Genetics
Abstract
Glycine encephalopathy (GE), or nonketotic hyperglycinemia (NKH), is a rare recessive genetic disease caused by defective glycine cleavage and characterized by increased accumulation of glycine in all tissues. Here, based on new case reports of GLDC loss-of-function mutations in GE patients, we aimed to generate a zebrafish model of severe GE in order to unravel the molecular mechanism of the disease. Using CRISPR/Cas9, we knocked out the gldc gene and showed that gldc–/– fish recapitulate GE on a molecular level and present a motor phenotype reminiscent of severe GE symptoms. The molecular characterization of gldc–/– mutants showed a broad metabolic disturbance affecting amino acids and neurotransmitters other than glycine, with lactic acidosis at stages preceding death. Although a transient imbalance was found in cell proliferation in the brain of gldc–/– zebrafish, the main brain networks were not affected, thus suggesting that GE pathogenicity is mainly due to metabolic defects. We confirmed that the gldc–/– hypotonic phenotype is due to NMDA and glycine receptor overactivation, and demonstrated that gldc–/– larvae depict exacerbated hyperglycinemia at these synapses. Remarkably, we were able to rescue the motor dysfunction of gldc–/– larvae by counterbalancing pharmacologically or genetically the level of glycine at the synapse.
Authors
Raphaëlle Riché, Meijiang Liao, Izabella A. Pena, Kit-Yi Leung, Nathalie Lepage, Nicolas D.E. Greene, Kyriakie Sarafoglou, Lisa A. Schimmenti, Pierre Drapeau, Éric Samarut
Abstract
Defects in genes mediating thyroid hormone biosynthesis result in dyshormonogenic congenital hypothyroidism (CH). Here, we report homozygous truncating mutations in SLC26A7 in 6 unrelated families with goitrous CH and show that goitrous hypothyroidism also occurs in Slc26a7-null mice. In both species, the gene is expressed predominantly in the thyroid gland, and loss of function is associated with impaired availability of iodine for thyroid hormone synthesis, partially corrected in mice by iodine supplementation. SLC26A7 is a member of the same transporter family as SLC26A4 (pendrin), an anion exchanger with affinity for iodide and chloride (among others), whose gene mutations cause congenital deafness and dyshormonogenic goiter. However, in contrast to pendrin, SLC26A7 does not mediate cellular iodide efflux and hearing in affected individuals is normal. We delineate a hitherto unrecognized role for SLC26A7 in thyroid hormone biosynthesis, for which the mechanism remains unclear.
Authors
Hakan Cangul, Xiao-Hui Liao, Erik Schoenmakers, Jukka Kero, Sharon Barone, Panudda Srichomkwun, Hideyuki Iwayama, Eva G. Serra, Halil Saglam, Erdal Eren, Omer Tarim, Adeline K. Nicholas, Ilona Zvetkova, Carl A. Anderson, Fiona E. Karet Frankl, Kristien Boelaert, Marja Ojaniemi, Jarmo Jääskeläinen, Konrad Patyra, Christoffer Löf, E. Dillwyn Williams, UK10K Consortium, Manoocher Soleimani, Timothy Barrett, Eamonn R. Maher, V. Krishna Chatterjee, Samuel Refetoff, Nadia Schoenmakers
Abstract
BACKGROUND. Crohn’s disease (CD) is highly heterogeneous, due in large part to variability in cellular processes that underlie the natural history of CD, thereby confounding effective therapy. There is a critical need to advance understanding of the cellular mechanisms that drive CD heterogeneity. METHODS. We performed small RNA sequencing of adult colon tissue from CD and NIBD controls. Colonic epithelial cells and immune cells were isolated from colonic tissues, and microRNA-31 (miR-31) expression was measured. miR-31 expression was measured in colonoid cultures generated from controls and patients with CD. We performed small RNA-sequencing of formalin-fixed paraffin-embedded colon and ileum biopsies from treatment-naive pediatric patients with CD and controls and collected data on disease features and outcomes. RESULTS. Small RNA-sequencing and microRNA profiling in the colon revealed 2 distinct molecular subtypes, each with different clinical associations. Notably, we found that miR-31 expression was a driver of these 2 subtypes and, further, that miR-31 expression was particularly pronounced in epithelial cells. Colonoids revealed that miR-31 expression differences are preserved in this ex vivo system. In adult patients, low colonic miR-31 expression levels at the time of surgery were associated with worse disease outcome as measured by need for an end ileostomy and recurrence of disease in the neoterminal ileum. In pediatric patients, lower miR-31 expression at the time of diagnosis was associated with future development of fibrostenotic ileal CD requiring surgery CONCLUSIONS. These findings represent an important step forward in designing more effective clinical trials and developing personalized CD therapies. FUNDING. This work was supported by CCF Career Development Award (SZS), R01-ES024983 from NIEHS (SZS and TSF), 1R01DK104828-01A1 from NIDDK (SZS and TSF), P01-DK094779-01A1 from NIDDK (SZS), P30-DK034987 from NIDDK (SZS), 1-16-ACE-47 ADA Pathway Award (PS), UNC Nutrition Obesity Research Center Pilot & Feasibility Grant P30DK056350 (PS), CCF PRO-KIIDS NETWORK (SZS and PS), UNC CGIBD T32 Training Grant from NIDDK (JBB), T32 Training Grant (5T32GM007092-42) from NIGMS (MH), and SHARE from the Helmsley Trust (SZS). The UNC Translational Pathology Laboratory is supported, in part, by grants from the National Cancer Institute (3P30CA016086) and the UNC University Cancer Research Fund (UCRF) (PS).
