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Birt-Hogg-Dubé syndrome (BHD syndrome) is an autosomal dominant multisystem disorder with variable expression due to pathogenic constitutional variants in the FLCN gene. Patients with BHD syndrome are predisposed to benign cutaneous fibrofolliculomas/trichodischomas, pulmonary cysts with an associated risk of spontaneous pneumothorax, and renal cell carcinoma. A requirement for updated International consensus recommendations for the diagnosis and management of BHD syndrome was identified. Based on a comprehensive literature review and expert consensus within the fields of respiratory medicine, urology, radiology, dermatology, clinical oncology and clinical genetics, updated recommendations for diagnosis, surveillance and management in BHD syndrome were developed. With the widespread availability of FLCN genetic testing, clinical scenarios in which a diagnosis should be considered and criteria for genetic testing were defined. Following a clinical and/or molecular diagnosis of BHD syndrome, a multidisciplinary approach to disease management is required. Regular renal cancer surveillance is recommended in adulthood and life-long, but the evidence base for additional tumour surveillance is limited and further research warranted. Recommendations for the treatment of cutaneous, pulmonary and renal manifestations are provided. Awareness of BHD syndrome needs to be raised and better knowledge of the clinical settings in which the diagnosis should be considered should enable earlier diagnosis. Further details, including areas for future research topics are available at: https://www.genturis.eu/l=eng/Guidelines-and-pathways/Clinical-practice-guidelines.html .
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OTX2 is a transcription factor and known driver in medulloblastoma (MB), where it is amplified in a subset of tumours and overexpressed in most cases of group 3 and group 4 MB. Here we demonstrate a noncanonical role for OTX2 in group 3 MB alternative splicing. OTX2 associates with the large assembly of splicing regulators complex through protein-protein interactions and regulates a stem cell splicing program. OTX2 can directly or indirectly bind RNA and this may be partially independent of its DNA regulatory functions. OTX2 controls a pro-tumorigenic splicing program that is mirrored in human cerebellar rhombic lip origins. Among the OTX2-regulated differentially spliced genes, PPHLN1 is expressed in the most primitive rhombic lip stem cells, and targeting PPHLN1 splicing reduces tumour growth and enhances survival in vivo. These findings identify OTX2-mediated alternative splicing as a major determinant of cell fate decisions that drive group 3 MB progression.
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Empalme Alternativo , Neoplasias Cerebelosas , Meduloblastoma , Células Madre Neoplásicas , Factores de Transcripción Otx , Factores de Transcripción Otx/metabolismo , Factores de Transcripción Otx/genética , Meduloblastoma/genética , Meduloblastoma/patología , Meduloblastoma/metabolismo , Empalme Alternativo/genética , Humanos , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Neoplasias Cerebelosas/genética , Neoplasias Cerebelosas/patología , Neoplasias Cerebelosas/metabolismo , Animales , Regulación Neoplásica de la Expresión Génica , Línea Celular Tumoral , Ratones , Proliferación CelularRESUMEN
BACKGROUND: Von Hippel-Lindau disease (VHL) is a rare autosomal dominant hereditary cancer-predisposition syndrome caused by germline pathogenic variants (PV) in VHL gene. It is associated with a high penetrance of benign and malignant vascular tumors in multiples organs, including pancreatic neuroendocrine tumors (PanNETs), whose long-term natural history is ill-known. METHODS: Patients with both documented germline PV in VHL gene and PanNETs included in the French PREDIR database between 1995 and 2022 were included. Primary endpoint was the proportion of patients with PanNET-related metastases and secondary endpoint was overall survival (OS). Genotype/phenotype correlations were studied. RESULTS: We included 121 patients with 259 PanNETs. Median age at diagnosis was 38 years. Median follow-up was 89.5 months. PanNET surgical resection was performed in 51 patients. Overall, 29 patients (24%) had metastases (5 synchronous, 10 metachronous), with a higher risk in case of larger PanNET size (p=0.0089; best threshold 28 mm) and grade 2 PanNET (p=0.048), and a pejorative prognostic impact (p=0.043). Patients with PV in VHL exon 1 had larger PanNETs (p=0.018), more often metastatic disease (48% vs 11.5%; p < 0.001) and a trend toward shorter OS (p=0.16). CONCLUSION: The risk of metastases associated to VHL-related PanNETs remains low (24%) but increases with tumor size >28 mm, higher grade and in case of PV located VHL exon 1. These data might help improving the management of these patients, who should be referred to an expert center.
