[en] Energy transduction is central to living organisms, but the impact of enzyme regulation and signaling on its thermodynamic efficiency is generally overlooked. Here, we analyze the efficiency of ATP production by the tricarboxylic acid cycle and oxidative phosphorylation, which generate most of the chemical energy in eukaryotes. Calcium signaling regulates this pathway and can affect its energetic output, but the concrete energetic impact of this cross-talk remains elusive. Calcium enhances ATP production by activating key enzymes of the tricarboxylic acid cycle while calcium homeostasis is ATP-dependent. We propose a detailed kinetic model describing the calcium-mitochondria cross-talk and analyze it using nonequilibrium thermodynamics: after identifying the effective reactions driving mitochondrial metabolism out of equilibrium, we quantify the mitochondrial thermodynamic efficiency for different conditions. Calcium oscillations, triggered by extracellular stimulation or energy deficiency, boost the thermodynamic efficiency of mitochondrial metabolism, suggesting a compensatory role of calcium signaling in mitochondrial bioenergetics.
Disciplines :
Physique, chimie, mathématiques & sciences de la terre: Multidisciplinaire, généralités & autres
Auteur, co-auteur :
VOORSLUIJS, Valerie ; University of Luxembourg > Luxembourg Centre for Systems Biomedicine (LCSB) > Integrative Cell Signalling
AVANZINI, Francesco ; University of Luxembourg > Faculty of Science, Technology and Medicine > Department of Physics and Materials Science > Team Massimiliano ESPOSITO ; Department of Chemical Sciences, University of Padova, 1 Via F. Marzolo, 35131 Padova, Italy
FALASCO, Gianmaria ; University of Luxembourg > Faculty of Science, Technology and Medicine > Department of Physics and Materials Science > Team Massimiliano ESPOSITO ; Department of Physics and Astronomy, University of Padova, 8 Via F. Marzolo, 35131 Padova, Italy
ESPOSITO, Massimiliano ; University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)
SKUPIN, Alexander ; University of Luxembourg > Luxembourg Centre for Systems Biomedicine (LCSB) > Integrative Cell Signalling ; Department of Neuroscience, University of California, San Diego, 9500 Gilman Drive, San Diego, CA 92093, USA
Co-auteurs externes :
yes
Langue du document :
Anglais
Titre :
Calcium oscillations optimize the energetic efficiency of mitochondrial metabolism.
V.V. is funded by the Complex Living Systems Initiative at the University of Luxembourg . F.A. and M.E. are funded by the Luxembourg National Research Fund , grant ChemComplex ( C21/MS/16356329 ). G.F. is funded by the European Union – NextGenerationEU – and by the program STARS@UNIPD with project “ThermoComplex”. F.A., A.S., and M.E. acknowledge financial support of the Institute for Advanced Studies of the University of Luxembourg through an Audacity Grant ( IDAE-2020 ). The experiments presented in this paper were carried out using the HPC facilities of the University of Luxembourg 84 – see hpc.uni.lu .
Calisto, F., Sousa, F.M., Sena, F.V., Refojo, P.N., Pereira, M.M., Mechanisms of Energy Transduction by Charge Translocating Membrane Proteins. Chem. Rev. 121 (2021), 1804–1844, 10.1021/acs.chemrev.0c00830.
Berman, M.C., Slippage and uncoupling in P-type cation pumps; implications for energy transduction mechanisms and regulation of metabolism. BBA 1513 (2001), 95–121, 10.1016/S0005-2736(01)00356-X.
Rubi, J.M., Naspreda, M., Kjelstrup, S., Bedeaux, D., Energy Transduction in Biological Systems: A Mesoscopic Non-Equilibrium Thermodynamics Perspective. J. Non-Equilib. Thermodyn. 32 (2007), 351–378, 10.1515/JNETDY.2007.027.
Hill, T.L., Free Energy Transduction in Biology: The Steady-State Kinetic and Thermodynamic Formalism. 2012, Academic Press.
Wikström, M., Springett, R., Thermodynamic efficiency, reversibility, and degree of coupling in energy conservation by the mitochondrial respiratory chain. Commun. Biol. 3 (2020), 451–459, 10.1038/s42003-020-01192-w.
