bims-medebr 2023-12-17 papers

bims-medebr

Biomed News

on Metabolism of the developing brain

Issue of 2023‒12‒17
23 papers selected by
Regina F. Fernández, Johns Hopkins University

Increased glucose metabolism and impaired glutamate transport in human astrocytes are potential early triggers of abnormal extracellular glutamate accumulation in hiPSC-derived models of Alzheimer's disease.
NPC1-like phenotype, with intracellular cholesterol accumulation and altered mTORC1 signaling in models of Parkinson's disease.
Characteristics of brain glucose metabolism and metabolic connectivity in noise-induced hearing loss.
Pathogenic Impact of Fatty Acid-Binding Proteins in Parkinson's Disease-Potential Biomarkers and Therapeutic Targets.
Ceramides Mediate Insulin-Induced Impairments in Cerebral Mitochondrial Bioenergetics in ApoE4 Mice.
Ndufs4 KO mice: A model to study comorbid mood disorders associated with mitochondrial dysfunction.
Acute and sub-acute metabolic change in different brain regions induced by moderate blunt traumatic brain injury.
Knockdown of Placental Major Facilitator Superfamily Domain Containing 2a in Pregnant Mice Reduces Fetal Brain Growth and Phospholipid Docosahexaenoic Acid Content.
Phospholipids are imported into mitochondria by VDAC, a dimeric beta barrel scramblase.
A hub for regulation of mitochondrial metabolism: Fatty acid and lipoic acid biosynthesis.
Altered Metabolism and DAM-signatures in Female Brains and Microglia with Aging.
Characteristic early changes of Glu and Cho in brain regions affected by different types of subjective cognitive decline and their clinical significance.
Loss of Slc35a2 alters development of the mouse cerebral cortex.
The lipid flippase ATP10B enables cellular lipid uptake under stress conditions.
Toward Omics-Scale Quantitative Mass Spectrometry Imaging of Lipids in Brain Tissue Using a Multiclass Internal Standard Mixture.
Red Flags in Primary Mitochondrial Diseases: What Should We Recognize?
The assembly of the Mitochondrial Complex I Assembly complex uncovers a redox pathway coordination.
A different perspective into clinical symptoms in CPT I deficiency.
SIRT3-Mediated Deacetylation of SDHA Rescues Mitochondrial Bioenergetics Contributing to Neuroprotection in Rotenone-Induced PD Models.
Microglial histone deacetylase 2 is dispensable for functional and histological outcomes in a mouse model of traumatic brain injury.
Leat-associated seizures the possible role of EAAT2, pyruvate carboxylase and glutamine synthetase.
Ablation of placental REST deregulates fetal brain metabolism and impacts gene expression of the offspring brain at the postnatal and adult stages.
Genetic, metabolic and clinical delineation of an MRPS23-associated mitochondrial disorder.

J Neurochem. 2023 Dec 08.

Increased glucose metabolism and impaired glutamate transport in human astrocytes are potential early triggers of abnormal extracellular glutamate accumulation in hiPSC-derived models of Alzheimer's disease.

Claudia Salcedo, Victoria Pozo Garcia, Bernat García-Adán, Aishat O Ameen, Georgi Gegelashvili, Helle S Waagepetersen, Kristine K Freude, Blanca I Aldana.

  Glutamate recycling between neurons and astrocytes is essential to maintain neurotransmitter homeostasis. Disturbances in glutamate homeostasis, resulting in excitotoxicity and neuronal death, have been described as a potential mechanism in Alzheimer's disease (AD) pathophysiology. However, glutamate neurotransmitter metabolism in different human brain cells, particularly astrocytes, has been poorly investigated at the early stages of AD. We sought to investigate glucose and glutamate metabolism in AD by employing human induced pluripotent stem cell (hiPSC)-derived astrocytes and neurons carrying mutations in the amyloid precursor protein (APP) or presenilin-1 (PSEN-1) gene as found in familial types of AD (fAD). Methods such as live-cell bioenergetics and metabolic mapping using [13 C]-enriched substrates were used to examine metabolism in the early stages of AD. Our results revealed greater glycolysis and glucose oxidative metabolism in astrocytes and neurons with APP or PSEN-1 mutations, accompanied by an elevated glutamate synthesis compared to control WT cells. Astrocytes with APP or PSEN-1 mutations exhibited reduced expression of the excitatory amino acid transporter 2 (EAAT2), and glutamine uptake increased in mutated neurons, with enhanced glutamate release specifically in neurons with a PSEN-1 mutation. These results demonstrate a hypermetabolic phenotype in astrocytes with fAD mutations possibly linked to toxic glutamate accumulation. Our findings further identify metabolic imbalances that may occur in the early phases of AD pathophysiology.

Keywords:  APP; PSEN-1; energy metabolism; excitotoxicity; hiPSC astrocytes; hiPSC neurons

DOI:  https://doi.org/10.1111/jnc.16014
Biochim Biophys Acta Mol Basis Dis. 2023 Dec 05. pii: S0925-4439(23)00346-0. [Epub ahead of print]1870(2): 166980

NPC1-like phenotype, with intracellular cholesterol accumulation and altered mTORC1 signaling in models of Parkinson's disease.

Inês Caria, Maria João Nunes, Viviana Ciraci, Andreia Neves Carvalho, Catarina Ranito, Susana G Santos, Maria João Gama, Margarida Castro-Caldas, Cecília M P Rodrigues, Jorge L Ruas, Elsa Rodrigues.

