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Pathogenic Proteotoxicity of Cryptic Splicing is Alleviated by Ubiquitination and ER-Phagy

ABSTRACT: RNA splicing and protein degradation systems allow the functional adaptation of the proteome in response to changing cellular contexts. However, the regulatory mechanisms connecting these processes remain poorly understood. Here, we show that impaired spliceosome assembly caused by USP39 deficiency leads to a pathogenic splicing profile characterized by the use of cryptic 5′ splice sites. Importantly, disruptive cryptic variants evade mRNA surveillance pathways and are translated into misfolded proteins. These spurious isoforms disrupt proteostasis causing cytosolic protein aggregates and ER stress. Proteotoxic exons activate unfolded protein response, causing CHOP-mediated cell death. In response to impaired splicing, eukaryotic cells enhance ubiquitination and ER-phagy to alleviate the pathogenic accumulation of proteotoxic isoforms. Our findings show how cryptic splicing-induced proteotoxicity can be mitigated, and provide insight into the molecular pathogenesis of spliceosome-associated diseases such as retinitis pigmentosa.

ORGANISM(S): Danio rerio

PROVIDER: GSE272836 | GEO | 2024/09/25

REPOSITORIES: GEO

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Pathogenic Proteotoxicity of Cryptic Splicing is Alleviated by Ubiquitination and ER-Phagy

Project description:RNA splicing and protein degradation systems allow the functional adaptation of the proteome in response to changing cellular contexts. However, the regulatory mechanisms connecting these processes remain poorly understood. Here, we show that impaired spliceosome assembly caused by USP39 deficiency leads to a pathogenic splicing profile characterized by the use of cryptic 5′ splice sites. Importantly, disruptive cryptic variants evade mRNA surveillance pathways and are translated into misfolded proteins. These spurious isoforms disrupt proteostasis causing cytosolic protein aggregates and ER stress. Proteotoxic exons activate unfolded protein response, causing CHOP-mediated cell death. In response to impaired splicing, eukaryotic cells enhance ubiquitination and ER-phagy to alleviate the pathogenic accumulation of proteotoxic isoforms. Our findings show how cryptic splicing-induced proteotoxicity can be mitigated, and provide insight into the molecular pathogenesis of spliceosome-associated diseases such as retinitis pigmentosa.

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Pathogenic Proteotoxicity of Cryptic Splicing is Alleviated by Ubiquitination and ER-Phagy

Project description:RNA splicing and protein degradation systems allow functional adaptation of the proteome in response to changing cellular contexts. However, the regulatory mechanisms connecting these processes remain poorly understood. Here, we show that impaired spliceosome assembly caused by USP39 deficiency leads to a pathogenic splicing profile characterized by the use of cryptic 5′ splice sites. Importantly, disruptive cryptic variants evade mRNA surveillance pathways and are translated into misfolded proteins. These spurious isoforms disrupt proteostasis causing proteotoxic aggregates, ER stress and CHOP-mediated cell death. In response to impaired splicing, eukaryotic cells enhance ubiquitination and ER-phagy to alleviate the pathogenic translation of proteotoxic exons. Our findings show how cryptic splicing-inducedproteotoxicity can be mitigated, and provide insight into the molecular pathogenesis of spliceosome-associated diseases, such as retinitis pigmentosa.

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Project description:RNA splicing and the ubiquitin system allow the functional proteome to adapt in response to changing cellular contexts. However, the regulatory mechanisms connecting these processes remain poorly understood. Here we show that the deregulation of the spliceosome B complex caused by USP39 deficiency leads to a novel splicing profile characterized by the use of cryptic 5′splice sites. Importantly, disruptive variants evade mRNA surveillance pathways and are translated into topologically incorrect proteins. These cryptic isoforms disrupt proteostasis and activate the unfolded protein response, causing ER stress-induced cell death. Human cells respond to this proteotoxicity by enhancing ubiquitin-mediated proteolysis and ER-phagy. Our findings show how cell death triggered by cryptic splicing can be mitigated, and provide insight into the molecular pathogenesis of diseases such as retinitis pigmentosa.

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