scholarly journals Neuronal control of astrocytic respiration through a variant of the Crabtree effect

2018 ◽  
Vol 115 (7) ◽  
pp. 1623-1628 ◽  
Author(s):  
Ignacio Fernández-Moncada ◽  
Iván Ruminot ◽  
Daniel Robles-Maldonado ◽  
Karin Alegría ◽  
Joachim W. Deitmer ◽  
...  
Keyword(s):  
Energy Demand ◽  
Aerobic Glycolysis ◽  
Hippocampal Slices ◽  
Energetic Efficiency ◽  
Crabtree Effect ◽  
Proliferating Cells ◽  
Neuronal Control ◽  
Synaptic Formation ◽  
Oxygen Measurements

Aerobic glycolysis is a phenomenon that in the long term contributes to synaptic formation and growth, is reduced by normal aging, and correlates with amyloid beta deposition. Aerobic glycolysis starts within seconds of neural activity and it is not obvious why energetic efficiency should be compromised precisely when energy demand is highest. Using genetically encoded FRET nanosensors and real-time oxygen measurements in culture and in hippocampal slices, we show here that astrocytes respond to physiological extracellular K+ with an acute rise in cytosolic ATP and a parallel inhibition of oxygen consumption, explained by glycolytic stimulation via the Na+-bicarbonate cotransporter NBCe1. This control of mitochondrial respiration via glycolysis modulation is reminiscent of a phenomenon previously described in proliferating cells, known as the Crabtree effect. Fast brain aerobic glycolysis may be interpreted as a strategy whereby neurons manipulate neighboring astrocytes to obtain oxygen, thus maximizing information processing.

scholarly journals Deletion or Overexpression of Mitochondrial NAD+Carriers inSaccharomyces cerevisiaeAlters Cellular NAD and ATP Contents and Affects Mitochondrial Metabolism and the Rate of Glycolysis

2011 ◽  
Vol 77 (7) ◽  
pp. 2239-2246 ◽  
Author(s):  
Gennaro Agrimi ◽  
Luca Brambilla ◽  
Gianni Frascotti ◽  
Isabella Pisano ◽  
Danilo Porro ◽  
...  
Keyword(s):  
Cellular Metabolism ◽  
Growth Conditions ◽  
Glycolytic Flux ◽  
Energetic Efficiency ◽  
Crabtree Effect ◽  
Wild Type ◽  
Glucose Flux ◽  
Chemostat Cultures ◽  
Biomass Yields

ABSTRACTThe modification of enzyme cofactor concentrations can be used as a method for both studying and engineering metabolism. We variedSaccharomyces cerevisiaemitochondrial NAD levels by altering expression of its specific mitochondrial carriers. Changes in mitochondrial NAD levels affected the overall cellular concentration of this coenzyme and the cellular metabolism. In batch culture, a strain with a severe NAD depletion in mitochondria succeeded in growing, albeit at a low rate, on fully respiratory media. Although the strain increased the efficiency of its oxidative phosphorylation, the ATP concentration was low. Under the same growth conditions, a strain with a mitochondrial NAD concentration higher than that of the wild type similarly displayed a low cellular ATP level, but its growth rate was not affected. In chemostat cultures, when cellular metabolism was fully respiratory, both mutants showed low biomass yields, indicative of impaired energetic efficiency. The two mutants increased their glycolytic fluxes, and as a consequence, the Crabtree effect was triggered at lower dilution rates. Strikingly, the mutants switched from a fully respiratory metabolism to a respirofermentative one at the same specific glucose flux as that of the wild type. This result seems to indicate that the specific glucose uptake rate and/or glycolytic flux should be considered one of the most important independent variables for establishing the long-term Crabtree effect. In cells growing under oxidative conditions, bioenergetic efficiency was affected by both low and high mitochondrial NAD availability, which suggests the existence of a critical mitochondrial NAD concentration in order to achieve optimal mitochondrial functionality.

scholarly journals The distinct roles of calcium in rapid control of neuronal glycolysis and the tricarboxylic acid cycle

