Biology subjects

Kimonis, V.

Publications and source records attributed to Kimonis, V..

6 recordsLinked to original sources

bioRxiv2026

Characterization of the frameshift c.515dupC knock-in mouse model of HSPB8-associated myopathy (MFM13) and evaluation of Trehalose as autophagy modulating therapy.

Heat shock protein family B member 8 (HSPB8) is a chaperone involved in the chaperone-assisted selective autophagy (CASA) complex. HSPB8 in conjunction with cochaperone BAG3, promotes autophagy-mediated removal of misfolded proteins associated with various neurodegenerative diseases. Mutations in HSPB8, previously associated with Charcot Marie Tooth disease type 2L, have recently been linked to an autosomal dominant rimmed vacuolar myopathy (MFM13), and is considered a multisystem proteinopathy. Patients have distal and proximal limb girdle myopathy with muscle biopsy showing fatty replacement, endomysial fibrosis, and rimmed vacuoles leading to muscle atrophy and early demise. We have demonstrated reduced expression of HSPB8, altered autophagy and TDP-43 accumulation in patient fibroblasts. Using CRISPR technology, we generated a knock-in Hspb8 mouse model of the c.515dupC hot spot frameshift variant to study disease pathology. Overexpressed murine Hspb8 frameshift mutant (c.515dupC, fs) displays insolubility and aggregation propensity in Murine Neuroblastoma X Spinal Cord 34 (NSC-34) cells. Mutant Hspb8 mice developed late-onset muscle weakness beginning at 15 months. Muscle biochemical analyses revealed reduced HSPB8 levels, increased TDP-43, and altered autophagy markers, partially recapitulating the human phenotype. Fiber type analysis, neuromuscular junction integrity, and motor neurons show mild myopathy without neurodegeneration. Given the lack of available treatments, we evaluated trehalose, a natural disaccharide that induces HSPB8 and enhances autophagy. Administration of 2% trehalose in drinking water improves motor performance, restores HSPB8 expression, and ameliorates autophagic and TDP-43 pathology in mutant mice. These findings support the value of our preclinical models for translational studies, and autophagy enhancement as a potential therapeutic strategy for HSPB8-related myopathy.

genetics↗

bioRxiv2026

ZDHHC17 Links S-Acylation, Huntington Disease, VCP-associated Multisystem Proteinopathy, and Amyotrophic Lateral Sclerosis.

Protein mislocalization is an important contributor to neurodegeneration. We have identified disrupted S-acylation as a driver of mislocalization. S11acylation, the addition of long-chain fatty acids to cysteine residues, is mediated by the ZDHHC family of S-acyltransferases, and regulates protein localization by modulating protein hydrophobicity. Among these enzymes, we have identified ZDHHC17 as a central node in neurodegenerative disease. Although decreased ZDHHC17 activity is correlated with Huntington disease (HD) pathology, its broader contributions to neurodegeneration remain poorly defined. Here, we present new evidence that ZDHHC17 S-acylates or interacts with multiple proteins implicated in amyotrophic lateral sclerosis (ALS), including Valosin-containing protein (VCP) and TAR DNA Binding Protein (TDP1143). We further confirm that VCP, TDP-43, FUS, C9ORF72, and SQSTM1 are S-acylated across rodent models of multiple neurodegenerative diseases, including HD, VCP-associated multisystem proteinopathy, and ALS. Using biochemical S-acylation assays and confocal microscopy, we show that ZDHHC17 S-acylates VCP, depletes the nuclear localization of both VCP and TDP-43, and modulates VCP-dependent toxicity via ER-stress. We additionally demonstrate that TDP-43 is S-acylated by ZDHHC9. Motivated by these findings, we investigated the functional significance of motor-neuronal (MN) ZDHHC17 by studying dHip14 (the fly analog of ZDHHC17) in Drosophila melanogaster. Here, we found that motor neuron-specific dHip14 knockdown (KD) in flies resulted in impaired motor function, whereas ubiquitous depletion led to pharate-adult lethality. Together, these results highlight a shared mechanism across neurodegenerative diseases. Collectively, our findings position ZDHHC17 as a critical enzyme that links fatty acylation, protein homeostasis, and neurodegeneration. Understanding how ZDHHC17 orchestrates S-acylation across different cellular pathways may reveal new therapeutic strategies to restore proteostasis in neurodegenerative disease.

molecular biology↗

bioRxiv2025

Antisense oligonucleotides targeting Valosin-containing protein improve muscle pathology and molecular defects in cell and mouse models of multisystem proteinopathy.

Valosin-containing protein (VCP) related disease, also known as multisystem proteinopathy 1 (MSP1), is an autosomal dominant disease caused by gain-of-function pathogenic variants of the VCP gene. The disease is associated with inclusion body myopathy, early-onset Pagets disease of bone, frontotemporal dementia, and familial amyotrophic lateral sclerosis. There is currently no treatment for this progressive disease associated with early demise resulting from proximal limb girdle and respiratory muscle weakness. We hypothesize that regulating VCP hyperactivity to normal levels can reduce the disease pathology. In this study, we assessed the effect of antisense oligonucleotides (ASOs) specifically targeting the human VCP gene in the patient (R155H) iPSC-derived skeletal muscle progenitor cells (SMPCs). ASOs were well tolerated up to a concentration of 5 {micro}M, and significantly reduced VCP protein expression in the SMPCs by 48% (95% CI [39-56]). We also treated the transgenic mouse model of VCP disease with the overexpressed humanized VCP gene severe A232E pathogenic variant with weekly subcutaneous ASO injections starting from 6 months of age for 3 months. In the skeletal muscle of transgenic mice, ASOs resulted in 30% (95%CI [27-32]) knockdown of VCP protein compared to control ASO. The ASO-mediated reduction of VCP expression in muscle tissue was associated with improvement in autophagy flux and reduction in TDP-43 expression, hallmarks of VCP disease. In addition, ASO-treated VCP A232E mice showed improvements in functional tests of muscle strength, such as rotarod and inverted screen test compared to mice treated with control ASO. These results suggest that targeting VCP could be beneficial in preventing the progression of the VCP myopathy and hold promise for the treatment of patients with VCP MSP1.