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Hereditary renal cell carcinoma (RCC) is caused by germline mutations in a subset of genes, including VHL, MET, FLCN, and FH. However, many familial RCC cases do not harbor mutations in the known predisposition genes. Using Whole Exome Sequencing, we identified two germline missense variants in the DCLRE1B/Apollo gene (ApolloN246I and ApolloY273H) in two unrelated families with several RCC cases. Apollo encodes an exonuclease involved in DNA Damage Response and Repair (DDRR) and telomere integrity. We characterized these two functions in the human renal epithelial cell line HKC8. The decrease or inhibition of Apollo expression sensitizes these cells to DNA interstrand crosslink damage (ICLs). HKC8 Apollo-/- cells appear defective in the DDRR and present an accumulation of telomere damage. Wild-type and mutated Apollo forms could interact with TRF2, a shelterin protein involved in telomere protection. However, only ApolloWT can rescue the telomere damage in HKC8 Apollo-/- cells. Our results strongly suggest that ApolloN246I and ApolloY273H are loss-of-function mutants that cause impaired telomere integrity and could lead to genomic instability. Altogether, our results suggest that mutations in Apollo could induce renal oncogenesis.
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Carcinoma de Células Renales , Humanos , Carcinoma de Células Renales/genética , Mutación de Línea Germinal , Telómero/genética , Daño del ADN , Reparación del ADN/genética , Exodesoxirribonucleasas/genéticaRESUMEN
BACKGROUND: The von Hippel-Lindau (VHL) disease is a hereditary tumour syndrome caused by germline mutations in VHL tumour suppressor gene. The identification of VHL variants requires accurate classification which has an impact on patient management and genetic counselling. METHODS: The TENGEN (French oncogenetics network of neuroendocrine tumors) and PREDIR (French National Cancer Institute network for Inherited predispositions to kidney cancer) networks have collected VHL genetic variants and clinical characteristics of all VHL-suspected patients analysed from 2003 to 2021 by one of the nine laboratories performing VHL genetic testing in France. Identified variants were registered in a locus-specific database, the Universal Mutation Database-VHL database (http://www.umd.be/VHL/). RESULTS: Here we report the expert classification of 164 variants, including all missense variants (n=124), all difficult interpretation variants (n=40) and their associated phenotypes. After initial American College of Medical Genetics classification, first-round classification was performed by the VHL expert group followed by a second round for discordant and ambiguous cases. Overall, the VHL experts modified the classification of 87 variants including 30 variants of uncertain significance that were as (likely)pathogenic variants for 19, and as likely benign for 11. CONCLUSION: Consequently, this work has allowed the diagnosis and influenced the genetic counselling of 45 VHL-suspected families and can benefit to the worldwide VHL community, through this review.
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Neoplasias Renales , Enfermedad de von Hippel-Lindau , Humanos , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genética , Pruebas Genéticas , Predisposición Genética a la Enfermedad , Enfermedad de von Hippel-Lindau/genética , Enfermedad de von Hippel-Lindau/patología , Estudios de Asociación Genética , Neoplasias Renales/genética , Mutación de Línea GerminalRESUMEN
In skeletal muscle, muscle stem cells (MuSC) are the main cells responsible for regeneration upon injury. In diseased skeletal muscle, it would be therapeutically advantageous to replace defective MuSCs, or rejuvenate them with drugs to enhance their self-renewal and ensure long-term regenerative potential. One limitation of the replacement approach has been the inability to efficiently expand MuSCs ex vivo, while maintaining their stemness and engraftment abilities. Herein, we show that inhibition of type I protein arginine methyltransferases (PRMTs) with MS023 increases the proliferative capacity of ex vivo cultured MuSCs. Single cell RNA sequencing (scRNAseq) of ex vivo cultured MuSCs revealed the emergence of subpopulations in MS023-treated cells which are defined by elevated Pax7 expression and markers of MuSC quiescence, both features of enhanced self-renewal. Furthermore, the scRNAseq identified MS023-specific subpopulations to be metabolically altered with upregulated glycolysis and oxidative phosphorylation (OxPhos). Transplantation of MuSCs treated with MS023 had a better ability to repopulate the MuSC niche and contributed efficiently to muscle regeneration following injury. Interestingly, the preclinical mouse model of Duchenne muscular dystrophy had increased grip strength with MS023 treatment. Our findings show that inhibition of type I PRMTs increased the proliferation capabilities of MuSCs with altered cellular metabolism, while maintaining their stem-like properties such as self-renewal and engraftment potential.
