Raniero Chimienti, Silvia Torchio, Gabriel Siracusano, Valentina Zamarian, Laura Monaco, Marta Tiffany Lombardo, Silvia Pellegrini, Fabio Manenti, Federica Cuozzo, Greta Rossi, Paola Carrera, Valeria Sordi, Vania Broccoli, Riccardo Bonfanti, Giorgio Casari, Giulio Frontino, Lorenzo Piemonti
{"title":"破坏接受剪接位点的 WFS1 变体揭示了替代剪接对沃尔夫拉姆综合征患者β细胞凋亡的影响","authors":"Raniero Chimienti, Silvia Torchio, Gabriel Siracusano, Valentina Zamarian, Laura Monaco, Marta Tiffany Lombardo, Silvia Pellegrini, Fabio Manenti, Federica Cuozzo, Greta Rossi, Paola Carrera, Valeria Sordi, Vania Broccoli, Riccardo Bonfanti, Giorgio Casari, Giulio Frontino, Lorenzo Piemonti","doi":"10.1007/s00125-024-06307-0","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Aims/hypothesis</h3><p>Wolfram syndrome 1 (WS1) is an inherited condition mainly manifesting in childhood-onset diabetes mellitus and progressive optic nerve atrophy. The causative gene, <i>WFS1</i>, encodes wolframin, a master regulator of several cellular responses, and the gene’s mutations associate with clinical variability. Indeed, nonsense/frameshift variants correlate with more severe symptoms than missense/in-frame variants. As achieving a genotype–phenotype correlation is crucial for dealing with disease outcome, works investigating the impact of transcriptional and translational landscapes stemming from such mutations are needed. Therefore, we sought to elucidate the molecular determinants behind the pathophysiological alterations in a WS1 patient carrying compound heterozygous mutations in <i>WFS1</i>: c.316-1G>A, affecting the acceptor splice site (ASS) upstream of exon 4; and c.757A>T, introducing a premature termination codon (PTC) in exon 7.</p><h3 data-test=\"abstract-sub-heading\">Methods</h3><p>Bioinformatic analysis was carried out to infer the alternative splicing events occurring after disruption of ASS, followed by RNA-seq and PCR to validate the transcriptional landscape. Patient-derived induced pluripotent stem cells (iPSCs) were used as an in vitro model of WS1 and to investigate the <i>WFS1</i> alternative splicing isoforms in pancreatic beta cells. CRISPR/Cas9 technology was employed to correct ASS mutation and generate a syngeneic control for the endoplasmic reticulum stress induction and immunotoxicity assays.</p><h3 data-test=\"abstract-sub-heading\">Results</h3><p>We showed that patient-derived iPSCs retained the ability to differentiate into pancreatic beta cells. We demonstrated that the allele carrying the ASS mutation c.316-1G>A originates two PTC-containing alternative splicing transcripts (c.316del and c.316–460del), and two open reading frame-conserving mRNAs (c.271–513del and c.316–456del) leading to N-terminally truncated polypeptides. By retaining the C-terminal domain, these isoforms sustained the endoplasmic reticulum stress response in beta cells. Otherwise, PTC-carrying transcripts were regulated by the nonsense-mediated decay (NMD) in basal conditions. Exposure to cell stress inducers and proinflammatory cytokines affected expression levels of the NMD-related gene <i>SMG7</i> (>twofold decrease; <i>p</i><0.001) without eliciting a robust unfolded protein response in WFS1 beta cells. This resulted in a dramatic accumulation of the PTC-containing isoforms c.316del (>100-fold increase over basal; <i>p</i><0.001) and c.316–460del (>20-fold increase over basal; <i>p</i><0.001), predisposing affected beta cells to undergo apoptosis. Cas9-mediated recovery of ASS retrieved the canonical transcriptional landscape, rescuing the normal phenotype in patient-derived beta cells.</p><h3 data-test=\"abstract-sub-heading\">Conclusions/interpretation</h3><p>This study represents a new model to study wolframin, highlighting how each single mutation of the <i>WFS1</i> gene can determine dramatically different functional outcomes. Our data point to increased vulnerability of WFS1 beta cells to stress and inflammation and we postulate that this is triggered by escaping NMD and accumulation of mutated transcripts and truncated proteins. These findings pave the way for further studies on the molecular basis of genotype–phenotype relationship in WS1, to uncover the key determinants that might be targeted to ameliorate the clinical outcome of patients affected by this rare disease.</p><h3 data-test=\"abstract-sub-heading\">Data availability</h3><p>The in silico predicted N-terminal domain structure file of WT wolframin was deposited in the ModelArchive, together with procedures, ramachandran plots, inter-residue distance deviation and IDDT scores, and Gromacs configuration files (doi/10.5452/ma-cg3qd). The deep-sequencing data as fastq files used to generate consensus sequences of AS isoforms of WFS1 are available in the SRA database (BioProject PRJNA1109747).