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Organ specificity and lactate-dehydrogenase activity. Some properties of human spermatozoal lactate dehydrogenase.

ABSTRACT: 1. The presence of a characteristic lactate-dehydrogenase isoenzyme (LD(x)) in human, mouse and dog testis and in human spermatozoa has been confirmed by electrophoresis on cellulose acetate and on polyacrylamide gel. 2. The human spermatozoal isoenzyme exhibits a much higher affinity for 2-oxobutyrate than any of the five isoenzymes found in other tissues. K(m) values of 0.05mm for pyruvate and 0.18mm for 2-oxobutyrate were obtained. 3. LD(x) differs from other lactate-dehydrogenase isoenzymes in that its properties cannot be correlated with its electrophoretic mobility. It resembles LD(1) in being strongly inhibited by 0.2mm-oxalate and relatively resistant to 2m-urea, and in being relatively stable to heat. 4. The surprisingly high activity of LD(x) with 2-oxobutyrate suggests that this substance or 2-hydroxybutyrate may play a part in spermatozoal metabolism.

SUBMITTER: Wilkinson JH

PROVIDER: S-EPMC1264743 | biostudies-other | 1965 Dec

REPOSITORIES: biostudies-other

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ORGAN SPECIFICITY AND LACTATE-DEHYDROGENASE ACTIVITY. DIFFERENTIAL INHIBITION BY UREA AND RELATED COMPOUNDS.

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Lactate dehydrogenase activity drives hair follicle stem cell activation.

Project description:Although normally dormant, hair follicle stem cells (HFSCs) quickly become activated to divide during a new hair cycle. The quiescence of HFSCs is known to be regulated by a number of intrinsic and extrinsic mechanisms. Here we provide several lines of evidence to demonstrate that HFSCs utilize glycolytic metabolism and produce significantly more lactate than other cells in the epidermis. Furthermore, lactate generation appears to be critical for the activation of HFSCs as deletion of lactate dehydrogenase (Ldha) prevented their activation. Conversely, genetically promoting lactate production in HFSCs through mitochondrial pyruvate carrier 1 (Mpc1) deletion accelerated their activation and the hair cycle. Finally, we identify small molecules that increase lactate production by stimulating Myc levels or inhibiting Mpc1 carrier activity and can topically induce the hair cycle. These data suggest that HFSCs maintain a metabolic state that allows them to remain dormant and yet quickly respond to appropriate proliferative stimuli.

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Accelerated Lactate Dehydrogenase Activity Potentiates Osteoclastogenesis via NFATc1 Signaling.

Project description:Osteoclasts seem to be metabolic active during their differentiation and bone-resorptive activation. However, the functional role of lactate dehydrogenase (LDH), a tetrameric enzyme consisting of an A and/or B subunit that catalyzes interconversion of pyruvate to lactate, in RANKL-induced osteoclast differentiation is not known. In this study, RANKL treatment induced gradual gene expression and activation of the LDH A2B2 isotype during osteoclast differentiation as well as the LDH A1B3 and B4 isotypes during osteoclast maturation after pre-osteoclast formation. Glucose consumption and lactate production in growth media were accelerated during osteoclast differentiation, together with enhanced expression of H+-lactate co-transporter and increased extracellular acidification, demonstrating that glycolytic metabolism was stimulated during differentiation. Further, oxygen consumption via mitochondria was stimulated during osteoclast differentiation. On the contrary, depletion of LDH-A or LDH-B subunit suppressed both glycolytic and mitochondrial metabolism, resulting in reduced mature osteoclast formation via decreased osteoclast precursor fusion and down-regulation of the osteoclastogenic critical transcription factor NFATc1 and its target genes. Collectively, our findings suggest that RANKL-induced LDH activation stimulates glycolytic and mitochondrial respiratory metabolism, facilitating mature osteoclast formation via osteoclast precursor fusion and NFATc1 signaling.

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Properties of human testis-specific lactate dehydrogenase expressed from Escherichia coli.

Project description:The cDNA encoding the C4 isoenzyme of lactate dehydrogenase (LDH-C4) was engineered for expression in Escherichia coli. The Ldh-c open reading frame was constructed as a cassette for production of the native protein. The modified Ldh-c cDNA was subcloned into the prokaryotic expression vector pKK223-3. Transformed E. coli cells were grown to mid-exponential phase, and induced with isopropyl beta-D-thiogalactopyranoside for positive regulation of the tac promoter. Induced cells expressed the 35 kDa subunit, which spontaneously formed the enzymically active 140 kDa tetramer. Human LDH-C4 was purified over 200-fold from litre cultures of cells by AMP and oxamate affinity chromatography to a specific activity of 106 units/mg. The enzyme was inhibited by pyruvate concentrations above 0.3 mM, had a Km for pyruvate of 0.03 mM, a turnover number (nmol of NADH oxidized/mol of LDH-C4 per min at 25 degrees C) of 14,000 and was heat-stable.

| S-EPMC1149803 | biostudies-other

Transport-exclusion pharmacology to localize lactate dehydrogenase activity within cells.

Project description:Background:Recent in vitro and in vivo work has shown that lactate provides an important source of carbon for metabolic reactions in cancer cell mitochondria. An interesting question is whether lactate is oxidized by lactate dehydrogenase (LDH) in the cytosol and/or in mitochondria. Since metabolic processes in the cytosol and mitochondria are affected by redox balance, the location of LDH may have important regulatory implications in cancer metabolism. Methods:Within most mammalian cells, metabolic processes are physically separated by membrane-bound compartments. Our general understanding of this spatial organization and its role in cellular function, however, suffers from the limited number of techniques to localize enzymatic activities within a cell. Here, we describe an approach to assess metabolic compartmentalization by monitoring the activity of pharmacological inhibitors that cannot be transported into specific cellular compartments. Results:Oxamate, which chemically resembles pyruvate, is transported into mitochondria and inhibits LDH activity in purified mitochondria. GSK-2837808A, in contrast, is a competitive inhibitor of NAD, which cannot cross the inner mitochondrial membrane. GSK-2837808A did not inhibit the LDH activity of intact mitochondria, but GSK-2837808A did inhibit LDH activity after the inner mitochondrial membrane was disrupted. Conclusions:Our results are consistent with some mitochondrial LDH that is accessible to oxamate, but inaccessible to GSK-2837808A until mitochondria are homogenized. This strategy of using inhibitors with selective access to subcellular compartments, which we refer to as transport-exclusion pharmacology, is broadly applicable to localize other metabolic reactions within cells.

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Increased lactate dehydrogenase activity is dispensable in squamous carcinoma cells of origin

Project description:We sought to determine whether Ldh activity in SCC tumors is a marker of the cell type from which these cells arise, or a key metabolic activity important for tumor initiation or progression. Here we show that genetic abrogation of Ldh enzyme activity in HFSC-mediated tumorigenesis had no effect on tumor number, time to tumor formation, tumor proliferation, epithelial to mesenchymal transition in tumors, gene expression in tumors, tumor pathology, or the immune response to tumors.

2018-12-04 | GSE111997 | GEO

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