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Lin X, Zhou C, Wang T, Huang X, Chen J, Li Z, Zhang J, Lu Y. CO2-elevated cell-free protein synthesis. Synth Syst Biotechnol 2022; 7:911-917. [PMID: 35664930 PMCID: PMC9136254 DOI: 10.1016/j.synbio.2022.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/20/2022] [Accepted: 05/12/2022] [Indexed: 11/26/2022] Open
Abstract
Gases are the vital nutrition of all organisms as the precursor of metabolism pathways. As a potential biological process, protein synthesis is inevitably regulated by gas transport and utilization. However, the effect of carbon dioxide (CO2) present in many metabolic pathways on protein synthesis has not been studied well. In this work, carbon dioxide combined with oxygen was employed for cell-free protein synthesis (CFPS) in the tube-in-tube reactor with precise control of gas concentration. In this in vitro system, gases could directly affect the protein synthesis process without transmembrane transport. Varied concentrations of carbon dioxide (0–1%) and constant oxygen concentration (21%) were employed for CFPS to assess the effects. The cell-free reactions with 0.3% CO2 and 21% O2 showed the highest protein yields. The combined effect of CO2 and O2 also resulted in relatively high protein expression under high oxygen conditions (0.3% CO2 and 100% O2). Moreover, metabolomics assays were performed to gain insight into metabolic changes, which showed that CO2 slightly improved energy metabolism and redox balance. In particular, the extra supplied CO2 activated the decarboxylating reactions and removed toxic metabolites to recover the protein synthesis activity. The exploration of CO2 on protein synthesis could provide guiding implications for basic studies and biomanufacturing.
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Chen W, Liu J, Zheng C, Bai Q, Gao Q, Zhang Y, Dong K, Lu T. Research Progress on Improving the Efficiency of CDT by Exacerbating Tumor Acidification. Int J Nanomedicine 2022; 17:2611-2628. [PMID: 35712639 PMCID: PMC9196673 DOI: 10.2147/ijn.s366187] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 05/16/2022] [Indexed: 12/21/2022] Open
Abstract
In recent years, chemodynamic therapy (CDT) has received extensive attention as a novel means of cancer treatment. The CDT agents can exert Fenton and Fenton-like reactions in the acidic tumor microenvironment (TME), converting hydrogen peroxide (H2O2) into highly toxic hydroxyl radicals (·OH). However, the pH of TME, as an essential factor in the Fenton reaction, does not catalyze the reaction effectively, hindering its efficiency, which poses a significant challenge for the future clinical application of CDT. Therefore, this paper reviews various strategies to enhance the antitumor properties of nanomaterials by modulating tumor acidity. Ultimately, the performance of CDT can be further improved by inducing strong oxidative stress to produce sufficient ·OH. In this paper, the various acidification pathways and proton pumps with potential acidification functions are mainly discussed, such as catalytic enzymes, exogenous acids, CAIX, MCT, NHE, NBCn1, etc. The problems, opportunities, and challenges of CDT in the cancer field are also discussed, thereby providing new insights for the design of nanomaterials and laying the foundation for their future clinical applications.
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Affiliation(s)
- Wenting Chen
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, People's Republic of China
| | - Jinxi Liu
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, People's Republic of China
| | - Caiyun Zheng
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, People's Republic of China
| | - Que Bai
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, People's Republic of China
| | - Qian Gao
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, People's Republic of China
| | - Yanni Zhang
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, People's Republic of China
| | - Kai Dong
- School of Pharmacy, Xi'an Jiaotong University, Xi'an, 710072, People's Republic of China
| | - Tingli Lu
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, 710072, People's Republic of China
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3
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Luo S, Li Y, Li S, Jiang R, Deng F, Liu G, Zhang J. Expression Regulation of Water Reabsorption Genes and Transcription Factors in the Kidneys of Lepus yarkandensis. Front Physiol 2022; 13:856427. [PMID: 35721542 PMCID: PMC9204326 DOI: 10.3389/fphys.2022.856427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 05/10/2022] [Indexed: 11/13/2022] Open
Abstract
Lepus yarkandensis is a desert-dwelling animal that has various adaptations to cope with drought. The kidney maintains water and acid-base balance mainly through the vasopressin-regulated water reabsorption pathway and proximal tubular bicarbonate reabsorption pathway. In this study, we compared the differentially expressed genes (DEGs) and transcription factors in the kidneys of L. yarkandensis and Oryctolagus cuniculus to explore the relationship between the DEGs in kidneys and the animals’ adaptations. Transcriptome sequencing data were used to predict the differentially-expressed water reabsorption genes and their transcription factors. Quantitative real-time PCR, immunohistochemistry, and western blotting were used to detect and verify the expression of DEGs in the kidney at mRNA and protein levels. Transcriptome analysis of the kidney of L. yarkandensis and O. cuniculus showed that 6,610 genes were up-regulated and 5,727 genes down-regulated in data shared by both species. According to the data, 232 transcription factors and their corresponding target genes were predicted, from which genes and transcription factors related to renal water reabsorption were screened. Quantitative RT-PCR results showed AQP1, AQP2, ADCY3, HIF1A, CREB3, and NFATc1 had higher expression in the L. yarkandensis kidney; in comparison, FXYD2 mRNA expression levels were lower. In western blotting, transcription factors HIF1A, NFATc1, NF-κB1, and critical genes ADCY3, ATPA1, and SLC4A4, were highly expressed in the kidneys of L. yarkandensis. Immunohistochemical results showed that the ADCY3 protein was in the basolateral membrane of the collecting duct, the ATP1A1 protein was in the basolateral membrane and medulla of proximal tubules, and the SLC4A4 protein was in the basolateral membrane of proximal tubules. According to these results can be inferred that HIF1A, NFATc1, and NF-κB1 play a certain role in regulating the expression of genes related to water reabsorption in the kidney of L. yarkandensis, thus improving the water reclamation efficiency of L. yarkandensis, so as to adapt to the arid desert environment.