  Disruption of brain cholesterol homeostasis has been implicated in neurodegeneration. Nevertheless, the role of cholesterol in Parkinson's Disease (PD) remains unclear. We have used N2a mouse neuroblastoma cells and primary cultures of mouse neurons and 1-methyl-4-phenylpyridinium (MPP+), a known mitochondrial complex I inhibitor and the toxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), known to trigger a cascade of events associated with PD neuropathological features. Simultaneously, we utilized other mitochondrial toxins, including antimycin A, oligomycin, and carbonyl cyanide chlorophenylhydrazone. MPP+ treatment resulted in elevated levels of total cholesterol and in a Niemann Pick type C1 (NPC1)-like phenotype characterized by accumulation of cholesterol in lysosomes. Interestingly, NPC1 mRNA levels were specifically reduced by MPP+. The decrease in NPC1 levels was also seen in midbrain and striatum from MPTP-treated mice and in primary cultures of neurons treated with MPP+. Together with the MPP+-dependent increase in intracellular cholesterol levels in N2a cells, we observed an increase in 5' adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and a concomitant increase in the phosphorylated levels of mammalian target of rapamycin (mTOR). NPC1 knockout delayed cell death induced by acute mitochondrial damage, suggesting that transient cholesterol accumulation in lysosomes could be a protective mechanism against MPTP/MPP+ insult. Interestingly, we observed a negative correlation between NPC1 protein levels and disease stage, in human PD brain samples. In summary, MPP+ decreases NPC1 levels, elevates lysosomal cholesterol accumulation and alters mTOR signaling, adding to the existing notion that PD may rise from alterations in mitochondrial-lysosomal communication.

Keywords:  Brain cholesterol metabolism; Lysosomes; Mitochondria dysfunction; NPC1; Parkinson's disease

DOI:  https://doi.org/10.1016/j.bbadis.2023.166980
Sci Rep. 2023 Dec 11. 13(1): 21889

Characteristics of brain glucose metabolism and metabolic connectivity in noise-induced hearing loss.

Seunghyeon Shin, Hyun-Yeol Nam.

The purpose of this study was to evaluate the differences in cerebral glucose metabolism and metabolic connectivity between noise-induced hearing loss (NIHL) subjects and normal subjects. Eighty-nine subjects who needed close observation for NIHL or were diagnosed with NIHL and 89 normal subjects were enrolled. After pre-processing of positron emission tomography images including co-registration, spatial normalization, and smoothing, a two-sample t-test was conducted to compare cerebral glucose metabolism between the two groups. To evaluate metabolic connectivity between two groups, BRAPH-BRain Analysis using graPH theory, a software package to perform graph theory analysis of the brain connectome was used. NIHL subjects showed hypometabolism compared to normal subjects in both insulae (x - 38, y - 18, z 4; × 42, y - 12, z 4) and right superior temporal gyrus (× 44, y 16, z - 20). No brain regions showed hypermetabolism in the NIHL subjects. In metabolic connectivity analysis, NIHL subjects showed decreased average strength, global efficiency, local efficiency, and mean clustering coefficient when compared with normal subjects. Decreased glucose metabolism and metabolic connectivity in NIHL subject might reflect decreased auditory function. It might be characteristic of sensorineural hearing loss.

DOI: https://doi.org/10.1038/s41598-023-48911-x
Int J Mol Sci. 2023 Dec 01. pii: 17037. [Epub ahead of print]24(23):

Pathogenic Impact of Fatty Acid-Binding Proteins in Parkinson's Disease-Potential Biomarkers and Therapeutic Targets.

Ichiro Kawahata, Kohji Fukunaga.

  Parkinson's disease is a neurodegenerative condition characterized by motor dysfunction resulting from the degeneration of dopamine-producing neurons in the midbrain. This dopamine deficiency gives rise to a spectrum of movement-related symptoms, including tremors, rigidity, and bradykinesia. While the precise etiology of Parkinson's disease remains elusive, genetic mutations, protein aggregation, inflammatory processes, and oxidative stress are believed to contribute to its development. In this context, fatty acid-binding proteins (FABPs) in the central nervous system, FABP3, FABP5, and FABP7, impact α-synuclein aggregation, neurotoxicity, and neuroinflammation. These FABPs accumulate in mitochondria during neurodegeneration, disrupting their membrane potential and homeostasis. In particular, FABP3, abundant in nigrostriatal dopaminergic neurons, is responsible for α-synuclein propagation into neurons and intracellular accumulation, affecting the loss of mesencephalic tyrosine hydroxylase protein, a rate-limiting enzyme of dopamine biosynthesis. This review summarizes the characteristics of FABP family proteins and delves into the pathogenic significance of FABPs in the pathogenesis of Parkinson's disease. Furthermore, it examines potential novel therapeutic targets and early diagnostic biomarkers for Parkinson's disease and related neurodegenerative disorders.

Keywords:  Parkinson’s disease; biomarkers; dementia with Lewy bodies; dopaminergic neurons; early diagnostic techniques; fatty acid-binding protein; mitochondria; therapeutic target; tyrosine hydroxylase; α-synuclein

DOI:  https://doi.org/10.3390/ijms242317037
Int J Mol Sci. 2023 Nov 23. pii: 16635. [Epub ahead of print]24(23):

Ceramides Mediate Insulin-Induced Impairments in Cerebral Mitochondrial Bioenergetics in ApoE4 Mice.

Sheryl T Carr, Erin R Saito, Chase M Walton, Jeremy Y Saito, Cameron M Hanegan, Cali E Warren, Annie M Trumbull, Benjamin T Bikman.

  Alzheimer's disease (AD) is the most common form of neurodegenerative disease worldwide. A large body of work implicates insulin resistance in the development and progression of AD. Moreover, impairment in mitochondrial function, a common symptom of insulin resistance, now represents a fundamental aspect of AD pathobiology. Ceramides are a class of bioactive sphingolipids that have been hypothesized to drive insulin resistance. Here, we describe preliminary work that tests the hypothesis that hyperinsulinemia pathologically alters cerebral mitochondrial function in AD mice via accrual of the ceramides. Homozygous male and female ApoE4 mice, an oft-used model of AD research, were given chronic injections of PBS (control), insulin, myriocin (an inhibitor of ceramide biosynthesis), or insulin and myriocin over four weeks. Cerebral ceramide content was assessed using liquid chromatography-mass spectrometry. Mitochondrial oxygen consumption rates were measured with high-resolution respirometry, and H2O2 emissions were quantified via biochemical assays on brain tissue from the cerebral cortex. Significant increases in brain ceramides and impairments in brain oxygen consumption were observed in the insulin-treated group. These hyperinsulinemia-induced impairments in mitochondrial function were reversed with the administration of myriocin. Altogether, these data demonstrate a causative role for insulin in promoting brain ceramide accrual and subsequent mitochondrial impairments that may be involved in AD expression and progression.

