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Scaglione, K. M.

Publications and source records attributed to Scaglione, K. M..

5 recordsLinked to original sources
bioRxiv2025

Domain-specific decoupling of co-chaperone and ligase functions in STUB1 underlies biochemical and clinical heterogeneity in SCA48

AO_SCPLOWBSTRACTC_SCPLOWThe carboxyl terminus of HSC70-interacting protein (CHIP, encoded by STUB1) integrates co-chaperone and E3 ubiquitin ligase activities to maintain proteostasis. Heterozygous STUB1 mutations cause the dominant cerebellar ataxia SCA48 through incompletely understood mechanisms. We characterized 13 SCA48-associated variants in the TPR and U-box domains using recombinant protein and cellular assays. TPR mutations retained intrinsic ligase activity but lost HSC70 binding, substrate ubiquitination efficiency, and protein stability. Conversely, U-box mutations abolished ligase function, induced aberrant high-molecular-weight oligomerization, and frequently elevated steady-state CHIP levels while only partially impairing co-chaperone activity. Many variants exhibited temperature-sensitive defects and stress-induced nuclear mislocalization. Principal component analysis revealed robust domain-specific biochemical clustering. RNA-seq following STUB1 knockdown demonstrated preserved HSF1-dependent transactivation but a loss of CHIP-dependent amplification of ubiquitination, chaperone, and transcriptional pathways under heat stress. Meta-analysis of 87 SCA48 patients linked TPR-like biochemical profiles to upper motor neuron involvement and U-box profiles to prominent dysarthria. Collectively, SCA48 mutations decouple CHIPs dual functions in a domain-dependent manner, exerting dominant-negative or gain-of-toxic effects that drive the observed clinical heterogeneity. These findings establish a direct biochemical-clinical correlation in SCA48 and provide a framework for domain-targeted therapeutic strategies exploiting residual ligase or chaperone activity.

neuroscience↗
bioRxiv2025

14-3-3ϵ UFMylation promotes RIG-I-mediated signaling

Post-translational modifications regulate RIG-I signaling in diverse ways. We previously showed that UFMylation, the covalent attachment of the ubiquitin-fold modifier UFM1 to proteins, enhances RIG-I signaling by promoting its interaction with its membrane-targeting adaptor 14-3-3{varepsilon}. Here, we map UFM1 conjugation to lysines K50 and K215 on 14-3-3{varepsilon} and demonstrate how these UFMylation events control RIG-I signaling. Using in vitro and cellular UFMylation assays, we reveal that K50R/K215R mutations abolish UFMylation and reduce type I and III interferon induction following RIG-I activation. Unexpectedly, these mutations do not disrupt 14-3-3{varepsilon}-RIG-I interaction. Instead, they paradoxically enhance RIG-I interaction with MAVS while simultaneously reducing 14-3-3{varepsilon}-MAVS interaction. These findings establish UFMylation of 14-3-3{varepsilon} as an important control that shapes MAVS complex architecture to ensure optimal RIG-I signaling and highlights the broader regulatory role of UFMylation in antiviral innate immunity. ImportancePost-translational modifications provide regulatory control of antiviral innate immune responses. Our study reveals that UFMylation of 14-3-3{varepsilon} is required for RIG-I-mediated innate immune signaling. We demonstrate that conjugation of UFM1 to specific lysine residues on 14-3-3{varepsilon} enhances downstream signaling events that facilitate interferon induction. It does this by stabilizing 14-3-3{varepsilon} association with the MAVS signaling complex and coordinating productive complex architecture. By identifying the precise sites of UFMylation on 14-3-3{varepsilon} and their functional consequences, we provide insights into the regulatory layers governing antiviral innate immunity. These findings complement emerging evidence that UFMylation serves as a versatile modulator across diverse immune pathways. Furthermore, our work highlights how protein chaperones like 14-3-3{varepsilon} can be dynamically modified to orchestrate complex signaling cascades, suggesting potential therapeutic approaches for targeting dysregulated innate immunity.

immunology↗
bioRxiv2020

The novel chaperone protein SRCP1 reduces insoluble SOD1 protein in vivo without extending ALS mouse lifespan

Protein misfolding and aggregation are shared features of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), and protein quality control disruption contributes to neuronal toxicity. Therefore, reducing protein aggregation could hold therapeutic potential. We previously identified a novel chaperone protein, serine-rich chaperone protein 1 (SRCP1), that effectively prevents protein aggregation in cell culture and zebrafish models of Huntingtons disease. Here we tested whether this benefit extends to aggregated proteins found in ALS. We used viral-mediated expression of SRCP1 in in vitro and in vivo models of ALS. We found that SRCP1 reduced insoluble SOD1 protein levels in HEK293T cells overexpressing either the A4V or G93R mutant SOD1. However, the reduction of insoluble protein was not observed in either mutant C9orf72 or SOD1 ALS iPSC-derived motor neurons infected with a lentivirus expressing SRCP1. SOD1 G93A ALS mice injected with AAV-SRCP1 showed a small but significant reduction in insoluble and soluble SOD1 in both the brain and spinal cord, but SRCP1 expression did not improve mouse survival. These data indicate that SRCP1 likely reduces insoluble protein burden in a protein and/or context-dependent manner indicating a need for additional insight into SRCP1 function and therapeutic potential.

neuroscience↗
bioRxiv2019

Modeling clinical phenotypes with protein function to explain the disease spectrum in patients with CHIP mutations

Monogenetic disorders that cause cerebellar ataxia are characterized by defects in gait and atrophy of the cerebellum; however, patients often suffer from a spectrum of disease, complicating treatment options. Spinocerebellar ataxia autosomal recessive 16 (SCAR16) is caused by coding mutations in STUB1, a gene that encodes the multi-functional enzyme CHIP (C-terminus of HSC70-interacting protein). The spectrum of disease found in SCAR16 patients includes a wide range in the age of disease onset, cognitive dysfunction, increased tendon reflex, and hypogonadism. Although SCAR16 mutations span the multiple functional domains of CHIP, it is unclear if the location of the mutation contributes to the clinical spectrum of SCAR16 or with changes in the biochemical properties of CHIP. In this study, we examined the associations and relationships between the clinical phenotypes of SCAR16 patients and how they relate to changes in the biophysical, biochemical, and functional properties of the corresponding mutated protein. We found that the severity of ataxia did not correlate with age of onset; however, cognitive dysfunction, increased tendon reflex, and ancestry were able to predict 54% of the variation in ataxia severity. We further identified domain-specific relationships between biochemical changes in CHIP and clinical phenotypes, and specific biochemical activities that associate selectively to either increased tendon reflex or cognitive dysfunction, suggesting that specific changes to CHIP-HSC70 dynamics contributes to the clinical spectrum of SCAR16. Finally, linear models of SCAR16 as a function of the biochemical properties of CHIP support the concept that further inhibiting mutant CHIP activity lessens disease severity and may be useful in the design of patient-speciflc targeted approaches to treat SCAR16.

neuroscience↗