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1.
Glia ; 2024 Jun 20.
Article in English | MEDLINE | ID: mdl-38899762

ABSTRACT

The neurometabolic disorder succinic semialdehyde dehydrogenase (SSADH) deficiency leads to great neurochemical imbalances and severe neurological manifestations. The cause of the disease is loss of function of the enzyme SSADH, leading to impaired metabolism of the principal inhibitory neurotransmitter GABA. Despite the known identity of the enzymatic deficit, the underlying pathology of SSADH deficiency remains unclear. To uncover new mechanisms of the disease, we performed an untargeted integrative analysis of cerebral protein expression, functional metabolism, and lipid composition in a genetic mouse model of SSADH deficiency (ALDH5A1 knockout mice). Our proteomic analysis revealed a clear regional vulnerability, as protein alterations primarily manifested in the hippocampus and cerebral cortex of the ALDH5A1 knockout mice. These regions displayed aberrant expression of proteins linked to amino acid homeostasis, mitochondria, glial function, and myelination. Stable isotope tracing in acutely isolated brain slices demonstrated an overall maintained oxidative metabolism of glucose, but a selective decrease in astrocyte metabolic activity in the cerebral cortex of ALDH5A1 knockout mice. In contrast, an elevated capacity of oxidative glutamine metabolism was observed in the ALDH5A1 knockout brain, which may serve as a neuronal compensation of impaired astrocyte glutamine provision. In addition to reduced expression of critical oligodendrocyte proteins, a severe depletion of myelin-enriched sphingolipids was found in the brains of ALDH5A1 knockout mice, suggesting degeneration of myelin. Altogether, our study highlights that impaired astrocyte and oligodendrocyte function is intimately linked to SSADH deficiency pathology, suggesting that selective targeting of glial cells may hold therapeutic potential in this disease.

2.
Article in English | MEDLINE | ID: mdl-38838189

ABSTRACT

In order to assess compliance with maximum residue levels in foods and evaluate the exposure of the Danish population to pesticides, a comprehensive monitoring programme was conducted. The work from 2012-2017 involved testing pesticide residues in fruits, vegetables, cereals, animal product and processed commodities. The sampling strategy, mainly based on exposure calculations and previous findings, involved the collection of 13,492 samples primarily from fresh conventional and organic produces on the Danish market. The origin of the samples varied, with 34% being of Danish origin and 67% originating from EU and non-EU countries. The results revealed that residues in conventionally grown produce were detected in 54% of the fruit and vegetable samples, and 30% of the cereal samples. Additionally, residues above the maximum residue limits were found in 1.8% of these samples, most frequently in fruits. As previous years, more residues were found in samples of foreign origin compared to samples of Danish origin. Compared to earlier findings more than 40 pesticides were detected for the first time and including boscalid, imidacloprid, thiacloprid, etofenprox, and spinosad, all detected more than 100 times. The data shows that detection of PFAS pesticides has increased dramatically, from 24 in 2006 to 412 in 2022.

3.
Homeopathy ; 2024 Jun 12.
Article in English | MEDLINE | ID: mdl-38866048

ABSTRACT

BACKGROUND: Previously we developed a test system which yielded highly significant evidence for specific effects of a Stannum metallicum 30x preparation in a multi-center replication trial. This test system is based on cress seed germination in homeopathic or control samples, CuCl2 crystallization of the cress extract, and subsequent digital textural image analysis of the resulting crystallization patterns. OBJECTIVES: The current study aimed to investigate whether three novel outcome parameters could further corroborate and possibly characterize the specific effects of Stannum metallicum 30x. METHODS: To this end, (1) cress seedling length, (2) a second texture analysis parameter, entropy and (3) the local connected fractal dimension (LCFD) of crystallization patterns as a measure of complexity were considered. The stability of the experimental setup was monitored throughout the entire investigation with systematic negative control (SNC) experiments. RESULTS: Cress length and entropy revealed a time-modulated potency treatment effect, in the absence of a significant main treatment effect. This indicated that the effect of the potency treatment varied significantly across the different experimental days. LCFD yielded a highly significant potency treatment effect. In addition, a significant interaction of treatment with experimental day seems to indicate a modulation of this effect. No significant effects were observed in any of the evaluations of the SNC experiments, indicative of a stable experimental setup and a reliable and specific treatment effect. Neither significant nor strong correlations were found between the four parameters, indicating that they reflect different effects of Stannum metallicum 30x on the organism treated. CONCLUSION: This quadruple characterization of the biological effects of Stannum metallicum 30x provides an unprecedented opportunity for basic homeopathy research into, among others, the presumed specificity of homeopathic preparations.