Authors
Benjamin P. Keith, Jasmine B. Barrow, Takahiko Toyonaga, Nevzat Kazgan, Michelle Hoffner O’Connor, Neil D. Shah, Matthew S. Schaner, Elisabeth A. Wolber, Omar K. Trad, Greg R. Gipson, Wendy A. Pitman, Matthew Kanke, Shruti J. Saxena, Nicole Chaumont, Timothy S. Sadiq, Mark J. Koruda, Paul A. Cotney, Nancy Allbritton, Dimitri G. Trembath, Francisco Sylvester, Terrence S. Furey, Praveen Sethupathy, Shehzad Z. Sheikh
Abstract
Cystic fibrosis (CF) is a genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. The major cause of limited life span in CF patients is progressive lung disease. CF models have been generated in 4 species (mice, rats, ferrets, and pigs) to enhance our understanding of the CF pathogenesis. Sheep may be a particularly relevant animal to model CF in humans due to the similarities in lung anatomy and development in the two species. Here, we describe the generation of a sheep model for CF using CRISPR/Cas9 genome editing and somatic cell nuclear transfer (SCNT) techniques. We generated cells with CFTR gene disruption and used them for production of CFTR–/– and CFTR+/– lambs. The newborn CFTR–/– sheep developed severe disease consistent with CF pathology in humans. Of particular relevance were pancreatic fibrosis, intestinal obstruction, and absence of the vas deferens. Also, substantial liver and gallbladder disease may reflect CF liver disease that is evident in humans. The phenotype of CFTR–/– sheep suggests this large animal model will be a useful resource to advance the development of new CF therapeutics. Moreover, the generation of specific human CF disease–associated mutations in sheep may advance personalized medicine for this common genetic disorder.
Authors
Zhiqiang Fan, Iuri Viotti Perisse, Calvin U. Cotton, Misha Regouski, Qinggang Meng, Chaim Domb, Arnaud J. Van Wettere, Zhongde Wang, Ann Harris, Kenneth L. White, Irina A. Polejaeva
Abstract
While it has been recognized that human papillomavirus–associated (HPV-associated) oropharyngeal cancer (OPC) portends an improved prognosis, distinct patterns of disease recurrence have emerged. Molecular characterization of this subset of HPV patients remains unexplored. We evaluated 52 metastatic HPV+ OPC patients from our institution and paired massively parallel sequencing data with clinical parameters and survival outcomes in 81% of patients. Genomic data were then compared with 2 molecularly defined, curable HPV+ cohorts. Metastatic HPV+ OPC patients with pulmonary-only metastases demonstrated worse outcomes. Nonexclusive somatic alterations in KMT2D and PIK3CA were most frequent, with PRKDC alterations occurring at higher frequency when compared with all sequenced HPV+ OPC patients. PI3K pathway alterations were associated with improved outcomes among metastatic HPV+ OPC patients. We demonstrate subtle differences in the mutational landscape between curable and metastatic HPV+ OPC populations, with a trend towards more frequent DNA repair protein alterations in the latter. We demonstrate improved outcomes when PI3K pathway alterations are present in these patients. We provide molecular insights for this important HPV+ subgroup that have significant therapeutic implications.