Yang, X., Heinemann, M., Howard, J., Huber, G., Iyer-Biswas, S., Le Treut, G., Lynch, M., Montooth, K.L., Needleman, D.J., Pigolotti, S., et al. Physical bioenergetics: Energy fluxes, budgets, and constraints in cells. Proc. Natl. Acad. Sci. USA, 118, 2021, 10.1073/pnas.2026786118 e2026786118.
Estrada, J., Wong, F., DePace, A., Gunawardena, J., Information Integration and Energy Expenditure in Gene Regulation. Cell 166 (2016), 234–244, 10.1016/j.cell.2016.06.012.
Goloubinoff, P., Sassi, A.S., Fauvet, B., Barducci, A., De Los Rios, P., Chaperones convert the energy from ATP into the nonequilibrium stabilization of native proteins. Nat. Chem. Biol. 14 (2018), 388–395, 10.1038/s41589-018-0013-8.
Flamholz, A., Noor, E., Bar-Even, A., Liebermeister, W., Milo, R., Glycolytic strategy as a tradeoff between energy yield and protein cost. Proc. Natl. Acad. Sci. USA 110 (2013), 10039–10044, 10.1073/pnas.1215283110.
Cao, Y., Wang, H., Ouyang, Q., Tu, Y., The free-energy cost of accurate biochemical oscillations. Nat. Phys. 11 (2015), 772–778, 10.1038/nphys3412.
Rodenfels, J., Neugebauer, K.M., Howard, J., Heat Oscillations Driven by the Embryonic Cell Cycle Reveal the Energetic Costs of Signaling. Dev. Cell 48 (2019), 646–658.e6, 10.1016/j.devcel.2018.12.024.
Wachtel, A., Rao, R., Esposito, M., Free-energy transduction in chemical reaction networks: From enzymes to metabolism. J. Chem. Phys., 157, 2022, 024109, 10.1063/5.0091035.
Berridge, M.J., Bootman, M.D., Lipp, P., Calcium–a life and death signal. Nature 395 (1998), 645–648, 10.1038/27094.
Berridge, M.J., Lipp, P., Bootman, M.D., The versatility and universality of calcium signalling. Nat. Rev. Mol. Cell Biol. 1 (2000), 11–21, 10.1038/35036035.
Dupont, G., Combettes, L., Fine tuning of cytosolic Ca 2+ oscillations. F1000Res., 5, 2016, 10.12688/f1000research.8438.1 F1000 Faculty Rev-2036.
McCormack, J.G., Characterization of the effects of Ca2+ on the intramitochondrial Ca2+-sensitive enzymes from rat liver and within intact rat liver mitochondria. Biochem. J. 231 (1985), 581–595, 10.1042/bj2310581.
Hajnóczky, G., Robb-Gaspers, L.D., Seitz, M.B., Thomas, A.P., Decoding of cytosolic calcium oscillations in the mitochondria. Cell 82 (1995), 415–424, 10.1016/0092-8674(95)90430-1.
Griffiths, E.J., Rutter, G.A., Mitochondrial calcium as a key regulator of mitochondrial ATP production in mammalian cells. Biochim. Biophys. Acta 1787 (2009), 1324–1333, 10.1016/j.bbabio.2009.01.019.
Denton, R.M., Regulation of mitochondrial dehydrogenases by calcium ions. BBA 1787 (2009), 1309–1316, 10.1016/j.bbabio.2009.01.005.
Dudycha, S., A Detailed Model of the Tricarboxylic Acid Cycle in Heart Cells. 2000.
Berndt, N., Kann, O., Holzhütter, H.G., Physiology-based kinetic modeling of neuronal energy metabolism unravels the molecular basis of NAD(P)H fluorescence transients. J. Cerebr. Blood Flow Metabol. 35 (2015), 1494–1506, 10.1038/jcbfm.2015.70.
Komin, N., Moein, M., Ellisman, M.H., Skupin, A., Multiscale Modeling Indicates That Temperature Dependent [Ca2+]i Spiking in Astrocytes Is Quantitatively Consistent with Modulated SERCA Activity. Neural Plast., 2015, 2015, 683490, 10.1155/2015/683490.
Wacquier, B., Combettes, L., Van Nhieu, G.T., Dupont, G., Interplay Between Intracellular Ca Oscillations and Ca-stimulated Mitochondrial Metabolism. Sci. Rep., 6, 2016, 19316, 10.1038/srep19316.
