bims-medebr 2024-03-10 papers

bims-medebr

Biomed News

on Metabolism of the developing brain

Issue of 2024‒03‒10
eighteen papers selected by
Regina F. Fernández, Johns Hopkins University

Disturbed brain energy metabolism in a rodent model of DYT-TOR1A dystonia.
Lower GLUT1 and unchanged MCT1 in Alzheimer's disease cerebrovasculature.
Cholesterol 25-hydroxylase mediates neuroinflammation and neurodegeneration in a mouse model of tauopathy.
Neural and metabolic dysregulation in PMM2-deficient human in vitro neural models.
TREM2 deficiency impairs the energy metabolism of Schwann cells and exacerbates peripheral neurological deficits.
Preclinical Evaluation of the Reversible Monoacylglycerol Lipase PET Tracer (R)-[11 C]YH132: Application in Drug Development and Neurodegenerative Diseases.
Neuron-astrocyte metabolic coupling facilitates spinal plasticity and maintenance of inflammatory pain.
Binding of the monoacylglycerol lipase (MAGL) radiotracer [3H]T-401 in the rat brain after status epilepticus.
GBA1 inactivation in oligodendrocytes affects myelination and induces neurodegenerative hallmarks and lipid dyshomeostasis in mice.
Effects of Sex and Western Diet on Spatial Lipidomic Profiles for the Hippocampus, Cortex, and Corpus Callosum in Mice Using MALDI MSI.
Lack of SPNS1 results in accumulation of lysolipids and lysosomal storage disease in mouse models.
The Astrocyte: Metabolic Hub of the Brain.
Profiling of Oxylipins as Markers of Oxidative Stress in Biological Samples.
Spatial neurolipidomics-MALDI mass spectrometry imaging of lipids in brain pathologies.
Current methods for hyperpolarized [1-13 C]pyruvate MRI human studies.
Development of an advanced liquid chromatography-tandem mass spectrometry measurement system for simultaneous sphingolipid analysis.
Alternative splicing expands the clinical spectrum of NDUFS6-related mitochondrial disorders.
The lysosomal β-glucocerebrosidase strikes mitochondria: implications for Parkinson's therapeutics.

Neurobiol Dis. 2024 Mar 03. pii: S0969-9961(24)00061-5. [Epub ahead of print] 106462

Disturbed brain energy metabolism in a rodent model of DYT-TOR1A dystonia.

Susanne Knorr, Lisa Rauschenberger, Muthuraman Muthuraman, Rhonda McFleder, Thomas Ott, Kathrin Grundmann-Hauser, Takahiro Higuchi, Jens Volkmann, Chi Wang Ip.

  DYT-TOR1A (DYT1) dystonia, characterized by reduced penetrance and suspected environmental triggers, is explored using a "second hit" DYT-TOR1A rat model. We aim to investigate the biological mechanisms driving the conversion into a dystonic phenotype, focusing on the striatum's role in dystonia pathophysiology. Sciatic nerve crush injury was induced in ∆ETorA rats, lacking spontaneous motor abnormalities, and wild-type (wt) rats. Twelve weeks post-injury, unbiased RNA-sequencing was performed on the striatum to identify differentially expressed genes (DEGs) and pathways. Fenofibrate, a PPARα agonist, was introduced to assess its effects on gene expression. 18F-FDG autoradiography explored metabolic alterations in brain networks. Low transcriptomic variability existed between naïve wt and ∆ETorA rats (17 DEGs). Sciatic nerve injury significantly impacted ∆ETorA rats (1009 DEGs) compared to wt rats (216 DEGs). Pathway analyses revealed disruptions in energy metabolism, specifically in fatty acid β-oxidation and glucose metabolism. Fenofibrate induced gene expression changes in wt rats but failed in ∆ETorA rats. Fenofibrate increased dystonia-like movements in wt rats but reduced them in ∆ETorA rats. 18F-FDG autoradiography indicated modified glucose metabolism in motor and somatosensory cortices and striatum in both ∆ETorA and wt rats post-injury. Our findings highlight perturbed energy metabolism pathways in DYT-TOR1A dystonia, emphasizing compromised PPARα agonist efficacy in the striatum. Furthermore, we identify impaired glucose metabolism in the brain network, suggesting a potential shift in energy substrate utilization in dystonic DYT-TOR1A rats. These results contribute to understanding the pathophysiology and potential therapeutic targets for DYT-TOR1A dystonia.

Keywords:  Brain energy metabolism; DYT-TOR1A; Dystonia; Fatty acid β-oxidation; Fenofibrate; Glucose; Sciatic nerve crush injury

DOI:  https://doi.org/10.1016/j.nbd.2024.106462
J Cereb Blood Flow Metab. 2024 Mar 05. 271678X241237484

Lower GLUT1 and unchanged MCT1 in Alzheimer's disease cerebrovasculature.

