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Álvarez-Rodríguez S, Alvite CM, Reigosa MJ, Sánchez-Moreiras AM, Araniti F. Application of Indole-Alkaloid Harmaline Induces Physical Damage to Photosystem II Antenna Complexes in Adult Plants of Arabidopsis thaliana (L.) Heynh. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:6073-6086. [PMID: 37026701 PMCID: PMC10119982 DOI: 10.1021/acs.jafc.3c00531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 06/19/2023]
Abstract
Finding herbicides with new and multiple modes of action is a solution to stop the increase in resistant weed species. Harmaline, a natural alkaloid with proven phytotoxic potential, was tested on Arabidopsis adult plants by watering and spraying; watering resulted as the more effective treatment. Harmaline altered several photosynthetic parameters, reducing the efficiency of the light- (ΦII) and dark-adapted (Fv/Fm) PSII, suggesting physical damages in photosystem II, although dissipation of the energy in excess under the form of heat was not compromised as demonstrated by the significant increase in ΦNPQ. Metabolomic alterations, such as osmoprotectant accumulation and reduction in sugars' content, also indicate a reduction of photosynthetic efficiency and suggest early senescence and water status alteration induced by harmaline. Data suggest that harmaline might be considered a new phytotoxic molecule interesting for further studies.
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Affiliation(s)
- Sara Álvarez-Rodríguez
- Departamento
de Bioloxía Vexetal e Ciencias do Solo, Facultade de Bioloxía, Universidade de Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain
| | - Carla M. Alvite
- Departamento
de Bioloxía Vexetal e Ciencias do Solo, Facultade de Bioloxía, Universidade de Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain
| | - Manuel J. Reigosa
- Departamento
de Bioloxía Vexetal e Ciencias do Solo, Facultade de Bioloxía, Universidade de Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain
| | - Adela M. Sánchez-Moreiras
- Departamento
de Bioloxía Vexetal e Ciencias do Solo, Facultade de Bioloxía, Universidade de Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain
| | - Fabrizio Araniti
- Dipartimento
di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia, Università Statale di Milano, Via Celoria n° 2, 20133 Milano, Italy
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2
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Marmagne A, Masclaux-Daubresse C, Chardon F. Modulation of plant nitrogen remobilization and postflowering nitrogen uptake under environmental stresses. JOURNAL OF PLANT PHYSIOLOGY 2022; 277:153781. [PMID: 36029571 DOI: 10.1016/j.jplph.2022.153781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 07/16/2022] [Accepted: 07/16/2022] [Indexed: 06/15/2023]
Abstract
Plants are sessile organisms that take up nitrogen (N) from the soil for growth and development. At the postflowering stage, N that plants require for seed growth and filling derives from either root uptake or shoot remobilization. The balance between N uptake and N remobilization determines the final carbon (C) and N composition of the seed. The N uptake and N remobilization mechanisms are regulated by endogenous signals, including hormones, developmental stage, and carbon/nitrogen ratio, and by environmental factors. The cellular responses to the environment are relatively well known. However, the effects of environmental stresses on the balance between N uptake and N remobilization are still poorly understood. Thus, this study aims to analyze the impact of environmental stresses (drought, heat, darkness, triggered defense, and low nitrate) on N fluxes within plants during seed filling. Using publicly available Arabidopsis transcriptome data, expression of several marker genes involved in N assimilation, transport, and recycling was analyzed in relation to stress. Results showed that the responses of genes encoding inorganic N transporters, N assimilation, and N recycling are mainly regulated by N limitation, the genes encoding housekeeping proteases are principally sensitive to C limitation, and the response of genes involved in the transport of organic N is controlled by both C and N limitations. In addition, 15N data were used to examine the effects of severe environmental stresses on N remobilization and N uptake, and a schematic representation of the major factors that regulate the balance between N remobilization and N uptake under the stress and control conditions was provided.
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Affiliation(s)
- Anne Marmagne
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000, Versailles, France
| | - Céline Masclaux-Daubresse
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000, Versailles, France
| | - Fabien Chardon
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000, Versailles, France.