4.
Int J Mol Sci ; 25(12)2024 Jun 19.
Article in English | MEDLINE | ID: mdl-38928443

ABSTRACT

This paper presents the work performed to transition a lab-scale synthesis (1 g) to a large-scale (400 g) synthesis of the 3-5-diamino-1H-Pyrazole Disperazol, a new pharmaceutical for treatment of antibiotic-resistant Pseudomonas aeruginosa biofilm infections. The potentially hazardous diazotisation step in the lab-scale synthesis was transformed to a safe and easy-to-handle flow chemistry step. Additionally, the paper presents an OSHA-recommended safety assessment of active compound E, as performed by Fauske and Associates, LLC, Burr Ridge, IL, USA.


Subject(s)
Pseudomonas aeruginosa , Pyrazoles , Pyrazoles/chemistry , Pyrazoles/pharmacology , Pyrazoles/chemical synthesis , Pseudomonas aeruginosa/drug effects , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Biofilms/drug effects , Humans , Pseudomonas Infections/drug therapy , Pseudomonas Infections/microbiology , Risk Assessment
5.
Antimicrob Agents Chemother ; : e0148123, 2024 May 08.
Article in English | MEDLINE | ID: mdl-38717093

ABSTRACT

Persistent urinary tract infections (UTIs) in hospitalized patients constitute an important medical problem. It is estimated that 75% of nosocomial UTIs are associated with urinary tract catheters with P. aeruginosa being a species that forms biofilms on these catheters. These infections are highly resistant to standard-of-care antibiotics, and the effects of the host immune defenses, which allows for development of persistent infections. With antibiotics losing their efficacy, new treatment options against resilient infections, such as catheter-associated urinary tract infections (CAUTIs), are critically needed. Central to our anti-biofilm approach is the manipulation of the c-di-GMP signaling pathway in P. aeruginosa to switch bacteria from the protective biofilm to the unprotected planktonic mode of life. We recently identified a compound (H6-335-P1), that stimulates the c-di-GMP degrading activity of the P. aeruginosa BifA protein which plummets the intracellular c-di-GMP content and induces dispersal of P. aeruginosa biofilm bacteria into the planktonic state. In the present study, we formulated H6-335-P1 as a hydrochloride salt (Disperazol), which is water-soluble and facilitates delivery via injection or oral administration. Disperazol can work as a monotherapy, but we observed a 100-fold improvement in efficacy when treating murine P. aeruginosa CAUTIs with a Disperazol/ciprofloxacin combination. Biologically active Disperazol reached the bladder 30 min after oral administration. Our study provides proof of concept that Disperazol can be used in combination with a relevant antibiotic for effective treatment of CAUTIs.

6.
Dis Model Mech ; 17(6)2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38436085

ABSTRACT

P4-ATPases flip lipids from the exoplasmic to cytoplasmic leaflet of cell membranes, a property crucial for many biological processes. Mutations in P4-ATPases are associated with severe inherited and complex human disorders. We determined the expression, localization and ATPase activity of four variants of ATP8A2, the P4-ATPase associated with the neurodevelopmental disorder known as cerebellar ataxia, impaired intellectual development and disequilibrium syndrome 4 (CAMRQ4). Two variants, G447R and A772P, harboring mutations in catalytic domains, expressed at low levels and mislocalized in cells. In contrast, the E459Q variant in a flexible loop displayed wild-type expression levels, Golgi-endosome localization and ATPase activity. The R1147W variant expressed at 50% of wild-type levels but showed normal localization and activity. These results indicate that the G447R and A772P mutations cause CAMRQ4 through protein misfolding. The E459Q mutation is unlikely to be causative, whereas the R1147W may display a milder disease phenotype. Using various programs that predict protein stability, we show that there is a good correlation between the experimental expression of the variants and in silico stability assessments, suggesting that such analysis is useful in identifying protein misfolding disease-associated variants.