2020 ◽  
Author(s):  
Carlos Manlio Díaz-García ◽  
Dylan J. Meyer ◽  
Nidhi Nathwani ◽  
Mahia Rahman ◽  
Juan Ramón Martínez-François ◽  
...  
Keyword(s):  
Energy Demand ◽  
Calcium Influx ◽  
Aerobic Glycolysis ◽  
Tricarboxylic Acid Cycle ◽  
Hippocampal Slices ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Autofluorescence Imaging ◽  
Acute Hippocampal Slices ◽  
Calmodulin Signaling

ABSTRACTWhen neurons engage in intense periods of activity, the consequent increase in energy demand can be counteracted by the coordinated activation of glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation. However, the trigger for glycolytic activation is unknown and the role for Ca2+ in the mitochondrial responses has been debated. Using genetically-encoded fluorescent biosensors and NAD(P)H autofluorescence imaging in acute hippocampal slices, here we find that Ca2+ uptake into the mitochondria is responsible for the buildup of mitochondrial NADH, probably through Ca2+ activation of dehydrogenases in the TCA cycle. In the cytosol, we do not observe a role for the Ca2+/calmodulin signaling pathway, or AMPK, in mediating the rise in glycolytic NADH in response to acute stimulation. Calcium, nevertheless, is a major contributor to glycolysis, although not strictly necessary. Aerobic glycolysis in neurons is triggered mainly by the energy demand resulting from either Na+ or Ca2+ extrusion.Impact StatementWhen neurons are stimulated, calcium influx instructs mitochondria to increase energy metabolism, but it is increased energy demand in cytosol rather than Ca2+ signaling that leads to increased neuronal glycolysis.

scholarly journals The distinct roles of calcium in rapid control of neuronal glycolysis and the tricarboxylic acid cycle

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Carlos Manlio Díaz-García ◽  
Dylan J Meyer ◽  
Nidhi Nathwani ◽  
Mahia Rahman ◽  
Juan Ramón Martínez-François ◽  
...  
Keyword(s):  
Energy Demand ◽  
Granule Cells ◽  
Aerobic Glycolysis ◽  
Tricarboxylic Acid Cycle ◽  
Hippocampal Slices ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Autofluorescence Imaging ◽  
Acute Hippocampal Slices ◽  
Calmodulin Signaling

When neurons engage in intense periods of activity, the consequent increase in energy demand can be met by the coordinated activation of glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation. However, the trigger for glycolytic activation is unknown and the role for Ca2+ in the mitochondrial responses has been debated. Using genetically encoded fluorescent biosensors and NAD(P)H autofluorescence imaging in acute hippocampal slices, here we find that Ca2+ uptake into the mitochondria is responsible for the buildup of mitochondrial NADH, probably through Ca2+ activation of dehydrogenases in the TCA cycle. In the cytosol, we do not observe a role for the Ca2+/calmodulin signaling pathway, or AMPK, in mediating the rise in glycolytic NADH in response to acute stimulation. Aerobic glycolysis in neurons is triggered mainly by the energy demand resulting from either Na+ or Ca2+ extrusion, and in mouse dentate granule cells, Ca2+ creates the majority of this demand.

Untangling the Metabolic Reprogramming in Brain Cancer: Discovering Key Molecular Players Using Mass Spectrometry

2019 ◽  
Vol 19 (17) ◽  
pp. 1521-1534 ◽  
Author(s):  
Anatoly Sorokin ◽  
Vsevolod Shurkhay ◽  
Stanislav Pekov ◽  
Evgeny Zhvansky ◽  
Daniil Ivanov ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Brain Cancer ◽  
De Novo ◽  
Aerobic Glycolysis ◽  
Lipid Production ◽  
Dietary Fatty Acids ◽  
Metabolic Reprogramming ◽  
Detection Methods ◽  
Malignant Cells ◽  
Proliferating Cells

Cells metabolism alteration is the new hallmark of cancer, as well as an important method for carcinogenesis investigation. It is well known that the malignant cells switch to aerobic glycolysis pathway occurring also in healthy proliferating cells. Recently, it was shown that in malignant cells de novo synthesis of the intracellular fatty acid replaces dietary fatty acids which change the lipid composition of cancer cells noticeably. These alterations in energy metabolism and structural lipid production explain the high proliferation rate of malignant tissues. However, metabolic reprogramming affects not only lipid metabolism but many of the metabolic pathways in the cell. 2-hydroxyglutarate was considered as cancer cell biomarker and its presence is associated with oxidative stress influencing the mitochondria functions. Among the variety of metabolite detection methods, mass spectrometry stands out as the most effective method for simultaneous identification and quantification of the metabolites. As the metabolic reprogramming is tightly connected with epigenetics and signaling modifications, the evaluation of metabolite alterations in cells is a promising approach to investigate the carcinogenesis which is necessary for improving current diagnostic capabilities and therapeutic capabilities. In this paper, we overview recent studies on metabolic alteration and oncometabolites, especially concerning brain cancer and mass spectrometry approaches which are now in use for the investigation of the metabolic pathway.

