Novel Filamin C Myofibrillar Myopathy Variants Cause Different Pathomechanisms and Alterations in Protein Quality Systems

Autor: Dominik Sellung, Lorena Heil, Nassam Daya, Frank Jacobsen, Janine Mertens-Rill, Heidi Zhuge, Kristina Döring, Misagh Piran, Hendrik Milting, Andreas Unger, Wolfgang A. Linke, Rudi Kley, Corinna Preusse, Andreas Roos, Dieter O. Fürst, Peter F. M. van der Ven, Matthias Vorgerd
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Cells, Vol 12, Iss 9, p 1321 (2023)
Druh dokumentu: article
ISSN: 2073-4409
55298931
DOI: 10.3390/cells12091321
Popis: Myofibrillar myopathies (MFM) are a group of chronic muscle diseases pathophysiologically characterized by accumulation of protein aggregates and structural failure of muscle fibers. A subtype of MFM is caused by heterozygous mutations in the filamin C (FLNC) gene, exhibiting progressive muscle weakness, muscle structural alterations and intracellular protein accumulations. Here, we characterize in depth the pathogenicity of two novel truncating FLNc variants (p.Q1662X and p.Y2704X) and assess their distinct effect on FLNc stability and distribution as well as their impact on protein quality system (PQS) pathways. Both variants cause a slowly progressive myopathy with disease onset in adulthood, chronic myopathic alterations in muscle biopsy including the presence of intracellular protein aggregates. Our analyses revealed that p.Q1662X results in FLNc haploinsufficiency and p.Y2704X in a dominant-negative FLNc accumulation. Moreover, both protein-truncating variants cause different PQS alterations: p.Q1662X leads to an increase in expression of several genes involved in the ubiquitin-proteasome system (UPS) and the chaperone-assisted selective autophagy (CASA) system, whereas p.Y2704X results in increased abundance of proteins involved in UPS activation and autophagic buildup. We conclude that truncating FLNC variants might have different pathogenetic consequences and impair PQS function by diverse mechanisms and to varying extents. Further studies on a larger number of patients are necessary to confirm our observations.
Databáze: Directory of Open Access Journals
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