to be an exceedingly useful tool for investigating NADPH homeostasis.

Metabolism of Glycolate to Oxalate in Kidney Proximal Tubule Cells

BackgroundExcessive synthesis of oxalate is a hallmark of the inherited kidney stones disease primary hyperoxaluria. Evidence indicates that the liver is the main site of oxalate synthesis but that other tissues may also contribute up to 20%. Glycolate is one of the precursors of oxalate and both plasma and urine glycolate are elevated alongside oxalate in primary hyperoxaluria type 1, the most frequent and severe of PH types. New therapeutic strategies in PH1 further increase glycolate levels by inhibiting a liver‐specific enzyme, hydroxyacid oxidase 1 (HAO1), which catalyzes the oxidation of glycolate to glyoxylate, a precursor of oxalate. To examine whether kidneys contribute to oxalate synthesis, the metabolism of glycolate was studied in human and mouse kidney cell lines and tissue.MethodsTissue culture cells derived from human proximal tubule (HK2 cells) and mouse collecting duct (mIMCD cells) lineages were incubated with 13C2‐labeled glycolate (0 – 10mM) for up to 24 hours. Kidney tissue incubations with 13C2‐glycolate were performed on mouse kidneys and human surgical kidney remnants, by isolating and digesting cortical and medullary tissue fragments. The amount of 13C2‐labeled oxalate synthesized by the cells (and released in the media) was measured by ion chromatography coupled with mass spectrometry and normalized to total cell protein.ResultsMetabolism of glycolate to oxalate was observed in proximal tubule cells (HK2) in as little a time as 3 hours and with concentrations as low as 500 uM in contrast to cells isolated from the medulla and collecting duct (mIMCD). The synthesis of oxalate was also observed in human and mouse kidney cortical tissue but not medullary tissue. The involvement of the intermediate metabolite glyoxylate was suggested by the higher oxalate synthesis observed in the glyoxylate reductase knock‐out mouse model of PH type 2.ConclusionRenal cells, in particular proximal tubule cells, are equipped to metabolize glycolate to glyoxylate and oxalate. The time and dose dependence of glycolate to oxalate metabolism is compatible with an enzymatic pathway. The role of the candidate enzyme hydroxyacid oxidase 2, an isoenzyme of HAO1 and which is expressed in the proximal tubule, is currently being investigated.Support or Funding InformationNIH NIDDK K01DK114332This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.