Keywords:  Alzheimer’s disease; ApoE4; ceramides; cerebral cortex; dyslipidemia; insulin resistance; mitochondrial bioenergetics

DOI:  https://doi.org/10.3390/ijms242316635
Pharmacol Biochem Behav. 2023 Dec 07. pii: S0091-3057(23)00176-4. [Epub ahead of print]234 173689

Ndufs4 KO mice: A model to study comorbid mood disorders associated with mitochondrial dysfunction.

Daniël J van Rensburg, Zander Lindeque, Brian H Harvey, Stephan F Steyn.

  The Ndufs4 knockout (KO) mouse is a validated and robust preclinical model of mitochondrial diseases (specifically Leigh syndrome), that displays a narrow window of relative phenotypical normality, despite its inherent mitochondrial complex I dysfunction and severe phenotype. Preclinical observations related to psychiatric comorbidities that arise in patients with mitochondrial diseases and indeed in Leigh syndrome are, however, yet to be investigated in this model. Strengthening this narrative is the fact that major depression and bipolar disorder are known to present with deficits in mitochondrial function. We therefore screened the behavioural profile of male and female Ndufs4 KO mice (relative to heterozygous; HET and wildtype; WT mice) between postnatal days 28 and 35 for locomotor, depressive- and anxiety-like alterations and linked it with selected brain biomarkers, viz. serotonin, kynurenine, and redox status in brain areas relevant to psychiatric pathologies (i.e., prefrontal cortex, hippocampus, and striatum). The Ndufs4 KO mice initially displayed depressive-like behaviour in the tail suspension test on PND31 but not on PND35 in the forced swim test. In the mirror box test, increased risk resilience was observed. Serotonin levels of KO mice, compared to HET controls, were increased on PND36, together with increased tryptophan to serotonin and kynurenine turnover. Kynurenine to kynurenic acid turnover was however decreased, while reduced versus oxidized glutathione ratio (GSH/GSSG) was increased. When considering the comorbid psychiatric traits of patients with mitochondrial disorders, this work elaborates on the neuropsychiatric profile of the Ndufs KO mouse. Secondly, despite locomotor differences, Ndufs4 KO mice present with a behavioural profile not unlike rodent models of bipolar disorder, namely variable mood states and risk-taking behaviour. The model may elucidate the bio-energetic mechanisms underlying mood disorders, especially in the presence of mitochondrial disease. Studies are however required to further validate the model's translational relevance.

Keywords:  Monoamines; Mood; Oxidative stress; Tryptophan metabolism

DOI:  https://doi.org/10.1016/j.pbb.2023.173689
Neuroreport. 2023 Dec 04.

Acute and sub-acute metabolic change in different brain regions induced by moderate blunt traumatic brain injury.

Megha Kumari, Yasha Hasija, Richa Trivedi.

The objective of the study was to observe the effect of moderate closed-head injury on hippocampal, thalamic, and striatal tissue metabolism with time. Closed head injury is responsible for metabolic changes. These changes can be permanent or temporary, depending on the injury's impact. For the experiment, 20 rats were randomly divided into four groups, each containing five animals. Animals were subjected to injury using a modified Marmarou's weight drop device; hippocampal, thalamic, and striatal tissue samples were collected after 1 day, 3 days, and 7 days of injury. NMR spectra were acquired following sample processing. Changes in myo-inositol, creatine, glutamate, succinate, lactate, and N-acetyl aspartic acid in hippocampal tissues were observed at day 3 PI. The tyrosine level in the hippocampus was altered at day 7 PI. While thalamic and striatal tissue samples showed altered levels of branched-chain amino acids and myo-inositol at day 1PI. Taurine, gamma amino butyric acid (GABA), choline, and alpha keto-glutarate levels were found to be significantly altered in striatal tissues at days 1 and 3PI. Acetate and GABA levels were altered in the thalamus on day 1 PI. The choline level in the thalamus was found to alter at all-time points after injury. The alteration in these metabolites may be due to the alteration in their respective pathways. Neurotransmitter and energy metabolism pathways were found to be altered in all three brain regions after TBI. This study may help better understand the effect of injury on the metabolic balance of a specific brain region and recovery.

DOI: https://doi.org/10.1097/WNR.0000000000001982
Nutrients. 2023 Nov 29. pii: 4956. [Epub ahead of print]15(23):

Knockdown of Placental Major Facilitator Superfamily Domain Containing 2a in Pregnant Mice Reduces Fetal Brain Growth and Phospholipid Docosahexaenoic Acid Content.

Theresa L Powell, Kenneth Barentsen, Owen Vaughan, Charis Uhlson, Karin Zemski Berry, Kathryn Erickson, Kelsey Faer, Stephanie S Chassen, Thomas Jansson.

  INTRODUCTION: Docosahexaenoic acid (DHA) is an n-3 long chain polyunsaturated fatty acid critical for fetal brain development that is transported to the fetus from the mother by the placenta. The lysophosphatidylcholine (LPC) transporter, Major Facilitator Superfamily Domain Containing 2a (MFSD2a), is localized in the basal plasma membrane of the syncytiotrophoblast of the human placenta, and MFSD2a expression correlates with umbilical cord blood LPC-DHA levels in human pregnancy. We hypothesized that placenta-specific knockdown of MFSD2a in pregnant mice reduces phospholipid DHA accumulation in the fetal brain.METHODS: Mouse blastocysts (E3.5) were transduced with an EGFP-expressing lentivirus containing either an shRNA targeting MFSD2a or a non-coding sequence (SCR), then transferred to pseudopregnant females. At E18.5, fetuses were weighed and their placenta, brain, liver and plasma were collected. MFSD2a mRNA expression was determined by qPCR in the brain, liver and placenta and phospholipid DHA was quantified by LC-MS/MS.
RESULTS: MFSD2a-targeting shRNA reduced placental mRNA MFSD2a expression by 38% at E18.5 (n = 45, p < 0.008) compared with SCR controls. MFSD2a expression in the fetal brain and liver were unchanged. Fetal brain weight was reduced by 13% (p = 0.006). Body weight, placenta and liver weights were unaffected. Fetal brain phosphatidyl choline and phosphatidyl ethanolamine DHA content was lower in fetuses with placenta-specific MFSD2a knockdown.
CONCLUSIONS: Placenta-specific reduction in expression of the LPC-DHA transporter MFSD2a resulted in reduced fetal brain weight and lower phospholipid DHA content in the fetal brain. These data provide mechanistic evidence that placental MFSD2a mediates maternal-fetal transfer of LPC-DHA, which is critical for brain growth.