Manon Leclerc, Cyntia Tremblay, Philippe Bourassa, Julie A Schneider, David A Bennett, Frédéric Calon.

  The brain is a highly demanding organ, utilizing mainly glucose but also ketone bodies as sources of energy. Glucose transporter-1 (GLUT1) and monocarboxylates transporter-1 (MCT1) respectively transport glucose and ketone bodies across the blood-brain barrier. While reduced glucose uptake by the brain is one of the earliest signs of Alzheimer's disease (AD), no change in the uptake of ketone bodies has been evidenced yet. To probe for changes in GLUT1 and MCT1, we performed Western immunoblotting in microvessel extracts from the parietal cortex of 60 participants of the Religious Orders Study. Participants clinically diagnosed with AD had lower cerebrovascular levels of GLUT1, whereas MCT1 remained unchanged. GLUT1 reduction was associated with lower cognitive scores. No such association was found for MCT1. GLUT1 was inversely correlated with neuritic plaques and cerebrovascular β-secretase-derived fragment levels. No other significant associations were found between both transporters, markers of Aβ and tau pathologies, sex, age at death or apolipoprotein-ε4 genotype. These results suggest that, while a deficit of GLUT1 may underlie the reduced transport of glucose to the brain in AD, no such impairment occurs for MCT1. This study thus supports the exploration of ketone bodies as an alternative energy source for the aging brain.

Keywords:  Alzheimer’s disease; Glucose transporter; cerebrovasculature; cognitive impairment; monocarboxylate transporter

DOI:  https://doi.org/10.1177/0271678X241237484
J Exp Med. 2024 Apr 01. pii: e20232000. [Epub ahead of print]221(4):

Cholesterol 25-hydroxylase mediates neuroinflammation and neurodegeneration in a mouse model of tauopathy.

Danira Toral-Rios, Justin M Long, Jason D Ulrich, Jinsheng Yu, Michael R Strickland, Xianlin Han, David M Holtzman, Anil G Cashikar, Steven M Paul.

Alzheimer's disease (AD) is characterized by amyloid plaques and neurofibrillary tangles, in addition to neuroinflammation and changes in brain lipid metabolism. 25-Hydroxycholesterol (25-HC), a known modulator of both inflammation and lipid metabolism, is produced by cholesterol 25-hydroxylase encoded by Ch25h expressed as a "disease-associated microglia" signature gene. However, whether Ch25h influences tau-mediated neuroinflammation and neurodegeneration is unknown. Here, we show that in the absence of Ch25h and the resultant reduction in 25-HC, there is strikingly reduced age-dependent neurodegeneration and neuroinflammation in the hippocampus and entorhinal/piriform cortex of PS19 mice, which express the P301S mutant human tau transgene. Transcriptomic analyses of bulk hippocampal tissue and single nuclei revealed that Ch25h deficiency in PS19 mice strongly suppressed proinflammatory signaling in microglia. Our results suggest a key role for Ch25h/25-HC in potentiating proinflammatory signaling to promote tau-mediated neurodegeneration. Ch25h may represent a novel therapeutic target for primary tauopathies, AD, and other neuroinflammatory diseases.

DOI: https://doi.org/10.1084/jem.20232000
Cell Rep. 2024 Mar 01. pii: S2211-1247(24)00211-0. [Epub ahead of print]43(3): 113883

Neural and metabolic dysregulation in PMM2-deficient human in vitro neural models.

Silvia Radenkovic, Rohit Budhraja, Teun Klein-Gunnewiek, Alexia Tyler King, Tarun N Bhatia, Anna N Ligezka, Karen Driesen, Rameen Shah, Bart Ghesquière, Akhilesh Pandey, Nael Nadif Kasri, Steven A Sloan, Eva Morava, Tamas Kozicz.

  Phosphomannomutase 2-congenital disorder of glycosylation (PMM2-CDG) is a rare inborn error of metabolism caused by deficiency of the PMM2 enzyme, which leads to impaired protein glycosylation. While the disorder presents with primarily neurological symptoms, there is limited knowledge about the specific brain-related changes caused by PMM2 deficiency. Here, we demonstrate aberrant neural activity in 2D neuronal networks from PMM2-CDG individuals. Utilizing multi-omics datasets from 3D human cortical organoids (hCOs) derived from PMM2-CDG individuals, we identify widespread decreases in protein glycosylation, highlighting impaired glycosylation as a key pathological feature of PMM2-CDG, as well as impaired mitochondrial structure and abnormal glucose metabolism in PMM2-deficient hCOs, indicating disturbances in energy metabolism. Correlation between PMM2 enzymatic activity in hCOs and symptom severity suggests that the level of PMM2 enzyme function directly influences neurological manifestations. These findings enhance our understanding of specific brain-related perturbations associated with PMM2-CDG, offering insights into the underlying mechanisms and potential directions for therapeutic interventions.

