Genetics
Abstract
Shwachman-Diamond syndrome (SDS) is characterized by neutropenia, exocrine pancreatic insufficiency, and bony abnormalities with an increased risk of myeloid neoplasia. Almost all cases of SDS result from biallelic mutations in SBDS. SBDS interacts with EFL1 to displace EIF6 from the 60S ribosomal subunit. Released EIF6 permits the assembly of ribosomal large and small subunits in the cytoplasm. Decreased EIF6 levels due to haploinsufficiency or missense mutations which lead to decreased protein expression may provide a somatic genetic rescue and anti-leukemic effects. We observed accumulation of EIF6 protein in sbds knockout (KO) zebrafish models, confirmed in patient-derived tissues, and correlated with changes in ribosome proteins and TP53 pathways. The mechanism of action for this adaptive response is unknown. To address this, we generated an eif6 zebrafish KO line which do not survive past 10 days post fertilization. We also created two mutants with low Eif6 expression, 5-25% of the wildtype levels, that can survive until adulthood. We bred them with sbds-null strains and analyzed their phenotype and biochemical properties. Low Eif6 levels reduced Tp53 pathway activation but did not rescue neutropenia in Sbds-deficient zebrafish. Further studies elucidating the interplay between SBDS, EIF6, TP53, and cellular stress responses offer promising insights into SDS pathogenesis, somatic genetic rescue, and therapeutic strategies.
Authors
Usua Oyarbide, Valentino Bezzerri, Morgan Staton, Christian Boni, Arish Shah, Marco Cipolli, Eliezer Calo, Seth J. Corey
Abstract
Myotonic Dystrophy Type 1 (DM1) is an autosomal dominant disease caused by a CTG repeat expansion in the DMPK gene. The expanded CUG repeat RNA (CUGexp RNA) transcribed from the mutant allele sequesters the muscleblind-like (MBNL) family of RNA-binding proteins, causing their loss of function and disrupting regulated pre-mRNA processing. We used a DM1 heart mouse model that inducibly expresses CUGexp RNA to test the contribution of MBNL loss to DM1 cardiac abnormalities and explore MBNL restoration as a potential therapy. AAV9-mediated overexpression of MBNL1 and/or MBNL2 significantly rescued DM1 cardiac phenotypes including conduction delays, contractile dysfunction, hypertrophy, and mis-regulated alternative splicing and gene expression. While robust, rescue was partial compared to reduced CUGexp RNA and plateaued with increased exogenous MBNL expression. These findings demonstrate that MBNL loss is a major contributor to DM1 cardiac manifestations, and suggest that additional mechanisms play a role, highlighting the complex nature of DM1 pathogenesis.
Authors
Rong-Chi Hu, Yi Zhang, Larissa Nitschke, Sara J. Johnson, Ayrea E. Hurley, William R. Lagor, Zheng Xia, Thomas A. Cooper
Abstract
Although nucleoporin 98 (NUP98) fusion oncogenes often drive aggressive pediatric leukemia by altering chromatin structure and expression of HOX genes, underlying mechanisms remain elusive. Here, we report that a Hoxb-associated lncRNA HoxBlinc was aberrantly activated in NUP98-PHF23 fusion-driven leukemias. HoxBlinc chromatin occupancies led to elevated MLL1 recruitment and aberrant homeotic topologically associated domains (TADs) that enhanced chromatin accessibilities and activated homeotic/hematopoietic oncogenes. HoxBlinc-depletion in NUP98 fusion-driven leukemia impaired HoxBlinc binding, TAD integrity, MLL1 recruitment, and MLL1-driven chromatin signature within HoxBlinc-defined TADs in a CTCF-independent manner, leading to inhibited homeotic/leukemic oncogenes that mitigated NUP98 fusion-driven leukemogenesis in xenografted mouse models. Mechanistically, HoxBlinc overexpression in mouse hematopoietic compartment induced leukemias resembling those in NUP98-PHF23 knock-in mice via enhancing HoxBlinc chromatin binding, TAD formation, and Hox gene aberration leading to expansion of hematopoietic stem and progenitor cell (HSPC) and myeloid/lymphoid subpopulations. Thus, our studies reveal a CTCF-independent role of HoxBlinc in leukemic TAD organization and oncogene regulatory networks.
