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1.
Proc Natl Acad Sci U S A ; 121(15): e2314763121, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38557194

RESUMO

Although sudden sensorineural hearing loss (SSNHL) is a serious condition, there are currently no approved drugs for its treatment. Nevertheless, there is a growing understanding that the cochlear pathologies that underlie SSNHL include apoptotic death of sensory outer hair cells (OHCs) as well as loss of ribbon synapses connecting sensory inner hair cells (IHCs) and neurites of the auditory nerve, designated synaptopathy. Noise-induced hearing loss (NIHL) is a common subtype of SSNHL and is widely used to model hearing loss preclinically. Here, we demonstrate that a single interventive application of a small pyridoindole molecule (AC102) into the middle ear restored auditory function almost to prenoise levels in a guinea pig model of NIHL. AC102 prevented noise-triggered loss of OHCs and reduced IHC synaptopathy suggesting a role of AC102 in reconnecting auditory neurons to their sensory target cells. Notably, AC102 exerted its therapeutic properties over a wide frequency range. Such strong improvements in hearing have not previously been demonstrated for other therapeutic agents. In vitro experiments of a neuronal damage model revealed that AC102 protected cells from apoptosis and promoted neurite growth. These effects may be explained by increased production of adenosine triphosphate, indicating improved mitochondrial function, and reduced levels of reactive-oxygen species which prevents the apoptotic processes responsible for OHC death. This action profile of AC102 might be causal for the observed hearing recovery in in vivo models.


Assuntos
Perda Auditiva Provocada por Ruído , Perda Auditiva Neurossensorial , Cobaias , Animais , Audição , Cóclea , Ruído/efeitos adversos , Células Ciliadas Auditivas Externas/fisiologia , Limiar Auditivo
2.
J Cell Sci ; 136(14)2023 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-37358264

RESUMO

Cancer-associated fibroblasts (CAFs) have distinct roles within the tumor microenvironment, which can impact the mode and efficacy of tumor cell migration. CAFs are known to increase invasion of less-aggressive breast cancer cells through matrix remodeling and leader-follower dynamics. Here, we demonstrate that CAFs communicate with breast cancer cells through the formation of contact-dependent tunneling nanotubes (TNTs), which allow for the exchange of cargo between cell types. CAF mitochondria are an integral cargo component and are sufficient to increase the 3D migration of cancer cells. This cargo transfer results in an increase in mitochondrial ATP production in cancer cells, whereas it has a negligible impact on glycolytic ATP production. Manually increasing mitochondrial oxidative phosphorylation (OXPHOS) by providing extra substrates for OXPHOS fails to enhance cancer cell migration unless glycolysis is maintained at a constant level. Together, these data indicate that tumor-stromal cell crosstalk via TNTs and the associated metabolic symbiosis is a finely controlled mechanism by which tumor cells co-opt their microenvironment to promote cancer progression and may become a potential therapeutic target.


Assuntos
Neoplasias da Mama , Fibroblastos Associados a Câncer , Humanos , Feminino , Neoplasias da Mama/patologia , Fibroblastos Associados a Câncer/metabolismo , Linhagem Celular Tumoral , Mitocôndrias/metabolismo , Trifosfato de Adenosina/metabolismo , Fibroblastos/metabolismo , Microambiente Tumoral
3.
FASEB J ; 38(1): e23368, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38100644

RESUMO

The uterine contraction during labor, a process with repetitive hypoxia and high energy consumption, is essential for successful delivery. However, the molecular mechanism of myometrial contraction regulation is unknown. Serpin family E member 1 (SERPINE1), one of the most upregulated genes in laboring myometrium in both transcriptome and proteome, was highlighted in our previous study. Here, we confirmed SERPINE1 is upregulated in myometrium during labor. Blockade of SERPINE1 using small interfering RNA (siRNA) or inhibitor (Tiplaxtinin) under hypoxic conditions in myocytes or myometrium in vitro showed a decrease contractility, which was achieved by regulating ATP production. Chromatin immunoprecipitation (ChIP-seq), Co-immunoprecipitation (Co-IP), and glutathione-S-transferase (GST) pull down explored that the promoter of SERPINE1 is directly activated by hypoxia-inducible factor-1α (HIF-1α) and SERPINE1 interacts with ATP Synthase Peripheral Stalk Subunit F6 (ATP5PF). Together they enhance hypoxia driven myometrial contraction by maintaining ATP production in the key oxidative phosphorylation pathway. The results provide new insight for uterine contraction regulation, and potential novel therapeutic targets for labor management.