Keywords:  CP: Neuroscience; congenital disorder of glycosylation; disease model; hiPSC-derived cortical organoids; hiPSC-derived iNeuronal networks; neurodevelopmental disorder; phosphomannomutase 2

DOI:  https://doi.org/10.1016/j.celrep.2024.113883
Cell Death Dis. 2024 Mar 07. 15(3): 193

TREM2 deficiency impairs the energy metabolism of Schwann cells and exacerbates peripheral neurological deficits.

Nannan Zhang, Qingjie Ji, Yunfeng Chen, Xiwu Wen, Fangzhen Shan.

Triggering receptor expressed on myeloid cells-2 (TREM2) has been implicated in susceptibility to neurodegenerative disease. Schwann cells (SCs), the predominant glial cell type in the peripheral nervous system (PNS), play a crucial role in myelination, providing trophic support for neurons and nerve regeneration. However, the function of TREM2 in SCs has not been fully elucidated. Here, we found that TREM2 is expressed in SCs but not in neurons in the PNS. TREM2 deficiency leads to disruption of glycolytic flux and oxidative metabolism in SCs, impairing cell proliferation. The energy crisis caused by TREM2 deficiency triggers mitochondrial damage and autophagy by activating AMPK and impairing PI3K-AKT-mTOR signaling. Combined metabolomic analysis demonstrated that energic substrates and energy metabolic pathways were significantly impaired in TREM2-deficient SCs. Moreover, TREM2 deficiency impairs energy metabolism and axonal growth in sciatic nerve, accompanied by exacerbation of neurological deficits and suppression of nerve regeneration in a mouse model of acute motor axonal neuropathy. These results indicate that TREM2 is a critical regulator of energy metabolism in SCs and exerts neuroprotective effects on peripheral neuropathy. TREM2 deficiency impairs glycolysis and oxidative metabolism in Schwann cells, resulting in compromised cell proliferation. The energy crisis caused by TREM2 deficiency induces mitochondrial damage and autophagy by activating AMPK and impairing PI3K-AKT-mTOR signaling. Moreover, TREM2 deficiency disrupts the energy metabolism of the sciatic nerve and impairs support for axonal regeneration, accompanied by exacerbation of neurological deficits and suppression of nerve regeneration in a mouse model of acute motor axonal neuropathy (by FigDraw).

DOI: https://doi.org/10.1038/s41419-024-06579-9
Chembiochem. 2024 Mar 05. e202300819

Preclinical Evaluation of the Reversible Monoacylglycerol Lipase PET Tracer (R)-[11 C]YH132: Application in Drug Development and Neurodegenerative Diseases.

Yingfang He, Aro Delparente, Caitlin V M L Jie, Claudia Keller, Roland Humm, Dominik Heer, Ludovic Collin, Roger Schibli, Luca Gobbi, Uwe Grether, Linjing Mu.

  Monoacylglycerol lipase (MAGL) plays a crucial role in the degradation of 2-arachidonoylglycerol (2-AG), one of the major endocannabinoids in the brain. Inhibiting MAGL could lead to increased levels of 2-AG, which showed beneficial effects on pain management, anxiety, inflammation, and neuroprotection. In the current study, we report the characterization of an enantiomerically pure (R)-[11 C]YH132 as a novel MAGL PET tracer. It demonstrates an improved pharmacokinetic profile compared to its racemate. High in vitro MAGL specificity of (R)-[11 C]YH132 was confirmed by autoradiography studies using mouse and rat brain sections. In vivo, (R)-[11 C]YH132 displayed a high brain penetration, and high specificity and selectivity toward MAGL by dynamic PET imaging using MAGL knockout and wild-type mice. Pretreatment with a MAGL drug candidate revealed a dose-dependent reduction of (R)-[11 C]YH132 accumulation in WT mouse brains. This result validates its utility as a PET probe to assist drug development. Moreover, its potential application in neurodegenerative diseases was explored by in vitro autoradiography using brain sections from animal models of Alzheimer's disease and Parkinson's disease.

Keywords:  PET imaging; in vitro autoradiography; monoacylglycerol lipase

DOI:  https://doi.org/10.1002/cbic.202300819
Nat Metab. 2024 Mar 05.

Neuron-astrocyte metabolic coupling facilitates spinal plasticity and maintenance of inflammatory pain.