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3
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Koper K, Han SW, Pastor DC, Yoshikuni Y, Maeda HA. Evolutionary Origin and Functional Diversification of Aminotransferases. J Biol Chem 2022; 298:102122. [PMID: 35697072 PMCID: PMC9309667 DOI: 10.1016/j.jbc.2022.102122] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 11/30/2022] Open
Abstract
Aminotransferases (ATs) are pyridoxal 5′-phosphate–dependent enzymes that catalyze the transamination reactions between amino acid donor and keto acid acceptor substrates. Modern AT enzymes constitute ∼2% of all classified enzymatic activities, play central roles in nitrogen metabolism, and generate multitude of primary and secondary metabolites. ATs likely diverged into four distinct AT classes before the appearance of the last universal common ancestor and further expanded to a large and diverse enzyme family. Although the AT family underwent an extensive functional specialization, many AT enzymes retained considerable substrate promiscuity and multifunctionality because of their inherent mechanistic, structural, and functional constraints. This review summarizes the evolutionary history, diverse metabolic roles, reaction mechanisms, and structure–function relationships of the AT family enzymes, with a special emphasis on their substrate promiscuity and multifunctionality. Comprehensive characterization of AT substrate specificity is still needed to reveal their true metabolic functions in interconnecting various branches of the nitrogen metabolic network in different organisms.
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Affiliation(s)
- Kaan Koper
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Sang-Woo Han
- The US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Yasuo Yoshikuni
- The US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Global Center for Food, Land, and Water Resources, Research Faculty of Agriculture, Hokkaido University, Hokkaido 060-8589, Japan
| | - Hiroshi A Maeda
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
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Sachdev S, Ansari SA, Ansari MI, Fujita M, Hasanuzzaman M. Abiotic Stress and Reactive Oxygen Species: Generation, Signaling, and Defense Mechanisms. Antioxidants (Basel) 2021; 10:277. [PMID: 33670123 PMCID: PMC7916865 DOI: 10.3390/antiox10020277] [Citation(s) in RCA: 284] [Impact Index Per Article: 94.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022] Open
Abstract
Climate change is an invisible, silent killer with calamitous effects on living organisms. As the sessile organism, plants experience a diverse array of abiotic stresses during ontogenesis. The relentless climatic changes amplify the intensity and duration of stresses, making plants dwindle to survive. Plants convert 1-2% of consumed oxygen into reactive oxygen species (ROS), in particular, singlet oxygen (1O2), superoxide radical (O2•-), hydrogen peroxide (H2O2), hydroxyl radical (•OH), etc. as a byproduct of aerobic metabolism in different cell organelles such as chloroplast, mitochondria, etc. The regulatory network comprising enzymatic and non-enzymatic antioxidant systems tends to keep the magnitude of ROS within plant cells to a non-damaging level. However, under stress conditions, the production rate of ROS increases exponentially, exceeding the potential of antioxidant scavengers instigating oxidative burst, which affects biomolecules and disturbs cellular redox homeostasis. ROS are similar to a double-edged sword; and, when present below the threshold level, mediate redox signaling pathways that actuate plant growth, development, and acclimatization against stresses. The production of ROS in plant cells displays both detrimental and beneficial effects. However, exact pathways of ROS mediated stress alleviation are yet to be fully elucidated. Therefore, the review deposits information about the status of known sites of production, signaling mechanisms/pathways, effects, and management of ROS within plant cells under stress. In addition, the role played by advancement in modern techniques such as molecular priming, systems biology, phenomics, and crop modeling in preventing oxidative stress, as well as diverting ROS into signaling pathways has been canvassed.
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Affiliation(s)
- Swati Sachdev
- Department of Environmental Science, School for Environmental Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Rae Bareli Road, Lucknow 226 025, India;
| | | | | | - Masayuki Fujita
- Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0795, Japan
| | - Mirza Hasanuzzaman
- Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka 1207, Bangladesh
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Metabolome and proteome of ethylene-treated papayas reveal different pathways to volatile compounds biosynthesis. Food Res Int 2020; 131:108975. [PMID: 32247445 DOI: 10.1016/j.foodres.2019.108975] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 12/23/2019] [Accepted: 12/31/2019] [Indexed: 11/20/2022]
Abstract
Papayas undergo fast postharvest changes triggered by the plant hormone ethylene. Some important pathways have been analyzed in limited studies (transcriptomics and targeted metabolomics); however, broad use of proteomics or untargeted metabolomics have not yet been used in papayas. In this study, two groups of green papayas (150 days after anthesis-physiological maturity for papayas) were treated with ethylene at different times (6 and 12 h) and their metabolic changes in fruit pulp were evaluated with untargeted metabolomics (general metabolites and volatile compounds) and proteomics. Polar metabolites exhibited distinct patterns, especially with regard to some amino and fatty acids during stimulated ripening. In particular, glutamate increased through a possible gamma aminobutyric acid (GABA) shunt and/or proteases activity. Moreover, the stimulated ripening altered the volatile compounds and the protein profiles. The results suggest that changes in membrane breakdown and the resulting oxidative processes could be responsible for volatile compound production, altering some sensorial qualities of papayas, such as pulp softening and the specific papaya linalool volatile compound increment. Thus, GABA levels could also be a strong biological marker for papaya development and ripening stages. This study applied two "omic" techniques that provided insight into how the plant hormone ethylene could influence papaya postharvest quality.