Keywords:  docosahexaenoic acids; fatty acids; maternal–fetal exchange; pregnancy; trophoblast

DOI:  https://doi.org/10.3390/nu15234956
Nat Commun. 2023 Dec 08. 14(1): 8115

Phospholipids are imported into mitochondria by VDAC, a dimeric beta barrel scramblase.

Helene Jahn, Ladislav Bartoš, Grace I Dearden, Jeremy S Dittman, Joost C M Holthuis, Robert Vácha, Anant K Menon.

Mitochondria are double-membrane-bounded organelles that depend critically on phospholipids supplied by the endoplasmic reticulum. These lipids must cross the outer membrane to support mitochondrial function, but how they do this is unclear. We identify the Voltage Dependent Anion Channel (VDAC), an abundant outer membrane protein, as a scramblase-type lipid transporter that catalyzes lipid entry. On reconstitution into membrane vesicles, dimers of human VDAC1 and VDAC2 catalyze rapid transbilayer translocation of phospholipids by a mechanism that is unrelated to their channel activity. Coarse-grained molecular dynamics simulations of VDAC1 reveal that lipid scrambling occurs at a specific dimer interface where polar residues induce large water defects and bilayer thinning. The rate of phospholipid import into yeast mitochondria is an order of magnitude lower in the absence of VDAC homologs, indicating that VDACs provide the main pathway for lipid entry. Thus, VDAC isoforms, members of a superfamily of beta barrel proteins, moonlight as a class of phospholipid scramblases - distinct from alpha-helical scramblase proteins - that act to import lipids into mitochondria.

DOI: https://doi.org/10.1038/s41467-023-43570-y
IUBMB Life. 2023 Dec 13.

A hub for regulation of mitochondrial metabolism: Fatty acid and lipoic acid biosynthesis.

Carol L Dieckmann.

  Having evolved from a prokaryotic origin, mitochondria retain pathways required for the catabolism of energy-rich molecules and for the biosynthesis of molecules that aid catabolism and/or participate in other cellular processes essential for life of the cell. Reviewed here are details of the mitochondrial fatty acid biosynthetic pathway (FAS II) and its role in building both the octanoic acid precursor for lipoic acid biosynthesis (LAS) and longer-chain fatty acids functioning in chaperoning the assembly of mitochondrial multisubunit complexes. Also covered are the details of mitochondrial lipoic acid biosynthesis, which is distinct from that of prokaryotes, and the attachment of lipoic acid to subunits of pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and glycine cleavage system complexes. Special emphasis has been placed on presenting what is currently known about the interconnected paths and loops linking the FAS II-LAS pathway and two other mitochondrial realms, the organellar translation machinery and Fe-S cluster biosynthesis and function.

Keywords:  Saccharomyces; fatty acid biosynthesis; lipoic acid biosynthesis; mitochondrial biogenesis

DOI:  https://doi.org/10.1002/iub.2802
bioRxiv. 2023 Nov 30. pii: 2023.11.28.569104. [Epub ahead of print]

Altered Metabolism and DAM-signatures in Female Brains and Microglia with Aging.

Nicholas R W Cleland, Garrett J Potter, Courtney Buck, Daphne Quang, Dean Oldham, Mikaela Neal, Anthony Saviola, Christy S Niemeyer, Evgenia Dobrinskikh, Kimberley D Bruce.

Despite Alzheimer's disease (AD) disproportionately affecting women, the mechanisms remain elusive. In AD, microglia undergo 'metabolic reprogramming', which contributes to microglial dysfunction and AD pathology. However, how sex and age contribute to metabolic reprogramming in microglia is understudied. Here, we use metabolic imaging, transcriptomics, and metabolic assays to probe age-and sex-associated changes in brain and microglial metabolism. Glycolytic and oxidative metabolism in the whole brain was determined using Fluorescence Lifetime Imaging Microscopy (FLIM). Young female brains appeared less glycolytic than male brains, but with aging, the female brain became 'male-like.' Transcriptomic analysis revealed increased expression of disease-associated microglia (DAM) genes (e.g., ApoE , Trem2 , LPL ), and genes involved in glycolysis and oxidative metabolism in microglia from aged females compared to males. To determine whether estrogen can alter the expression of these genes, BV-2 microglia-like cell lines, which abundantly express DAM genes, were supplemented with 17β-estradiol (E2). E2 supplementation resulted in reduced expression of DAM genes, reduced lipid and cholesterol transport, and substrate-dependent changes in glycolysis and oxidative metabolism. Consistent with the notion that E2 may suppress DAM-associated factors, LPL activity was elevated in the brains of aged female mice. Similarly, DAM gene and protein expression was higher in monocyte-derived microglia-like (MDMi) cells derived from middle-aged females compared to age-matched males and was responsive to E2 supplementation. FLIM analysis of MDMi from young and middle-aged females revealed reduced oxidative metabolism and FAD+ with age. Overall, our findings show that altered metabolism defines age-associated changes in female microglia and suggest that estrogen may inhibit the expression and activity of DAM-associated factors, which may contribute to increased AD risk, especially in post-menopausal women.

DOI: https://doi.org/10.1101/2023.11.28.569104
Medicine (Baltimore). 2023 Dec 08. 102(49): e36457

Characteristic early changes of Glu and Cho in brain regions affected by different types of subjective cognitive decline and their clinical significance.

Zhen Zeng, Jing He, Tao Yao.