Authors
Karina Hamamoto, Ganqian Zhu, Qian Lai, Julia Lesperance, Huacheng Luo, Ying Li, Nupur Nigam, Arati Sharma, Feng-Chun Yang, David Claxton, Yi Qiu, Peter D. Aplan, Mingjiang Xu, Suming Huang
Abstract
Oncostatin M (OSM) is a cytokine with the unique ability to interact with both the OSM receptor (OSMR) and the leukemia inhibitory factor receptor (LIFR). On the other hand, OSMR interacts with IL31RA to form the interleukin-31 receptor. This intricate network of cytokines and receptors makes it difficult to understand the specific function of OSM. While monoallelic loss-of-function (LoF) mutations in OSMR underlie autosomal dominant familial primary localized cutaneous amyloidosis, the in vivo consequences of human OSM deficiency have never been reported so far. Here, we identified three young individuals from a consanguineous family presenting with inherited severe bone marrow failure syndromes (IBMFS) characterized by profound anemia, thrombocytopenia, and neutropenia. Genetic analysis revealed a homozygous one base-pair insertion in the sequence of OSM associated with the disease. Structural and functional analyses showed that this variant causes a frameshift that replaces the C-terminal portion of OSM, which contains the FxxK motif that interacts with both OSMR and LIFR, with a neopeptide. The lack of detection and signaling of the mutant OSM suggests a LoF mutation. Analysis of zebrafish models further supported the role of the OSM/OSMR signaling in erythroid progenitor proliferation and neutrophil differentiation. Our study provides the previously uncharacterized and unexpectedly limited in vivo consequence of OSM deficiency in humans.
Authors
Alexandrine Garrigue, Laëtitia Kermasson, Sandrine Susini, Ingrid Fert, Christopher B. Mahony, Hanem Sadek, Sonia Luce, Myriam Chouteau, Marina Cavazzana, Emmanuelle Six, Marie-Caroline Le Bousse-Kerdilès, Adrienne Anginot, Jean-Baptiste Souraud, Valérie Cormier-Daire, Marjolaine Willems, Anne Sirvent, Jennifer Russello, Isabelle Callebaut, Isabelle André, Julien Y. Bertrand, Chantal Lagresle-Peyrou, Patrick Revy
Abstract
Achondroplasia, the most prevalent short-stature disorder, is caused by missense variants overactivating the fibroblast growth factor receptor 3 (FGFR3). As current surgical and pharmaceutical treatments only partially improve some disease features, we sought to explore a genetic approach. We show that an enhancer located 29 kb upstream of mouse Fgfr3 (–29E) is sufficient to confer a transgenic mouse reporter with a domain of expression in cartilage matching that of Fgfr3. Its CRISPR/Cas9-mediated deletion in otherwise WT mice reduced Fgfr3 expression in this domain by half without causing adverse phenotypes. Importantly, its deletion in mice harboring the ortholog of the most common human achondroplasia variant largely normalized long bone and vertebral body growth, markedly reduced spinal canal and foramen magnum stenosis, and improved craniofacial defects. Consequently, mouse achondroplasia is no longer lethal, and adults are overall healthy. These findings, together with high conservation of –29E in humans, open a path to develop genetic therapies for people with achondroplasia.
Authors
Marco Angelozzi, Arnaud Molin, Anirudha Karvande, Ángela Fernández-Iglesias, Samantha Whipple, Andrew M. Bloh, Véronique Lefebvre
Abstract
Nasopharyngeal carcinoma (NPC) presents a substantial clinical challenge due to the limited understanding of its genetic underpinnings. Here we conduct the largest scale whole-exome sequencing association study of NPC to date, encompassing 6,969 NPC cases and 7,100 controls. We unveil 3 germline genetic variants linked to NPC susceptibility: a common rs2276868 in RPL14, a rare rs5361 in SELE, and a common rs1050462 in HLA-B. We also underscore the critical impact of rare genetic variants on NPC heritability and introduce a refined composite polygenic risk score (rcPRS), which outperforms existing models in predicting NPC risk. Importantly, we reveal that the polygenic risk for NPC is mediated by EBV infection status. Utilizing a comprehensive multiomics approach that integrates both bulk-transcriptomic (n = 356) and single-cell RNA sequencing (n = 56) data with experimental validations, we demonstrate that the RPL14 variant modulates the EBV life cycle and NPC pathogenesis. Furthermore, our data indicate that the SELE variant contributes to modifying endothelial cell function, thereby facilitating NPC progression. Collectively, our study provides crucial insights into the intricate genetic architecture of NPC, spotlighting the vital interplay between genetic variations and tumor microenvironment components, including EBV and endothelial cells, in predisposing to NPC. This study opens new avenues for advancements in personalized risk assessments, early diagnosis, and targeted therapies for NPC.
