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Grimm F, Asuaje A, Jain A, Silva Dos Santos M, Kleinjung J, Nunes PM, Gehrig S, Fets L, Darici S, MacRae JI, Anastasiou D. Metabolic priming by multiple enzyme systems supports glycolysis, HIF1α stabilisation, and human cancer cell survival in early hypoxia. EMBO J 2024; 43:1545-1569. [PMID: 38485816 PMCID: PMC11021510 DOI: 10.1038/s44318-024-00065-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/08/2024] [Accepted: 02/15/2024] [Indexed: 04/18/2024] Open
Abstract
Adaptation to chronic hypoxia occurs through changes in protein expression, which are controlled by hypoxia-inducible factor 1α (HIF1α) and are necessary for cancer cell survival. However, the mechanisms that enable cancer cells to adapt in early hypoxia, before the HIF1α-mediated transcription programme is fully established, remain poorly understood. Here we show in human breast cancer cells, that within 3 h of hypoxia exposure, glycolytic flux increases in a HIF1α-independent manner but is limited by NAD+ availability. Glycolytic ATP maintenance and cell survival in early hypoxia rely on reserve lactate dehydrogenase A capacity as well as the activity of glutamate-oxoglutarate transaminase 1 (GOT1), an enzyme that fuels malate dehydrogenase 1 (MDH1)-derived NAD+. In addition, GOT1 maintains low α-ketoglutarate levels, thereby limiting prolyl hydroxylase activity to promote HIF1α stabilisation in early hypoxia and enable robust HIF1α target gene expression in later hypoxia. Our findings reveal that, in normoxia, multiple enzyme systems maintain cells in a primed state ready to support increased glycolysis and HIF1α stabilisation upon oxygen limitation, until other adaptive processes that require more time are fully established.
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Affiliation(s)
- Fiona Grimm
- Cancer Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Agustín Asuaje
- Cancer Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Aakriti Jain
- Cancer Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Mariana Silva Dos Santos
- Metabolomics Science Technology Platform, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Jens Kleinjung
- Computational Biology Science Technology Platform, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Patrícia M Nunes
- Cancer Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Stefanie Gehrig
- Cancer Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Louise Fets
- Cancer Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Salihanur Darici
- Cancer Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - James I MacRae
- Metabolomics Science Technology Platform, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK
| | - Dimitrios Anastasiou
- Cancer Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT, London, UK.
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Britton S, Alber M, Cannon WR. Enzyme activities predicted by metabolite concentrations and solvent capacity in the cell. J R Soc Interface 2020; 17:20200656. [PMID: 33050777 PMCID: PMC7653389 DOI: 10.1098/rsif.2020.0656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/17/2020] [Indexed: 12/23/2022] Open
Abstract
Experimental measurements or computational model predictions of the post-translational regulation of enzymes needed in a metabolic pathway is a difficult problem. Consequently, regulation is mostly known only for well-studied reactions of central metabolism in various model organisms. In this study, we use two approaches to predict enzyme regulation policies and investigate the hypothesis that regulation is driven by the need to maintain the solvent capacity in the cell. The first predictive method uses a statistical thermodynamics and metabolic control theory framework while the second method is performed using a hybrid optimization-reinforcement learning approach. Efficient regulation schemes were learned from experimental data that either agree with theoretical calculations or result in a higher cell fitness using maximum useful work as a metric. As previously hypothesized, regulation is herein shown to control the concentrations of both immediate and downstream product concentrations at physiological levels. Model predictions provide the following two novel general principles: (1) the regulation itself causes the reactions to be much further from equilibrium instead of the common assumption that highly non-equilibrium reactions are the targets for regulation; and (2) the minimal regulation needed to maintain metabolite levels at physiological concentrations maximizes the free energy dissipation rate instead of preserving a specific energy charge. The resulting energy dissipation rate is an emergent property of regulation which may be represented by a high value of the adenylate energy charge. In addition, the predictions demonstrate that the amount of regulation needed can be minimized if it is applied at the beginning or branch point of a pathway, in agreement with common notions. The approach is demonstrated for three pathways in the central metabolism of E. coli (gluconeogenesis, glycolysis-tricarboxylic acid (TCA) and pentose phosphate-TCA) that each require different regulation schemes. It is shown quantitatively that hexokinase, glucose 6-phosphate dehydrogenase and glyceraldehyde phosphate dehydrogenase, all branch points of pathways, play the largest roles in regulating central metabolism.