To discuss the early changes of Glu and Cho in the affected areas of different types of subjective cognitive decline, including amnestic MCI (aMCl), non-amnestic MCI (naMCI) and vascular cognitive impairment no dementia (VCIND), using Proton Magnetic Resonance Spectroscopy (1H-MRS) technology. Routine head MRI and lH-MRS examinations were performed on 50 clearly diagnosed aMCI patients, 44 naMCI patients, 44 VCIND patients, and 44 elderly individuals with normal cognitive function. Measure the volume of the patient bilateral hippocampus. Using the bilateral hippocampus, left posterior cingulate gyrus (PCG), and frontal lobe as regions of interest, the scope under the peak of N-acetylaspartate (NAA), choline complex (Cho), glutamate (Glu), Metabolic Images (mI), and creatine (Cr) was tested. Perform a correlation analysis between the NAA/Cho/Cr values of the VCIND group and the MoCA score. All experimental subjects were right-handed. The NAACr values in both hippocampus of the VCIND were greatly lower than those in control (P < .05). The NAA/Cr values on both sides of the VCIND were correlated with the MoCA score (P < .05). The NAA/Cr values in the LHp and PCG of subjects in the aMCI and naMCI groups were lower than those in the NC group (P < .05). The NAA/Cr values in the left frontal lobe of the aMCI and naMCI showed no obvious decrease compared to the NC. The Glu/Cr of subjects in the aMCI was lower in the left PCG than those in the naMCI and NC (P < .05). The discrepancy between the naMCI and the NC was P > .05. In the LHp and frontal lobe, in contrast with the naMCI and NC, the mI/Cr values in the LHp and PCG of subjects in the aMCI were higher (P < .05). In the left frontal lobe, relative to the aMCI and NC, the mI/Cr values in the naMCI were higher (P < .05). The changes in the concentration of 1H-MRS metabolites in the hippocampus can indicate the presence of hippocampal neuronal damage before morphological changes occur in the hippocampus. 1H-MRS NAA/Cr can reflect the cognitive function changes of patients to a certain extent. There are regional differences in mI and Glu metabolism in the brain between aMCI and naMCI groups. 1H-MRS provides an effective basis for clinical differentiation between aMCI and naMCI.

DOI: https://doi.org/10.1097/MD.0000000000036457
bioRxiv. 2023 Nov 30. pii: 2023.11.29.569243. [Epub ahead of print]

Loss of Slc35a2 alters development of the mouse cerebral cortex.

Soad Elziny, Sahibjot Sran, Hyojung Yoon, Rachel R Corrigan, John Page, Amanda Ringland, Anna Lanier, Sara Lapidus, James Foreman, Erin L Heinzen, Philip Iffland, Peter B Crino, Tracy A Bedrosian.

Brain somatic variants in SLC35A2 are associated with clinically drug-resistant epilepsy and developmental brain malformations, including mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). SLC35A2 encodes a uridine diphosphate galactose translocator that is essential for protein glycosylation; however, the neurodevelopmental mechanisms by which SLC35A2 disruption leads to clinical and histopathological features remain unspecified. We hypothesized that focal knockout (KO) or knockdown (KD) of Slc35a2 in the developing mouse cortex would disrupt cerebral cortical development through altered neuronal migration and cause changes in network excitability. We used in utero electroporation (IUE) to introduce CRISPR/Cas9 and targeted guide RNAs or short-hairpin RNAs to achieve Slc35a2 KO or KD, respectively, during early corticogenesis. Following Slc35a2 KO or KD, we observed disrupted radial migration of transfected neurons evidenced by heterotopic cells located in lower cortical layers and in the sub-cortical white matter. Slc35a2 KO in neurons did not induce changes in oligodendrocyte number, suggesting that the oligodendroglial hyperplasia observed in MOGHE originates from distinct cell autonomous effects. Spontaneous seizures were not observed, but intracranial EEG recordings after focal KO showed a reduced seizure threshold following pentylenetetrazol injection. These results demonstrate that Slc35a2 KO or KD in vivo disrupts corticogenesis through altered neuronal migration.

DOI: https://doi.org/10.1101/2023.11.29.569243
Biochim Biophys Acta Mol Cell Res. 2023 Dec 10. pii: S0167-4889(23)00225-2. [Epub ahead of print] 119652

The lipid flippase ATP10B enables cellular lipid uptake under stress conditions.

Rosanne Wouters, Igor Beletchi, Chris Van den Haute, Veerle Baekelandt, Shaun Martin, Jan Eggermont, Peter Vangheluwe.

  Pathogenic ATP10B variants have been described in patients with Parkinson's disease and dementia with Lewy body disease, and we previously established ATP10B as a late endo-/lysosomal lipid flippase transporting both phosphatidylcholine (PC) and glucosylceramide (GluCer) from the lysosomal exoplasmic to cytoplasmic membrane leaflet. Since several other lipid flippases regulate cellular lipid uptake, we here examined whether also ATP10B impacts cellular lipid uptake. Transient co-expression of ATP10B with its obligatory subunit CDC50A stimulated the uptake of fluorescently (NBD-) labeled PC in HeLa cells. This uptake is dependent on the transport function of ATP10B, is impaired by disease-associated variants and appears specific for NBD-PC. Uptake of non-ATP10B substrates, such as NBD-sphingomyelin or NBD-phosphatidylethanolamine is not increased. Remarkably, in stable cell lines co-expressing ATP10B/CDC50A we only observed increased NBD-PC uptake following treatment with rotenone, a mitochondrial complex I inhibitor that induces transport-dependent ATP10B phenotypes. Conversely, Im95m and WM-115 cells with endogenous ATP10B expression, present a decreased NBD-PC uptake following ATP10B knockdown, an effect that is exacerbated under rotenone stress. Our data show that the endo-/lysosomal lipid flippase ATP10B contributes to cellular PC uptake under specific cell stress conditions.

Keywords:  Endo-/lysosomes; Glucosylceramide; Lipid transport; Parkinson's disease; Phosphatidylcholine

DOI:  https://doi.org/10.1016/j.bbamcr.2023.119652
Anal Chem. 2023 Dec 11.

Toward Omics-Scale Quantitative Mass Spectrometry Imaging of Lipids in Brain Tissue Using a Multiclass Internal Standard Mixture.