Assuntos
Trabalho de Parto , Serpinas , Gravidez , Feminino , Humanos , Serpinas/metabolismo , Miométrio/metabolismo , Contração Uterina , RNA Interferente Pequeno/metabolismo , Hipóxia/metabolismo , Trifosfato de Adenosina/metabolismo
4.
J Pharmacol Sci ; 154(4): 274-278, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38485345

RESUMO

2-Deoxy-d-glucose (2DG) induces anticancer effects through glycolytic inhibition but it may raise the risk of arrhythmia. The rare monosaccharide d-allose also has anticancer properties, but its cardiac effects are unknown. We examined the effects of d-allose on adenosine triphosphate (ATP) production in neonatal rat cardiomyocytes. We showed that 25 mM d-allose selectively reduced glycolytic ATP, but had minimal impact on mitochondrial ATP, while 1 mM 2DG strongly inhibited both. Furthermore, d-allose had less impact on cell viability and was less cytotoxic than 2DG; neither compound caused apoptosis. Thus, d-allose selectively diminished glycolytic ATP production with no apparent effects on cardiomyocytes.


Assuntos
Trifosfato de Adenosina , Miócitos Cardíacos , Ratos , Animais , Animais Recém-Nascidos , Sobrevivência Celular , Glucose/farmacologia
5.
Int J Mol Sci ; 25(2)2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38279231

RESUMO

Potassium (K+) is the most abundant cation in the cytosol and is maintained at high concentrations within the mitochondrial matrix through potassium channels. However, many effects of K+ at such high concentrations on mitochondria and the underlying mechanisms remain unclear. This study aims to elucidate these effects and mechanisms by employing fluorescence imaging techniques to distinguish and precisely measure signals inside and outside the mitochondria. We stained the mitochondrial matrix with fluorescent dyes sensitive to K+, pH, reactive oxygen species (ROS), and membrane potential in plasma membrane-permeabilized C6 cells and isolated mitochondria from C6 cells. Fluorescence microscopy facilitated the accurate measurement of fluorescence intensity inside and outside the matrix. Increasing extramitochondrial K+ concentration from 2 mM to 127 mM led to a reduction in matrix pH and a decrease in the generation of highly reactive ROS. In addition, elevated K+ levels electrically polarized the inner membrane of the mitochondria and promoted efficient ATP synthesis via FoF1-ATPase. Introducing protons (H+) into the matrix through phosphate addition led to further mitochondrial polarization, and this effect was more pronounced in the presence of K+. K+ at high concentrations, reaching sub-hundred millimolar levels, increased H+ concentration within the matrix, suppressing ROS generation and boosting ATP synthesis. Although this study does not elucidate the role of specific types of potassium channels in mitochondria, it does suggest that mitochondrial K+ plays a beneficial role in maintaining cellular health.


Assuntos
Mitocôndrias , Canais de Potássio , Espécies Reativas de Oxigênio/metabolismo , Mitocôndrias/metabolismo , Prótons , Trifosfato de Adenosina/farmacologia , Concentração de Íons de Hidrogênio , Potássio/metabolismo
6.
Int J Mol Sci ; 25(17)2024 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-39273587

