Reduced mitochondrial fission and impaired energy metabolism in human primary skeletal muscle cells of Megaconial Congenital Muscular Dystrophy

Evrim Aksu-Menges,Cemil Can Eylem,Merve Gizer,Petek Korkusuz,Haluk Topaloglu,Beril Talim,Emirhan Nemutlu,Burcu Balci-Hayta

doi:10.1038/s41598-021-97294-4

Evrim Aksu-Menges, Cemil Can Eylem + Show 6 more

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https://doi.org/10.1038/s41598-021-97294-4

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Journal: Scientific Reports	Publication Date: Sep 13, 2021
Citations: 8	License type: open-access

Affiliation: Hacettepe University

Abstract

Megaconial Congenital Muscular Dystrophy (CMD) is a rare autosomal recessive disorder characterized by enlarged mitochondria located mainly at the periphery of muscle fibers and caused by mutations in the Choline Kinase Beta (CHKB) gene. Although the pathogenesis of this disease is not well understood, there is accumulating evidence for the presence of mitochondrial dysfunction. In this study, we aimed to investigate whether imbalanced mitochondrial dynamics affects mitochondrial function and bioenergetic efficiency in skeletal muscle cells of Megaconial CMD. Immunofluorescence, confocal and transmission electron microscopy studies revealed impaired mitochondrial network, morphology, and localization in primary skeletal muscle cells of Megaconial CMD. The organelle disruption was specific only to skeletal muscle cells grown in culture. The expression levels of mitochondrial fission proteins (DRP1, MFF, FIS1) were found to be decreased significantly in both primary skeletal muscle cells and tissue sections of Megaconial CMD by Western blotting and/or immunofluorescence analysis. The metabolomic and fluxomic analysis, which were performed in Megaconial CMD for the first time, revealed decreased levels of phosphonucleotides, Krebs cycle intermediates, ATP, and altered energy metabolism pathways. Our results indicate that reduced mitochondrial fission and altered mitochondrial energy metabolism contribute to mitochondrial dysmorphology and dysfunction in the pathogenesis of Megaconial CMD.

Highlights

Muscle biopsies of patients[5,6,7,8]
We demonstrate for the first time that abnormal mitochondrial morphology in skeletal muscle of Megaconial Congenital Muscular Dystrophy (CMD) is associated with unbalanced mitochondrial dynamics and impaired mitochondrial energy metabolism, which was indicated by the observation of reduced mitochondrial fission and decreased levels of phosphonucleotide, Krebs cycle intermediates, and ATP
In order to analyze the mitochondrial network and morphology, differentiated myotubes were co-stained with antibodies against desmin, a marker of muscle cells, and TOM20, a mitochondrial translocase located in the outer membrane of the organelle

Summary

Introduction

Functional studies of the Chkb knock-out mouse model, called as rostrocaudal muscular dystrophy (rmd) mice[9] displayed impaired respiratory function, increased reactive oxygen species (ROS), and enhanced mitophagy in skeletal muscle tissue[10]. Since this is a rare disease, there are no comprehensive studies to elucidate its pathogenesis in human biological samples. We first investigated morphological characteristics of mitochondria, and the potential role of mitochondrial fusion and fission mechanisms in human primary skeletal muscle cells of Megaconial CMD patient. We demonstrate for the first time that abnormal mitochondrial morphology in skeletal muscle of Megaconial CMD is associated with unbalanced mitochondrial dynamics and impaired mitochondrial energy metabolism, which was indicated by the observation of reduced mitochondrial fission and decreased levels of phosphonucleotide, Krebs cycle intermediates, and ATP

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