Michiel Vandenbosch, Shadrack M Mutuku, Maria José Q Mantas, Nathan H Patterson, Tucker Hallmark, Marc Claesen, Ron M A Heeren, Nathan G Hatcher, Nico Verbeeck, Kim Ekroos, Shane R Ellis.

Mass spectrometry imaging (MSI) has accelerated our understanding of lipid metabolism and spatial distribution in tissues and cells. However, few MSI studies have approached lipid imaging quantitatively and those that have focused on a single lipid class. We overcome this limitation by using a multiclass internal standard (IS) mixture sprayed homogeneously over the tissue surface with concentrations that reflect those of endogenous lipids. This enabled quantitative MSI (Q-MSI) of 13 lipid classes and subclasses representing almost 200 sum-composition lipid species using both MALDI (negative ion mode) and MALDI-2 (positive ion mode) and pixel-wise normalization of each lipid species in a manner analogous to that widely used in shotgun lipidomics. The Q-MSI approach covered 3 orders of magnitude in dynamic range (lipid concentrations reported in pmol/mm2) and revealed subtle changes in distribution compared to data without normalization. The robustness of the method was evaluated by repeating experiments in two laboratories using both timsTOF and Orbitrap mass spectrometers with an ∼4-fold difference in mass resolution power. There was a strong overall correlation in the Q-MSI results obtained by using the two approaches. Outliers were mostly rationalized by isobaric interferences or the higher sensitivity of one instrument for a particular lipid species. These data provide insight into how the mass resolving power can affect Q-MSI data. This approach opens up the possibility of performing large-scale Q-MSI studies across numerous lipid classes and subclasses and revealing how absolute lipid concentrations vary throughout and between biological tissues.

DOI: https://doi.org/10.1021/acs.analchem.3c02724
Int J Mol Sci. 2023 Nov 25. pii: 16746. [Epub ahead of print]24(23):

Red Flags in Primary Mitochondrial Diseases: What Should We Recognize?

Federica Conti, Serena Di Martino, Filippo Drago, Claudio Bucolo, Vincenzo Micale, Vincenzo Montano, Gabriele Siciliano, Michelangelo Mancuso, Piervito Lopriore.

  Primary mitochondrial diseases (PMDs) are complex group of metabolic disorders caused by genetically determined impairment of the mitochondrial oxidative phosphorylation (OXPHOS). The unique features of mitochondrial genetics and the pivotal role of mitochondria in cell biology explain the phenotypical heterogeneity of primary mitochondrial diseases and the resulting diagnostic challenges that follow. Some peculiar features ("red flags") may indicate a primary mitochondrial disease, helping the physician to orient in this diagnostic maze. In this narrative review, we aimed to outline the features of the most common mitochondrial red flags offering a general overview on the topic that could help physicians to untangle mitochondrial medicine complexity.

Keywords:  mitochondria; primary mitochondrial diseases; rare diseases; red flags

DOI:  https://doi.org/10.3390/ijms242316746
Nat Commun. 2023 Dec 12. 14(1): 8248

The assembly of the Mitochondrial Complex I Assembly complex uncovers a redox pathway coordination.

Lindsay McGregor, Samira Acajjaoui, Ambroise Desfosses, Melissa Saïdi, Maria Bacia-Verloop, Jennifer J Schwarz, Pauline Juyoux, Jill von Velsen, Matthew W Bowler, Andrew A McCarthy, Eaazhisai Kandiah, Irina Gutsche, Montserrat Soler-Lopez.

The Mitochondrial Complex I Assembly (MCIA) complex is essential for the biogenesis of respiratory Complex I (CI), the first enzyme in the respiratory chain, which has been linked to Alzheimer's disease (AD) pathogenesis. However, how MCIA facilitates CI assembly, and how it is linked with AD pathogenesis, is poorly understood. Here we report the structural basis of the complex formation between the MCIA subunits ECSIT and ACAD9. ECSIT binding induces a major conformational change in the FAD-binding loop of ACAD9, releasing the FAD cofactor and converting ACAD9 from a fatty acid β-oxidation (FAO) enzyme to a CI assembly factor. We provide evidence that ECSIT phosphorylation downregulates its association with ACAD9 and is reduced in neuronal cells upon exposure to amyloid-β (Aβ) oligomers. These findings advance our understanding of the MCIA complex assembly and suggest a possible role for ECSIT in the reprogramming of bioenergetic pathways linked to Aβ toxicity, a hallmark of AD.

DOI: https://doi.org/10.1038/s41467-023-43865-0
Mol Genet Metab Rep. 2024 Mar;38 101032

A different perspective into clinical symptoms in CPT I deficiency.

Mehmet Cihan Balci, Meryem Karaca, Arzu Selamioglu, Huseyin Kutay Korbeyli, Asli Durmus, Belkis Ak, Tugba Kozanoglu, Gulden Fatma Gokcay.

  Carnitine palmitoyltransferase I (CPT I) deficiency is an autosomal recessive disorder causing long-chain fatty acid oxidation defect, characterized by metabolic decompensation episodes accompanied by hypoketotic hypoglycemia, hepatomegaly, seizures, renal tubular acidosis, and hyperammonemia. The aim of this study was to investigate the neurological symptoms in CPT I deficiency and different outcomes with respect to predisposing factors for sequela and to draw attention to the neurological impairment that may develop during the course of the disease. The retrospective study reviewed clinical characteristics of 14 patients. Mean follow-up period was 10.3 ± 4.7 (range: 8 months-18.6 years; median: 10 years) years. Three patients were diagnosed with newborn screening. In the symptomatic group (n = 12) most common presenting symptoms were psychomotor retardation (n = 6), seizures (n = 5), encephalopathy (n = 5), dystonia (n = 1), Reye-like syndrome (n = 5), muscle weakness (n = 3), and autism (n = 1). Neurologic findings detected in the follow-up period included speech disorder (n = 9), abnormal cranial MRI findings (n = 5), neuropathy (n = 1), and attention deficit hyperactivity disorder (n = 1). Speech disorders collectively included delayed expressive language development, speech articulation disorder, speech delay, stuttering, and specific speech difficulties. After starting treatment for CPT I deficiency, speech disorders improved in 3 patients. Our findings confirmed that the clinical manifestations of CPT I deficiency is wider than previously thought, causing specific neurologic dysfunction, mainly speech disorders at a large scale, that were unexpected in a fatty acid oxidation disorder. We suggest that early diagnosis and treatment is the key factor to prevent neurologic sequelae while an extensive neurological evaluation is essential in patients with CPT I deficiency both at the time of diagnosis and during the follow-up period.