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Affiliation(s)
- Samuel Britton
- Department of Mathematics, University of California Riverside, Riverside, CA 92505, USA
- Center for Quantitative Modeling in Biology, University of California Riverside, Riverside, CA 92505, USA
| | - Mark Alber
- Department of Mathematics, University of California Riverside, Riverside, CA 92505, USA
- Center for Quantitative Modeling in Biology, University of California Riverside, Riverside, CA 92505, USA
| | - William R. Cannon
- Department of Mathematics, University of California Riverside, Riverside, CA 92505, USA
- Center for Quantitative Modeling in Biology, University of California Riverside, Riverside, CA 92505, USA
- Physical and Computational Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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Mangiferin Accelerates Glycolysis and Enhances Mitochondrial Bioenergetics. Int J Mol Sci 2018; 19:ijms19010201. [PMID: 29315239 PMCID: PMC5796150 DOI: 10.3390/ijms19010201] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 12/23/2017] [Accepted: 12/27/2017] [Indexed: 01/18/2023] Open
Abstract
One of the main causes of hyperglycemia is inefficient or impaired glucose utilization by skeletal muscle, which can be exacerbated by chronic high caloric intake. Previously, we identified a natural compound, mangiferin (MGF) that improved glucose utilization in high fat diet (HFD)-induced insulin resistant mice. To further identify the molecular mechanisms of MGF action on glucose metabolism, we conducted targeted metabolomics and transcriptomics studies of glycolyic and mitochondrial bioenergetics pathways in skeletal muscle. These data revealed that MGF increased glycolytic metabolites that were further augmented as glycolysis proceeded from the early to the late steps. Consistent with an MGF-stimulation of glycolytic flux there was a concomitant increase in the expression of enzymes catalyzing glycolysis. MGF also increased important metabolites in the tricarboxylic acid (TCA) cycle, such as α-ketoglutarate and fumarate. Interestingly however, there was a reduction in succinate, a metabolite that also feeds into the electron transport chain to produce energy. MGF increased succinate clearance by enhancing the expression and activity of succinate dehydrogenase, leading to increased ATP production. At the transcriptional level, MGF induced mRNAs of mitochondrial genes and their transcriptional factors. Together, these data suggest that MGF upregulates mitochondrial oxidative capacity that likely drives the acceleration of glycolysis flux.
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Metabolic plasticity underpins innate and acquired resistance to LDHA inhibition. Nat Chem Biol 2016; 12:779-86. [PMID: 27479743 DOI: 10.1038/nchembio.2143] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 05/12/2016] [Indexed: 12/31/2022]
Abstract
Metabolic reprogramming in tumors represents a potential therapeutic target. Herein we used shRNA depletion and a novel lactate dehydrogenase (LDHA) inhibitor, GNE-140, to probe the role of LDHA in tumor growth in vitro and in vivo. In MIA PaCa-2 human pancreatic cells, LDHA inhibition rapidly affected global metabolism, although cell death only occurred after 2 d of continuous LDHA inhibition. Pancreatic cell lines that utilize oxidative phosphorylation (OXPHOS) rather than glycolysis were inherently resistant to GNE-140, but could be resensitized to GNE-140 with the OXPHOS inhibitor phenformin. Acquired resistance to GNE-140 was driven by activation of the AMPK-mTOR-S6K signaling pathway, which led to increased OXPHOS, and inhibitors targeting this pathway could prevent resistance. Thus, combining an LDHA inhibitor with compounds targeting the mitochondrial or AMPK-S6K signaling axis may not only broaden the clinical utility of LDHA inhibitors beyond glycolytically dependent tumors but also reduce the emergence of resistance to LDHA inhibition.