Robinson, P.J.J., Fairall, L., Huynh, V.A.T., Rhodes, D., EM measurements define the dimensions of the « 30-nm » chromatin fiber: Evidence for a compact, interdigitated structure. Proc. Natl. Acad. Sci. USA 103 (2006), 6506–6511, 10.1073/pnas.0601212103.
Flamholz, A., Noor, E., Bar-Even, A., Milo, R., eQuilibrator—the biochemical thermodynamics calculator. Nucleic Acids Res. 40 (2012), D770–D775, 10.1093/nar/gkr874.
Magnus, G., Keizer, J., Minimal model of beta-cell mitochondrial Ca2+ handling. Am. J. Physiol. 273 (1997), C717–C733, 10.1152/ajpcell.1997.273.2.C717.
Magnus, G., Keizer, J., Model of beta-cell mitochondrial calcium handling and electrical activity. I. Cytoplasmic variables. Am. J. Physiol. 274 (1998), C1158–C1173, 10.1152/ajpcell.1998.274.4.C1158.
Magnus, G., Keizer, J., Model of beta-cell mitochondrial calcium handling and electrical activity. II. Mitochondrial variables. Am. J. Physiol. 274 (1998), C1174–C1184, 10.1152/ajpcell.1998.274.4.C1174.
Cortassa, S., Aon, M.A., Marbán, E., Winslow, R.L., et O'Rourke, B., An integrated model of cardiac mitochondrial energy metabolism and calcium dynamics. Biophys. J. 84 (2003), 2734–2755, 10.1016/S0006-3495(03)75079-6.
Bertram, R., Gram Pedersen, M., Luciani, D.S., Sherman, A., A simplified model for mitochondrial ATP production. J. Theor. Biol. 243 (2006), 575–586, 10.1016/j.jtbi.2006.07.019.
Wei, A.-C., Aon, M.A., O'Rourke, B., Winslow, R.L., Cortassa, S., Mitochondrial Energetics, pH Regulation, and Ion Dynamics: A Computational-Experimental Approach. Biophys. J. 100 (2011), 2894–2903, 10.1016/j.bpj.2011.05.027.
Moein, M., Dissecting the Crosstalk between Intracellular Calcium Signalling and Mitochondrial Metabolism. 2017.
Rao, R., Esposito, M., Nonequilibrium Thermodynamics of Chemical Reaction Networks: Wisdom from Stochastic Thermodynamics. Phys. Rev. X, 6, 2016, 041064, 10.1103/PhysRevX.6.041064.
Rao, R., Esposito, M., Conservation laws and work fluctuation relations in chemical reaction networks. J. Chem. Phys., 149, 2018, 245101, 10.1063/1.5042253.
Wachtel, A., Rao, R., Esposito, M., Thermodynamically consistent coarse graining of biocatalysts beyond Michaelis–Menten. New J. Phys., 20, 2018, 042002, 10.1088/1367-2630/aab5c9.
Avanzini, F., Falasco, G., Esposito, M., Thermodynamics of non-elementary chemical reaction networks. New J. Phys., 22, 2020, 093040, 10.1088/1367-2630/abafea.
Avanzini, F., Penocchio, E., Falasco, G., Esposito, M., Nonequilibrium thermodynamics of non-ideal chemical reaction networks. J. Chem. Phys., 154, 2021, 094114, 10.1063/5.0041225.
Avanzini, F., Esposito, M., Thermodynamics of concentration vs flux control in chemical reaction networks. J. Chem. Phys., 156, 2022, 014116, 10.1063/5.0076134.
Avanzini, F., Freitas, N., Esposito, M., Circuit Theory for Chemical Reaction Networks. Phys. Rev. X, 13, 2023, 021041, 10.1103/PhysRevX.13.021041.
Ronowska, A., Szutowicz, A., Bielarczyk, H., Gul-Hinc, S., Klimaszewska-Łata, J., Dyś, A., Zyśk, M., Jankowska-Kulawy, A., The Regulatory Effects of Acetyl-CoA Distribution in the Healthy and Diseased Brain. Front. Cell. Neurosci., 12, 2018, 169.