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Affiliation(s)
- Shengjie Luo
- College of Life Sciences and Technology, Tarim University, Alar, China
| | - Yongle Li
- College of Life Sciences and Technology, Tarim University, Alar, China
| | - Shuwei Li
- College of Life Sciences and Technology, Tarim University, Alar, China.,Xinjiang Production and Construction Corps Key Laboratory of Protection and Utilization of Biological Resources, Tarim University, Alar, China
| | - Renjun Jiang
- College of Life Sciences and Technology, Tarim University, Alar, China
| | - Fang Deng
- College of Life Sciences and Technology, Tarim University, Alar, China
| | - Guoquan Liu
- Anhui Province Key Laboratory of Translational Cancer Research and Department of Biochemistry, College of Laboratory Medicine, Bengbu Medical College, Bengbu, China.,College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Jianping Zhang
- College of Life Sciences and Technology, Tarim University, Alar, China.,Xinjiang Production and Construction Corps Key Laboratory of Protection and Utilization of Biological Resources, Tarim University, Alar, China
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Modulation of Tubular pH by Acetazolamide in a Ca 2+ Transport Deficient Mice Facilitates Calcium Nephrolithiasis. Int J Mol Sci 2021; 22:ijms22063050. [PMID: 33802660 PMCID: PMC8002449 DOI: 10.3390/ijms22063050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 01/16/2023] Open
Abstract
Proximal tubular (PT) acidosis, which alkalinizes the urinary filtrate, together with Ca2+ supersaturation in PT can induce luminal calcium phosphate (CaP) crystal formation. While such CaP crystals are known to act as a nidus for CaP/calcium oxalate (CaOx) mixed stone formation, the regulation of PT luminal Ca2+ concentration ([Ca2+]) under elevated pH and/or high [Ca2+] conditions are unknown. Since we found that transient receptor potential canonical 3 (TRPC3) knockout (KO; -/-) mice could produce mild hypercalciuria with CaP urine crystals, we alkalinized the tubular pH in TRPC3-/- mice by oral acetazolamide (0.08%) to develop mixed urinary crystals akin to clinical signs of calcium nephrolithiasis (CaNL). Our ratiometric (λ340/380) intracellular [Ca2+] measurements reveal that such alkalization not only upsurges Ca2+ influx into PT cells, but the mode of Ca2+ entry switches from receptor-operated to store-operated pathway. Electrophysiological experiments show enhanced bicarbonate related current activity in treated PT cells which may determine the stone-forming phenotypes (CaP or CaP/CaOx). Moreover, such alkalization promotes reactive oxygen species generation, and upregulation of calcification, inflammation, fibrosis, and apoptosis in PT cells, which were exacerbated in absence of TRPC3. Altogether, the pH-induced alteration of the Ca2+ signaling signature in PT cells from TRPC3 ablated mice exacerbated the pathophysiology of mixed urinary stone formation, which may aid in uncovering the downstream mechanism of CaNL.