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Zhang Z, Xu M, Guo Y. Ring/U-Box Protein AtUSR1 Functions in Promoting Leaf Senescence Through JA Signaling Pathway in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2020; 11:608589. [PMID: 33391323 PMCID: PMC7772223 DOI: 10.3389/fpls.2020.608589] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/17/2020] [Indexed: 05/10/2023]
Abstract
Leaf senescence is regulated by a large number of internal and environmental factors. Here, we report that AtUSR1 (U-box Senescence Related 1) which encodes a plant Ring/U-box protein, is involved in age-dependent and dark-induced leaf senescence in Arabidopsis. Expression of AtUSR1 gene in leaves was up-regulated in darkness and during aging. Plants of usr1, an AtUSR1 gene knock-down mutant, showed a significant delay in age-dependent and dark-induced leaf senescence and the delayed senescence phenotype was rescued when the AtUSR1 gene was transferred back to the mutant plants. Meanwhile, overexpression of AtUSR1 caused accelerated leaf senescence. Furthermore, the role of AtUSR1 in regulating leaf senescence is related to MYC2-mediuated jasmonic acid (JA) signaling pathway. MeJA treatments promoted the accumulation of AtUSR1 transcripts and this expression activation was dependent on the function of MYC2, a key transcription factor in JA signaling. Dual-luciferase assay results indicated that MYC2 promoted the expression of AtUSR1. Overexpression of AtUSR1 in myc2 mutant plants showed precocious senescence, while myc2 mutation alone caused a delay in leaf senescence, suggesting that AtUSR1 functions downstream to MYC2 in the JA signaling pathway in promoting leaf senescence.
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7
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Jalil SU, Zahera M, Khan MS, Ansari MI. Biochemical synthesis of gold nanoparticles from leaf protein of Nicotiana tabacum L. cv. xanthi and their physiological, developmental, and ROS scavenging responses on tobacco plant under stress conditions. IET Nanobiotechnol 2019; 13:23-29. [PMID: 30964033 PMCID: PMC8676148 DOI: 10.1049/iet-nbt.2018.5148] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 06/01/2018] [Accepted: 07/16/2018] [Indexed: 08/06/2023] Open
Abstract
The stress conditions imposed by the impact of metal and non-metal oxide nanoparticles over plant systems enhances the synthesis of reactive oxygen species (ROS), resulting in oxidative damage at cellular level. The objective of this study was to synthesise the gold nanoparticles (GNps) from the leaves protein of Nicotiana tabacum L. cv. xanthi, its characterisation, and response on plant physiology and ROS scavenging activity on plants after exposure to different stresses. The authors have treated N. tabacum L. cv. xanthi plants with 100, 200, 300, 400, and 500 ppm biochemically synthesised GNps and examined physiological as well as biochemical changes. Results showed that biochemically synthesised GNps exposure significantly increased the seed germination (P < 0.001), root (P < 0.001), shoot growth (P < 0.001), and antioxidant ability (P < 0.05) of plants depending on bioengineered GNPs concentrations. Low concentrations (200-300 ppm) of GNps boosted growth by ∼50% and significantly increase in photosynthetic parameters such as total chlorophyll content (P < 0.05), membrane ion leakage (P < 0.05) as well as malondialdehyde (P < 0.05) content with respect to untreated plants under stress conditions. The high concentration (400-500 ppm) of GNps affected these parameters in a negative manner. The total antioxidant activity was also elevated in the exposed plants in a dose-dependent manner.