</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\n","PeriodicalId":11164,"journal":{"name":"Diabetologia","volume":null,"pages":null},"PeriodicalIF":8.4000,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A WFS1 variant disrupting acceptor splice site uncovers the impact of alternative splicing on beta cell apoptosis in a patient with Wolfram syndrome\",\"authors\":\"Raniero Chimienti, Silvia Torchio, Gabriel Siracusano, Valentina Zamarian, Laura Monaco, Marta Tiffany Lombardo, Silvia Pellegrini, Fabio Manenti, Federica Cuozzo, Greta Rossi, Paola Carrera, Valeria Sordi, Vania Broccoli, Riccardo Bonfanti, Giorgio Casari, Giulio Frontino, Lorenzo Piemonti\",\"doi\":\"10.1007/s00125-024-06307-0\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<h3 data-test=\\\"abstract-sub-heading\\\">Aims/hypothesis</h3><p>Wolfram syndrome 1 (WS1) is an inherited condition mainly manifesting in childhood-onset diabetes mellitus and progressive optic nerve atrophy. The causative gene, <i>WFS1</i>, encodes wolframin, a master regulator of several cellular responses, and the gene’s mutations associate with clinical variability. Indeed, nonsense/frameshift variants correlate with more severe symptoms than missense/in-frame variants. As achieving a genotype–phenotype correlation is crucial for dealing with disease outcome, works investigating the impact of transcriptional and translational landscapes stemming from such mutations are needed. Therefore, we sought to elucidate the molecular determinants behind the pathophysiological alterations in a WS1 patient carrying compound heterozygous mutations in <i>WFS1</i>: c.316-1G>A, affecting the acceptor splice site (ASS) upstream of exon 4; and c.757A>T, introducing a premature termination codon (PTC) in exon 7.</p><h3 data-test=\\\"abstract-sub-heading\\\">Methods</h3><p>Bioinformatic analysis was carried out to infer the alternative splicing events occurring after disruption of ASS, followed by RNA-seq and PCR to validate the transcriptional landscape. Patient-derived induced pluripotent stem cells (iPSCs) were used as an in vitro model of WS1 and to investigate the <i>WFS1</i> alternative splicing isoforms in pancreatic beta cells. CRISPR/Cas9 technology was employed to correct ASS mutation and generate a syngeneic control for the endoplasmic reticulum stress induction and immunotoxicity assays.</p><h3 data-test=\\\"abstract-sub-heading\\\">Results</h3><p>We showed that patient-derived iPSCs retained the ability to differentiate into pancreatic beta cells. We demonstrated that the allele carrying the ASS mutation c.316-1G>A originates two PTC-containing alternative splicing transcripts (c.316del and c.316–460del), and two open reading frame-conserving mRNAs (c.271–513del and c.316–456del) leading to N-terminally truncated polypeptides. By retaining the C-terminal domain, these isoforms sustained the endoplasmic reticulum stress response in beta cells. Otherwise, PTC-carrying transcripts were regulated by the nonsense-mediated decay (NMD) in basal conditions. Exposure to cell stress inducers and proinflammatory cytokines affected expression levels of the NMD-related gene <i>SMG7</i> (>twofold decrease; <i>p</i><0.001) without eliciting a robust unfolded protein response in WFS1 beta cells. This resulted in a dramatic accumulation of the PTC-containing isoforms c.316del (>100-fold increase over basal; <i>p</i><0.001) and c.316–460del (>20-fold increase over basal; <i>p</i><0.001), predisposing affected beta cells to undergo apoptosis. Cas9-mediated recovery of ASS retrieved the canonical transcriptional landscape, rescuing the normal phenotype in patient-derived beta cells.</p><h3 data-test=\\\"abstract-sub-heading\\\">Conclusions/interpretation</h3><p>This study represents a new model to study wolframin, highlighting how each single mutation of the <i>WFS1</i> gene can determine dramatically different functional outcomes. Our data point to increased vulnerability of WFS1 beta cells to stress and inflammation and we postulate that this is triggered by escaping NMD and accumulation of mutated transcripts and truncated proteins. These findings pave the way for further studies on the molecular basis of genotype–phenotype relationship in WS1, to uncover the key determinants that might be targeted to ameliorate the clinical outcome of patients affected by this rare disease.</p><h3 data-test=\\\"abstract-sub-heading\\\">Data availability</h3><p>The in silico predicted N-terminal domain structure file of WT wolframin was deposited in the ModelArchive, together with procedures, ramachandran plots, inter-residue distance deviation and IDDT scores, and Gromacs configuration files (doi/10.5452/ma-cg3qd). The deep-sequencing data as fastq files used to generate consensus sequences of AS isoforms of WFS1 are available in the SRA database (BioProject PRJNA1109747).</p><h3 data-test=\\\"abstract-sub-heading\\\">Graphical Abstract</h3>\\n\",\"PeriodicalId\":11164,\"journal\":{\"name\":\"Diabetologia\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":8.4000,\"publicationDate\":\"2024-11-09\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Diabetologia\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1007/s00125-024-06307-0\",\"RegionNum\":1,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ENDOCRINOLOGY & METABOLISM\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Diabetologia","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1007/s00125-024-06307-0","RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENDOCRINOLOGY & METABOLISM","Score":null,"Total":0}