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Kao L, Azimov R, Shao XM, Abuladze N, Newman D, Zhekova H, Noskov S, Pushkin A, Kurtz I. SLC4A11 function: evidence for H +(OH -) and NH 3-H + transport. Am J Physiol Cell Physiol 2019; 318:C392-C405. [PMID: 31774702 PMCID: PMC7052617 DOI: 10.1152/ajpcell.00425.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Whether SLC4A11 transports ammonia and its potential mode of ammonia transport (NH4+, NH3, or NH3-2H+ transport have been proposed) are controversial. In the absence of ammonia, whether SLC4A11 mediates significant conductive H+(OH-) transport is also controversial. The present study was performed to determine the mechanism of human SLC4A11 ammonia transport and whether the transporter mediates conductive H+(OH-) transport in the absence of ammonia. We quantitated H+ flux by monitoring changes in intracellular pH (pHi) and measured whole cell currents in patch-clamp studies of HEK293 cells expressing the transporter in the absence and presence of NH4Cl. Our results demonstrate that SLC4A11 mediated conductive H+(OH-) transport that was stimulated by raising the extracellular pH (pHe). Ammonia-induced HEK293 whole cell currents were also stimulated by an increase in pHe. In studies using increasing NH4Cl concentrations with equal NH4+ extracellular and intracellular concentrations, the shift in the reversal potential (Erev) due to the addition of ammonia was compatible with NH3-H+ transport competing with H+(OH-) rather than NH3-nH+ (n ≥ 2) transport. The increase in equivalent H+(OH-) flux observed in the presence of a transcellular H+ gradient was also compatible with SLC4A11-mediated NH3-H+ flux. The NH3 versus Erev data fit a theoretical model suggesting that NH3-H+ and H+(OH-) competitively interact with the transporter. Studies of mutant SLC4A11 constructs in the putative SLC4A11 ion coordination site showed that both H+(OH-) transport and ammonia-induced whole cell currents were blocked suggesting that the H+(OH-) and NH3-H+ transport processes share common features involving the SLC4A11 transport mechanism.
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Affiliation(s)
- Liyo Kao
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Rustam Azimov
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Xuesi M Shao
- Department of Neurobiology, University of California, Los Angeles, California
| | - Natalia Abuladze
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Debra Newman
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Hristina Zhekova
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - Sergei Noskov
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - Alexander Pushkin
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ira Kurtz
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, California.,Brain Research Institute, University of California, Los Angeles, California
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Jiang S, Wang X, Wei J, Zhang G, Zhang J, Xie P, Xu L, Wang L, Zhao L, Li L, Wilcox CS, Chen J, Lai EY, Liu R. NaHCO 3 Dilates Mouse Afferent Arteriole Via Na +/HCO 3- Cotransporters NBCs. Hypertension 2019; 74:1104-1112. [PMID: 31522618 DOI: 10.1161/hypertensionaha.119.13235] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sodium bicarbonate has long been used to treat chronic kidney disease. It has been demonstrated to slow the decline in glomerular filtration rate in chronic kidney disease patient; however, the mechanisms are not completely understood. We hypothesized that NaHCO3 dilates afferent arterioles (Af-Art) by stimulating nitric oxide (NO) release mediated by the Na+/HCO3- cotransporter (NBC) contributing to the elevation in glomerular filtration rate. Isolated microperfused mouse renal Af-Art, preconstricted with norepinephrine (1 µmol/L), dilated 45±2% (n=6, P<0.05) in response to NaHCO3 (44 mmol/L). Whereas, NaCl solution containing the same Na+ concentration was not effective. The mRNA for NBCn1 and NBCe1 were detected in microdissected Af-Art using reverse transcription-polymerase chain reaction and quantitative polymerase chain reaction. The Af-Art intracellular pH measured with 2',7'-bis-(2-carboxyethyl)-5-(and-6) carboxyfluorescein, acetoxymethyl ester increased significantly by 0.29±0.02 (n=6; P<0.05) in the presence of NaHCO3, which was blunted by N-cyanosulphonamide compound (S0859) that is an inhibitor of the NBC family. After clamping the intracellular pH with 10 μM nigericin, changing the bath solution pH from 7.4 to 7.8 still dilates the Af-Art by 53±4% (n=7; P<0.005) and increases NO generation by 22±3% (n=7; P<0.005). Both pH-induced NO generation and vasodilation were blocked by L-NG-Nitroarginine Methyl Ester. NaHCO3 increased NO generation in Af-Art by 19±4% (n=5; P<0.005) and elevated glomerular filtration rate in conscious mice by 36% (233 versus 318 ul/min; n=9-10; P<0.0001). S0859 and L-NG-nitroarginine methyl ester blocked NaHCO3-induced increases in NO generation and vasodilation. We conclude that NBCn1 and NBCe1 are expressed in Af-Art and that NaHCO3 dilates Af-Art via NBCs mediated by NO that increases the glomerular filtration rate.