RESUMO

Epilepsy is characterized by hypersynchronous neuronal discharges, which are associated with an increased cerebral metabolic rate of oxygen and ATP demand. Uncontrolled seizure activity (status epilepticus) results in mitochondrial exhaustion and ATP depletion, which potentially generate energy mismatch and neuronal loss. Many cells can adapt to increased energy demand by increasing metabolic capacities. However, acute metabolic adaptation during epileptic activity and its relationship to chronic epilepsy remains poorly understood. We elicited seizure-like events (SLEs) in an in vitro model of status epilepticus for eight hours. Electrophysiological recording and tissue oxygen partial pressure recordings were performed. After eight hours of ongoing SLEs, we used proteomics-based kinetic modeling to evaluate changes in metabolic capacities. We compared our findings regarding acute metabolic adaptation to published proteomic and transcriptomic data from chronic epilepsy patients. Epileptic tissue acutely responded to uninterrupted SLEs by upregulating ATP production capacity. This was achieved by a coordinated increase in the abundance of proteins from the respiratory chain and oxidative phosphorylation system. In contrast, chronic epileptic tissue shows a 25-40% decrease in ATP production capacity. In summary, our study reveals that epilepsy leads to dynamic metabolic changes. Acute epileptic activity boosts ATP production, while chronic epilepsy reduces it significantly.


Assuntos
Trifosfato de Adenosina , Epilepsia , Trifosfato de Adenosina/metabolismo , Humanos , Epilepsia/metabolismo , Animais , Adaptação Fisiológica , Masculino , Metabolismo Energético , Proteômica/métodos , Mitocôndrias/metabolismo , Doença Crônica , Fosforilação Oxidativa , Estado Epiléptico/metabolismo
7.
Int J Mol Sci ; 25(13)2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38999952

RESUMO

Vibration and sound are the shaping matrix of the entire universe. Everything in nature is shaped by energy vibrating and communicating through its own sound trail. Every cell within our body vibrates at defined frequencies, generating its peculiar "sound signature". Mitochondria are dynamic, energy-transforming, biosynthetic, and signaling organelles that actively transduce biological information. Novel research has shown that the mitochondrial function of mammalian cells can be modulated by various energetic stimuli, including sound vibrations. Regarding acoustic vibrations, definite types of music have been reported to produce beneficial impacts on human health. In very recent studies, the effects of different sound stimuli and musical styles on cellular function and mitochondrial activity were evaluated and compared in human cells cultured in vitro, investigating the underlying responsible molecular mechanisms. This narrative review will take a multilevel trip from macro to intracellular microenvironment, discussing the intimate vibrational sound activities shaping living matter, delving deeper into the molecular mechanisms underlying the sound modulation of biological systems, and mainly focusing our discussion on novel evidence showing the competence of mitochondria in acting as energy portals capable of sensing and transducing the subtle informational biofields of sound vibration.


Assuntos
Microambiente Celular , Mitocôndrias , Som , Vibração , Humanos , Mitocôndrias/metabolismo , Animais , Música , Metabolismo Energético
8.
Semin Cancer Biol ; 86(Pt 2): 347-357, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35868515

RESUMO

Several metabolic pathways for the supply of adenosine triphosphate (ATP) have been proposed; however, the major source of reducing power for ADP in cancer remains unclear. Although glycolysis is the source of ATP in tumors according to the Warburg effect, ATP levels do not differ between cancer cells grown in the presence and absence of glucose. Several theories have been proposed to explain the supply of ATP in cancer, including metabolic reprograming in the tumor microenvironment. However, these theories are based on the production of ATP by the TCA-OxPhos pathway, which is inconsistent with the Warburg effect. We found that blocking fatty acid oxidation (FAO) in the presence of glucose significantly decreased ATP production in various cancer cells. This suggests that cancer cells depend on fatty acids to produce ATP through FAO instead of glycolysis. We observed that cancer cell growth mainly relies on metabolic nutrients and oxygen systemically supplied through the bloodstream instead of metabolic reprogramming. In a spontaneous mouse tumor model (KrasG12D; Pdx1-cre), tumor growth was 2-fold higher in mice fed a high-fat diet (low-carbo diet) that caused obesity, whereas a calorie-balanced, low-fat diet (high-carbo diet) inhibited tumor growth by 3-fold compared with that in mice fed a control/normal diet. This 5-fold difference in tumor growth between mice fed low-fat and high-fat diets suggests that fat-induced obesity promotes cancer growth, and tumor growth depends on fatty acids as the primary source of energy.