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Affiliation(s)
- Syed Uzma Jalil
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Lucknow, India
| | - Manaal Zahera
- Nanomedicine and Nanobiotechnology Lab, Department of Biosciences, Integral University, Lucknow, India
| | - Mohd Sajid Khan
- Nanomedicine and Nanobiotechnology Lab, Department of Biosciences, Integral University, Lucknow, India
| | - Mohammad Israil Ansari
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Lucknow, India.
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8
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Ma X, Zhang Y, Turečková V, Xue GP, Fernie AR, Mueller-Roeber B, Balazadeh S. The NAC Transcription Factor SlNAP2 Regulates Leaf Senescence and Fruit Yield in Tomato. PLANT PHYSIOLOGY 2018; 177:1286-1302. [PMID: 29760199 PMCID: PMC6052983 DOI: 10.1104/pp.18.00292] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/02/2018] [Indexed: 05/18/2023]
Abstract
Leaf senescence is an essential physiological process in plants that supports the recycling of nitrogen and other nutrients to support the growth of developing organs, including young leaves, seeds, and fruits. Thus, the regulation of senescence is crucial for evolutionary success in wild populations and for increasing yield in crops. Here, we describe the influence of a NAC transcription factor, SlNAP2 (Solanum lycopersicum NAC-like, activated by Apetala3/Pistillata), that controls both leaf senescence and fruit yield in tomato (S. lycopersicum). SlNAP2 expression increases during age-dependent and dark-induced leaf senescence. We demonstrate that SlNAP2 activates SlSAG113 (S. lycopersicum SENESCENCE-ASSOCIATED GENE113), a homolog of Arabidopsis (Arabidopsis thaliana) SAG113, chlorophyll degradation genes such as SlSGR1 (S. lycopersicum senescence-inducible chloroplast stay-green protein 1) and SlPAO (S. lycopersicum pheide a oxygenase), and other downstream targets by directly binding to their promoters, thereby promoting leaf senescence. Furthermore, SlNAP2 directly controls the expression of genes important for abscisic acid (ABA) biosynthesis, S. lycopersicum 9-cis-epoxycarotenoid dioxygenase 1 (SlNCED1); transport, S. lycopersicum ABC transporter G family member 40 (SlABCG40); and degradation, S. lycopersicum ABA 8'-hydroxylase (SlCYP707A2), indicating that SlNAP2 has a complex role in establishing ABA homeostasis during leaf senescence. Inhibiting SlNAP2 expression in transgenic tomato plants impedes leaf senescence but enhances fruit yield and sugar content likely due to prolonged leaf photosynthesis in aging tomato plants. Our data indicate that SlNAP2 has a central role in controlling leaf senescence and fruit yield in tomato.
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Affiliation(s)
- Xuemin Ma
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
- University of Potsdam, Institute of Biochemistry and Biology, 14476 Potsdam-Golm, Germany
| | - Youjun Zhang
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
- Center of Plant Systems Biology and Biotechnology, 4000 Plovdiv, Bulgaria
| | - Veronika Turečková
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University and Institute of Experimental Botany, Czech Academy of Sciences, 78371 Olomouc, Czech Republic
| | | | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
- Center of Plant Systems Biology and Biotechnology, 4000 Plovdiv, Bulgaria
| | - Bernd Mueller-Roeber
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
- University of Potsdam, Institute of Biochemistry and Biology, 14476 Potsdam-Golm, Germany
- Center of Plant Systems Biology and Biotechnology, 4000 Plovdiv, Bulgaria
| | - Salma Balazadeh
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
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Rodríguez-Calcerrada J, Rodrigues AM, Perdiguero P, António C, Atkin OK, Li M, Collada C, Gil L. A molecular approach to drought-induced reduction in leaf CO 2 exchange in drought-resistant Quercus ilex. PHYSIOLOGIA PLANTARUM 2018; 162:394-408. [PMID: 28984911 DOI: 10.1111/ppl.12649] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/20/2017] [Accepted: 10/03/2017] [Indexed: 06/07/2023]
Abstract
Drought-induced reduction of leaf gas exchange entails a complex regulation of the plant leaf metabolism. We used a combined molecular and physiological approach to understand leaf photosynthetic and respiratory responses of 2-year-old Quercus ilex seedlings to drought. Mild drought stress resulted in glucose accumulation while net photosynthetic CO2 uptake (Pn ) remained unchanged, suggesting a role of glucose in stress signaling and/or osmoregulation. Simple sugars and sugar alcohols increased throughout moderate-to-very severe drought stress conditions, in parallel to a progressive decline in Pn and the quantum efficiency of photosystem II; by contrast, minor changes occurred in respiration rates until drought stress was very severe. At very severe drought stress, 2-oxoglutarate dehydrogenase complex gene expression significantly decreased, and the abundance of most amino acids dramatically increased, especially that of proline and γ-aminobutyric acid (GABA) suggesting enhanced protection against oxidative damage and a reorganization of the tricarboxylic cycle acid cycle via the GABA shunt. Altogether, our results point to Q. ilex drought tolerance being linked to signaling and osmoregulation by hexoses during early stages of drought stress, and enhanced protection against oxidative damage by polyols and amino acids under severe drought stress.