Subject(s)
Adenosine Triphosphatases , Computer Simulation , Genetic Diseases, Inborn , Mutation , Phospholipid Transfer Proteins , Humans , Adenosine Triphosphatases/metabolism , Adenosine Triphosphatases/genetics , Cerebellar Ataxia/genetics , Genetic Diseases, Inborn/genetics , Genetic Diseases, Inborn/enzymology , Golgi Apparatus/metabolism , HEK293 Cells , Intellectual Disability/genetics , Mutation/genetics , Phospholipid Transfer Proteins/genetics , Phospholipid Transfer Proteins/metabolism , Protein Stability , Protein Transport
7.
Sci Rep ; 14(1): 6541, 2024 03 19.
Article in English | MEDLINE | ID: mdl-38504103

ABSTRACT

The neurotransmitter serotonin plays a pivotal role in mood and depression. It also acts as a vasoconstrictor within blood vessels and is the main neurotransmitter in the gastrointestinal system. In neurotransmission, released serotonin is taken up by serotonin transporters, which are principal targets of antidepressants and the psychostimulant, ecstasy. The investigation of serotonin transporters have relied almost exclusively on the use of radiolabeled serotonin in heterogenous end-point assays. Here we adapt the genetically encoded fluorescent biosensor, iSeroSnFR, to establish and validate the Serotonin (5-HT) Fluorescence Assay for Transport and Release (5-HT_FAsTR) for functional and pharmacological studies of serotonin transport and release. We demonstrate the applicability of the method for the study of a neuronal, high-affinity, low-capacity serotonin transporter (SERT) as well as an extraneuronal low-affinity, high-capacity organic cation transporter and mutants thereof. 5HT_FAsTR offers an accessible, versatile and reliable semi-homogenous assay format that only relies on a fluorescence plate reader for repeated, real-time measurements of serotonin influx and efflux. 5HT_FAsTR accelerates and democratizes functional characterization and pharmacological studies of serotonin transporters and genetic variants thereof in disease states such as depression, anxiety and ADHD.


Subject(s)
Serotonin Plasma Membrane Transport Proteins , Serotonin , Fluorescence , Serotonin Plasma Membrane Transport Proteins/genetics , Antidepressive Agents , Neurotransmitter Agents
8.
Nat Commun ; 15(1): 2687, 2024 Mar 27.
Article in English | MEDLINE | ID: mdl-38538594

ABSTRACT

Centrosomes and cilia are microtubule-based superstructures vital for cell division, signaling, and motility. The once thought hollow lumen of their microtubule core structures was recently found to hold a rich meshwork of microtubule inner proteins (MIPs). To address the outstanding question of how distinct MIPs evolved to recognize microtubule inner surfaces, we applied computational sequence analyses, structure predictions, and experimental validation to uncover evolutionarily conserved microtubule- and MIP-binding modules named NWE, SNYG, and ELLEn, and PYG and GFG-repeat by their signature motifs. These modules intermix with MT-binding DM10-modules and Mn-repeats in 24 Chlamydomonas and 33 human proteins. The modules molecular characteristics provided keys to identify elusive cross-species homologs, hitherto unknown human MIP candidates, and functional properties for seven protein subfamilies, including the microtubule seam-binding NWE and ELLEn families. Our work defines structural innovations that underpin centriole and axoneme assembly and demonstrates that MIPs co-evolved with centrosomes and cilia.