Assuntos
Ácidos Graxos , Neoplasias , Camundongos , Humanos , Animais , Ácidos Graxos/metabolismo , Trifosfato de Adenosina/metabolismo , Dieta Hiperlipídica , Obesidade/complicações , Obesidade/metabolismo , Glucose/metabolismo , Neoplasias/etiologia , Microambiente Tumoral
9.
J Neurosci ; 42(42): 8019-8037, 2022 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-36261266

RESUMO

Mutations in the gene encoding vesicle-associated membrane protein B (VAPB) cause a familial form of amyotrophic lateral sclerosis (ALS). Expression of an ALS-related variant of vapb (vapbP58S ) in Drosophila motor neurons results in morphologic changes at the larval neuromuscular junction (NMJ) characterized by the appearance of fewer, but larger, presynaptic boutons. Although diminished microtubule stability is known to underlie these morphologic changes, a mechanism for the loss of presynaptic microtubules has been lacking. By studying flies of both sexes, we demonstrate the suppression of vapbP58S -induced changes in NMJ morphology by either a loss of endoplasmic reticulum (ER) Ca2+ release channels or the inhibition Ca2+/calmodulin (CaM)-activated kinase II (CaMKII). These data suggest that decreased stability of presynaptic microtubules at vapbP58S NMJs results from hyperactivation of CaMKII because of elevated cytosolic [Ca2+]. We attribute the Ca2+ dyshomeostasis to delayed extrusion of cytosolic Ca2+ Suggesting that this defect in Ca2+ extrusion arose from an insufficient response to the bioenergetic demand of neural activity, depolarization-induced mitochondrial ATP production was diminished in vapbP58S neurons. These findings point to bioenergetic dysfunction as a potential cause for the synaptic defects in vapbP58S -expressing motor neurons.SIGNIFICANCE STATEMENT Whether the synchrony between the rates of ATP production and demand is lost in degenerating neurons remains poorly understood. We report that expression of a gene equivalent to an amyotrophic lateral sclerosis (ALS)-causing variant of vesicle-associated membrane protein B (VAPB) in fly neurons decouples mitochondrial ATP production from neuronal activity. Consequently, levels of ATP in mutant neurons are unable to keep up with the bioenergetic burden of neuronal activity. Reduced rate of Ca2+ extrusion, which could result from insufficient energy to power Ca2+ ATPases, results in the accumulation of residual Ca2+ in mutant neurons and leads to alterations in synaptic vesicle (SV) release and synapse development. These findings suggest that synaptic defects in a model of ALS arise from the loss of activity-induced ATP production.


Assuntos
Esclerose Lateral Amiotrófica , Masculino , Animais , Feminino , Esclerose Lateral Amiotrófica/metabolismo , Drosophila/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Calmodulina/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Neurônios Motores/metabolismo , Proteínas R-SNARE/metabolismo , Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo
10.
Biochem Biophys Res Commun ; 682: 365-370, 2023 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-37839105

RESUMO

In non-small cell lung cancer (NSCLC), the receptor tyrosine kinase AXL has been identified as a potent activator of tumor progression and resistance to therapies. However, the molecular mechanisms behind AXL-mediated oncogenesis remain elusive. Current study thus aimed to uncover potential downstream genes regulated by AXL in NSCLC. Through transcriptomic RNA sequencing of AXL-silenced NSCLC cells, TMEM14A was identified as a significantly up-regulated gene. Clinical evaluations using GEPIA2 revealed that TMEM14A mRNA expression was notably higher in lung adenocarcinoma (LUAD) tumor tissues compared to normal tissues. Further, significantly increased TMEM14A levels were associated with poorer overall survival in LUAD patients. Experimentally, silencing TMEM14A in NSCLC cells led to reduced cellular proliferation and ATP levels, highlighting a key role of TMEM14A in NSCLC progression. Moreover, our promoter analysis demonstrated that AXL-mediated regulation of TMEM14A transcription could involve binding of transcription factors STAT and NF-κB to 5'-promoter of TMEM14A. Collectively, current study unveils TMEM14A as a novel downstream target of AXL, suggesting its potential as a therapeutic target to counteract resistance in future NSCLC patients undergoing AXL-targeted therapies.