Oura, T., Murata, K., Morita, T., Nezu, A., Arisawa, M., Shuto, S., Tanimura, A., Highly Sensitive Measurement of Inositol 1,4,5-Trisphosphate by Using a New Fluorescent Ligand and Ligand Binding Domain Combination. Chembiochem 17 (2016), 1509–1512, 10.1002/cbic.201600096.
Larcombe-McDouall, J., Buttell, N., Harrison, N., Wray, S., In vivo pH and metabolite changes during a single contraction in rat uterine smooth muscle. J. Physiol. 518 (1999), 783–790, 10.1111/j.1469-7793.1999.0783p.x.
Gribble, F.M., Loussouarn, G., Tucker, S.J., Zhao, C., Nichols, C.G., Ashcroft, F.M., A Novel Method for Measurement of Submembrane ATP Concentration. J. Biol. Chem. 275 (2000), 30046–30049, 10.1074/jbc.M001010200.
Mei, M., Mu, L., Wang, Y., Liang, S., Zhao, Q., Huang, L., She, G., Shi, W., Simultaneous Monitoring of the Adenosine Triphosphate Levels in the Cytoplasm and Nucleus of a Single Cell with a Single Nanowire-Based Fluorescent Biosensor. Anal. Chem. 94 (2022), 11813–11820, 10.1021/acs.analchem.2c02030.
Falcke, M., Reading the patterns in living cells —the physics of ca2+ signaling. Adv. Phys. X. 53 (2004), 255–440, 10.1080/00018730410001703159.
Dupont, G., Combettes, L., Leybaert, L., Calcium dynamics: spatio-temporal organization from the subcellular to the organ level. Int. Rev. Cytol. 261 (2007), 193–245, 10.1016/S0074-7696(07)61005-5.
Thurley, K., Tovey, S.C., Moenke, G., Prince, V.L., Meena, A., Thomas, A.P., Skupin, A., Taylor, C.W., Falcke, M., Reliable Encoding of Stimulus Intensities Within Random Sequences of Intracellular Ca2+ Spikes. Sci. Signal., 7, 2014, ra59, 10.1126/scisignal.2005237.
Jouaville, L.S., Ichas, F., Holmuhamedov, E.L., Camacho, P., Lechleiter, J.D., Synchronization of calcium waves by mitochondrial substrates in Xenopus laevis oocytes. Nature 377 (1995), 438–441, 10.1038/377438a0.
Boitier, E., Rea, R., Duchen, M.R., Mitochondria Exert a Negative Feedback on the Propagation of Intracellular Ca2+ Waves in Rat Cortical Astrocytes. J. Cell Biol. 145 (1999), 795–808, 10.1083/jcb.145.4.795.
Duchen, M.R., Mitochondria and calcium: from cell signalling to cell death. J. Physiol. 529 (2000), 57–68, 10.1111/j.1469-7793.2000.00057.x.
Wu, F., Yang, F., Vinnakota, K.C., Beard, D.A., Computer Modeling of Mitochondrial Tricarboxylic Acid Cycle, Oxidative Phosphorylation, Metabolite Transport, and Electrophysiology. J. Biol. Chem. 282 (2007), 24525–24537, 10.1074/jbc.M701024200.
Siess, E.A., Brocks, D.G., Wieland, O.H., Subcellular distribution of key metabolites in isolated liver cells from fasted rats. FEBS Lett. 69 (1976), 265–271, 10.1016/0014-5793(76)80701-6.
Lund, P., Wiggins, D., The matrix water space of mitochondria in situ in isolated hepatocytes. Biosci. Rep. 7 (1987), 59–66, 10.1007/BF01122728.
Buckler, K.J., Vaughan-Jones, R.D., Application of a new pH-sensitive fluoroprobe (carboxy-SNARF-1) for intracellular pH measurement in small, isolated cells. Pflügers Archiv 417 (1990), 234–239, 10.1007/BF00370705.
Scofano, H.M., Vieyra, A., de Meis, L., Substrate regulation of the sarcoplasmic reticulum ATPase. Transient kinetic studies. J. Biol. Chem. 254 (1979), 10227–10231, 10.1016/S0021-9258(19)86697-8.
Dupont, G., Erneux, C., Simulations of the effects of inositol 1,4,5-trisphosphate 3-kinase and 5-phosphatase activities on Ca2+ oscillations. Cell Calcium 22 (1997), 321–331, 10.1016/S0143-4160(97)90017-8.