Authors
Glenn J. Hanna, Alec Kacew, Nicole G. Chau, Priyanka Shivdasani, Jochen H. Lorch, Ravindra Uppaluri, Robert I. Haddad, Laura E. MacConaill
Abstract
BACKGROUND. The extent of weight loss among patients undergoing bariatric surgery is highly variable. Herein, we tested the contribution of genetic background to such interindividual variability after biliopancreatic diversion with duodenal switch. METHODS. Percentage of excess body weight loss (%EBWL) was monitored in 865 patients over a period of 48 months after bariatric surgery, and two polygenic risk scores were constructed with 186 and 11 (PRS186 and PRS11) single nucleotide polymorphisms previously associated with body mass index (BMI). RESULTS. The accuracy of the %EBWL logistic prediction model — including initial BMI, age, sex, and surgery modality, and assessed as the area under the receiver operating characteristics (ROC) curve adjusted for optimism (AUCadj = 0.867) — significantly increased after the inclusion of PRS186 (ΔAUCadj = 0.021; 95% CI of the difference [95% CIdiff] = 0.005–0.038) but not PRS11 (ΔAUCadj= 0.008; 95% CIdiff= –0.003–0.019). The overall fit of the longitudinal linear mixed model for %EBWL showed a significant increase after addition of PRS186 (–2 log-likelihood = 12.3; P = 0.002) and PRS11 (–2 log-likelihood = 9.9; P = 0.007). A significant interaction with postsurgery time was found for PRS186 (β = –0.003; P = 0.008) and PRS11 (β = –0.008; P = 0.03). The inclusion of PRS186 and PRS11 in the model improved the cost-effectiveness of bariatric surgery by reducing the percentage of false negatives from 20.4% to 10.9% and 10.2%, respectively. CONCLUSION. These results revealed that genetic background has a significant impact on weight loss after biliopancreatic diversion with duodenal switch. Likewise, the improvement in weight loss prediction after addition of polygenic risk scores is cost-effective, suggesting that genetic testing could potentially be used in the presurgical assessment of patients with severe obesity. FUNDING. Heart and Stroke Foundation of Canada (G-17-0016627) and Canada Research Chair in Genomics Applied to Nutrition and Metabolic Health (no. 950-231-580).
Authors
Juan de Toro-Martín, Frédéric Guénard, André Tchernof, Louis Pérusse, Simon Marceau, Marie-Claude Vohl
Abstract
Offspring of women with gestational diabetes mellitus (GDM) are at increased risk of developing metabolic disease, potentially mediated by epigenetic mechanisms. We recruited 608 GDM and 626 control offspring from the Danish National Birth Cohort, aged between 9 and 16 years. DNA methylation profiles were measured in peripheral blood of 93 GDM offspring and 95 controls using the Illumina HumanMethylation450 BeadChip. Pyrosequencing was performed for validation/replication of putative GDM-associated, differentially methylated CpGs in additional 905 offspring (462 GDM, 444 control offspring). We identified 76 differentially methylated CpGs in GDM offspring compared with controls in the discovery cohort (FDR, P < 0.05). Adjusting for offspring BMI did not affect the association between methylation levels and GDM status for any of the 76 CpGs. Most of these epigenetic changes were due to confounding by maternal prepregnancy BMI; however, 13 methylation changes were independently associated with maternal GDM. Three prepregnancy BMI–associated CpGs (cg00992687 and cg09452568 of ESM1 and cg14328641 of MS4A3) were validated in the replication cohort, while cg09109411 (PDE6A) was found to be associated with GDM status. The identified methylation changes may reflect developmental programming of organ disease mechanisms and/or may serve as disease biomarkers.
Authors
Line Hjort, David Martino, Louise Groth Grunnet, Haroon Naeem, Jovana Maksimovic, Anders Henrik Olsson, Cuilin Zhang, Charlotte Ling, Sjurdur Frodi Olsen, Richard Saffery, Allan Arthur Vaag
Abstract
Ion channel-controlled cell volume regulation is of fundamental significance to the physiological function of sperm. In addition to volume regulation, LRRC8A-dependent volume-regulated anion channel (VRAC) activity is involved in cell cycle progression, insulin signaling, and cisplatin resistance. Nevertheless, the contribution of LRRC8A and its dependent VRAC activity in the germ cell lineage remain unknown. By utilizing a spontaneous Lrrc8a mouse mutation (c.1325delTG, p.F443*) and genetically engineered mouse models, we demonstrate that LRRC8A-dependent VRAC activity is essential for male germ cell development and fertility. Lrrc8a-null male germ cells undergo progressive degeneration independent of the apoptotic pathway during postnatal testicular development. Lrrc8a-deficient mouse sperm exhibit multiple morphological abnormalities of the flagella (MMAF), a feature commonly observed in the sperm of infertile human patients. Importantly, we identified a human patient with a rare LRRC8A hypomorphic mutation (c.1634G>A, p.Arg545His) possibly linked to Sertoli cell–only syndrome (SCOS), a male sterility disorder characterized by the loss of germ cells. Thus, LRRC8A is a critical factor required for germ cell development and volume regulation in the mouse, and it might serve as a novel diagnostic and therapeutic target for SCOS patients.