Assuntos
Receptor Tirosina Quinase Axl , Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Receptor Tirosina Quinase Axl/metabolismo , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Proliferação de Células , Neoplasias Pulmonares/patologia , Proteínas de Membrana/genética , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo
11.
Mol Genet Metab ; 139(4): 107629, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37392701

RESUMO

PMM2-CDG is the most prevalent type of congenital disorders of glycosylation (CDG). It is caused by pathogenic variants in the gene encoding phosphomannomutase 2 (PMM2), which converts mannose-6-phosphate to mannose-1-phosphate and thus activates this saccharide for further glycosylation processes. Defective glycosylation can lead to an abnormal accumulation of unfolded proteins in endoplasmic reticulum (ER) and cause its stress. The ER is a key compartment for glycosylation, and its connection and communication with mitochondria has been described extensively in literature. Their crosstalk is important for cell proliferation, calcium homeostasis, apoptosis, mitochondrial fission regulation, bioenergetics, autophagy, lipid metabolism, inflammasome formation and unfolded protein response. Therefore, in the present study we posed a question, whether defective glycosylation leads to bioenergetic disruption. Our data reveal possible chronic stress in ER and activated unfolded protein response via PERK pathway in PMM2-CDG fibroblasts. Presumably, it leads to bioenergetic reorganization and increased assembly of respiratory chain complexes into supercomplexes together with suppressed glycolysis in PMM2-CDG patient cells. These changes cause alterations in Krebs cycle, which is tightly connected to electron transport system in mitochondria. In summary, we present data showing metabolic adaptation of cells to glycosylation defect caused by various pathogenic variants in PMM2.


Assuntos
Defeitos Congênitos da Glicosilação , Fosfotransferases (Fosfomutases) , Humanos , Glicosilação , Defeitos Congênitos da Glicosilação/patologia , Fosfotransferases (Fosfomutases)/genética , Fibroblastos/metabolismo
12.
FASEB J ; 36(4): e22218, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35218567

RESUMO

An immunoregulatory role of stem cells, often mediated by their secretome, has been claimed by several studies. Stem cell-derived extracellular vesicles (EVs) are crucial components of the secretome. EVs, a heterogeneous group of membranous vesicles released by many cell types into the extracellular space, are now considered as an additional mechanism for intercellular communication. In this study, we aimed at investigating whether human amniotic stem cell-derived extracellular vesicles (HASC-EVs) were able to interfere with inflammasome activation in the THP-1 cell line. Two subsets of HASC-EVs were collected by sequential centrifugation, namely HASC-P10 and HASC-P100. We demonstrated that HASC-EVs were neither internalized into nor undertake a direct interaction with THP-1 cells. We showed that HASC-P10 and P100 were able to intrinsically produce ATP, which was further converted to adenosine by 5'-nucleotidase (CD73) and ectonucleoside triphosphate diphosphohydrolase-1 (CD39). We found that THP-1 cells conditioned with both types of HASC-EVs failed to activate the NLRP3/caspase-1/inflammasome platform in response to LPS and ATP treatment by a mechanism involving A2a adenosine receptor activation. These results support a role for HASC-EVs as independent metabolic units capable of modifying the cellular functions, leading to anti-inflammatory effects in monocytic cells.


Assuntos
Líquido Amniótico/citologia , Anti-Inflamatórios/farmacologia , Vesículas Extracelulares/metabolismo , Inflamassomos/antagonistas & inibidores , Inflamação/prevenção & controle , Monócitos/citologia , Células-Tronco/citologia , Adenosina/metabolismo , Líquido Amniótico/metabolismo , Humanos , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Monócitos/metabolismo , Antagonistas de Receptores Purinérgicos P1/farmacologia , Receptores Purinérgicos P1/química , Receptores Purinérgicos P1/metabolismo , Células-Tronco/metabolismo , Células THP-1
13.
Nano Lett ; 22(19): 7927-7935, 2022 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-36137175

