Browsing by Author "Walker, Susan"

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    The circulating microbiome signature and inferred functional metagenomics in alcoholic hepatitis
    (Wiley, 2017) Puri, Puneet; Liangpunsakul, Suthat; Christensen, Jeffrey E.; Shah, Vijay H.; Kamath, Patrick S.; Gores, Gregory J.; Walker, Susan; Comerford, Megan; Katz, Barry; Borst, Andrew; Yu, Qigui; Kumar, Divya P.; Mirshahi, Faridoddin; Radaeva, Svetlana; Chalasani, Naga P.; Crabb, David W.; Sanyal, Arun J.; Medicine, School of Medicine
    Intestinal dysbiosis is implicated in alcoholic hepatitis (AH). However, changes in the circulating microbiome, its association with the presence and severity of AH and its functional relevance in AH is unknown. Qualitative and quantitative assessment of changes in the circulating microbiome were performed by sequencing bacterial DNA in subjects with moderate (n=18) or severe AH (n=19). These data were compared to heavy drinking controls (HDC) without obvious liver disease (n=19) and non-alcohol consuming controls (NAC, n=20). The data were related to endotoxin levels and markers of monocyte activation. Linear Discriminant Analysis (LDA) Effect Size (LEfSe) analysis, inferred metagenomics and predictive functional analysis using PICRUSt were performed. There was a significant increase in 16S copies/ng DNA both in MAH (p<0.01) and SAH (p<0.001) subjects. Compared to NAC, the relative abundance of phylum Bacteroidetes was significantly decreased in HDC, MAH, and SAH (p<0.001). In contrast, all alcohol consuming groups had enrichment with Fusobacteria; this was greatest for HDC and decreased progressively in MAH and SAH. Subjects with SAH had significantly higher endotoxemia (p=0.01). Compared to alcohol consuming groups, predictive functional metagenomics indicated an enrichment of bacteria with genes related to methanogenesis and denitrification. Also, both HDC and SAH showed activation of type III secretion system which has been linked to gram negative bacterial virulence. Metagenomics in SAH vs NAC predicted increased isoprenoid synthesis via mevalonate and anthranilate degradation, known modulators of gram positive bacterial growth and biofilm production respectively. In conclusion, heavy alcohol consumption appears to be the primary driver of changes in the circulating microbiome associated with a shift in its inferred metabolic functions.
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    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 Medicine
    Neurodevelopmental 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.