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Fuentes L, Muñoz EM, Aguilera Merlo C, Dominguez S, Scardapane L, Piezzi RS. Bilateral Enucleation and Captivity Influence the Reproductive Cycle of Male Viscacha (Lagostomus maximus maximus). Physiol Biochem Zool 2004; 77:321-31. [PMID: 15095252 DOI: 10.1086/378922] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2003] [Indexed: 11/03/2022]
Abstract
The viscacha (Lagostomus maximus maximus) is a seasonal rodent living in the Southern Hemisphere. The adult males exhibit an annual reproductive cycle characterized by a gonadal regression period during winter. In this study, we investigated the effects of bilateral enucleation and captivity on their annual reproductive cycle. Testicular volume relative to body weight was recorded monthly in intact and bilaterally enucleated animals placed under natural photoperiod, water, and food ad lib. and constant temperature. Testes and accessory organs were evaluated by qualitative and quantitative light microscopic studies. The intact animals showed an annual reproductive cycle with complete gonadal atrophy in the first year. In the second year, testicular regression was observed but attenuated in regard to that recorded in the first winter period, indicating that adaptive changes might be involved. Bilateral enucleation in the viscacha dampened and extended the period of its annual reproductive cycle. The results suggest that both conditions, constant captivity and enucleation, produced stimulatory effects on the reproductive system of this rodent. Furthermore, local control mechanisms might be responsible for the morphological differences observed in testes, epididymis, and seminal vesicles from both groups, which exhibited similar levels of serum testosterone. Finally, an intact retinohypothalamic-pineal axis and/or photoperiodic input would be necessary to maintain the reproductive cycle amplitude and timing in viscacha.
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Affiliation(s)
- Lucía Fuentes
- Area de Farmacología y Toxicología, Universidad Nacional de San Luis, 5700 San Luis, Argentina.
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Malpaux B, Migaud M, Tricoire H, Chemineau P. Biology of mammalian photoperiodism and the critical role of the pineal gland and melatonin. J Biol Rhythms 2001; 16:336-47. [PMID: 11506379 DOI: 10.1177/074873001129002051] [Citation(s) in RCA: 248] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In mammals, photoperiodic information is transformed into a melatonin secretory rhythm in the pineal gland (high levels at night, low levels during the day). Melatonin exerts its effects in discrete hypothalamic areas, most likely through MT1 melatonin receptors. Whether melatonin is brought to the hypothalamus from the cerebrospinal fluid or the blood is still unclear. The final action of this indoleamine at the level of the central nervous system is a modulation of GnRH secretion but it does not act directly on GnRH neurones; rather, its action involves a complex neural circuit of interneurones that includes at least dopaminergic, serotoninergic and aminoacidergic neurones. In addition, this network appears to undergo morphological changes between seasons.
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Affiliation(s)
- B Malpaux
- UMR 6073 INRA-CNRS-Université François Rabelais, Physiologie de la Reproduction et des Comportements, Nouzilly, France.
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Hiebert SM, Thomas EM, Lee TM, Pelz KM, Yellon SM, Zucker I. Photic entrainment of circannual rhythms in golden-mantled ground squirrels: role of the pineal gland. J Biol Rhythms 2000; 15:126-34. [PMID: 10762031 DOI: 10.1177/074873040001500207] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Entrainment of circannual rhythms of body mass and reproduction was monitored for 3 years in female golden-mantled ground squirrels maintained in a simulated natural photoperiod. Both pinealectomized and pineal-intact squirrels generated circannual rhythms of body mass and estrus, but only the intact animals entrained these rhythms to a period of 365 days. In the second and third years after treatment, the period of the body mass rhythm was significantly shorter than 365 days for pinealectomized squirrels, and variance in tau among these animals was significantly greater than for intact squirrels. A similar pattern was evident in the rhythm of reproduction, which was phase-disrupted in pinealectomized squirrels but entrained in intacts. Seasonal changes in duration of nocturnal melatonin secretion by the pineal appear to be necessary to produce phase-delays required to entrain the circannual clock to a period of 12 months.
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Affiliation(s)
- S M Hiebert
- Department of Biology, Swarthmore College, PA 19081, USA
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10
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Laychock SG. Modulation of glyceraldehyde 3-phosphate dehydrogenase activity in isolated pancreatic islets. Biochem Pharmacol 1996; 52:793-9. [PMID: 8765477 DOI: 10.1016/0006-2952(96)00391-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Culture of isolated rat islets at either 5.5 or 11 mM glucose for up to 6 days was associated with significant time-dependent increases in glyceraldehyde 3-phosphate dehydrogenase (G3PD) activity of islet homogenates compared with freshly isolated islet G3PD activity. In addition, after 6 days of culture of islets at 11 mM glucose, there was a significant increase in G3PD activity compared with the enzyme activity of islets cultured at 5.5 mM glucose. Culture of islets at 5.5 mM glucose for 2 days in the presence of forskolin, 3-isobutylmethylxanthine (IBMX), and 8-bromo-cyclic AMP also significantly increased G3PD activity compared with control islets, although there was no change in enzyme activity after only 1 day of culture with forskolin. Treatment with forskolin was associated with an increase in the Vmax of G3PD, but no change was observed in the apparent K(m) with NAD. IBMX and 8-bromo-cyclic AMP also increased G3PD activity in islets cultured at 11 mM glucose for 2 days. 8-Bromo-cyclic AMP did not affect or inhibit G3PD activity when added directly to islet homogenates. Islets cultured with 8-bromo-cyclic GMP for 2 days at 5.5 or 11 mM glucose did not show changes in G3PD activity. Increases in G3PD activity did not correlate with significant changes in islet glucose utilization. Thus, G3PD activity is modulated by the duration of glucose stimulation in cultured islets, and cyclic AMP may mediate changes in G3PD activity in islet cells.