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Distrofia Muscular de Duchenne , Células Satélite del Músculo Esquelético , Animales , Ratones , Músculo Esquelético/metabolismo , Células Satélite del Músculo Esquelético/metabolismo , Células Cultivadas , Distrofia Muscular de Duchenne/terapia , Distrofia Muscular de Duchenne/metabolismo , Proteína-Arginina N-Metiltransferasas/metabolismoRESUMEN
Positively selected germinal center B cells (GCBC) can either resume proliferation and somatic hypermutation or differentiate. The mechanisms dictating these alternative cell fates are incompletely understood. We show that the protein arginine methyltransferase 1 (Prmt1) is upregulated in murine GCBC by Myc and mTORC-dependent signaling after positive selection. Deleting Prmt1 in activated B cells compromises antibody affinity maturation by hampering proliferation and GCBC light zone to dark zone cycling. Prmt1 deficiency also results in enhanced memory B cell generation and plasma cell differentiation, albeit the quality of these cells is compromised by the GCBC defects. We further demonstrate that Prmt1 intrinsically limits plasma cell differentiation, a function co-opted by B cell lymphoma (BCL) cells. Consistently, PRMT1 expression in BCL correlates with poor disease outcome, depends on MYC and mTORC1 activity, is required for cell proliferation, and prevents differentiation. Collectively, these data identify PRMT1 as a determinant of normal and cancerous mature B cell proliferation and differentiation balance.
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Linfocitos B , Proteína-Arginina N-Metiltransferasas , Animales , Ratones , Afinidad de Anticuerpos , Diferenciación Celular , Centro Germinal , Proteína-Arginina N-Metiltransferasas/genética , Proliferación CelularRESUMEN
R-loops, formed transiently during gene transcription, are tightly controlled to avoid conflict with ongoing processes. Marchena-Cruz et al. identified DExD/H box RNA helicase DDX47 using a new R-loop resolving screen and defined a unique role for this helicase in nucleolar R-loops and its interplay with senataxin (SETX) and DDX39B.
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ARN Helicasas DEAD-box , Estructuras R-Loop , Humanos , ARN Helicasas DEAD-box/genética , ARN Helicasas DEAD-box/metabolismo , ADN Helicasas , ARN Helicasas/genética , Enzimas Multifuncionales/genéticaRESUMEN
Uncertainty is omnipresent in medical practice. It occurs when the available data do not allow predicting with accuracy the patient's outcome. Paradoxically, despite the exponential progress of medical knowledge, uncertainty in medical practice seems to increase. Even though uncertainty is present at every stage of medical practice, this uncertainty is rarely discussed with the patient. However, there is an ethical and legal necessity to communicate it with the patient. The aim of this review is to describe the barriers and impacts of the communication of uncertainty with the patient and suggest strategies to enhance its communication.
L'incertitude est omniprésente dans la pratique médicale. Elle apparaît quand les données à disposition ne permettent pas de prédire avec exactitude le devenir du patient. Paradoxalement, malgré l'augmentation des connaissances médicales, elle semble s'accroître dans la pratique médicale. Bien que présente à chaque étape de la prise en charge du patient, cette incertitude est peu discutée avec lui. Cependant, il existe une nécessité éthique et légale à sa communication avec le patient. Cet article a pour but de décrire les barrières et les conséquences de la communication de l'incertitude avec le patient et de proposer des stratégies pour améliorer sa communication.