Keywords:  Carnitine palmitoyltransferase I deficiency; Fatty acids; Language development disorders; Neurologic manifestations; Reye-like syndrome; Speech disorders

DOI:  https://doi.org/10.1016/j.ymgmr.2023.101032
Mol Neurobiol. 2023 Dec 13.

SIRT3-Mediated Deacetylation of SDHA Rescues Mitochondrial Bioenergetics Contributing to Neuroprotection in Rotenone-Induced PD Models.

Yanhua Shen, Xueting Wang, Nan Nan, Xiaolong Fu, Ru Zeng, Yonggang Yang, Siting Xian, Jingshan Shi, Qin Wu, Shaoyu Zhou.

  Mitochondrial dysfunction is critically involved in the degeneration of dopamine (DA) neurons in the substantia nigra, a common pathological feature of Parkinson's disease (PD). Previous studies have demonstrated that the NAD+-dependent acetylase Sirtuin 3 (SIRT3) participates in maintaining mitochondrial function and is downregulated in aging-related neurodegenerative disorders. The exact mechanism of action of SIRT3 on mitochondrial bioenergetics in PD pathogenesis, however, has not been fully described. In this study, we investigated the regulatory role of SIRT3-mediated deacetylation of mitochondrial complex II (succinate dehydrogenase) subunit A (SDHA) and its effect on neuronal cell survival in rotenone (ROT)-induced rat and differentiated MN9D cell models. The results revealed that SIRT3 activity was suppressed in both in vivo and in vitro PD models. Accompanying this downregulation of SIRT3 was the hyperacetylation of SDHA, impaired activity of mitochondrial complex II, and decreased ATP production. It was found that the inhibition of SIRT3 activity was attributed to a reduction in the NAD+/NADH ratio caused by ROT-induced inhibition of mitochondrial complex I. Activation of SIRT3 by icariin and honokiol inhibited SDHA hyperacetylation and increased complex II activity, leading to increased ATP production and protection against ROT-induced neuronal damage. Furthermore, overexpression of SDHA also exerted potent protective benefits in cells treated with ROT. In addition, treatment of MN9D cells with the NAD+ precursor nicotinamide mononucleotide increased SIRT3 activity and complex II activity and promoted the survival of cells exposed to ROT. These findings unravel a regulatory SIRT3-SDHA axis, which may be closely related to PD pathology. Bioenergetic rescue through SIRT3 activation-dependent improvement of mitochondrial complex II activity may provide an effective strategy for protection from neurodegeneration.

Keywords:  Deacetylation; Mitochondrial complex II; Neurodegeneration; Rotenone; SIRT3; Succinate dehydrogenase subunit A (SDHA)

DOI:  https://doi.org/10.1007/s12035-023-03830-w
J Cereb Blood Flow Metab. 2023 Dec 09. 271678X231197173

Microglial histone deacetylase 2 is dispensable for functional and histological outcomes in a mouse model of traumatic brain injury.

Yue Zhang, Yongfang Zhao, Yana Wang, Jiaying Li, Yichen Huang, Fan Lyu, Yangfan Wang, Pengju Wei, Yiwen Yuan, Yi Fu, Yanqin Gao.

  The Class-I histone deacetylases (HDACs) mediate microglial inflammation and neurological dysfunction after traumatic brain injury (TBI). However, whether the individual Class-I HDACs play an indispensable role in TBI pathogenesis remains elusive. HDAC2 has been shown to upregulate pro-inflammatory genes in myeloid cells under brain injuries such as intracerebral hemorrhage, thereby worsening outcomes. Thus, we hypothesized that HDAC2 drives microglia toward a pro-inflammatory neurotoxic phenotype in a murine model of controlled cortical impact (CCI). Our results revealed that HDAC2 expression was highly induced in CD16/CD32+ pro-inflammatory microglia 3 and 7d after TBI. Surprisingly, microglia-targeted HDAC2 knockout (HDAC2 miKO) mice failed to demonstrate a beneficial phenotype after CCI/TBI compared to their wild-type (WT) littermates. HDAC2 miKO mice exhibited comparable levels of grey and white matter injury, efferocytosis, and sensorimotor and cognitive deficits after CCI/TBI as WT mice. RNA sequencing of isolated microglia 3d after CCI/TBI indicated the elevation of a panel of pro-inflammatory cytokines/chemokines in HDAC2 miKO mice over WT mice, and flow cytometry showed further elevated brain infiltration of neutrophils and B cells in HDAC2 miKO mice. Together, this study does not support a detrimental role for HDAC2 in microglial responses after TBI and calls for investigation into alternative mechanisms.

Keywords:  Conditional gene knockout; HDAC2; long-term sensorimotor outcomes; microglia; neuroinflammation

DOI:  https://doi.org/10.1177/0271678X231197173
Epilepsy Res. 2023 Nov 21. pii: S0920-1211(23)00183-3. [Epub ahead of print]199 107258

Leat-associated seizures the possible role of EAAT2, pyruvate carboxylase and glutamine synthetase.

Anna Maria Buccoliero, Chiara Caporalini, Selene Moscardi, Valentina Cetica, Davide Mei, Valerio Conti, Filippo Nozzoli, Camilla Bonaudo, Francesca Battista, Flavio Giordano, Regina Mura, Barbara Spacca, Federico Mussa, Vittoria D'Onofrio, Renzo Guerrini, Lorenzo Genitori, Mirko Scagnet.