Pietrobon, D., Caplan, S.R., Flow-force relationships for a six-state proton pump model: intrinsic uncoupling, kinetic equivalence of input and output forces, and domain of approximate linearity. Biochemistry 24 (1985), 5764–5776, 10.1021/bi00342a012.
Matsuoka, Y., Srere, P.A., Kinetic Studies of Citrate Synthase from Rat Kidney and Rat Brain. J. Biol. Chem. 248 (1973), 8022–8030, 10.1016/S0021-9258(19)43188-8.
Kurz, L.C., Shah, S., Frieden, C., Nakra, T., Stein, R.E., Drysdale, G.R., Evans, C.T., Srere, P.A., Catalytic strategy of citrate synthase: subunit interactions revealed as a consequence of a single amino acid change in the oxaloacetate binding site. Biochemistry 34 (1995), 13278–13288, 10.1021/bi00041a003.
Donoso, P., Mill, J.G., O'Neill, S.C., Eisner, D.A., Fluorescence measurements of cytoplasmic and mitochondrial sodium concentration in rat ventricular myocytes. J. Physiol. 448 (1992), 493–509, 10.1113/jphysiol.1992.sp019053.
Beard, D.A., A Biophysical Model of the Mitochondrial Respiratory System and Oxidative Phosphorylation. PLoS Comput. Biol., 1, 2005, e36, 10.1371/journal.pcbi.0010036.
Bevington, A., Mundy, K.I., Yates, A.J., Kanis, J.A., Russell, R.G., Taylor, D.J., Rajagopalan, B., Radda, G.K., A study of intracellular orthophosphate concentration in human muscle and erythrocytes by 31P nuclear magnetic resonance spectroscopy and selective chemical assay. Clin. Sci. 71 (1986), 729–735, 10.1042/cs0710729.
Eisner, D.A., Valdeolmillos, M., A study of intracellular calcium oscillations in sheep cardiac Purkinje fibres measured at the single cell level. J. Physiol. 372 (1986), 539–556, 10.1113/jphysiol.1986.sp016024.
Baiesi, M., Maes, C., Life efficiency does not always increase with the dissipation rate. J. Phys. Commun., 2, 2018, 045017, 10.1088/2399-6528/aab654.
Beard, D.A., Liang, S.d., Qian, H., Energy Balance for Analysis of Complex Metabolic Networks. Biophys. J. 83 (2002), 79–86, 10.1016/S0006-3495(02)75150-3.
Niebel, B., Leupold, S., Heinemann, M., An upper limit on Gibbs energy dissipation governs cellular metabolism. Nat. Metab. 1 (2019), 125–132, 10.1038/s42255-018-0006-7.
Noor, E., Flamholz, A., Liebermeister, W., Bar-Even, A., Milo, R., A note on the kinetics of enzyme action: A decomposition that highlights thermodynamic effects. FEBS Lett. 587 (2013), 2772–2777, 10.1016/j.febslet.2013.07.028.
Stettner, A.I., Segrè, D., The cost of efficiency in energy metabolism. Proc. Natl. Acad. Sci. USA 110 (2013), 9629–9630, 10.1073/pnas.1307485110.
Visch, H.-J., Koopman, W.J.H., Zeegers, D., van Emst-de Vries, S.E., van Kuppeveld, F.J.M., van den Heuvel, L.W.P.J., Smeitink, J.A.M., Willems, P.H.G.M., Ca2+-mobilizing agonists increase mitochondrial ATP production to accelerate cytosolic Ca2+ removal: aberrations in human complex I deficiency. Am. J. Physiol. Cell. Physiol. 291 (2006), C308–C316, 10.1152/ajpcell.00561.2005.
Celsi, F., Pizzo, P., Brini, M., Leo, S., Fotino, C., Pinton, P., Rizzuto, R., Mitochondria, calcium and cell death: A deadly triad in neurodegeneration. Biochim. Biophys. Acta 1787 (2009), 335–344, 10.1016/j.bbabio.2009.02.021.
Filadi, R., Pizzo, P., Mitochondrial calcium handling and neurodegeneration: when a good signal goes wrong. Curr. Opin. Physiol. 17 (2020), 224–233, 10.1016/j.cophys.2020.08.009.