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Comunicación , Pacientes , Humanos , IncertidumbreRESUMEN
AIMS: In the heart, splicing factors orchestrate the functional properties of cardiomyocytes by regulating the alternative splicing of multiple genes. Work in embryonic stem cells has shown that the splicing factor Quaking (QKI) regulates alternative splicing during cardiomyocyte differentiation. However, the relevance and function of QKI in adult cardiomyocytes remains unknown. In this study, we aim to identify the in vivo function of QKI in the adult mouse heart. METHODS AND RESULTS: We generated mice with conditional deletion of QKI in cardiomyocytes by the Cre-Lox system. Mice with cardiomyocyte-specific deletion of QKI died during the foetal period (E14.5), without obvious anatomical abnormalities of the heart. Adult mice with tamoxifen-inducible QKI deletion rapidly developed heart failure associated with severe disruption of sarcomeres, already 7 days after knocking out QKI. RNA sequencing revealed that QKI regulates the alternative splicing of more than 1000 genes, including sarcomere and cytoskeletal components, calcium-handling genes, and (post-)transcriptional regulators. Many of these splicing changes corresponded to the loss of muscle-specific isoforms in the heart. Forced overexpression of QKI in cultured neonatal rat ventricular myocytes directed these splicing events in the opposite direction and enhanced contractility of cardiomyocytes. CONCLUSION: Altogether, our findings show that QKI is an important regulator of the muscle-specific alternative splicing program that builds the contractile apparatus of cardiomyocytes.
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Empalme Alternativo , Miocitos Cardíacos , Ratones , Ratas , Animales , Miocitos Cardíacos/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Comunicación Celular , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismoRESUMEN
Data on preimplantation genetic testing (PGT-M) in patients with genetic susceptibility to cancer are scarce in the literature, while there is, in our experience, a growing familiarity with assisted reproduction techniques (ART) among pathogenic variant heterozygotes. We performed a retrospective multicenter study of PGT-M outcomes among French patients with genetic susceptibility to cancer. Our objectives were to collect data on this complex issue, and to help cancer geneticists counsel their patients of reproductive age. We also wanted to increase awareness regarding PGT-M among cancer genetics professionals. Patients from three university hospital cancer genetics clinics who had requested PGT-M between 2000 and 2019 were included retrospectively. Data were extracted from medical records. Patients were then contacted directly to collect missing and up-to-date information. Out of 41 eligible patients, 28 agreed explicitly to participate when contacted and were therefore included. They carried PV in VHL (n = 9), APC (n = 8), CDH1 (n = 5), STK11 (n = 2), AXIN2, BRCA1, MEN1, and FH (n = 1). Seven patients were denied PGT-M based on multidisciplinary team meetings or subsequently by the ART hospital teams, two changed their minds, and two were yet to start the process. PGT-M was successful in seven patients (25%), with a mean age at PGT-M request of 27. Most had von Hippel-Lindau. PGT-M failed in the remaining ten, with a mean age at PGT-M request of 32. The main reason for failure was non-implantation of the embryo. Of these, four patients were pursuing PGT-M at the time of last contact. PGT-M outcomes in patients with cancer susceptibility syndromes were satisfactory. These patients should be informed about PGT-M more systematically, which would imply greater awareness among cancer genetics professionals regarding ART. Our series was not representative of cancer susceptibility syndromes in general; the predominance of cases with syndromes characterized by early-onset, highly penetrant disease is explained by the restrictive French guidelines.