Subject(s)
Cilia , Microtubule Proteins , Humans , Cilia/metabolism , Microtubule Proteins/metabolism , Axoneme/metabolism , Microtubules/metabolism , Centrioles/metabolism
9.
Nutrients ; 16(2)2024 Jan 18.
Article in English | MEDLINE | ID: mdl-38257176

ABSTRACT

BACKGROUND: Cancer and side effects from cytostatic treatment commonly affect nutritional status manifested as a decrease in muscle mass. We aimed to investigate the impact of nutrition and lifestyle-related factors on muscle mass in patients with hematological cancer. METHODS: Dietary intake, food preferences, quality of life (QoL), and physical activity level (PAL) were monitored during 1-2 cytostatic treatment series. Body composition was estimated using bioelectrical impedance analysis (BIA). RESULTS: 61 patients were included. Weight loss and loss of muscle mass were detected in 64% and 59% of the patients, respectively. Muscle mass was significantly positively correlated to increasing PAL (p = 0.003), while negatively correlated to increasing age (p = 0.03), physical QoL (p = 0.007), functional QoL (p = 0.05), self-perceived health (p = 0.004), and self-perceived QoL (p = 0.007). Weight was significantly positively correlated to increased intake of soft drinks (p = 0.02) as well as the favoring of bitter grain and cereal products (p = 0.03), while negatively correlated to increasing age (p = 0.03) and increasing meat intake (p = 0.009) Conclusions: Several nutritional and lifestyle-related factors affected change in body composition. The clinical significance of these changes should be investigated in controlled, interventional studies.


Subject(s)
Cytostatic Agents , Hematologic Neoplasms , Humans , Quality of Life , Nutritional Status , Muscular Atrophy , Life Style , Hematologic Neoplasms/complications , Edible Grain
10.
Biomolecules ; 14(1)2024 Jan 22.
Article in English | MEDLINE | ID: mdl-38275764

ABSTRACT

Na+,K+-ATPase actively extrudes three cytoplasmic Na+ ions in exchange for two extracellular K+ ions for each ATP hydrolyzed. The atomic structure with bound Na+ identifies three Na+ sites, named I, II, and III. It has been proposed that site III is the first to be occupied and site II last, when Na+ binds from the cytoplasmic side. It is usually assumed that the occupation of all three Na+ sites is obligatory for the activation of phosphoryl transfer from ATP. To obtain more insight into the individual roles of the ion-binding sites, we have analyzed a series of seven mutants with substitution of the critical ion-binding residue Ser777, which is a shared ligand between Na+ sites I and III. Surprisingly, mutants with large and bulky substituents expected to prevent or profoundly disturb Na+ access to sites I and III retain the ability to form a phosphoenzyme from ATP, even with increased apparent Na+ affinity. This indicates that Na+ binding solely at site II is sufficient to promote phosphorylation. These mutations appear to lock the membrane sector into an E1-like configuration, allowing Na+ but not K+ to bind at site II, while the cytoplasmic sector undergoes conformational changes uncoupled from the membrane sector.


Subject(s)
Adenosine Triphosphate , Sodium-Potassium-Exchanging ATPase , Sodium-Potassium-Exchanging ATPase/genetics , Sodium-Potassium-Exchanging ATPase/metabolism , Phosphorylation , Adenosine Triphosphate/metabolism , Binding Sites , Ions/metabolism
11.
Antimicrob Agents Chemother ; 68(2): e0138723, 2024 Feb 07.
Article in English | MEDLINE | ID: mdl-38189278