scholarly journals Imaging spatio-temporal patterns of long-term potentiation in mouse hippocampus

2003 ◽  
Vol 358 (1432) ◽  
pp. 689-693 ◽  
Author(s):  
Toshiyuki Hosokawa ◽  
Masaki Ohta ◽  
Takeshi Saito ◽  
Alan Fine
Keyword(s):  
Hippocampal Slices ◽  
Temporal Patterns ◽  
Long Term Potentiation ◽  
Optical Recording ◽  
Stratum Radiatum ◽  
High Frequency Stimulation ◽  
Optical Signals ◽  
Term Potentiation ◽  
Spatio Temporal

Spatio-temporal patterns of neuronal activity before and after the induction of long-term potentiation in mouse hippocampal slices were studied using a real-time high-resolution optical recording system. After staining the slices with voltage-sensitive dye, transmitted light images and extracellular field potentials were recorded in response to stimuli applied to CA1 stratum radiatum. Optical and electrical signals in response to single test pulses were enhanced for at least 30 minutes after brief high-frequency stimulation at the same site. In two-pathway experiments, potentiation was restricted to the tetanized pathway. The optical signals demonstrated that both the amplitude and area of the synaptic response were increased, in patterns not predictable from the initial, pretetanus, pattern of activation. Optical signals will be useful for investigating spatio-temporal patterns of synaptic enhancement underlying information storage in the brain.

Phosphorylation of connexin 43 induced by traumatic brain injury promotes exosome release

2018 ◽  
Vol 119 (1) ◽  
pp. 305-311 ◽  
Author(s):  
Wei Chen ◽  
Yijun Guo ◽  
Wenjin Yang ◽  
Lei Chen ◽  
Dabin Ren ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Gap Junction ◽  
Connexin 43 ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Cx43 Expression ◽  
Term Potentiation ◽  
Junction Protein

Traumatic brain injury (TBI) caused by the external force leads to the neuronal dysfunction and even death. TBI has been reported to significantly increase the phosphorylation of glial gap junction protein connexin 43 (Cx43), which in turn propagates damages into surrounding brain tissues. However, the neuroprotective and anti-apoptosis effects of glia-derived exosomes have also been implicated in recent studies. Therefore, we detected whether TBI-induced phosphorylation of Cx43 would promote exosome release in rat brain. To generate TBI model, adult male Sprague-Dawley rats were subjected to lateral fluid percussion injury. Phosphorylated Cx43 protein levels and exosome activities were quantified using Western blot analysis following TBI. Long-term potentiation (LTP) was also tested in rat hippocampal slices. TBI significantly increased the phosphorylated Cx43 and exosome markers expression in rat ipsilateral hippocampus, but not cortex. Blocking the activity of Cx43 or ERK, but not JNK, significantly suppressed TBI-induced exosome release in hippocampus. Furthermore, TBI significantly inhibited the induction of LTP in hippocampal slices, which could be partially but significantly restored by pretreatment with exosomes. The results imply that TBI-activated Cx43 could mediate a nociceptive effect by propagating the brain damages, as well as a neuroprotective effect by promoting exosome release. NEW & NOTEWORTHY We have demonstrated in rat traumatic brain injury (TBI) models that both phosphorylated connexin 43 (p-Cx43) expression and exosome release were elevated in the hippocampus following TBI. The promoted exosome release depends on the phosphorylation of Cx43 and requires ERK signaling activation. Exosome treatment could partially restore the attenuated long-term potentiation. Our results provide new insight for future therapeutic direction on the functional recovery of TBI by promoting p-Cx43-dependent exosome release but limiting the gap junction-mediated bystander effect.

Sign in / Sign up

Export Citation Format

Share Document