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Affiliation(s)
- Shan Jiang
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Ximing Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.).,Shandong Provincial Hospital, Affiliated Hospital of Shandong University, Jinan, China (X.W.)
| | - Jin Wei
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Gensheng Zhang
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Jie Zhang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Peng Xie
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.)
| | - Lan Xu
- College of Public Health, University of South Florida, Tampa (L.X.)
| | - Lei Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Liang Zhao
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Physiology, School of Basic Medical Sciences, Guangzhou Medical University, China (L.Z., E.Y.L.).,Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Germany (L.Z., E.Y.L.)
| | - Lingli Li
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Division of Nephrology and Hypertension, and Hypertension Center, Georgetown University, Washington, DC (L.L., C.S.W.)
| | - Christopher S Wilcox
- Division of Nephrology and Hypertension, and Hypertension Center, Georgetown University, Washington, DC (L.L., C.S.W.)
| | - Jianghua Chen
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.)
| | - En Yin Lai
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Physiology, School of Basic Medical Sciences, Guangzhou Medical University, China (L.Z., E.Y.L.).,Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Germany (L.Z., E.Y.L.)
| | - Ruisheng Liu
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
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Kao L, Azimov R, Shao XM, Frausto RF, Abuladze N, Newman D, Aldave AJ, Kurtz I. Multifunctional ion transport properties of human SLC4A11: comparison of the SLC4A11-B and SLC4A11-C variants. Am J Physiol Cell Physiol 2016; 311:C820-C830. [PMID: 27581649 DOI: 10.1152/ajpcell.00233.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 08/30/2016] [Indexed: 12/13/2022]
Abstract
Congenital hereditary endothelial dystrophy (CHED), Harboyan syndrome (CHED with progressive sensorineural deafness), and potentially a subset of individuals with late-onset Fuchs' endothelial corneal dystrophy are caused by mutations in the SLC4A11 gene that results in corneal endothelial cell abnormalities. Originally classified as a borate transporter, the function of SLC4A11 as a transport protein remains poorly understood. Elucidating the transport function(s) of SLC4A11 is needed to better understand how its loss results in the aforementioned posterior corneal dystrophic disease processes. Quantitative PCR experiments demonstrated that, of the three known human NH2-terminal variants, SLC4A11-C is the major transcript expressed in human corneal endothelium. We studied the expression pattern of the three variants in mammalian HEK-293 cells and demonstrated that the SLC4A11-B and SLC4A11-C variants are plasma membrane proteins, whereas SLC4A11-A is localized intracellularly. SLC4A11-B and SLC4A11-C were shown to be multifunctional ion transporters capable of transporting H+ equivalents in both a Na+-independent and Na+-coupled mode. In both transport modes, SLC4A11-C H+ flux was significantly greater than SLC4A11-B. In the presence of ammonia, SLC4A11-B and SLC4A11-C generated inward currents that were comparable in magnitude. Chimera SLC4A11-C-NH2-terminus-SLC4A11-B experiments demonstrated that the SLC4A11-C NH2-terminus functions as an autoactivating domain, enhancing Na+-independent and Na+-coupled H+ flux without significantly affecting the electrogenic NH3-H(n)+ cotransport mode. All three modes of transport were significantly impaired in the presence of the CHED causing p.R109H (SLC4A11-C numbering) mutation. These complex ion transport properties need to be addressed in the context of corneal endothelial disease processes caused by mutations in SLC4A11.
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Affiliation(s)
- Liyo Kao
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Rustam Azimov
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Xuesi M Shao
- Department of Neurobiology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ricardo F Frausto
- Stein Eye Institute, and.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Natalia Abuladze
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Debra Newman
- Division of Nephrology.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Anthony J Aldave
- Stein Eye Institute, and.,David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ira Kurtz
- Division of Nephrology, .,Brain Research Institute.,David Geffen School of Medicine, University of California, Los Angeles, California
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Blombach B, Takors R. CO2 - Intrinsic Product, Essential Substrate, and Regulatory Trigger of Microbial and Mammalian Production Processes. Front Bioeng Biotechnol 2015; 3:108. [PMID: 26284242 PMCID: PMC4522908 DOI: 10.3389/fbioe.2015.00108] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 07/13/2015] [Indexed: 11/22/2022] Open
Abstract
Carbon dioxide formation mirrors the final carbon oxidation steps of aerobic metabolism in microbial and mammalian cells. As a consequence, CO2/HCO3− dissociation equilibria arise in fermenters by the growing culture. Anaplerotic reactions make use of the abundant CO2/HCO3− levels for refueling citric acid cycle demands and for enabling oxaloacetate-derived products. At the same time, CO2 is released manifold in metabolic reactions via decarboxylation activity. The levels of extracellular CO2/HCO3− depend on cellular activities and physical constraints such as hydrostatic pressures, aeration, and the efficiency of mixing in large-scale bioreactors. Besides, local CO2/HCO3− levels might also act as metabolic inhibitors or transcriptional effectors triggering regulatory events inside the cells. This review gives an overview about fundamental physicochemical properties of CO2/HCO3− in microbial and mammalian cultures effecting cellular physiology, production processes, metabolic activity, and transcriptional regulation.
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Affiliation(s)
- Bastian Blombach
- Institute of Biochemical Engineering, University of Stuttgart , Stuttgart , Germany
| | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart , Stuttgart , Germany
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