Sebastián Marty-Lombardi, Shiying Lu, Wojciech Ambroziak, Katrin Schrenk-Siemens, Jialin Wang, Anna A DePaoli-Roach, Anna M Hagenston, Hagen Wende, Anke Tappe-Theodor, Manuela Simonetti, Hilmar Bading, Jürgen G Okun, Rohini Kuner, Thomas Fleming, Jan Siemens.

Long-lasting pain stimuli can trigger maladaptive changes in the spinal cord, reminiscent of plasticity associated with memory formation. Metabolic coupling between astrocytes and neurons has been implicated in neuronal plasticity and memory formation in the central nervous system, but neither its involvement in pathological pain nor in spinal plasticity has been tested. Here we report a form of neuroglia signalling involving spinal astrocytic glycogen dynamics triggered by persistent noxious stimulation via upregulation of the Protein Targeting to Glycogen (PTG) in spinal astrocytes. PTG drove glycogen build-up in astrocytes, and blunting glycogen accumulation and turnover by Ptg gene deletion reduced pain-related behaviours and promoted faster recovery by shortening pain maintenance in mice. Furthermore, mechanistic analyses revealed that glycogen dynamics is a critically required process for maintenance of pain by facilitating neuronal plasticity in spinal lamina 1 neurons. In summary, our study describes a previously unappreciated mechanism of astrocyte-neuron metabolic communication through glycogen breakdown in the spinal cord that fuels spinal neuron hyperexcitability.

DOI: https://doi.org/10.1038/s42255-024-01001-2
Neurochem Int. 2024 Mar 04. pii: S0197-0186(24)00044-5. [Epub ahead of print] 105717

Binding of the monoacylglycerol lipase (MAGL) radiotracer [3H]T-401 in the rat brain after status epilepticus.

Jens D Mikkelsen, Sanjay S Aripaka, Cansu B Egilmez, Burcu A Pazarlar.

OBJECTIVES: Monoacylglycerol lipase (MAGL) is a cytosolic serine hydrolase considered a potential novel drug target for the treatment of CNS disorders including epilepsy. Here we examined MAGL levels in a rat model of epilepsy.METHODS: Autoradiography has been used to validate the binding properties of the MAGL radiotracer, [3H]T-401, in the rat brain, and to explore spatial and temporal changes in binding levels in a model of temporal lobe epilepsy model using unilateral intra-hippocampal injections of kainic acid (KA) in rats.
RESULTS: Specific and saturable binding of [3H]T-401 was detected in both cortical grey and subcortical white matter. Saturation experiments revealed a KD in the range between 15 nM and 17 nM, and full saturation was achieved at concentrations around 30 nM. The binding could be completely blocked with the cold ligand (Ki 44.2 nM) and at higher affinity (Ki 1.27 nM) with another structurally different MAGL inhibitor, ABD 1970. Bilateral reduction in [3H]T-401 binding was observed in the cerebral cortex and the hippocampus few days after status epilepticus that further declined to a level of around 30% compared to the control. No change in binding was observed in either the hypothalamus nor the white matter at any time point. Direct comparison to [3H]UCB-J binding to synaptic vesicle glycoprotein 2 A (SV2A), another protein localized in the pre-synapse, revealed that while binding to MAGL remained low in the chronic phase, SV2A was increased significantly in some cortical areas.
SIGNIFICANCE: These data show that MAGL is reduced in the cerebral cortex and hippocampus in a chronic epilepsy model and indicate that MAGL inhibitors may further reduce MAGL activity in the treatment resistant epilepsy patient.

DOI: https://doi.org/10.1016/j.neuint.2024.105717
Mol Neurodegener. 2024 Mar 07. 19(1): 22

GBA1 inactivation in oligodendrocytes affects myelination and induces neurodegenerative hallmarks and lipid dyshomeostasis in mice.

Ilaria Gregorio, Loris Russo, Enrica Torretta, Pietro Barbacini, Gabriella Contarini, Giada Pacinelli, Dario Bizzotto, Manuela Moriggi, Paola Braghetta, Francesco Papaleo, Cecilia Gelfi, Enrico Moro, Matilde Cescon.