RESUMO

Electron transfer through the mitochondrial electron transport chain (ETC) can be critically blocked by the dysfunction of protein complexes. Redox-active molecules have been used to mediate the electron transfer in place of the dysfunctional complexes; however, they are limited to replacing complex I and are known to be toxic. Here we report artificial mitochondrial electron transfer pathways that enhance ETC activity by exploiting inner-membrane-bound gold nanoparticles (GNPs) as efficient electron transfer mediators. The hybridization of mitochondria with GNPs, driven by electrostatic interaction, is successfully visualized in real time at the level of a single mitochondrion. By observing quantized quenching dips via plasmon resonance energy transfer, we reveal that the hybridized GNPs are bound to the inner membrane of mitochondria irrespective of the presence of the outer membrane. The ETC activity of mitochondria with GNPs such as membrane potential, oxygen consumption, and ATP production is remarkably increased in vitro.


Assuntos
Ouro , Nanopartículas Metálicas , Trifosfato de Adenosina , Transporte de Elétrons , Elétrons
14.
Int J Mol Sci ; 24(12)2023 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-37373263

RESUMO

The mechanism of maintaining myometrial contractions during labor remains unclear. Autophagy has been reported to be activated in laboring myometrium, along with the high expression of Golgi reassembly stacking protein 2 (GORASP2), a protein capable of regulating autophagy activation. This study aimed to investigate the role and mechanism of GORASP2 in uterine contractions during labor. Western blot confirmed the increased expression of GORASP2 in laboring myometrium. Furthermore, the knockdown of GORASP2 in primary human myometrial smooth muscle cells (hMSMCs) using siRNA resulted in reduced cell contractility. This phenomenon was independent of the contraction-associated protein and autophagy. Differential mRNAs were analyzed using RNA sequencing. Subsequently, KEGG pathway analysis identified that GORASP2 knockdown suppressed several energy metabolism pathways. Furthermore, reduced ATP levels and aerobic respiration impairment were observed in measuring the oxygen consumption rate (OCR). These findings suggest that GORASP2 is up-regulated in the myometrium during labor and modulates myometrial contractility mainly by maintaining ATP production.


Assuntos
Trabalho de Parto , Miométrio , Gravidez , Feminino , Humanos , Miométrio/metabolismo , Trabalho de Parto/metabolismo , Contração Uterina/fisiologia , RNA Interferente Pequeno/metabolismo , Trifosfato de Adenosina/metabolismo , Proteínas da Matriz do Complexo de Golgi/metabolismo
15.
J Cell Physiol ; 237(1): 763-773, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34346059

RESUMO

Hydrogen sulfide (H2 S) is a gasotransmitter that regulates both physiological and pathophysiological processes in mammalian cells. Recent studies have demonstrated that H2 S promotes aerobic energy production in the mitochondria in response to hypoxia, but its effect on anaerobic energy production has yet to be established. Glycolysis is the anaerobic process by which ATP is produced through the metabolism of glucose. Mammalian red blood cells (RBCs) extrude mitochondria and nucleus during erythropoiesis. These cells would serve as a unique model to observe the effect of H2 S on glycolysis-mediated energy production. The purpose of this study was to determine the effect of H2 S on glycolysis-mediated energy production in mitochondria-free mouse RBCs. Western blot analysis showed that the only H2 S-generating enzyme expressed in mouse RBCs is 3-mercaptopyruvate sulfurtransferase (MST). Supplement of the substrate for MST stimulated, but the inhibition of the same suppressed, the endogenous production of H2 S. Both exogenously administered H2 S salt and MST-derived endogenous H2 S stimulated glycolysis-mediated ATP production. The effect of NaHS on ATP levels was not affected by oxygenation status. On the contrary, hypoxia increased intracellular H2 S levels and MST activity in mouse RBCs. The mitochondria-targeted H2 S donor, AP39, did not affect ATP levels of mouse RBCs. NaHS at low concentrations (3-100 µM) increased ATP levels and decreased cell viability after 3 days of incubation in vitro. Higher NaHS concentrations (300-1000 µM) lowered ATP levels, but prolonged cell viability. H2 S may offer a cytoprotective effect in mammalian RBCs to maintain oxygen-independent energy production.


