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Item Aberrant Function of the C-Terminal Tail of HIST1H1E Accelerates Cellular Senescence and Causes Premature Aging(Cell Press, 2019-09-05) Flex, Elisabetta; Martinelli, Simone; Van Dijck, Anke; Ciolfi, Andrea; Cecchetti, Serena; Coluzzi, Elisa; Pannone, Luca; Andreoli, Cristina; Radio, Francesca Clementina; Pizzi, Simone; Carpentieri, Giovanna; Bruselles, Alessandro; Catanzaro, Giuseppina; Pedace, Lucia; Miele, Evelina; Carcarino, Elena; Ge, Xiaoyan; Chijiwa, Chieko; Lewis, M.E. Suzanne; Meuwissen, Marije; Kenis, Sandra; Van der Aa, Nathalie; Larson, Austin; Brown, Kathleen; Wasserstein, Melissa P.; Skotko, Brian G.; Begtrup, Amber; Person, Richard; Karayiorgou, Maria; Roos, J. Louw; Van Gassen, Koen L.; Koopmans, Marije; Bijlsma, Emilia K.; Santen, Gijs W.E.; Barge-Schaapveld, Daniela Q.C.M.; Ruivenkamp, Claudia A.L.; Hoffer, Mariette J.V.; Lalani, Seema R.; Streff, Haley; Craigen, William J.; Graham, Brett H.; van den Elzen, Annette P.M.; Kamphuis, Daan J.; Ounap, Katrin; Reinson, Karit; Pajusalu, Sander; Wojcik, Monica H.; Viberti, Clara; Di Gaetano, Cornelia; Bertini, Enrico; Petrucci, Simona; De Luca, Alessandro; Rota, Rossella; Ferretti, Elisabetta; Matullo, Giuseppe; Dallapiccola, Bruno; Sgura, Antonella; Walkiewicz, Magdalena; Kooy, R. Frank; Tartaglia, Marco; Medical and Molecular Genetics, School of MedicineHistones mediate dynamic packaging of nuclear DNA in chromatin, a process that is precisely controlled to guarantee efficient compaction of the genome and proper chromosomal segregation during cell division and to accomplish DNA replication, transcription, and repair. Due to the important structural and regulatory roles played by histones, it is not surprising that histone functional dysregulation or aberrant levels of histones can have severe consequences for multiple cellular processes and ultimately might affect development or contribute to cell transformation. Recently, germline frameshift mutations involving the C-terminal tail of HIST1H1E, which is a widely expressed member of the linker histone family and facilitates higher-order chromatin folding, have been causally linked to an as-yet poorly defined syndrome that includes intellectual disability. We report that these mutations result in stable proteins that reside in the nucleus, bind to chromatin, disrupt proper compaction of DNA, and are associated with a specific methylation pattern. Cells expressing these mutant proteins have a dramatically reduced proliferation rate and competence, hardly enter into the S phase, and undergo accelerated senescence. Remarkably, clinical assessment of a relatively large cohort of subjects sharing these mutations revealed a premature aging phenotype as a previously unrecognized feature of the disorder. Our findings identify a direct link between aberrant chromatin remodeling, cellular senescence, and accelerated aging.Item Germline variants in tumor suppressor FBXW7 lead to impaired ubiquitination and a neurodevelopmental syndrome(Elsevier, 2022) Stephenson, Sarah E.M.; Costain, Gregory; Blok, Laura E.R.; Silk, Michael A.; Nguyen, Thanh Binh; Dong, Xiaomin; Alhuzaimi, Dana E.; Dowling, James J.; Walker, Susan; Amburgey, Kimberly; Hayeems, Robin Z.; Rodan, Lance H.; Schwartz, Marc A.; Picker, Jonathan; Lynch, Sally A.; Gupta, Aditi; Rasmussen, Kristen J.; Schimmenti, Lisa A.; Klee, Eric W.; Niu, Zhiyv; Agre, Katherine E.; Chilton, Ilana; Chung, Wendy K.; Revah-Politi, Anya; Au, P.Y. Billie; Griffith, Christopher; Racobaldo, Melissa; Raas-Rothschild, Annick; Zeev, Bruria Ben; Barel, Ortal; Moutton, Sebastien; Morice-Picard, Fanny; Carmignac, Virginie; Cornaton, Jenny; Marle, Nathalie; Devinsky, Orrin; Stimach, Chandler; Burns Wechsler, Stephanie; Hainline, Bryan E.; Sapp, Katie; Willems, Marjolaine; Bruel, Ange-Line; Dias, Kerith-Rae; Evans, Carey-Anne; Roscioli, Tony; Sachdev, Rani; Temple, Suzanna