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A heterozygous p.S143P mutation in LMNA associates with proteasome dysfunction and enhanced autophagy-mediated degradation of mutant lamins A and C.

ABSTRACT: Lamins A and C are nuclear intermediate filament proteins that form a proteinaceous meshwork called lamina beneath the inner nuclear membrane. Mutations in the LMNA gene encoding lamins A and C cause a heterogenous group of inherited degenerative diseases known as laminopathies. Previous studies have revealed altered cell signaling pathways in lamin-mutant patient cells, but little is known about the fate of mutant lamins A and C within the cells. Here, we analyzed the turnover of lamins A and C in cells derived from a dilated cardiomyopathy patient with a heterozygous p.S143P mutation in LMNA. We found that transcriptional activation and mRNA levels of LMNA are increased in the primary patient fibroblasts, but the protein levels of lamins A and C remain equal in control and patient cells because of a meticulous interplay between autophagy and the ubiquitin-proteasome system (UPS). Both endogenous and ectopic expression of p.S143P lamins A and C cause significantly reduced activity of UPS and an accumulation of K48-ubiquitin chains in the nucleus. Furthermore, K48-ubiquitinated lamins A and C are degraded by compensatory enhanced autophagy, as shown by increased autophagosome formation and binding of lamins A and C to microtubule-associated protein 1A/1B-light chain 3. Finally, chaperone 4-PBA augmented protein degradation by restoring UPS activity as well as autophagy in the patient cells. In summary, our results suggest that the p.S143P-mutant lamins A and C have overloading and deleterious effects on protein degradation machinery and pharmacological interventions with compounds enhancing protein degradation may be beneficial for cell homeostasis.

SUBMITTER: West G

PROVIDER: S-EPMC9468711 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature

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A heterozygous p.S143P mutation in <i>LMNA</i> associates with proteasome dysfunction and enhanced autophagy-mediated degradation of mutant lamins A and C.

West Gun G Turunen Minttu M Aalto Anna A Virtanen Laura L Li Song-Ping SP Heliö Tiina T Meinander Annika A Taimen Pekka P

Frontiers in cell and developmental biology 20220830

Lamins A and C are nuclear intermediate filament proteins that form a proteinaceous meshwork called lamina beneath the inner nuclear membrane. Mutations in the <i>LMNA</i> gene encoding lamins A and C cause a heterogenous group of inherited degenerative diseases known as laminopathies. Previous studies have revealed altered cell signaling pathways in lamin-mutant patient cells, but little is known about the fate of mutant lamins A and C within the cells. Here, we analyzed the turnover of lamins ...[more]

PMID: 36111332

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Project description:Background:Lamin A/C (LMNA) gene mutations cause a heterogeneous group of progeroid disorders, including Hutchinson-Gilford progeria syndrome, mandibuloacral dysplasia, and atypical progeroid syndrome (APS). Five of the 31 previously reported patients with APS harbored a recurrent de novo heterozygous LMNA p.T10I mutation. All five had generalized lipodystrophy, as well as similar metabolic and clinical features, suggesting a distinct progeroid syndrome. Methods:We report nine new patients and follow-up of two previously reported patients with the heterozygous LMNA p.T10I mutation and compare their clinical and metabolic features with other patients with APS. Results:Compared with other patients with APS, those with the heterozygous LMNA p.T10I mutation were younger in age but had increased prevalence of generalized lipodystrophy, diabetes mellitus, acanthosis nigricans, hypertriglyceridemia, and hepatomegaly, together with higher fasting serum insulin and triglyceride levels and lower serum leptin and high-density lipoprotein cholesterol levels. Prominent clinical features included mottled skin pigmentation, joint contractures, and cardiomyopathy resulting in cardiac transplants in three patients at ages 13, 33, and 47 years. Seven patients received metreleptin therapy for 0.5 to 16 years with all, except one noncompliant patient, showing marked improvement in metabolic complications. Conclusions:Patients with the heterozygous LMNA p.T10I mutation have distinct clinical features and significantly worse metabolic complications compared with other patients with APS as well as patients with Hutchinson-Gilford progeria syndrome. We propose that they be recognized as having generalized lipodystrophy-associated progeroid syndrome. Patients with generalized lipodystrophy-associated progeroid syndrome should undergo careful multisystem assessment at onset and yearly metabolic and cardiac evaluation, as hyperglycemia, hypertriglyceridemia, hepatic steatosis, and cardiomyopathy are the major contributors to morbidity and mortality.

Dataset Information

A heterozygous p.S143P mutation in LMNA associates with proteasome dysfunction and enhanced autophagy-mediated degradation of mutant lamins A and C.

Publications

A heterozygous p.S143P mutation in <i>LMNA</i> associates with proteasome dysfunction and enhanced autophagy-mediated degradation of mutant lamins A and C.

Similar Datasets

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