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Affiliation(s)
- S G Laychock
- Department of Pharmacology, and Toxicology, State University of New York at Buffalo 14214, USA.
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11
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Masson-Pévet M, Naimi F, Canguilhem B, Saboureau M, Bonn D, Pévet P. Are the annual reproductive and body weight rhythms in the male European hamster (Cricetus cricetus) dependent upon a photoperiodically entrained circannual clock? J Pineal Res 1994; 17:151-63. [PMID: 7722865 DOI: 10.1111/j.1600-079x.1994.tb00127.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Most of the data obtained so far on the European hamster (Cricetus cricetus) suggest direct photoperiodically driven seasonal changes in sexual activity and body weight. The results of the present long-term study support the hypothesis that these annual changes are the expression of photoperiodically driven endogenous circannual rhythms. When subjected following capture (April-May) to constant conditions of long photoperiod (LP) and constant temperature a large number of the European hamsters present, in September-December, complete gonadal atrophy associated with a decrease in body weight. A sexual reactivation as well as an increase in body weight are observed in the same animals between January and April. Of the six animals that survived long enough, two only presented partial gonadal atrophy during the second year. These observations clearly demonstrate that the decline in sexual activity in subjective autumn does not require a decrease in photoperiod, at least in the first year. Theoretically, the observed rhythms, if circannual in nature, would be generated by a self-sustained annual oscillator (circannual clock) able to function in the absence of a photoperiodic input. Pinealectomy makes animals unable to detect or measure photoperiodic information. Of the six European hamsters tested (pinealectomized in June and then kept continuously under LP), five showed clear annual rhythms in body weight and reproductive capacities for two consecutive years. Clearly endogenous annual rhythms were expressed in these conditions. To be entrained to a 1-year period, such a circannual clock should, however, be able to react to either LP and/or to short-photoperiod (SP), at least at certain periods of the annual cycle. In animals exposed to LP in August or October, after gonadal atrophy had been established by exposure to natural SP, gonadal regrowth started in December or January, about 2 to 3 months earlier than in animals kept outside or in experimental SP. With the same experimental conditions, exactly the same results were obtained in pinealectomized animals; thus stimulatory effect of LP or LP-induced phase advance of the circannual clock can be excluded. The absence of the SP information would then induce such reaction. In animals kept under constant LP and temperature following capture, however, pinealectomy in January--when all animals are sexually active--induces gonadal atrophy within--weeks. This clearly demonstrates that LP is stimulatory at this time of the subjective year.
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Affiliation(s)
- M Masson-Pévet
- Neurobiologie des fonctions rythmiques et saisonnières, Université Louis Pasteur, Strasbourg, France
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Tao Y, Howlett A, Klein C. Nitric oxide regulation of glyceraldehyde-3-phosphate dehydrogenase activity in Dictyostelium discoideum cells and lysates. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 224:447-54. [PMID: 7925359 DOI: 10.1111/j.1432-1033.1994.00447.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The ability of compounds releasing nitric oxide (NO) to regulate glyceraldehyde-3-phosphate dehydrogenase (GraPDH) activity was analysed both in cell homogenates and in intact Dictyostelium discoideum. The time course of GraPDH inactivation in cell lysates by NO-releasing compounds suggests that two processes may be involved, one of which accounts for the majority of the inactivation and shows a close correlation with GraPDH ADP-ribosylation. Maximal ADP-ribosylation under these conditions exhibited a stoichiometry of about 0.4 mol ADP-ribose/mol enzyme tetramer. NO-mediated inhibition of GraPDH activity was attenuated if specific substrates, cofactors, or cysteine were added to cytosol preparations. Under such conditions, ADP-ribosylation of the enzyme was correspondingly reduced or negligible. Intact cells treated with NO-releasing compounds were shown to respond by rapidly decreasing their GraPDH activity. This inhibition was transient and, after a 10-min incubation, enzyme activity returned to the level seen in control cells. The time course of these in vivo changes correlated well with those of the NO-stimulated ADP-ribosylation of GraPDH also seen in intact cells. The basis underlying the NO-stimulated inhibition of GraPDH activity was investigated and found to reflect a decreased Vmax. No changes in either the Km of the enzyme for its substrates or its state of polymerization were observed.
