Functional analysis in stable H9c2 cardiomyoblast cell lines demonstrated significantly reduced MFN2 mutant protein expression, extensive mitochondrial clustering and fragmentation, suggesting a significant correlation with the pathogenesis of DCM.
The first functional characterization of the cardiomyopathy-associated SMYD1 N101S variant identified in a child with severe infantile cardiomyopathy is provided, establishing a mechanistic link between SMYD1 dysfunction and infantile cardiomyopathy and highlighting the importance of integrating genomic and functional approaches in rare cardiovascular disease.
Marta W. Szulik, Clint Gwynn, Magnus Creed et al.· bioRxiv· 0 citations
Patient mutations within Drp1, the master regulator of mitochondrial fission, lead to severe neurological defects and poor patient outcomes. Many of these mutations have been characterized as causing functional or assembly defects in Drp1, but our study highlights three mutations (G362S, E379K, E410K) that do not have an apparent defect in core Drp1 functions. We investigated the possibility that these mutations impact interactions with Mff, a pro-fission partner protein of Drp1. Negative stain electron microscopy and mass photometry were used to visualize and quantify assembly properties, while GTPase assays assessed the enzymatic activities of distinct proteins and protein complexes. In parallel, confocal microscopy highlighted the effects of overexpressing each mutation on mitochondrial morphology in cells. We discovered that G362S and E410K Drp1 mutations limit interactions with Mff, as co-assembly into larger filaments and the associated stimulation of GTPase activity was inhibited. Conversely, the E379K mutation is able to form functional complexes with Mff, and no apparent defect was observed, warranting additional studies focused on unique mitochondrial fission attributes. Overall, our data highlight the complex nature of disease-associated mutations in Drp1 and emphasize the importance of Drp1-Mff interactions in sustaining mitochondrial and cellular health.
Yuli Buckley, Anelise N. Hutson, Brianna L. Bauer et al.· Molecular Biology of the Cel...· 0 citations
These findings support the value of preclinical models for translational studies, and autophagy enhancement as a potential therapeutic strategy for HSPB8-related myopathy, and evaluated trehalose, a natural disaccharide that induces HSPB8 and enhances autophagy.
Alyaa Shmara, Lan Weiss, A. Gromova et al.· bioRxiv· 0 citations
Evidence is provided that biallelic CTNNA3 splice‐disrupting variants can cause human cardiomyopathy driven by ICD dysfunction, and the dissociation between ventricular recovery and persistent arrhythmia highlights the complex phenotypic spectrum of CTNNA3‐related disease.
Stefania Martino, Mara Doimo, M. Iacoviello et al.· Human Mutation· 0 citations
Variants in
LMNA
are established causes of inherited dilated cardiomyopathy (DCM); however, the clinical significance of many rare missense variants remains uncertain. We identified the rare
LMNA
c.929 A > G (p.Gln310Arg) variant in a patient with progressive DCM and performed preliminary variant-specific functional characterization in an AC16 transient overexpression model.
Duo whole-exome sequencing and copy-number variation analysis were performed in the proband and his son. Wild-type and p.Gln310Arg lamin A expression constructs were transiently transfected into AC16 cells. Flag-tagged protein expression, Flag-based transfection efficiency, and lamin A/C distribution were assessed by western blotting and immunofluorescence staining. Mitochondrial membrane potential and intracellular ROS-associated fluorescence were assessed using JC-1 and DCFH-DA staining, respectively. ERK1/2, JNK, and p38 MAPK phosphorylation was evaluated by western blotting. Hypertrophy-associated
NPPA
and
NPPB
expression was measured by RT-qPCR, and cell area was quantified after phalloidin staining.
The
LMNA
c.929 A > G variant was classified as a variant of uncertain significance. Wild-type and p.Gln310Arg lamin A constructs showed comparable Flag-tagged protein expression and Flag-based transfection efficiency. Expression of p.Gln310Arg lamin A was associated with an increased proportion of cells displaying ring-like lamin A/C staining patterns. Variant-expressing cells showed increased intracellular DCF fluorescence, reduced JC-1 red-to-green fluorescence ratio, and selectively increased ERK1/2 phosphorylation, whereas no significant changes were detected in JNK or p38 MAPK phosphorylation. The same cells also showed a hypertrophy-like phenotype characterized by increased
NPPA
and
NPPB
expression and enlarged cell area.
In an AC16 transient overexpression model, expression of p.Gln310Arg lamin A was associated with altered lamin A/C distribution, increased intracellular ROS-associated fluorescence, reduced mitochondrial membrane potential, selectively increased ERK1/2 phosphorylation, and a hypertrophy-like cellular phenotype. These findings provide preliminary variant-specific functional evidence but do not establish the pathogenicity of the variant or the causal relationships among the observed cellular abnormalities. Further validation in endogenous and physiologically relevant cardac models is required.
Zikang Han, Yonghao Sheng, Hanice Sun et al.· Hereditas· 0 citations
These findings establish a mechanistic link between mutation-induced structural dynamics and impaired PINK1–ubiquitin recognition at Ser65, providing a mutation-specific framework for understanding early mitophagy impairment in ARPD and supporting future molecular assessment and targeted therapeutic development.
Zhiguang Jia, B. Malik, Deborah Vincent et al.· Frontiers in Molecular Neuro...· 0 citations
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