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Affiliation(s)
- Jesús Rodríguez-Calcerrada
- Forest History, Physiology and Genetics Research Group, School of Forestry Engineering, Technical University of Madrid, Madrid 28040, Spain
| | - Ana M Rodrigues
- Plant Metabolomics Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), 2780-157 Oeiras, Portugal
| | - Pedro Perdiguero
- Forest History, Physiology and Genetics Research Group, School of Forestry Engineering, Technical University of Madrid, Madrid 28040, Spain
- Forest Biotech Laboratory, Instituto de Biologia Experimental e Tecnológica, iBET, 2781-901 Oeiras, Portugal
| | - Carla António
- Plant Metabolomics Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), 2780-157 Oeiras, Portugal
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, 2601, Australia
| | - Meng Li
- Forest History, Physiology and Genetics Research Group, School of Forestry Engineering, Technical University of Madrid, Madrid 28040, Spain
| | - Carmen Collada
- Forest History, Physiology and Genetics Research Group, School of Forestry Engineering, Technical University of Madrid, Madrid 28040, Spain
| | - Luis Gil
- Forest History, Physiology and Genetics Research Group, School of Forestry Engineering, Technical University of Madrid, Madrid 28040, Spain
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Salminen A, Jouhten P, Sarajärvi T, Haapasalo A, Hiltunen M. Hypoxia and GABA shunt activation in the pathogenesis of Alzheimer's disease. Neurochem Int 2015; 92:13-24. [PMID: 26617286 DOI: 10.1016/j.neuint.2015.11.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 11/16/2015] [Accepted: 11/18/2015] [Indexed: 12/21/2022]
Abstract
We have previously observed that the conversion of mild cognitive impairment to definitive Alzheimer's disease (AD) is associated with a significant increase in the serum level of 2,4-dihydroxybutyrate (2,4-DHBA). The metabolic generation of 2,4-DHBA is linked to the activation of the γ-aminobutyric acid (GABA) shunt, an alternative energy production pathway activated during cellular stress, when the function of Krebs cycle is compromised. The GABA shunt can be triggered by local hypoperfusion and subsequent hypoxia in AD brains caused by cerebral amyloid angiopathy. Succinic semialdehyde dehydrogenase (SSADH) is a key enzyme in the GABA shunt, converting succinic semialdehyde (SSA) into succinate, a Krebs cycle intermediate. A deficiency of SSADH activity stimulates the conversion of SSA into γ-hydroxybutyrate (GHB), an alternative route from the GABA shunt. GHB can exert not only acute neuroprotective activities but unfortunately also chronic detrimental effects which may lead to cognitive impairment. Subsequently, GHB can be metabolized to 2,4-DHBA and secreted from the brain. Thus, the activation of the GABA shunt and the generation of GHB and 2,4-DHBA can have an important role in the early phase of AD pathogenesis.
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Affiliation(s)
- Antero Salminen
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland.
| | - Paula Jouhten
- VTT Technical Research Centre of Finland, FIN-00014 Helsinki, Finland; EMBL European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Timo Sarajärvi
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland; Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland
| | - Annakaisa Haapasalo
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland; Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, Neulaniementie 2, P.O. Box 1627, FIN-70211 Kuopio, Finland; Department of Neurology, Kuopio University Hospital, P.O. Box 100, FI-70029 KYS, Finland
| | - Mikko Hiltunen
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland; Department of Neurology, Kuopio University Hospital, P.O. Box 100, FI-70029 KYS, Finland; Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland
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