ABSTRACT

The cell-to-cell communication system quorum sensing (QS), used by various pathogenic bacteria to synchronize gene expression and increase host invasion potentials, is studied as a potential target for persistent infection control. To search for novel molecules targeting the QS system in the Gram-negative opportunistic pathogen Pseudomonas aeruginosa, a chemical library consisting of 3,280 small compounds from LifeArc was screened. A series of 10 conjugated phenones that have not previously been reported to target bacteria were identified as inhibitors of QS in P. aeruginosa. Two lead compounds (ethylthio enynone and propylthio enynone) were re-synthesized for verification of activity and further elucidation of the mode of action. The isomeric pure Z-ethylthio enynone was used for RNA sequencing, revealing a strong inhibitor of QS-regulated genes, and the QS-regulated virulence factors rhamnolipid and pyocyanin were significantly decreased by treatment with the compounds. A transposon mutagenesis screen performed in a newly constructed lasB-gfp monitor strain identified the target of Z-ethylthio enynone in P. aeruginosa to be the MexEF-OprN efflux pump, which was further established using defined mex knockout mutants. Our data indicate that the QS inhibitory capabilities of Z-ethylthio enynone were caused by the drainage of intracellular signal molecules as a response to chemical-induced stimulation of the MexEF-oprN efflux pump, thereby inhibiting the autogenerated positive feedback and its enhanced signal-molecule synthesis.


Subject(s)
Pseudomonas aeruginosa , Quorum Sensing , Pseudomonas aeruginosa/genetics , Quorum Sensing/genetics , Virulence Factors/genetics , Bacterial Proteins/genetics
12.
Proc Natl Acad Sci U S A ; 121(3): e2315259121, 2024 Jan 16.
Article in English | MEDLINE | ID: mdl-38194449

ABSTRACT

Competing exonucleases that promote 3' end maturation or degradation direct quality control of small non-coding RNAs, but how these enzymes distinguish normal from aberrant RNAs is poorly understood. The Pontocerebellar Hypoplasia 7 (PCH7)-associated 3' exonuclease TOE1 promotes maturation of canonical small nuclear RNAs (snRNAs). Here, we demonstrate that TOE1 achieves specificity toward canonical snRNAs through their Sm complex assembly and cap trimethylation, two features that distinguish snRNAs undergoing correct biogenesis from other small non-coding RNAs. Indeed, disruption of Sm complex assembly via snRNA mutations or protein depletions obstructs snRNA processing by TOE1, and in vitro snRNA processing by TOE1 is stimulated by a trimethylated cap. An unstable snRNA variant that normally fails to undergo maturation becomes fully processed by TOE1 when its degenerate Sm binding motif is converted into a canonical one. Our findings uncover the molecular basis for how TOE1 distinguishes snRNAs from other small non-coding RNAs and explain how TOE1 promotes maturation specifically of canonical snRNAs undergoing proper processing.


Subject(s)
Exonucleases , RNA, Small Nuclear , RNA, Small Nuclear/genetics , RNA , Mutation , Quality Control
13.
Nutr Rev ; 82(5): 600-611, 2024 Apr 12.
Article in English | MEDLINE | ID: mdl-37437898

ABSTRACT

CONTEXT: Rheumatoid arthritis is a chronic inflammatory disease that causes synovitis. Vitamin D deficiency is common in rheumatoid arthritis. OBJECTIVE: This systematic review and meta-analysis investigated whether vitamin D supplementation affects the inflammatory and clinical outcomes in patients with rheumatoid arthritis on the basis of randomized clinical trials. DATA SOURCES: A literature search was performed in the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, MEDLINE, Embase, and Google Scholar for articles published until May 2022. DATA EXTRACTION: The studies were selected according to PRISMA guidelines, and the risk of bias was assessed for randomized controlled trials. DATA ANALYSIS: A random effects model was used to conduct a meta-analysis, and heterogeneity was assessed using the I2 statistic. Of 464 records, 11 studies were included from 3049 patients. Conclusion: Vitamin D supplementation did not significantly reduce C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), disease activity score in 28 joints (DAS28), or the health assessment questionnaire score; however, the response to supplementation was highly heterogeneous. The pooled analysis showed that vitamin D significantly reduced the pain-visual analogue scale (VAS) weighted mean difference (WMD = -1.30, 95% confidence interval [CI] [-2.34, -27], P = .01), DAS28-CRP (WMD = -.58, 95% CI [-.86, -.31], P < .0001), and DAS28-ESR (WMD = -.58, 95% CI [-.86, -.31], P = .0001). Subgroup analysis for vitamin D doses (>100 µg per day versus <100 µg per day) showed that the higher doses had a more significant effect on CRP than the lower doses (P < .05). CONCLUSIONS: There was no significant difference between the effect of 2 vitamin D doses on ESR and DAS28. To minimize the high heterogeneity among studies in this meta-analysis, other confounding factors such as baseline vitamin D, age, dietary vitamin D, time of year, sun exposure, drug interaction, effect dosage, and power of study should be examined.