molecular biology↗

bioRxiv2024

Skeletal muscle effects of antisense oligonucleotides targeting glycogen synthase 1 in a mouse model of Pompe disease

Pompe disease (PD) is a progressive myopathy caused by the aberrant accumulation of glycogen in skeletal and cardiac muscle resulting from the deficiency of the enzyme acid alpha-glucosidase (GAA). Administration of recombinant human GAA as enzyme replacement therapy (ERT) works well in alleviating the cardiac manifestations of PD but loses sustained benefit in ameliorating the skeletal muscle pathology. The limited efficacy of ERT in skeletal muscle is partially attributable to its inability to curb the accumulation of new glycogen produced by the muscle enzyme glycogen synthase 1 (GYS1). Substrate reduction therapies aimed at knocking down GYS1 expression represent a promising avenue to improve Pompe myopathy. However, finding specific inhibitors for GYS1 is challenging given the presence of the highly homologous GYS2 in the liver. Antisense oligonucleotides (ASOs) are chemically modified oligomers that hybridize to their complementary target RNA to induce their degradation with exquisite specificity. In the present study, we show that ASO-mediated Gys1 knockdown in the Gaa-/- mouse model of PD led to a robust reduction in glycogen accumulation in skeletal and cardiac muscle. In addition, combining Gys1 ASO with ERT further reduced glycogen content in muscle, eliminated autophagic buildup and lysosomal dysfunction, and improved motor function in Gaa-/- mice. Our results provide a strong foundation for further validation of the use of Gys1 ASO, alone or in combination with ERT, as a therapy for PD. We propose that early administration of Gys1 ASO in combination with ERT may be the key to preventative treatment options in PD.

molecular biology↗

bioRxiv2023

Single-cell and spatial transcriptomics identify a macrophage population associated with skeletal muscle fibrosis

The monocytic/macrophage system is essential for skeletal muscle homeostasis, but its dysregulation contributes to the pathogenesis of muscle degenerative disorders. Despite our increasing knowledge of the role of macrophages in degenerative disease, it still remains unclear how macrophages contribute to muscle fibrosis. Here, we used single-cell transcriptomics to determine the molecular attributes of dystrophic and healthy muscle macrophages. We identified six novel clusters. Unexpectedly, none corresponded to traditional definitions of M1 or M2 macrophage activation. Rather, the predominant macrophage signature in dystrophic muscle was characterized by high expression of fibrotic factors, galectin-3 and spp1. Spatial transcriptomics and computational inferences of intercellular communication indicated that spp1 regulates stromal progenitor and macrophage interactions during muscular dystrophy. Galectin-3+ macrophages were chronically activated in dystrophic muscle and adoptive transfer assays showed that the galectin-3+ phenotype was the dominant molecular program induced within the dystrophic milieu. Histological examination of human muscle biopsies revealed that galectin-3+ macrophages were also elevated in multiple myopathies. These studies advance our understanding of macrophages in muscular dystrophy by defining the transcriptional programs induced in muscle macrophages, and reveal spp1 as a major regulator of macrophage and stromal progenitor interactions.

immunology↗

bioRxiv2021

Evaluating Sleep Disturbances in Children with Rare Genetic Neurodevelopmental Syndromes

BackgroundAdequate sleep is important for proper neurodevelopment and positive health outcomes. Sleep disturbances are more prevalent in children with genetically determined neurodevelopmental syndromes compared to typically developing counterparts. We characterize sleep behavior in Rett (RTT), Angelman (AS) and Prader-Willi (PWS) syndromes in order to identify effective approaches for treating sleep problems in these populations. We compared sleep-related symptoms across individuals with these different syndromes to each other, and to typically developing controls. MethodsChildren were recruited from the Rare Diseases Clinical Research Network (RDCRN) consortium registries; unaffected siblings were enrolled as related controls. For each participant, a parent completed multiple sleep questionnaires including: Pediatric Sleep Questionnaire (Sleep-Disordered Breathing [SDB]); Childrens Sleep Habits Questionnaire; Pediatric Daytime Sleepiness Scale. ResultsSleep data were analyzed from 714 participants, ages 2-18 years. Young children with AS had more reported sleep problems than children with RTT or PWS. Older children with RTT had more reported daytime sleepiness than those with AS or PWS. Finally, all individuals with RTT had more evidence of sleep-disordered breathing when compared to individuals with PWS. Notably, typically developing siblings were also reported to have sleep problems, except for sleep-related breathing disturbances which were associated with each of the genetic syndromes. ConclusionsIndividuals with RTT, AS and PWS frequently experience sleep problems, including sleep-disordered breathing. Screening for sleep problems in individuals with these and other neurogenetic disorders should be included in clinical assessment and managements. These data may also be useful in developing treatment strategies and in clinical trials.

genetics↗