E.L.; Zhu, Ying; Baker, Joshua J.; Scheffer, Ingrid E.; Gardiner, Fiona J.; Schneider, Amy L.; Muir, Alison M.; Mefford, Heather C.; Crunk, Amy; Heise, Elizabeth M.; Millan, Francisca; Monaghan, Kristin G.; Person, Richard; Rhodes, Lindsay; Richards, Sarah; Wentzensen, Ingrid M.; Cogné, Benjamin; Isidor, Bertrand; Nizon, Mathilde; Vincent, Marie; Besnard, Thomas; Piton, Amelie; Marcelis, Carlo; Kato, Kohji; Koyama, Norihisa; Ogi, Tomoo; Suk-Ying Goh, Elaine; Richmond, Christopher; Amor, David J.; Boyce, Jessica O.; Morgan, Angela T.; Hildebrand, Michael S.; Kaspi, Antony; Bahlo, Melanie; Friðriksdóttir, Rún; Katrínardóttir, Hildigunnur; Sulem, Patrick; Stefánsson, Kári; Björnsson, Hans Tómas; Mandelstam, Simone; Morleo, Manuela; Mariani, Milena; TUDP Study Group; Scala, Marcello; Accogli, Andrea; Torella, Annalaura; Capra, Valeria; Wallis, Mathew; Jansen, Sandra; Weisfisz, Quinten; de Haan, Hugoline; Sadedin, Simon; Broad Center for Mendelian Genomics; Lim, Sze Chern; White, Susan M.; Ascher, David B.; Schenck, Annette; Lockhart, Paul J.; Christodoulou, John; Tan, Tiong Yang; Medical and Molecular Genetics, School of MedicineNeurodevelopmental disorders are highly heterogenous conditions resulting from abnormalities of brain architecture and/or function. FBXW7 (F-box and WD-repeat-domain-containing 7), a recognized developmental regulator and tumor suppressor, has been shown to regulate cell-cycle progression and cell growth and survival by targeting substrates including CYCLIN E1/2 and NOTCH for degradation via the ubiquitin proteasome system. We used a genotype-first approach and global data-sharing platforms to identify 35 individuals harboring de novo and inherited FBXW7 germline monoallelic chromosomal deletions and nonsense, frameshift, splice-site, and missense variants associated with a neurodevelopmental syndrome. The FBXW7 neurodevelopmental syndrome is distinguished by global developmental delay, borderline to severe intellectual disability, hypotonia, and gastrointestinal issues. Brain imaging detailed variable underlying structural abnormalities affecting the cerebellum, corpus collosum, and white matter. A crystal-structure model of FBXW7 predicted that missense variants were clustered at the substrate-binding surface of the WD40 domain and that these might reduce FBXW7 substrate binding affinity. Expression of recombinant FBXW7 missense variants in cultured cells demonstrated impaired CYCLIN E1 and CYCLIN E2 turnover. Pan-neuronal knockdown of the Drosophila ortholog, archipelago, impaired learning and neuronal function. Collectively, the data presented herein provide compelling evidence of an F-Box protein-related, phenotypically variable neurodevelopmental disorder associated with monoallelic variants in FBXW7.Item Recessive Rare Variants in Deoxyhypusine Synthase, an Enzyme Involved in the Synthesis of Hypusine, Are Associated with a Neurodevelopmental Disorder(Elsevier, 2019-02-07) Ganapathi, Mythily; Padgett, Leah R.; Yamada, Kentaro; Devinsky, Orrin; Willaert, Rebecca; Person, Richard; Au, Ping-Yee Billie; Tagoe, Julia; McDonald, Marie; Karlowicz, Danielle; Wolf, Barry; Lee, Joanna; Shen, Yufeng; Okur, Volkan; Deng, Liyong; LeDuc, Charles A.; Wang, Jiayao; Hanner, Ashleigh; Mirmira, Raghavendra G.; Park, Myung Hee; Mastracci, Teresa L.; Chung, Wendy K.; Pediatrics, School of MedicineHypusine is formed post-translationally from lysine and is found in a single cellular protein, eukaryotic translation initiation factor-5A (eIF5A), and its homolog eIF5A2. Biosynthesis of hypusine is a two-step reaction involving the enzymes deoxyhypusine synthase (DHPS) and deoxyhypusine hydroxylase (DOHH). eIF5A is highly conserved throughout eukaryotic evolution and plays a role in mRNA translation, cellular proliferation, cellular differentiation, and inflammation. DHPS is also highly conserved and is essential for life, as