Authors
Jianqiang Bao, Carlos J. Perez, Jeesun Kim, Huan Zhang, Caitlin J. Murphy, Tewfik Hamidi, Jean Jaubert, Craig D. Platt, Janet Chou, Meichun Deng, Meng-Hua Zhou, Yuying Huang, Héctor Gaitán-Peñas, Jean-Louis Guénet, Kevin Lin, Yue Lu, Taiping Chen, Mark T. Bedford, Sharon Y.R. Dent, John H. Richburg, Raúl Estévez, Hui-Lin Pan, Raif S. Geha, Qinghua Shi, Fernando Benavides
Abstract
BACKGROUND. There is currently no clinical distinction between different TP53 mutations, despite increasing evidence that not all mutations have equally deleterious effects on the activity of the encoded tumor suppressor protein p53. The objective of this study was to determine whether these biological differences have clinical significance. METHODS. This retrospective cohort analysis included 2,074 patients with sporadic TP53 mutations (403 unique mutations) and 1,049 germline TP53 mutation carriers (188 unique mutations). Survival was projected by stratifying patients according to their p53 mutant–specific residual transcriptional activity scores. RESULTS. Pan-cancer survival analyses revealed a strong association between increased mutant p53 residual activity and improved survival in males with glioma and gastric adenocarcinoma (P = 0.002 and P = 0.02) that was not present in the female cohorts (P = 0.16 and P = 0.50). Male glioma and gastric cancer patients with TP53 mutations resulting in >5% transcriptional activity had 3.1-fold (95% CI, 2.4–3.8; P = 0.002; multivariate analysis hazard ratio [HR]) and 4.6-fold (95% CI, 3.7–5.6; P = 0.001; multivariate analysis HR) lower risk of death as compared with patients harboring inactive (0% activity) p53 mutants. The correlation between mutant p53 residual activity with survival was recapitulated in the dataset of germline TP53 mutation carriers (HR = 3.0, 95% CI, 2.7–3.4, P < 0.001 [females]; HR = 2.2, 95% CI, 1.8–2.6, P < 0.001 [males]), where brain and gastric tumors were more common among males (P < 0.001 and P = 0.001, respectively). CONCLUSION. The retention of mutant p53 transcriptional activity prognosticates superior survival for men with glioma and gastric adenocarcinoma harboring sporadic TP53 mutations. Among germline TP53 mutation carriers, increased residual transcriptional activity is correlated with prolonged lifetime cancer survival and delayed tumor onset, and males are more prone to develop brain and gastric tumors. FUNDING. Canadian Institutes of Health Research (no. 148556).
Authors
Nicholas W. Fischer, Aaron Prodeus, Jean Gariépy
Abstract
Site-1 protease (S1P), encoded by MBTPS1, is a serine protease in the Golgi. S1P regulates lipogenesis, endoplasmic reticulum (ER) function, and lysosome biogenesis in mice and in cultured cells. However, how S1P differentially regulates these diverse functions in humans has been unclear. In addition, no human disease with S1P deficiency has been identified. Here, we report a pediatric patient with an amorphic and a severely hypomorphic mutation in MBTPS1. The unique combination of these mutations results in a frequency of functional MBTPS1 transcripts of approximately 1%, a finding that is associated with skeletal dysplasia and elevated blood lysosomal enzymes. We found that the residually expressed S1P is sufficient for lipid homeostasis but not for ER and lysosomal functions, especially in chondrocytes. The defective S1P function specifically impairs activation of the ER stress transducer BBF2H7, leading to ER retention of collagen in chondrocytes. S1P deficiency also causes abnormal secretion of lysosomal enzymes due to partial impairment of mannose-6-phosphate–dependent delivery to lysosomes. Collectively, these abnormalities lead to apoptosis of chondrocytes and lysosomal enzyme–mediated degradation of the bone matrix. Correction of an MBTPS1 variant or reduction of ER stress mitigated collagen-trafficking defects. These results define a new congenital human skeletal disorder and, more importantly, reveal that S1P is particularly required for skeletal development in humans. Our findings may also lead to new therapies for other genetic skeletal diseases, as ER dysfunction is common in these disorders.
Authors
Yuji Kondo, Jianxin Fu, Hua Wang, Christopher Hoover, J. Michael McDaniel, Richard Steet, Debabrata Patra, Jianhua Song, Laura Pollard, Sara Cathey, Tadayuki Yago, Graham Wiley, Susan Macwana, Joel Guthridge, Samuel McGee, Shibo Li, Courtney Griffin, Koichi Furukawa, Judith A. James, Changgeng Ruan, Rodger P. McEver, Klaas J. Wierenga, Patrick M. Gaffney, Lijun Xia
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