  BACKGROUND: Mutations in the β-glucocerebrosidase (GBA1) gene do cause the lysosomal storage Gaucher disease (GD) and are among the most frequent genetic risk factors for Parkinson's disease (PD). So far, studies on both neuronopathic GD and PD primarily focused on neuronal manifestations, besides the evaluation of microglial and astrocyte implication. White matter alterations were described in the central nervous system of paediatric type 1 GD patients and were suggested to sustain or even play a role in the PD process, although the contribution of oligodendrocytes has been so far scarcely investigated.METHODS: We exploited a system to study the induction of central myelination in vitro, consisting of Oli-neu cells treated with dibutyryl-cAMP, in order to evaluate the expression levels and function of β-glucocerebrosidase during oligodendrocyte differentiation. Conduritol-B-epoxide, a β-glucocerebrosidase irreversible inhibitor was used to dissect the impact of β-glucocerebrosidase inactivation in the process of myelination, lysosomal degradation and α-synuclein accumulation in vitro. Moreover, to study the role of β-glucocerebrosidase in the white matter in vivo, we developed a novel mouse transgenic line in which β-glucocerebrosidase function is abolished in myelinating glia, by crossing the Cnp1-cre mouse line with a line bearing loxP sequences flanking Gba1 exons 9-11, encoding for β-glucocerebrosidase catalytic domain. Immunofluorescence, western blot and lipidomic analyses were performed in brain samples from wild-type and knockout animals in order to assess the impact of genetic inactivation of β-glucocerebrosidase on myelination and on the onset of early neurodegenerative hallmarks, together with differentiation analysis in primary oligodendrocyte cultures.
RESULTS: Here we show that β-glucocerebrosidase inactivation in oligodendrocytes induces lysosomal dysfunction and inhibits myelination in vitro. Moreover, oligodendrocyte-specific β-glucocerebrosidase loss-of-function was sufficient to induce in vivo demyelination and early neurodegenerative hallmarks, including axonal degeneration, α-synuclein accumulation and astrogliosis, together with brain lipid dyshomeostasis and functional impairment.
CONCLUSIONS: Our study sheds light on the contribution of oligodendrocytes in GBA1-related diseases and supports the need for better characterizing oligodendrocytes as actors playing a role in neurodegenerative diseases, also pointing at them as potential novel targets to set a brake to disease progression.

Keywords:  Gaucher disease; Lipid dyshomeostasis; Myelination; Neurodegeneration; Oligodendrocyte; Parkinson’s disease; White matter; β-glucocerebrosidase

DOI:  https://doi.org/10.1186/s13024-024-00713-z
J Am Soc Mass Spectrom. 2024 Mar 08.

Effects of Sex and Western Diet on Spatial Lipidomic Profiles for the Hippocampus, Cortex, and Corpus Callosum in Mice Using MALDI MSI.

Catelynn C Shafer, Jacopo Di Lucente, Ulises Ruiz Mendiola, Izumi Maezawa, Lee-Way Jin, Elizabeth K Neumann.

Diet is inextricably linked to human health and biological functionality. Reduced cognitive function among other health issues has been correlated with a western diet (WD) in mouse models, indicating that increases in neurodegeneration could be fueled in part by a poor diet. In this study, we use matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) to spatially map the lipidomic profiles of male and female mice that were fed a high-fat, high-sucrose WD for a period of 7 weeks. Our findings concluded that the cortex and corpus callosum showed significant lipid variation by WD in female mice, while there was little to no variation in the hippocampus, regardless of sex. On the other hand, lipid profiles were significantly affected by sex in all regions. Overall, 83 lipids were putatively identified in the mouse brain; among them, HexCer(40:1;O3) and PE(34:0) were found to have the largest statistical difference based on diet for female mice in the cortex and corpus callosum, respectively. Additional lipid changes are noted and can serve as a metric for understanding the brain's metabolomic response to changes in diet, particularly as it relates to disease.

DOI: https://doi.org/10.1021/jasms.3c00446
JCI Insight. 2024 Mar 07. pii: e175462. [Epub ahead of print]

Lack of SPNS1 results in accumulation of lysolipids and lysosomal storage disease in mouse models.

Hoa Tt Ha, SiYi Liu, Xuan Ta Nguyen, Linh K Vo, Nancy Cp Leong, Dat T Nguyen, Shivaranjani Balamurugan, Pei Yen Lim, YaJun Wu, Eunju Seong, Toan Q Nguyen, Jeongah Oh, Markus R Wenk, Amaury Cazenave-Gassiot, Zuhal Yapici, Wei-Yi Ong, Margit Burmeister, Long N Nguyen.