Dhps-null mice are embryonic lethal. Using exome sequencing, we identified rare biallelic, recurrent, predicted likely pathogenic variants in DHPS segregating with disease in five affected individuals from four unrelated families. These individuals have similar neurodevelopmental features that include global developmental delay and seizures. Two of four affected females have short stature. All five affected individuals share a recurrent missense variant (c.518A>G [p.Asn173Ser]) in trans with a likely gene disrupting variant (c.1014+1G>A, c.912_917delTTACAT [p.Tyr305_Ile306del], or c.1A>G [p.Met1?]). cDNA studies demonstrated that the c.1014+1G>A variant causes aberrant splicing. Recombinant DHPS enzyme harboring either the p.Asn173Ser or p.Tyr305_Ile306del variant showed reduced (20%) or absent in vitro activity, respectively. We co-transfected constructs overexpressing HA-tagged DHPS (wild-type or mutant) and GFP-tagged eIF5A into HEK293T cells to determine the effect of these variants on hypusine biosynthesis and observed that the p.Tyr305_Ile306del and p.Asn173Ser variants resulted in reduced hypusination of eIF5A compared to wild-type DHPS enzyme. Our data suggest that rare biallelic variants in DHPS result in reduced enzyme activity that limits the hypusination of eIF5A and are associated with a neurodevelopmental disorder.Item WDR26 Haploinsufficiency Causes a Recognizable Syndrome of Intellectual Disability, Seizures, Abnormal Gait, and Distinctive Facial Features(Elsevier, 2017-07-06) Skraban, Cara M.; Wells, Constance F.; Markose, Preetha; Cho, Megan T.; Nesbitt, Addie I.; Au, P.Y. Billie; Begtrup, Amber; Bernat, John A.; Bird, Lynne M.; Cao, Kajia; de Brouwer, Arjan P.M.; Denenberg, Elizabeth H.; Douglas, Ganka; Gibson, Kristin M.; Grand, Katheryn; Goldenberg, Alice; Innes, A. Micheil; Juusola, Jane; Kempers, Marlies; Kinning, Esther; Markie, David M.; Owens, Martina M.; Payne, Katelyn; Person, Richard; Pfundt, Rolph; Stocco, Amber; Turner, Claire L.S.; Verbeek, Nienke E.; Walsh, Laurence E.; Warner, Taylor C.; Wheeler, Patricia G.; Wieczorek, Dagmar; Wilkens, Alisha B.; Zonneveld-Huijssoon, Evelien; Deciphering Developmental Disorders Study; Kleefstra, Tjitske; Robertson, Stephen P.; Santani, Avni; van Gassen, Koen L.I.; Deardorf, Matthew A.; Pediatrics, School of MedicineWe report 15 individuals with de novo pathogenic variants in WDR26. Eleven of the individuals carry loss-of-function mutations, and four harbor missense substitutions. These 15 individuals comprise ten females and five males, and all have intellectual disability with delayed speech, a history of febrile and/or non-febrile seizures, and a wide-based, spastic, and/or stiff-legged gait. These subjects share a set of common facial features that include a prominent maxilla and upper lip that readily reveal the upper gingiva, widely spaced teeth, and a broad nasal tip. Together, these features comprise a recognizable facial phenotype. We compared these features with those of chromosome 1q41q42 microdeletion syndrome, which typically contains WDR26, and noted that clinical features are consistent between the two subsets, suggesting that haploinsufficiency of WDR26 contributes to the pathology of 1q41q42 microdeletion syndrome. Consistent with this, WDR26 loss-of-function single-nucleotide mutations identified in these subjects lead to nonsense-mediated decay with subsequent reduction of RNA expression and protein levels. We derived a structural model of WDR26 and note that missense variants identified in these individuals localize to highly conserved residues of this WD-40-repeat-containing protein. Given that WDR26 mutations have been identified in ∼1 in 2,000 of subjects in our clinical cohorts and that WDR26 might be poorly annotated in exome variant-interpretation pipelines, we would anticipate that this disorder could be more common than currently appreciated.