  BACKGROUND: Drug-resistant epilepsy is a common condition in patients with brain neoplasms. The pathogenesis of tumor-associated seizures is poorly understood. Among the possible pathogenetic mechanisms, the increase in glutamate concentration has been proposed. Glutamate transporters, glutamine synthetase and pyruvate carboxylase are involved in maintaining the physiological concentration of glutamate in the intersynaptic spaces. In our previous research on angiocentric gliomas, we demonstrated that all tumors lacked the expression of the main glutamate transporter EAAT2, while the expression of glutamine synthetase and pyruvate carboxylase was mostly preserved.METHODS: In the present study, we evaluated the immunohistochemical expression of EAAT2, glutamine synthetase and pyruvate carboxylase in a heterogeneous series of 25 long-term epilepsy-associated tumors (10 dysembryoplastic neuroepithelial tumors, 7 gangliogliomas, 3 subependymal giant cell astrocytomas, 3 rosette forming glioneuronal tumors, 1 diffuse astrocytoma MYB- or MYBL1-altered and 1 angiocentric glioma). In order to evaluate the incidence of variants in the SLC1A2 gene, encoding EAAT2, in a large number of central nervous system tumors we also queried the PedcBioPortal.
RESULTS: EAAT2 protein expression was lost in 9 tumors (36 %: 3 dysembryoplastic neuroepithelial tumors, 1 ganglioglioma, 3 subependymal giant cell astrocytomas, 1 diffuse astrocytoma MYB- or MYBL1-altered and 1 angiocentric glioma). Glutamine synthetase protein expression was completely lost in 2 tumors (8 %; 1 ganglioglioma and 1 diffuse astrocytoma MYB- or MYBL1-altered). All tumors of our series but rosette forming glioneuronal tumors (in which neurocytic cells were negative) were diffusely positive for pyruvate carboxylase. Consultation of the PedcBioPortal revealed that of 2307 pediatric brain tumors of different histotype and grade, 20 (< 1%) had variants in the SLC1A2 gene. Among the SLC1A2-mutated tumors, there were no angiocentric gliomas or other LEATs CONCLUSIONS: In conclusion, unlike angiocentric gliomas where the EAAT2 loss is typical and constant, the current study shows the loss of EAAT2 expression only in a fraction of the LEATs. In these cases, we may hypothesize some possible epileptogenic role of the EAAT2 loss. The retained expression of pyruvate carboxylase may contribute to determining a pathological glutamate excess unopposed by glutamine synthetase that resulted expressed to a variable extent in the majority of the tumors. Furthermore, we can assume that the EAAT2 loss in brain tumors in general and in LEATs in particular is more conceivably epigenetic.

Keywords:  Brain tumors; EAAT2; Epilepsy; LEAT; SLC1A2

DOI:  https://doi.org/10.1016/j.eplepsyres.2023.107258
FASEB J. 2024 Jan;38(1): e23349

Ablation of placental REST deregulates fetal brain metabolism and impacts gene expression of the offspring brain at the postnatal and adult stages.

Maliha Islam, Ananya Samal, Daniel J Davis, Susanta K Behura.

  In this study, the transcriptional repressor REST (Repressor Element 1 Silencing Transcription factor) was ablated in the mouse placenta to investigate molecular and cellular impacts on the offspring brain at different life stages. Ablation of placental REST deregulated several brain metabolites, including glucose and lactate that fuel brain energy, vitamin C (ascorbic acid) that functions in the epigenetic programming of the brain during postnatal development, and glutamate and creatine that help the brain to respond to stress conditions during adult life. Bulk RNA-seq analysis showed that a lack of placental REST persistently altered multiple transport genes, including those related to oxygen transportation in the offspring brain. While metabolic genes were impacted in the postnatal brain, different stress response genes were activated in the adult brain. DNA methylation was also impacted in the adult brain due to the loss of placental REST, but in a sex-biased manner. Single-nuclei RNA-seq analysis showed that specific cell types of the brain, particularly those of the choroid plexus and ependyma, which play critical roles in producing cerebrospinal fluid and maintaining metabolic homeostasis, were significantly impacted due to the loss of placental REST. These cells showed significant differential expression of genes associated with the metabotropic (G coupled protein) and ionotropic (ligand-gated ion channel) glutamate receptors, suggesting an impact of ablation of placental REST on the glutamatergic signaling of the offspring brain. The study expands our understanding of placental influences on the offspring brain.

Keywords:  DNA methylation; RE1 silencing transcription factor; brain development; metabolomics; placenta; single-nuclei RNA sequencing

DOI:  https://doi.org/10.1096/fj.202301344R
Sci Rep. 2023 Dec 12. 13(1): 22005

Genetic, metabolic and clinical delineation of an MRPS23-associated mitochondrial disorder.

Chupong Ittiwut, Rungnapa Ittiwut, Chulaluck Kuptanon, Tetsuro Matsuhashi, Masaru Shimura, Yohei Sugiyama, Takanori Onuki, Akira Ohtake, Kei Murayama, Nithiwat Vatanavicharn, Waralee Dejputtawat, Nitchanund Tantisirivit, Phawin Kor-Anantakul, Wuttichart Kamolvisit, Kanya Suphapeetiporn, Vorasuk Shotelersuk.

MRPS23 is a nuclear gene encoding a mitochondrial ribosomal protein. A patient with a mitochondrial disorder was found to carry a variant in MRPS23. More cases are necessary to establish MRPS23 as a mitochondrial disease gene. Of 5134 exomes performed in our center, we identified five independent patients who had similar clinical manifestations and were homozygous for the same germline variant c.119C>T; p.P40L in MRPS23. Detailed clinical findings, mitochondrial enzyme activity assays from cultured skin fibroblasts, PCR-Sanger-sequencing, and variant age estimation were performed. Their available family members were also studied. Eight members homozygous for the MRPS23 p.P40L were identified. All were from Hmong hilltribe. Seven presented with alteration of consciousness and recurrent vomiting, while the eighth who was a younger brother of a proband was found pre-symptomatically. Patients showed delayed growth and development, hearing impairment, hypoglycemia, lactic acidosis, and liver dysfunction. In vitro assays of cultured fibroblasts showed combined respiratory chain complex deficiency with low activities of complexes I and IV. PCR-Sanger-sequencing confirmed the variant, which was estimated to have occurred 1550 years ago. These results establish the MRPS23-associated mitochondrial disorder inherited in an autosomal recessive pattern and provide insight into its clinical and metabolic features.

DOI: https://doi.org/10.1038/s41598-023-49161-7