  Accumulation of sphingolipids, especially sphingosines, in the lysosomes is a key driver of several lysosomal storage diseases. The transport mechanism for sphingolipids from the lysosome remains unclear. Here, we identified SPNS1, which shares the highest homology to SPNS2 - a sphingosine-1-phosphate (S1P) transporter, functions as a transporter for lysolipids from the lysosome. We generated Spns1 knockout cells and mice and employed lipidomic and metabolomic approaches to reveal SPNS1 ligand identity. Global knockout of Spns1 caused embryonic lethality between E12.5-E13.5 and an accumulation of sphingosine, lysophosphatidylcholines (LPC) and lysophosphatidylethanolamines (LPE) in the fetal livers. Similarly, metabolomic analysis of livers from postnatal Spns1 knockout (Spns1-KO) mice presented an accumulation of sphingosines and lysoglycerophospholipids including LPC and LPE. Subsequently, biochemical assays showed that SPNS1 is required for LPC and sphingosine release from lysosomes. The accumulation of these lysolipids in the lysosomes of Spns1-KO mice affected liver functions and altered the PI3K-AKT signaling pathway. Furthermore, we identified three human siblings with a homozygous variant in the SPNS1 gene. These patients suffer from developmental delay, neurological impairment, intellectual disability, and exhibiting cerebellar hypoplasia. These results reveal a critical role of SPNS1 as a promiscuous lysolipid transporter in the lysosomes and link its physiological functions with lysosomal storage diseases.

Keywords:  Aging; Autophagy; Embryonic development; Metabolism; Mouse models

DOI:  https://doi.org/10.1172/jci.insight.175462
Cold Spring Harb Perspect Biol. 2024 Mar 04. pii: a041355. [Epub ahead of print]

The Astrocyte: Metabolic Hub of the Brain.

L Felipe Barros, Stefanie Schirmeier, Bruno Weber.

Astrocytic metabolism has taken center stage. Interposed between the neuron and the vasculature, astrocytes exert control over the fluxes of energy and building blocks required for neuronal activity and plasticity. They are also key to local detoxification and waste recycling. Whereas neurons are metabolically rigid, astrocytes can switch between different metabolic profiles according to local demand and the nutritional state of the organism. Their metabolic state even seems to be instructive for peripheral nutrient mobilization and has been implicated in information processing and behavior. Here, we summarize recent progress in our understanding of astrocytic metabolism and its effects on metabolic homeostasis and cognition.

DOI: https://doi.org/10.1101/cshperspect.a041355
Curr Protoc. 2024 Mar;4(3): e992

Profiling of Oxylipins as Markers of Oxidative Stress in Biological Samples.

Liping Yang, Jaewoo Choi, Claudia S Maier, Jan F Stevens.

  Oxylipins are oxidized metabolites of polyunsaturated fatty acids (PUFAs). They represent a class of risk markers and/or therapeutic targets for diseases associated with inflammation, including cardiovascular disease and brain disorders. Because the biological activities of free PUFAs and oxylipins depend on their chemical structures and concentrations, monitoring PUFAs and oxylipin levels in biological systems is critical for understanding their roles in health and disease. Traditionally, accurate quantification of free PUFAs and oxylipins in biological samples was performed separately, as PUFAs are often 1000-fold more abundant than the derived oxidized fatty acids (oxylipins). This article describes a liquid chromatography multiple reaction monitoring tandem mass spectrometry method for the quantitative analysis of five free PUFAs and 88 oxylipins in various biological fluids, including plasma, platelet supernatants, and tissues. The same approach can also be used in conjunction with an alkaline hydrolysis step to quantify total oxylipins in fish oils. We observed that in some samples, linoleic acid levels in plasma and eicosapentaenoic acid and arachidonic acid levels in brain tissue were above the upper limit of quantification. To address this issue, we developed a data analysis method to obtain PUFA and oxylipin concentrations in these samples without additional sample preparation, thus significantly saving time and labor. © 2024 Wiley Periodicals LLC. Basic Protocol: Quantification of polyunsaturated fatty acids (PUFAs) and oxylipins using liquid chromatography multiple reaction monitoring tandem mass spectrometry Support Protocol 1: Preparation of internal standard mixed working solution Support Protocol 2: Preparation of standard mixed stock solution Support Protocol 3: Preparation of standard mixed working solution Alternate Protocol 1: Extraction and quantitation of free PUFAs and oxylipins from mouse brain tissue Alternate Protocol 2: Extraction and quantitation of total PUFAs and oxylipins from fish oil.

Keywords:  eicosanoids; multiple reaction monitoring mass spectrometry; oxylipins; polyunsaturated fatty acids; protectins; resolvins

DOI:  https://doi.org/10.1002/cpz1.992
J Mass Spectrom. 2024 Mar;59(3): e5008

Spatial neurolipidomics-MALDI mass spectrometry imaging of lipids in brain pathologies.

Durga Jha, Kaj Blennow, Henrik Zetterberg, Jeffrey N Savas, Jörg Hanrieder.