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Neoplasias , Diagnóstico Preimplantación , Embarazo , Femenino , Humanos , Predisposición Genética a la Enfermedad , Diagnóstico Preimplantación/métodos , Estudios Retrospectivos , Transferencia de Embrión/métodos , Pruebas Genéticas/métodos , Neoplasias/diagnóstico , Neoplasias/genéticaRESUMEN
BHD syndrome is characterized by an increased risk of bilateral and multifocal renal cell carcinoma (RCCs), but is rarely metastatic. Our report aims to analyze the outcome of patients with BHD syndrome who underwent percutaneous thermal ablation (TA). The present report included six BHD syndrome patients (five men) with a mean age of 66 ± 11 (SD) years who had a proven germline FLCN gene mutation and underwent TA for a renal tumor. Nineteen renal tumors (median two tumors per patient; range: 1-3), including seven chromophobe RCCs, five clear-cell RCCs, four papillary RCCs, two clear-cell papillary RCC, and one hybrid oncocytic/chromophobe tumor were treated in 14 ablation sessions. The mean size of the tumors was 21 ± 11 (SD) mm (median: 20 mm; interquartile range (IQR): 14-25 mm) for a mean volume of 7 ± 11 (SD) mL (median: 3; IQR: 1-5 mL). Technical success was achieved in all ablation sessions (primary success rate, 100%). The procedure was well tolerated under conscious sedation with no significant Clavien-Dindo complication (grade 2, 3, 4). All patients were alive with no distant metastasis during a median follow-up period of 74 months (range: 33-83 months). No local tumor progression was observed. The mean decrease in estimated glomerular filtration rate was 8 mL/min/1.73 m2. No patients required dialysis or renal transplantation. In this case series, percutaneous TA appeared as a safe and efficient nephron-sparing treatment for treating RCCs associated with BHD syndrome, even in the case of advanced chronic kidney disease.
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Von Hippel-Lindau (VHL) disease is one of the most common cancer predisposition syndromes. Penetrance is high with around 20% of children presenting detectable and curable manifestations of the disease at 15 years old. VHL predictive genetic testing (PGT) is recommended during childhood from age 5 years in France. Insufficient compliance to surveillance of VHL pathogenic variant (PV) carriers is associated with severe outcome. PGT experienced by children and their parents is probably critical in influencing future acceptance of the result and adherence to surveillance. We conducted a retrospective study on minors tested (aged 5 to 16 years old) from 2010 to 2020, in a multidisciplinary oncogenetics consultation which follows a 3-step protocol based on psychological familial support. The objectives were to assess the adherence to follow-up within the National Expert Center for inherited predispositions to renal tumors (PREDIR) network of VHL PV carriers and its benefit through tumor detection and medical interventions. A VHL PGT was carried out in 34 children. Among the 16 children diagnosed as VHL PV carriers addressed to the PREDIR network, none had discontinued surveillance after a median of 41 months. Follow-up examinations detected 11 tumors in 6 children, 4 have been surgically treated. All had a favorable outcome. Our data suggest that a specific and adapted procedure for PGT in at-risk VHL children as well as a follow-up, organized within a specialized expert network, fosters a complete adherence to the surveillance protocol and thus lead to a favorable clinical outcome.
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Neoplasias Renales , Enfermedad de von Hippel-Lindau , Adolescente , Niño , Preescolar , Estudios de Seguimiento , Pruebas Genéticas , Humanos , Neoplasias Renales/diagnóstico , Neoplasias Renales/genética , Estudios Retrospectivos , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genética , Enfermedad de von Hippel-Lindau/diagnóstico , Enfermedad de von Hippel-Lindau/genéticaRESUMEN
Remyelination failure in multiple sclerosis leads to progressive demyelination and inflammation, resulting in neurodegeneration and clinical decline. Microglia are innate immune cells that can acquire a regenerative phenotype to promote remyelination, yet little is known about the regulators controlling the regenerative microglia activation. Herein, using a cuprizone (CPZ)-diet induced de- and remyelination mice model, we identify PRMT1 as a driver for MHC-associated microglia population required for remyelination in the central nervous system. The loss of PRMT1, but not PRMT5, in microglia resulted in impairment of the remyelination with a reduction of oligoprogenitor cell number and prolonged microgliosis and astrogliosis. Using single-cell RNA sequencing, we found eight distinct microglial clusters during the CPZ diet, and PRMT1 depleted microglia hindered the formation of the MHC-associated cluster, expressing MHCII and CD11c. Mechanistically, PRMT1-KO microglia displayed reduced the H3K27ac peaks at the promoter regions of the MHC- and IFN-associated genes and further suppressed gene expression during CPZ diet. Overall, our findings demonstrate that PRMT1 is a critical regulator of the MHC- and IFN-associated microglia, necessary for central nervous system remyelination.