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Affiliation(s)
- Y Tao
- E. A. Doisy Department of Biochemistry and Molecular Biology, St Louis University School of Medicine, MO 63104
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Tao Y, Howlett AC, Klein C. Endogenous ADP-ribosylation of glyceraldehyde-3-phosphate dehydrogenase that is not regulated by nitric oxide in Dictyostelium discoideum. Cell Signal 1993; 5:763-75. [PMID: 7907497 DOI: 10.1016/0898-6568(93)90037-m] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A 41,000 M(r) cytosolic protein (p41) in Dictyostelium discoideum was shown to be modified by ADP-ribosylation that was not regulated by nitric oxide (NO). This endogenous ADP-ribosylation was optimal at conditions distinct from those optimal for the NO-stimulated ADP-ribosylation of p41. These two activities were also differentially sensitive to reducing agents and modified different amino acids. The addition of haemoglobin, which sequesters NO, and of NO synthase inhibitors failed to block the endogenous ADP-ribosylation. P41 was purified to homogeneity. The N-terminal sequence of the purified protein was shown to be highly homologous to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Both endogenous and NO-stimulated activities ADP-ribosylated three isoforms of the protein, with pI values of 6.6, 6.8 and 7.0. In each case, the isoform with pI 6.8 was preferentially modified. Experiments using purified GAPDH indicate that both the endogenous and NO-stimulated ADP-ribosylation are self-catalysed modifications.
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Affiliation(s)
- Y Tao
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, MO 63104
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15
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Lee TM, Zucker I. Suprachiasmatic nucleus and photic entrainment of circannual rhythms in ground squirrels. J Biol Rhythms 1991; 6:315-30. [PMID: 1773098 DOI: 10.1177/074873049100600403] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The efficacy of photoperiod as a zeitgeber for entrainment of circannual body weight and estrous rhythms was tested in female golden-mantled ground squirrels maintained for 3 or more years in either a simulated natural photoperiod (SNP) or a fixed LD 14:10 photoperiod (FP). The role of the retinohypothalamic tract--suprachiasmatic nucleus (RHT-SCN) projection in photic entrainment was assessed in animals that sustained destruction of the SCN (SCNX). Circannual rhythms were lengthened by the SNP as compared to the FP. Mean periods (tau's) for neurologically intact animals in the third year of testing were 49.6 +/- 0.3 weeks and 43.1 +/- 1.2 weeks (p less than 0.001) for the SNP and FP groups, respectively; furthermore, 56% and 7% of animals in these groups had tau's not significantly different from 365 days (p less than 0.005), and within-group variability was lower for SNP than for FP squirrels (p less than 0.01). SCNX squirrels differed from animals with the SCN intact (SCNC), as evidenced by higher within-group variability (p less than 0.001); only 29% of SCNX squirrels had tau's not different from 365 days (p less than 0.03 compared to the SCNC group). The coupling between estrous and body weight rhythms that was evident in SCN-intact SNP and FP squirrels was disrupted in SCNX animals. The RHT-SCN pathway is implicated in entrainment and in maintenance of normal phase relations among the several circannual rhythms. In a second experiment, female squirrels were maintained for 2.5 years in an accelerated SNP that compressed two normal annual photocycles into each calendar year. Of 12 squirrels, 3 had tau's that did not differ significantly from 6 months; 6 had tau's equivalent to 12 months; and 3 had tau's significantly different from both 6 months and 12 months. The data suggest that photoperiod is a major zeitgeber for entrainment of golden-mantled ground squirrels circannual rhythms.