Assuntos
Sulfeto de Hidrogênio , Trifosfato de Adenosina/metabolismo , Animais , Eritrócitos/metabolismo , Glicólise , Sulfeto de Hidrogênio/metabolismo , Sulfeto de Hidrogênio/farmacologia , Hipóxia , Mamíferos/metabolismo , Camundongos
16.
Biochem Biophys Res Commun ; 612: 30-36, 2022 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-35500439

RESUMO

Human embryonic stem cells (hESCs) can self-renew infinitely and differentiate into the cell types of all lineages of our body, holding great promise for investigating early human embryo development and providing functional cells for disease treatment. For the full application of hESCs, it is necessary to elucidate how hESCs maintain their identity. Recent studies have shown that glycolysis and mitochondrial respiration are linked to pluripotency states. However, the function of mitochondrial respiration in hESCs has not been fully understood. Herein, we report that the adenosine triphosphate (ATP) production rate is comparable between mitochondrial respiration and glycolysis, suggesting an important contribution of mitochondrial respiration to ATP production in conventionally cultured hESCs. To investigate the function of mitochondrial respiration, we silence OGDH expression in hESCs by the inducible CRISPRi method, and find that OGDH knockdown (KD) results in disrupted TCA (tricarboxylic acid) cycle, and diminished mitochondrial respiration activity and total ATP level. Moreover, OGDH KD leads to hESC death and aberrant transcriptional program. Interestingly, blockage of the electron transport chain (ETC) by small molecule inhibitors gives rise to the phenotype similar to that observed in OGDH deficient hESCs. Therefore, genetic and pharmacological perturbations of the mitochondrial respiration impair identity of hESCs. Collectively, our study highlights the pivotal role of the mitochondrial respiration activity for the stemness maintenance of primed hESCs, and unveils OGDH as a key regulator for the proper production of ATP and TCA cycle metabolites in primed hESCs.


Assuntos
Células-Tronco Embrionárias Humanas , Trifosfato de Adenosina/metabolismo , Diferenciação Celular/genética , Embrião de Mamíferos , Células-Tronco Embrionárias Humanas/metabolismo , Humanos , Respiração
17.
Biochem Biophys Res Commun ; 611: 165-171, 2022 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-35489203

RESUMO

Stress-inducible transcription factor ATF4 is essential for survival and identity of ß-cell during stress conditions. However, the physiological role of ATF4 in ß-cell function is not yet completely understood. To understand the role of ATF4 in glucose-stimulated insulin secretion (GSIS), ß-cell-specific Atf4 knockout (ßAtf4KO) mice were phenotypically characterized. Insulin secretion and mechanistic analyses were performed using islets from control Atf4f/f and ßAtf4KO mice to assess key regulators for triggering and amplifying signals for GSIS. ßAtf4KO mice displayed glucose intolerance due to reduced insulin secretion. Moreover, ßAtf4KO islets exhibited a decrease in both the insulin content and first-phase insulin secretion. The analysis of ßAtf4KO islets showed that ATF4 is required for insulin production and glucose-stimulated ATP and cAMP production. The results demonstrate that ATF4 contributes to the multifaceted regulatory process in GSIS even under stress-free conditions.


Assuntos
Intolerância à Glucose , Células Secretoras de Insulina , Ilhotas Pancreáticas , Animais , Glucose/metabolismo , Glucose/farmacologia , Intolerância à Glucose/genética , Intolerância à Glucose/metabolismo , Insulina/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Camundongos , Camundongos Knockout
18.
J Theor Biol ; 537: 111018, 2022 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-35063411

RESUMO

Adequate cerebral blood flow has long been recognized as essential for the maintenance of the neuronal function while interruption of cerebral blood flow for durations as short as minutes can result in permanent brain damage. A primary goal of this work is to determine how a neuron's ability to respond to synaptic input depends on parameters that control cerebral blood flow. A complex mathematical model is constructed that integrates detailed biophysical models of neuronal action potentials, mitochondrial ATP production and cerebral capillary blood flow. The model also provides insights of the role of astrocytes in maintaining neuronal responses, as well as the impact of elevated cytosolic calcium, due to increased synaptic activity, on mitochondrial ATP production. Both dynamical systems analysis and numerical simulations are used to determine how the maximum frequency at which the neurons can respond to synaptic input depends on capillary blow flow, as well as the ability of astrocytes to buffer extracellular potassium and cytosolic calcium handling. Results are presented for both the cases of homogenous and heterogeneous capillary networks. These results demonstrate, through this interconnected model, that heterogeneity of the capillary flow results in a decrease in the ability of neurons to respond to synaptic stimulation and that intact glial function provides a further protective role for the neurons.