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Enfermedades Desmielinizantes , Remielinización , Animales , Sistema Nervioso Central/metabolismo , Cuprizona/metabolismo , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/metabolismo , Ratones , Ratones Endogámicos C57BL , Microglía/metabolismoRESUMEN
Exploration in the field of epigenetics has revealed that protein arginine methyltransferases (PRMTs) contribute to disease, and this has given way to the development of specific small molecule compounds that inhibit arginine methylation. Protein arginine methylation is known to regulate fundamental cellular processes, such as transcription; pre-mRNA splicing and other RNA processing mechanisms; signal transduction, including the anti-viral response; and cellular metabolism. PRMTs are also implicated in the regulation of physiological processes, including embryonic development, myogenesis, and the immune system. Finally, the dysregulation of PRMTs is apparent in cancer, neurodegeneration, muscular disorders, and during inflammation. Herein, we review the functions of PRMTs in immunity and inflammation. We also discuss recent progress with PRMTs regarding the modulation of gene expression related to T and B lymphocyte differentiation, germinal center dynamics, and anti-viral signaling responses, as well as the clinical relevance of using PRMT inhibitors alone or in combination with other drugs to treat cancer, immune, and inflammatory-related diseases.
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Despite the success of immune checkpoint inhibitor (ICI) therapy for cancer, resistance and relapse are frequent. Combination therapies are expected to enhance response rates and overcome this resistance. Herein, we report that combining PRMT7 inhibition with ICI therapy induces a strong anti-tumor T cell immunity and restrains tumor growth in vivo by increasing immune cell infiltration. PRMT7-deficient B16.F10 melanoma exhibits increased expression of genes in the interferon pathway, antigen presentation, and chemokine signaling. PRMT7 deficiency or inhibition with SGC3027 in B16.F10 melanoma results in reduced DNMT expression, loss of DNA methylation in the regulatory regions of endogenous retroviral elements (ERVs) causing their increased expression. PRMT7-deficient cells increase RIG-I and MDA5 expression with a reduction in the H4R3me2s repressive histone mark at their gene promoters. Our findings identify PRMT7 as a regulatory checkpoint for RIG-I, MDA5, and their ERV-double-stranded RNA (dsRNA) ligands, facilitating immune escape and anti-tumor T cell immunity to restrain tumor growth.
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Retrovirus Endógenos , Melanoma Experimental , Animales , Inhibidores de Puntos de Control Inmunológico/farmacología , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Interferones/genética , Melanoma Experimental/genética , Recurrencia Local de Neoplasia/genéticaRESUMEN
Arsenic toxicity is a global concern to human health causing increased incidences of cancer, bronchopulmonary, and cardiovascular diseases. In human and mouse, inorganic arsenic (iAs) is metabolized in a series of methylation steps catalyzed by arsenic (3) methyltransferase (AS3MT), forming methylated arsenite (MAsIII), dimethylarsenite (DMAIII) and the volatile trimethylarsine (TMA). The methylation of arsenic is coordinated by four conserved cysteines proposed to participate in catalysis, namely C33, C62, C157, and C207 in mouse AS3MT. The current model consists of AS3MT methylating iAs in the presence of the cofactor S-adenosyl-L-methionine (SAM), and the formation of intramolecular disulfide bonds following the reduction of MAsV to MAsIII. In the presence of endogenous reductants, these disulfide bonds are reduced, the enzyme re-generates, and the second round of methylation ensues. Using in vitro methylation assays, we find that AS3MT undergoes an initial automethylation step in the absence of iAs. This automethylation is enhanced by glutathione (GSH) and dithiothreitol (DTT), suggesting that reduced cysteines accept methyl groups from SAM to form S-methylcysteines. Following the addition of iAs, automethylation of AS3MT is decreased. Furthermore, using a Flag-AS3MT immunoprecipitation coupled to MS/MS, we identify both C33 and C62 as acceptors of the methyl group in vivo. Site-directed mutagenesis (C to A) revealed that three of the previously described cysteines were required for AS3MT automethylation. In vitro experiments show that automethylated AS3MT can methylate iAs in the presence of SAM. Thus, we propose that automethylated may represent an active conformation of AS3MT.