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Affiliation(s)
- T M Lee
- Department of Psychology, University of California, Berkeley 94720
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Barnes BM, York AD. Effect of winter high temperatures on reproduction and circannual rhythms in hibernating ground squirrels. J Biol Rhythms 1990; 5:119-30. [PMID: 2133122 DOI: 10.1177/074873049000500204] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We tested whether prevention of hibernation in ground squirrels by midwinter exposure to high ambient temperatures influenced timing of the spring phase of reproductive maturation and the phase and period of subsequent circannual rhythms of reproduction and body mass. Exposing hibernating adult male Spermophilus lateralis to 30 degrees C for 6 weeks beginning December 4 advanced the timing of testicular recrudescence by 4-5 weeks, compared to controls left at 4 degrees C. Males exposed to 30 degrees C for 6 weeks beginning at the average time of spontaneous end of hibernation (January 15) reached reproductive maturation at a time intermediate to those of controls and of the December 4 experimental group. However, neither the date of the subsequent fall's body mass peak, the date of the next year's reproductive maturation, nor the periods of circannual rhythms of body mass and reproduction differed among groups. Premature interruption of hibernation appears to allow early expression of reproduction, but does not affect the underlying timing mechanism.
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Affiliation(s)
- B M Barnes
- Institute of Arctic Biology, University of Alaska, Fairbanks 99775-0180
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Aithal HN, Knigge KM, Kartha S, Czyzewski EA, Toback FG. An alternate method utilizing small quantities of ligand for affinity purification of monospecific antibodies. J Immunol Methods 1988; 112:63-9. [PMID: 3403990 DOI: 10.1016/0022-1759(88)90034-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
An alternate method was designed to couple a limited quantity of protein to an affinity support when a conventional technique was unsuccessful. This was achieved through the introduction of a small number of sulfhydryl groups to the ligand by reaction with 2-iminothiolane which resulted in a limited number of reactive sites on the protein. Amino groups on an AH-Sepharose 4B matrix were linked to sulfhydryl groups on the ligand using the heterobifunctional agent m-maleimidobenzoyl sulfosuccinimide ester (sulfo-MBS). This method was employed to prepare an affinity support using a cytosolic protein that activates glyceraldehyde-3-phosphate dehydrogenase as a ligand. Monospecific antibody purified from the affinity column recognized only this protein on a Western blot of a cytosolic extract of kidney epithelial cells.
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Affiliation(s)
- H N Aithal
- Department of Medicine, University of Chicago, IL 60637
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Affiliation(s)
- I Zucker
- Department of Psychology, University of California, Berkeley 94720
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19
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Allen RW, Trach KA, Hoch JA. Identification of the 37-kDa protein displaying a variable interaction with the erythroid cell membrane as glyceraldehyde-3-phosphate dehydrogenase. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75833-5] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Carmichael MS, Zucker I. Circannual rhythms of ground squirrels: a test of the frequency demultiplication hypothesis. J Biol Rhythms 1986; 1:277-84. [PMID: 2979590 DOI: 10.1177/074873048600100402] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The frequency demultiplication hypothesis (FDH) posits that circannual rhythms are generated from circadian cycles by frequency transformation to the lower-frequency rhythm. To test the FDH, we determined the periods of the circannual body mass and estrous cycles of golden-mantled ground squirrels with circadian locomotor activity rhythms entrained to 23-, 24-, or 25-hr days (T-cycles). Circannual period length did not differ among squirrels entrained to the different T-cycles; intergroup ranges were 298-314 days and 303-312 days, respectively, for body mass and estrus. These results are not consistent with the FDH and suggest instead that separate mechanisms generate circadian and circannual rhythms. In ground squirrels the circannual system influences circadian organization, but a reciprocal influence of circadian on circannual rhythms has yet to be demonstrated.
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Affiliation(s)
- M S Carmichael
- Department of Psychology, University of California, Berkeley 94720
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Dark J, Zucker I. Circannual rhythms of ground squirrels: role of the hypothalamic paraventricular nucleus. J Biol Rhythms 1986; 1:17-23. [PMID: 2979572 DOI: 10.1177/074873048600100104] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Female golden-mantled ground squirrels, maintained in an LD 14:10 photoperiod at 23 degrees C, sustained lesions of the paraventricular nucleus (PVN) or sham operations. Body weight and reproductive status were recorded weekly pre- and postoperatively. Bilateral lesions of the PVN did not eliminate, phase-shift, or otherwise disrupt the circannual rhythms of body mass or reproduction. Absolute levels of body weight were unaffected by PVN ablation. The PVN is not an essential component of the oscillatory system that generates circannual cycles in ground squirrels.
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Affiliation(s)
- J Dark
- Department of Psychology, University of California, Berkeley 94720
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