  Given the complexity of nervous tissues, understanding neurochemical pathophysiology puts high demands on bioanalytical techniques with respect to specificity and sensitivity. Mass spectrometry imaging (MSI) has evolved to become an important, biochemical imaging technology for spatial biology in biological and translational research. The technique facilitates comprehensive, sensitive elucidation of the spatial distribution patterns of drugs, lipids, peptides, and small proteins in situ. Matrix-assisted laser desorption ionization (MALDI)-based MSI is the dominating modality due to its broad applicability and fair compromise of selectivity, sensitivity price, throughput, and ease of use. This is particularly relevant for the analysis of spatial lipid patterns, where no other comparable spatial profiling tools are available. Understanding spatial lipid biology in nervous tissue is therefore a key and emerging application area of MSI research. The aim of this review is to give a concise guide through the MSI workflow for lipid imaging in central nervous system (CNS) tissues and essential parameters to consider while developing and optimizing MSI assays. Further, this review provides a broad overview of key developments and applications of MALDI MSI-based spatial neurolipidomics to map lipid dynamics in neuronal structures, ultimately contributing to a better understanding of neurodegenerative disease pathology.

Keywords:  Alzheimer's disease (AD); Niemann-Pick disease type C1 (NPC1); Parkinson's disease (PD); amyloid; gangliosides; inositols; lysolipids; mass spectrometry imaging (MSI); matrix-assisted laser desorption ionization (MALDI); neurolipidomics; spatial biology; sphingolipids

DOI:  https://doi.org/10.1002/jms.5008
Magn Reson Med. 2024 Mar 05.

Current methods for hyperpolarized [1-13 C]pyruvate MRI human studies.

HP 13C MRI Consensus Group

  MRI with hyperpolarized (HP) 13 C agents, also known as HP 13 C MRI, can measure processes such as localized metabolism that is altered in numerous cancers, liver, heart, kidney diseases, and more. It has been translated into human studies during the past 10 years, with recent rapid growth in studies largely based on increasing availability of HP agent preparation methods suitable for use in humans. This paper aims to capture the current successful practices for HP MRI human studies with [1-13 C]pyruvate-by far the most commonly used agent, which sits at a key metabolic junction in glycolysis. The paper is divided into four major topic areas: (1) HP 13 C-pyruvate preparation; (2) MRI system setup and calibrations; (3) data acquisition and image reconstruction; and (4) data analysis and quantification. In each area, we identified the key components for a successful study, summarized both published studies and current practices, and discuss evidence gaps, strengths, and limitations. This paper is the output of the "HP 13 C MRI Consensus Group" as well as the ISMRM Hyperpolarized Media MR and Hyperpolarized Methods and Equipment study groups. It further aims to provide a comprehensive reference for future consensus, building as the field continues to advance human studies with this metabolic imaging modality.

Keywords:  carbon-13; dissolution dynamic nuclear polarization; hyperpolarized MRI; metabolic imaging; pyruvate

DOI:  https://doi.org/10.1002/mrm.29875
Sci Rep. 2024 Mar 08. 14(1): 5699

Development of an advanced liquid chromatography-tandem mass spectrometry measurement system for simultaneous sphingolipid analysis.

Baasanjav Uranbileg, Eri Sakai, Masayuki Kubota, Hideaki Isago, Masahiko Sumitani, Yutaka Yatomi, Makoto Kurano.

  Mass spectrometry-based lipidomics approaches offer valuable tools for the detection and quantification of various lipid species, including sphingolipids. The present study aimed to develop a new method to simultaneously detect various sphingolipid species that applies to diverse biological samples. We developed and validated a measurement system by employing a single-column liquid chromatography-mass spectrometry system utilizing a normal-phase separation mode with positive ionization. The measurement system provided precision with a coefficient of variant below 20% for sphingolipids in all types of samples, and we observed good linearity in diluted serum samples. This system can measure the following sphingolipids: sphingosine 1-phosphate (S1P), sphingosine (Sph), dihydroS1P (dhS1P), dihydroSph (dhSph), ceramide 1-phosphate (Cer1P), hexosylceramide (HexCer), lactosylceramide (LacCer), dh-ceramide, deoxy-ceramide, deoxy-dh-ceramide, and sphingomyelin (SM). By measuring these sphingolipids in cell lysates where S1P lyase expression level was modulated, we could observe significant and dynamic modulations of sphingolipids in a comprehensive manner. Our newly established and validated measurement system can simultaneously measure many kinds of sphingolipids in biological samples. It holds great promise as a valuable tool for laboratory testing applications to detect overall modulations of sphingolipids, which have been proposed to be involved in pathogenesis processes in a series of elegant basic research studies.