Monteith, G.R., Prevarskaya, N., Roberts-Thomson, S.J., The calcium–cancer signalling nexus. Nat. Rev. Cancer 17 (2017), 367–380, 10.1038/nrc.2017.18.
Guerrero-Hernandez, A., Verkhratsky, A., Calcium signalling in diabetes. Cell Calcium 56 (2014), 297–301, 10.1016/j.ceca.2014.08.009.
Giorgi, C., Agnoletto, C., Bononi, A., Bonora, M., De Marchi, E., Marchi, S., Missiroli, S., Patergnani, S., Poletti, F., Rimessi, A., et al. Mitochondrial calcium homeostasis as potential target for mitochondrial medicine. Mitochondrion 12 (2012), 77–85, 10.1016/j.mito.2011.07.004.
Dejos, C., Gkika, D., Cantelmo, A.R., The Two-Way Relationship Between Calcium and Metabolism in Cancer. Front. Cell Dev. Biol., 8, 2020, 573747.
Soman, S., Keatinge, M., Moein, M., Da Costa, M., Mortiboys, H., Skupin, A., Sugunan, S., Bazala, M., Kuznicki, J., Bandmann, O., Inhibition of the mitochondrial calcium uniporter rescues dopaminergic neurons in pink1–/– zebrafish. Eur. J. Neurosci. 45 (2017), 528–535, 10.1111/ejn.13473.
García-Contreras, R., Vos, P., Westerhoff, H.V., Boogerd, F.C., Why in vivo may not equal in vitro – new effectors revealed by measurement of enzymatic activities under the same in vivo-like assay conditions. FEBS J. 279 (2012), 4145–4159, 10.1111/febs.12007.
Varrette, S., Bouvry, P., Cartiaux, H., et Georgatos, F., Management of an academic HPC cluster: The UL experience. Proc. of the 2014 intl. conf. on high performance computing & simulation (HPCS 2014), 2014, IEEE, 959–967.
Pasti, L., Pozzan, T., Carmignoto, G., Long-lasting Changes of Calcium Oscillations in Astrocytes: A NEW FORM OF GLUTAMATE-MEDIATED PLASTICITY. J. Biol. Chem. 270 (1995), 15203–15210, 10.1074/jbc.270.25.15203.
Peuchen, S., Clark, J.B., Duchen, M.R., Mechanisms of intracellular calcium regulation in adult astrocytes. Neuroscience 71 (1996), 871–883, 10.1016/0306-4522(95)00515-3.
Diaz, G., Falchi, A.M., Gremo, F., Isola, R., Diana, A., Homogeneous longitudinal profiles and synchronous fluctuations of mitochondrial transmembrane potential. FEBS Lett. 475 (2000), 218–224, 10.1016/S0014-5793(00)01683-5.
Wilhelm, F., Hirrlinger, J., The NAD+/NADH redox state in astrocytes: Independent control of the NAD+ and NADH content. J. Neurosci. Res. 89 (2011), 1956–1964, 10.1002/jnr.22638.
Williamson, D.H., Lund, P., Krebs, H.A., The redox state of free nicotinamide-adenine dinucleotide in the cytoplasm and mitochondria of rat liver. Biochem. J. 103 (1967), 514–527, 10.1042/bj1030514.
De Groot, S.R., Mazur, P., Non-Equilibrium Thermodynamics. 1984, Dover.
Alberty, R.A., Thermodynamics of Biochemical Reactions. 2003, John Wiley & Sons.
Noor, E., Bar-Even, A., Flamholz, A., Lubling, Y., Davidi, D., Milo, R., An integrated open framework for thermodynamics of reactions that combines accuracy and coverage. Bioinformatics 28 (2012), 2037–2044, 10.1093/bioinformatics/bts317.
Noor, E., Haraldsdóttir, H.S., Milo, R., Fleming, R.M.T., Consistent Estimation of Gibbs Energy Using Component Contributions. PLoS Comput. Biol., 9, 2013, e1003098, 10.1371/journal.pcbi.1003098.
Goldberg, R.N., Tewari, Y.B., Bhat, T.N., Thermodynamics of enzyme-catalyzed reactions—a database for quantitative biochemistry. Bioinformatics 20 (2004), 2874–2877, 10.1093/bioinformatics/bth314.