Assuntos
Circulação Cerebrovascular , Modelos Cardiovasculares , Modelos Neurológicos , Neurônios , Potenciais de Ação/fisiologia , Astrócitos/fisiologia , Capilares , Neurônios/fisiologia
19.
Nutr Neurosci ; 25(6): 1277-1286, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33258406

RESUMO

BACKGROUND: Fructose-common sweetener, consumed in large quantities, is now known to be associated with various metabolic diseases. Recent reports suggest fructose's involvement in neurodegeneration, neurotoxicity, and neuroinflammation. But, its impact at cellular and subcellular level and on energy metabolism, especially, mitochondrial bioenergetics, in neurons is not known. OBJECTIVES: To study the adverse effects of high fructose in general, and on the mitochondria in a spinal cord motor neuron cell line, NSC-34, in vitro, and Caenorhabditis elegans in vivo. METHODS: NSC-34 was treated with 0.5%-5% of fructose for different time periods. Fructose's effect on cell viability (MTT assay), metabolic activity (XF24 Seahorse assays) and C. elegans, chronically fed with 5% fructose and alteration in healthspan/mitochondria was monitored. RESULTS: In NSC-34: Fructose at 4-5% elicits 60% cell death. Unlike 1%, 5% fructose (F5%) decreased mitochondrial membrane potential by 29%. Shockingly, 6hours F5% treatment almost abolished mitochondrial respiration - basal-respiration (∨123%), maximal-respiration (∨ 95%) and spare-respiratory-capacity (∨ 83%) and ATP production (∨98%) as revealed by XF 24- Seahorse assays. But non - mitochondrial respiration was spared. F5% treatment for 48hrs resulted in the total shutdown of respiratory machinery including glycolysis. Chronic feeding of wildtype C.elegans to F5% throughout, shortened lifespan by ~3 days (∨ 17%), progressively reduced movement (day-2 -∨10.25%, day-5 -∨25% and day-10 -∨56%) and food intake with age (day-5-∨9% and day-10 -∨48%) and instigated mitochondrial swelling and disarray in their arrangement in adult worms body-wall muscle cells. CONCLUSION: Chronic exposure to high fructose negatively impacts cell viability, mitochondrial function, basal glycolysis, and healthspan.


Assuntos
Caenorhabditis elegans , Frutose , Animais , Caenorhabditis elegans/metabolismo , Metabolismo Energético , Camundongos , Mitocôndrias/metabolismo , Neurônios Motores/metabolismo
20.
Adv Exp Med Biol ; 1358: 257-273, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35641874

RESUMO

Nowadays, about 14% of couples have difficulty in conceiving, and half of the cases are attributed to men. Asthenozoospermia or poor sperm motility is considered as the cause of infertility in males which is most common. Even though energy metabolism is considered the main reason for the etiology of asthenospermia, few attempts are made to determine the pathway of its metabolic potential. Recognition of cellular as well as molecular pathways that lead to reduced sperm motility may lead to the implementation of new therapeutic strategies to eliminate low sperm motility in people with asthenozoospermia. This review article discusses the key causes of decreased sperm motility and some of the muted genes and metabolic causes of the same.


Assuntos
Astenozoospermia , Infertilidade Masculina , Astenozoospermia/genética , Astenozoospermia/metabolismo , Metabolismo Energético , Humanos , Infertilidade Masculina/genética , Infertilidade Masculina/metabolismo , Masculino , Motilidade dos Espermatozoides/genética , Espermatozoides/metabolismo
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