Authors
Yanni Zeng, Chun-Ling Luo, Guo-Wang Lin, Fugui Li, Xiaomeng Bai, Josephine Mun-Yee Ko, Lei Xiong, Yang Liu, Shuai He, Jia-Xin Jiang, Wen-Xin Yan, Enya Hui Wen Ong, Zheng Li, Ya-Qing Zhou, Yun-He Zhou, An-Yi Xu, Shu-Qiang Liu, Yun-Miao Guo, Jie-Rong Chen, Xi-Xi Cheng, Yu-Lu Cao, Xia Yu, Biaohua Wu, Pan-Pan Wei, Zhao-Hui Ruan, Qiu-Yan Chen, Lin-Quan Tang, James D. McKay, Wei-Hua Jia, Hai-Qiang Mai, Soon Thye Lim, Jian-Jun Liu, Dong-Xin Lin, Chiea Chuen Khor, Melvin Lee Kiang Chua, Mingfang Ji, Maria Li Lung, Yi-Xin Zeng, Jin-Xin Bei
Abstract
Heterozygous truncating variants in the sarcomere protein titin (TTN) are the most common genetic cause of heart failure. To understand mechanisms that regulate abundant cardiomyocyte TTN expression we characterized highly conserved intron 1 sequences that exhibited dynamic changes in chromatin accessibility during differentiation of human cardiomyocytes from induced pluripotent stem cells (hiPSC-CMs). Homozygous deletion of these sequences in mice caused embryonic lethality while heterozygous mice demonstrated allele-specific reduction in Ttn expression. A 296 bp fragment of this element, denoted E1, was sufficient to drive expression of a reporter gene in hiPSC-CMs. Deletion of E1 downregulated TTN expression, impaired sarcomerogenesis, and decreased contractility in hiPSC-CMs. Site-directed mutagenesis of predicted NKX2-5- and MEF2-binding sites within E1 abolished its transcriptional activity. Embryonic mice expressing E1 reporter gene constructs validated in vivo cardiac-specific activity of E1 and the requirement for NKX2-5 and MEF2 binding sequences. Moreover, isogenic hiPSC-CMs containing a rare E1 variant in the predicted MEF2 binding motif that was identified in a patient with unexplained DCM showed reduced TTN expression. Together these discoveries define an essential, functional enhancer that regulates TTN expression. Manipulation of this element may advance therapeutic strategies to treat DCM caused by TTN haploinsufficiency.
Authors
Yuri Kim, Seong Won Kim, David Saul, Meraj Neyazi, Manuel Schmid, Hiroko Wakimoto, Neil Slaven, Joshua H. Lee, Olivia G. Layton, Lauren K. Wasson, Justin H. Letendre, Feng Xiao, Jourdan K. Ewoldt, Konstantinos Gkatzis, Peter Sommer, Bénédicte Gobert, Nicolas Wiest-Daesslé, Quentin McAfee, Nandita Singhal, Mingyue Lun, Joshua M. Gorham, Zoltan Arany, Arun Sharma, Christopher N. Toepfer, Gavin Y. Oudit, William T. Pu, Diane E. Dickel, Len A. Pennacchio, Axel Visel, Christopher S. Chen, J.G. Seidman, Christine E. Seidman
Abstract
Authors
Mark Elliott, Krzysztof Kiryluk, Ali Gharavi
Abstract
Authors
Kristine Bousset, Stefano Donega, Najim Ameziane, Tabea Fleischhammer, Dhanya Ramachandran, Miriam Poley-Gil, Detlev Schindler, Ingrid M. van de Laar, Franco Pagani, Thilo Dörk
Abstract
Authors
Hong Wang, Maria Miranda, Eizo Marutani, Paul Lichtenegger, Gregory R. Wojtkiewicz, Fumito Ichinose, Vamsi K. Mootha
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)