An Isolated Complex V Inefficiency and Dysregulated Mitochondrial Function in Immortalized Lymphocytes from ME/CFS Patients
journal contributionposted on 2021-08-25, 01:43 authored by Daniel Missailidis, Sarah AnnesleySarah Annesley, Claire AllanClaire Allan, Oana SanislavOana Sanislav, BA Lidbury, Donald Lewis, Paul FisherPaul Fisher
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is an enigmatic condition characterized by exacerbation of symptoms after exertion (post-exertional malaise or “PEM”), and by fatigue whose severity and associated requirement for rest are excessive and disproportionate to the fatigue-inducing activity. There is no definitive molecular marker or known underlying pathological mechanism for the condition. Increasing evidence for aberrant energy metabolism suggests a role for mitochondrial dysfunction in ME/CFS. Our objective was therefore to measure mitochondrial function and cellular stress sensing in actively metabolizing patient blood cells. We immortalized lymphoblasts isolated from 51 ME/CFS patients diagnosed according to the Canadian Consensus Criteria and an age- and gender-matched control group. Parameters of mitochondrial function and energy stress sensing were assessed by Seahorse extracellular flux analysis, proteomics, and an array of additional biochemical assays. As a proportion of the basal oxygen consumption rate (OCR), the rate of ATP synthesis by Complex V was significantly reduced in ME/CFS lymphoblasts, while significant elevations were observed in Complex I OCR, maximum OCR, spare respiratory capacity, nonmitochondrial OCR and “proton leak” as a proportion of the basal OCR. This was accompanied by a reduction of mitochondrial membrane potential, chronically hyperactivated TOR Complex I stress signaling and upregulated expression of mitochondrial respiratory complexes, fatty acid transporters, and enzymes of the β-oxidation and TCA cycles. By contrast, mitochondrial mass and genome copy number, as well as glycolytic rates and steady state ATP levels were unchanged. Our results suggest a model in which ME/CFS lymphoblasts have a Complex V defect accompanied by compensatory upregulation of their respiratory capacity that includes the mitochondrial respiratory complexes, membrane transporters and enzymes involved in fatty acid β-oxidation. This homeostatically returns ATP synthesis and steady state levels to “normal” in the resting cells, but may leave them unable to adequately respond to acute increases in energy demand as the relevant homeostatic pathways are already activated.
This research was funded by grants from The Judith Jane Mason & Harold Stannett Williams Memorial Foundation (The Mason Foundation) (grant IDs: MAS2016F063, MAS2018F00026) and The McCusker Charitable Foundation as well as donations from individual patients and supporters.
JournalInternational journal of molecular science
Article NumberARTN 1074
PublisherMultidisciplinary Digital Publishing Institute (MDPI)
Rights StatementThe Author reserves all moral rights over the deposited text and must be credited if any re-use occurs. Documents deposited in OPAL are the Open Access versions of outputs published elsewhere. Changes resulting from the publishing process may therefore not be reflected in this document. The final published version may be obtained via the publisher’s DOI. Please note that additional copyright and access restrictions may apply to the published version.
Science & TechnologyLife Sciences & BiomedicinePhysical SciencesBiochemistry & Molecular BiologyChemistry, MultidisciplinaryChemistrymyalgic encephalomyelitischronic fatigue syndromemitochondriaComplex VTORC1seahorse respirometryACTIVATED PROTEIN-KINASECHRONIC-FATIGUE-SYNDROMELIVING CELLSFATTY-ACIDREGULATORUPSTREAMDISEASEMUSCLEGROWTH4E-BP1LymphocytesCells, CulturedMitochondriaHumansFatigue Syndrome, ChronicMitochondrial Proton-Translocating ATPasesAdenosine TriphosphateCell Culture TechniquesProteomicsCell ProliferationCell SurvivalEnergy MetabolismOxygen ConsumptionAdultAgedMiddle AgedCanadaFemaleMaleMechanistic Target of Rapamycin Complex 1Chemical Physics