Subject(s)
Arthritis, Rheumatoid , Vitamin D , Humans , Vitamin D/therapeutic use , Randomized Controlled Trials as Topic , Vitamins/therapeutic use , Arthritis, Rheumatoid/complications , Arthritis, Rheumatoid/drug therapy , C-Reactive Protein/analysis , Dietary Supplements
14.
J Microsc ; 294(2): 75-83, 2024 May.
Article in English | MEDLINE | ID: mdl-37742319

ABSTRACT

Towards the end of the 19th century and the early 20th century, France was the world's largest producer of antimony, especially due to the rich deposits in the Brioude-Massiac area. Even though all the mining and smelting activities are long gone, there are still some remains of those activities. The most original of those is the use of roasting slags as aggregates in former plant walls or industrial building. They are macroscopically characterised by a black or red colour with a vesicular aspect similar to natural pozzolanas. Common petrography and mineralogy tools have been used to characterise those slags: optical mineralogy, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). To gain an insight into their mineral complexity, a QEMSCAN map has been produced. The mineralogy is typical of high-temperature slags: cristobalite, quartz, mullite, fayalite-forsterite series and spinel. The antimony content is quite high, up to seven percent, under the form of various antimony oxides and native antimony.

15.
Ugeskr Laeger ; 185(49)2023 12 04.
Article in Danish | MEDLINE | ID: mdl-38078474

ABSTRACT

ECT is generally regarded as a safe and efficient treatment. In this case report, a 76-year-old female patient did not wake up as expected after ECT. The patient was transferred to the emergency department, and a CT-scan showed an intracerebral haemorrhage. She died within two days of the event, and an autopsy confirmed the diagnosis and did not reveal any underlying cerebral pathology.


Subject(s)
Cerebral Hemorrhage , Tomography, X-Ray Computed , Female , Humans , Aged , Fatal Outcome , Cerebral Hemorrhage/diagnostic imaging , Cerebral Hemorrhage/etiology
16.
Cell Rep ; 42(11): 113325, 2023 11 28.
Article in English | MEDLINE | ID: mdl-37889751

ABSTRACT

The RNA exosome is a versatile ribonuclease. In the nucleoplasm of mammalian cells, it is assisted by its adaptors the nuclear exosome targeting (NEXT) complex and the poly(A) exosome targeting (PAXT) connection. Via its association with the ARS2 and ZC3H18 proteins, NEXT/exosome is recruited to capped and short unadenylated transcripts. Conversely, PAXT/exosome is considered to target longer and adenylated substrates via their poly(A) tails. Here, mutational analysis of the core PAXT component ZFC3H1 uncovers a separate branch of the PAXT pathway, which targets short adenylated RNAs and relies on a direct ARS2-ZFC3H1 interaction. We further demonstrate that similar acidic-rich short linear motifs of ZFC3H1 and ZC3H18 compete for a common ARS2 epitope. Consequently, while promoting NEXT function, ZC3H18 antagonizes PAXT activity. We suggest that this organization of RNA decay complexes provides co-activation of NEXT and PAXT at loci with abundant production of short exosome substrates.