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Arsénico , Metiltransferasas , Animales , Arsénico/metabolismo , Arsénico/toxicidad , Cisteína , Disulfuros , Glutatión/metabolismo , Metiltransferasas/genética , Metiltransferasas/metabolismo , Ratones , Espectrometría de Masas en TándemRESUMEN
Muscle stem cells (MuSCs) have the ability to carry out the specialized function of cell polarization, which is required for the production of one repopulating cell and one myogenic progenitor cell with muscle regeneration capabilities. The mechanisms which regulate proteins involved in establishing MuSC polarity such as Dmd and Itga7 are currently not well understood. Herein, we define the RNA-binding protein Quaking (QKI) as a major regulator alternative splicing of key MuSC polarity factors including Dmd, Itga7, Mark2, and Numb. We generate a conditional QKI knockout mouse, and for the first time it is shown in vivo that deficiency of QKI in MuSCs results in reduced asymmetric cell divisions, leading to a loss of the myogenic progenitor cell population and striking muscle regeneration defects. Transcriptomic analysis of QKI-deficient MuSCs identifies QKI as a regulator of the splicing events which give rise to the mutually exclusive Itga7-X1 and -X2 isoforms. We observe increased X1 expression in QKI-deficient MuSCs and recapitulate this splicing event using antisense oligonucleotide directed against a quaking binding site within the Itga7 mRNA. Interestingly, recreating this single splicing event is detrimental to the polarization of Itga7 and Dmd proteins, and leads to a drastic reduction of the myogenic progenitor population, highlighting the significance of QKI-mediated alternative splicing of Itga7 in maintaining MuSC polarity. Altogether, these findings define a novel role for QKI as a post-transcriptional regulator of MuSC polarity.
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Antígenos CD/genética , Polaridad Celular/genética , Cadenas alfa de Integrinas/genética , Proteínas de Unión al ARN/metabolismo , Empalme Alternativo/genética , Animales , Antígenos CD/metabolismo , Polaridad Celular/fisiología , Femenino , Perfilación de la Expresión Génica/métodos , Cadenas alfa de Integrinas/metabolismo , Integrinas/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Músculo Esquelético/metabolismo , Músculos/metabolismo , Mioblastos/metabolismo , Isoformas de Proteínas/genética , Empalme del ARN/genética , ARN Mensajero/genética , Proteínas de Unión al ARN/genética , Células Madre/metabolismoRESUMEN
Hereditary papillary renal cell carcinoma (HPRC) is a rare inherited renal cancer syndrome characterized by bilateral and multifocal papillary type 1 renal tumors (PRCC1). Activating germline pathogenic variants of the MET gene were identified in HPRC families. We reviewed the medical and molecular records of a large French series of 158 patients screened for MET oncogenic variants. MET pathogenic and likely pathogenic variants rate was 12.4% with 40.6% among patients with familial PRCC1 and 5% among patients with sporadic PRCC1. The phenotype in cases with MET pathogenic and likely pathogenic variants was characteristic: PRCC1 tumors were mainly bilateral (84.3%) and multifocal (87.5%). Histologically, six out of seven patients with MET pathogenic variant harbored biphasic squamoid alveolar PRCC. Genetic screening identified one novel pathogenic variant MET c.3389T>C, p.(Leu1130Ser) and three novel likely pathogenic variants: MET c.3257A>T, p.(His1086Leu); MET c.3305T>C, p.(Ile1102Thr) and MET c.3373T>G, p.(Cys1125Gly). Functional assay confirmed their oncogenic effect as they induced an abnormal focus formation. The genotype-phenotype correlation between MET pathogenic variants and PRCC1 presentation should encourage to widen the screening, especially toward nonfamilial PRCC1. This precise phenotype also constitutes a strong argument for the classification of novel missense variants within the tyrosine kinase domain when functional assays are not accessible.