Keywords:  Ceramide1-phosphate (Cer1P); Deoxy-ceramide; Deoxy-dh-ceramide; Hexosylceramide (HexCer); Lactosylceramide (LacCer); Sphingolipid; dh-ceramide

DOI:  https://doi.org/10.1038/s41598-024-56321-w
Genet Med. 2024 Mar 05. pii: S1098-3600(24)00050-9. [Epub ahead of print] 101117

Alternative splicing expands the clinical spectrum of NDUFS6-related mitochondrial disorders.

Camila Armirola-Ricaurte, Noortje Zonnekein, Georgios Koutsis, Silvia Amor-Barris, Ana Lara Pelayo-Negro, Derek Atkinson, Stephanie Efthymiou, Valentina Turchetti, Argyris Dinopoulos, Antonio Garcia, Mert Karakaya, German Moris, Ayşe Ipek Polat, Uluc Yis, Carmen Espinos, Liedewei Van de Vondel, Els De Vriendt, Georgia Karadima, Brunhilde Wirth, Michael Hanna, Henry Houlden, Jose Berciano, Albena Jordanova.

  PURPOSE: We describe three families with Charcot-Marie-Tooth neuropathy (CMT), harboring a homozygous NDUFS6 NM_004553.6:c.309+5G>A variant previously linked to fatal Leigh syndrome. We aimed to characterize clinically and molecularly the newly identified patients and understand the mechanism underlying their milder phenotype.METHODS: The patients underwent extensive clinical examinations. Exome sequencing was done in four affected individuals. The functional effect of the c.309+5G>A variant was investigated in patient-derived EBV-transformed lymphoblasts at the cDNA, protein and mitochondrial level. Alternative splicing was evaluated using cDNA long-read sequencing.
RESULTS: All patients presented with early-onset, slowly progressive axonal CMT and nystagmus; some exhibited additional central nervous system symptoms. The c.309+5G>A substitution caused the expression of aberrantly spliced transcripts and negligible levels of the canonical transcript. Immunoblotting showed reduced levels of mutant isoforms. No detectable defects in mitochondrial complex stability or bioenergetics were found.
CONCLUSION: We expand the clinical spectrum of NDUFS6-related mitochondrial disorders to include axonal CMT, emphasizing the clinical and pathophysiologic overlap between these two clinical entities. This work demonstrates the critical role that alternative splicing may play in modulating the severity of a genetic disorder, emphasizing the need for careful consideration when interpreting splice variants and their implications on disease prognosis.

Keywords:  Charcot-Marie-Tooth; NDUFS6; mitochondrial disorders; peripheral neuropathy; splicing

DOI:  https://doi.org/10.1016/j.gim.2024.101117
Brain. 2024 Mar 04. pii: awae070. [Epub ahead of print]

The lysosomal β-glucocerebrosidase strikes mitochondria: implications for Parkinson's therapeutics.

Juan Carlos Rubilar, Tiago Fleming Outeiro, Andrés D Klein.

  Parkinson's disease (PD) is a neurodegenerative disorder primarily known for typical motor features that arise due to the loss of dopaminergic neurons in the substantia nigra. However, the precise molecular etiology of the disease is still unclear. Several cellular pathways have been linked to PD, including the autophagy-lysosome pathway (ALP), α-synuclein (α-syn) aggregation, and mitochondrial function. Interestingly, the mechanistic link between GBA1, the gene that encodes for lysosomal β-glucocerebrosidase (GCase), and PD lies in the interplay between GCase functions in the lysosome and mitochondria. GCase mutations alter mitochondria-lysosome contact sites. In the lysosome, reduced GCase activity leads to glycosphingolipid buildup, disrupting lysosomal function and autophagy, thereby triggering α-syn accumulation. Additionally, α-syn aggregates reduce GCase activity, creating a self-perpetuating cycle of lysosomal dysfunction and α-syn accumulation. GCase can also be imported into the mitochondria, where it promotes the integrity and function of mitochondrial complex I. Thus, GCase mutations that impair its normal function increase oxidative stress in mitochondria, the compartment where dopamine is oxidized. In turn, the accumulation of oxidized dopamine-adducts further impairs GCase activity, creating a second cycle of GCase dysfunction. The oxidative state triggered by GCase dysfunction can also induce mitochondrial DNA damage which, in turn, can cause dopaminergic cell death. In this review, we highlight the pivotal role of GCase in PD pathogenesis and discuss promising examples of GCase-based therapeutics such as gene and enzyme replacement therapies, small molecule chaperones, and substrate reduction therapies, among others, as potential therapeutic interventions.

Keywords:  Gaucher’s disease; Parkinson’s disease; lysosome; mitochondria; neurodegeneration; therapeutics

DOI:  https://doi.org/10.1093/brain/awae070