A WFS1 variant disrupting acceptor splice site uncovers the impact of alternative splicing on beta cell apoptosis in a patient with Wolfram syndrome
Aims/hypothesis
Wolfram syndrome 1 (WS1) is an inherited condition mainly manifesting in childhood-onset diabetes mellitus and progressive optic nerve atrophy. The causative gene, WFS1, encodes wolframin, a master regulator of several cellular responses, and the gene’s mutations associate with clinical variability. Indeed, nonsense/frameshift variants correlate with more severe symptoms than missense/in-frame variants. As achieving a genotype–phenotype correlation is crucial for dealing with disease outcome, works investigating the impact of transcriptional and translational landscapes stemming from such mutations are needed. Therefore, we sought to elucidate the molecular determinants behind the pathophysiological alterations in a WS1 patient carrying compound heterozygous mutations in WFS1: c.316-1G>A, affecting the acceptor splice site (ASS) upstream of exon 4; and c.757A>T, introducing a premature termination codon (PTC) in exon 7.
Methods
Bioinformatic analysis was carried out to infer the alternative splicing events occurring after disruption of ASS, followed by RNA-seq and PCR to validate the transcriptional landscape. Patient-derived induced pluripotent stem cells (iPSCs) were used as an in vitro model of WS1 and to investigate the WFS1 alternative splicing isoforms in pancreatic beta cells. CRISPR/Cas9 technology was employed to correct ASS mutation and generate a syngeneic control for the endoplasmic reticulum stress induction and immunotoxicity assays.
Results
We showed that patient-derived iPSCs retained the ability to differentiate into pancreatic beta cells. We demonstrated that the allele carrying the ASS mutation c.316-1G>A originates two PTC-containing alternative splicing transcripts (c.316del and c.316–460del), and two open reading frame-conserving mRNAs (c.271–513del and c.316–456del) leading to N-terminally truncated polypeptides. By retaining the C-terminal domain, these isoforms sustained the endoplasmic reticulum stress response in beta cells. Otherwise, PTC-carrying transcripts were regulated by the nonsense-mediated decay (NMD) in basal conditions. Exposure to cell stress inducers and proinflammatory cytokines affected expression levels of the NMD-related gene SMG7 (>twofold decrease; p<0.001) without eliciting a robust unfolded protein response in WFS1 beta cells. This resulted in a dramatic accumulation of the PTC-containing isoforms c.316del (>100-fold increase over basal; p<0.001) and c.316–460del (>20-fold increase over basal; p<0.001), predisposing affected beta cells to undergo apoptosis. Cas9-mediated recovery of ASS retrieved the canonical transcriptional landscape, rescuing the normal phenotype in patient-derived beta cells.
Conclusions/interpretation
This study represents a new model to study wolframin, highlighting how each single mutation of the WFS1 gene can determine dramatically different functional outcomes. Our data point to increased vulnerability of WFS1 beta cells to stress and inflammation and we postulate that this is triggered by escaping NMD and accumulation of mutated transcripts and truncated proteins. These findings pave the way for further studies on the molecular basis of genotype–phenotype relationship in WS1, to uncover the key determinants that might be targeted to ameliorate the clinical outcome of patients affected by this rare disease.
Data availability
The in silico predicted N-terminal domain structure file of WT wolframin was deposited in the ModelArchive, together with procedures, ramachandran plots, inter-residue distance deviation and IDDT scores, and Gromacs configuration files (doi/10.5452/ma-cg3qd). The deep-sequencing data as fastq files used to generate consensus sequences of AS isoforms of WFS1 are available in the SRA database (BioProject PRJNA1109747).
期刊介绍:
Diabetologia, the authoritative journal dedicated to diabetes research, holds high visibility through society membership, libraries, and social media. As the official journal of the European Association for the Study of Diabetes, it is ranked in the top quartile of the 2019 JCR Impact Factors in the Endocrinology & Metabolism category. The journal boasts dedicated and expert editorial teams committed to supporting authors throughout the peer review process.