Subject(s)
RNA, Nuclear , RNA-Binding Proteins , Animals , Cell Nucleus/metabolism , Exosome Multienzyme Ribonuclease Complex/metabolism , Mammals , RNA Stability/genetics , RNA, Messenger/genetics , RNA, Nuclear/genetics , RNA-Binding Proteins/genetics
17.
Nat Chem Biol ; 19(11): 1320-1330, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37783940

ABSTRACT

Covalent chemistry represents an attractive strategy for expanding the ligandability of the proteome, and chemical proteomics has revealed numerous electrophile-reactive cysteines on diverse human proteins. Determining which of these covalent binding events affect protein function, however, remains challenging. Here we describe a base-editing strategy to infer the functionality of cysteines by quantifying the impact of their missense mutation on cancer cell proliferation. The resulting atlas, which covers more than 13,800 cysteines on more than 1,750 cancer dependency proteins, confirms the essentiality of cysteines targeted by covalent drugs and, when integrated with chemical proteomic data, identifies essential, ligandable cysteines in more than 160 cancer dependency proteins. We further show that a stereoselective and site-specific ligand targeting an essential cysteine in TOE1 inhibits the nuclease activity of this protein through an apparent allosteric mechanism. Our findings thus describe a versatile method and valuable resource to prioritize the pursuit of small-molecule probes with high function-perturbing potential.


Subject(s)
Cysteine , Neoplasms , Humans , Cysteine/chemistry , Proteomics , Gene Editing , Proteome/chemistry , Neoplasms/genetics , Nuclear Proteins
18.
Neurochem Int ; 171: 105626, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37838084

ABSTRACT

Neurons and astrocytes work in close metabolic collaboration, linking neurotransmission to brain energy and neurotransmitter metabolism. Dysregulated energy metabolism is a hallmark of the aging brain and may underlie the progressive age-dependent cognitive decline. However, astrocyte and neurotransmitter metabolism remains understudied in aging brain research. In particular, how aging affects metabolism of glutamate, being the primary excitatory neurotransmitter, is still poorly understood. Here we investigated critical aspects of cellular energy metabolism in the aging male mouse hippocampus using stable isotope tracing in vitro. Metabolism of [U-13C]glucose demonstrated an elevated glycolytic capacity of aged hippocampal slices, whereas oxidative [U-13C]glucose metabolism in the TCA cycle was significantly reduced with aging. In addition, metabolism of [1,2-13C]acetate, reflecting astrocyte energy metabolism, was likewise reduced in the hippocampal slices of old mice. In contrast, uptake and subsequent metabolism of [U-13C]glutamate was elevated, suggesting increased capacity for cellular glutamate handling with aging. Finally, metabolism of [15N]glutamate was maintained in the aged slices, demonstrating sustained glutamate nitrogen metabolism. Collectively, this study reveals fundamental alterations in cellular energy and neurotransmitter metabolism in the aging brain, which may contribute to age-related hippocampal deficits.


Subject(s)
Energy Metabolism , Glutamic Acid , Male , Mice , Animals , Glutamic Acid/metabolism , Hippocampus/metabolism , Neurotransmitter Agents/metabolism , Carbon Isotopes/metabolism , Astrocytes/metabolism , Glucose/metabolism , Glutamine/metabolism
20.
bioRxiv ; 2023 Aug 17.
Article in English | MEDLINE | ID: mdl-37645788

ABSTRACT

Competing exonucleases that promote 3' end maturation or degradation direct quality control of small non-coding RNAs, but how these enzymes distinguish normal from aberrant RNAs is poorly understood. The Pontocerebellar Hypoplasia 7 (PCH7)-associated 3' exonuclease TOE1 promotes maturation of canonical small nuclear RNAs (snRNAs). Here, we demonstrate that TOE1 achieves specificity towards canonical snRNAs by recognizing Sm complex assembly and cap trimethylation, two features that distinguish snRNAs undergoing correct biogenesis from other small non-coding RNAs. Indeed, disruption of Sm complex assembly via snRNA mutations or protein depletions obstructs snRNA processing by TOE1, and in vitro snRNA processing by TOE1 is stimulated by a trimethylated cap. An unstable snRNA variant that normally fails to undergo maturation becomes fully processed by TOE1 when its degenerate Sm binding motif is converted into a canonical one. Our findings uncover the molecular basis for how TOE1 distinguishes snRNAs from other small non-coding RNAs and explain how TOE1 promotes maturation specifically of canonical snRNAs undergoing proper processing.

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