Genetics
Abstract
Glycogen storage disease type Ia (GSD Ia) is caused by a deficiency of glucose-6-phosphatase (G6Pase) in the liver leading to lethal hypoglycemia. Gene therapy with adeno-associated virus (AAV) vectors encoding G6Pase fails to stably treat GSD Ia early in life. We evaluated genome editing in 12 day-old infant mice with GSD Ia using two AAV vectors, one containing Cas9 from Streptococcus pyogenes and a second Donor vector that expresses a guide RNA and a G6PC transgene. Gene therapy with the Donor vector only was compared with genome editing using both Donor and CRISPR vectors. Treatment with genome editing (total vector dose 0.2 to 2E+13 vector genomes/kg) and bezafibrate (to stimulate autophagy) was efficacious as assessed by hypoglycemia prevention and the frequency of transgene integration, which correlated with improved survival. This therapy achieved 5.9% chromosomal transgene integration through homology directed repair, which surpassed a threshold to prevent long-term hepatic complications. No integration was detected in absence of the CRISPR vector. Importantly for safety, CRISPR vector genomes were depleted, and no intact, integrated CRISPR genomes were detected by long-read sequencing. Thus, genome editing warrants further development as a potentially stable treatment for human infants with GSD Ia.
Authors
Benjamin Arnson, Ekaterina Ilich, Troy von Beck, Songtao Li, Elizabeth D. Brooks, Dorothy Gheorghiu, Gordon He, Matthew Weinrub, Sze Ying Chan, Hye-Ri Kang, David Courtney, Jeffrey Everitt, Bryan R. Cullen, Dwight D. Koeberl
Abstract
Glycans are one of the 4 major macromolecules essential for life and are the most abundant family of organic molecules. However, in contrast with DNA and RNA, glycan structures have no template; this results in limited tools to study this challenging macromolecule with a diversity of glycan structures. A central bottleneck in studying glycosylation in vivo is that inhibitors and complete KOs are lethal. In a forward genetic screen, we identified a viable, hypomorphic mutation at a conserved site in mannose phosphate isomerase (Mpi) that causes a multisystemic phenotype affecting RBCs, liver, stomach, intestines, skin, size, fat, and fluid balance in mice. The phenotype could be rescued with mannose. Analyses of glycopeptides in mice with this mutation showed a 500% increase in unoccupied N-glycan sites. This is equivalent to a “glycan knockdown,” which would be useful for examining the role of glycans in biology and disease. Therefore, we report an in vivo tool to study global N-glycosylation deficiency with tissue-specific targeting and a rescue mechanism with mannose.
Authors
Elisa B. Lin, Steve Meregini, Zhao Zhang, Avishek Roy, Tandav Argula, James M. Mitchell, William J. Israelsen, Sara Ludwig, Jamie Russell, Jiexia Quan, Sara Hildebrand, Evan Nair-Gill, Bruce Beutler, Jeffrey A. SoRelle
Abstract
Uracil DNA glycosylase (UNG) excises uracil and 5-fluorouracil bases from DNA and is implicated in fluorodeoxyuridine (FdU) resistance. Here we explore the effects of inhibiting UNG activity, or depleting the UNG protein, in two mouse syngeneic models for colorectal cancer. Overexpressing the uracil DNA glycosylase inhibitor protein in mismatch repair (MMR)-deficient MC38 cells injected into C57/B6 mice delayed tumor growth and prolonged survival when combined with FdU. Combining UNG inhibition with FdU numerically increased CD4+ T lymphocytes and B cells compared to FdU or UNG inhibition alone, suggesting an immune component to the effects. In contrast, shRNA depletion of UNG in the absence of FdU treatment resulted in 70% of mice clearing their tumors, and a 3-fold increase in overall survival compared to FdU. Analysis of MC38 tumor-infiltrating immune cells showed UNG depletion increased monocyte and dendritic cell populations, with CD8+ T cells also numerically increased. shRNA depletion of UNG in MMR-proficient CT-26 cells injected into Balb/C mice produced minimal benefit; the addition of anti-PD-1 antibody synergized with UNG-depletion to increase survival. Cytotoxic T cell depletion abolished the benefits of UNG depletion in both models. These findings suggest UNG inhibition and/or depletion could enhance antitumor immune response in humans.
Authors
Eric S. Christenson, Brandon E. Smith, Thanh J. Nguyen, Alens Valentin, Soren Charmsaz, Nicole E Gross, Sarah M. Shin, Alexei Hernandez, Won Jin Ho, Srinivasan Yegnasubramanian, James T. Stivers
Abstract
Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disorder involving cycles of muscle degeneration and regeneration, leading to accumulation of intramuscular fibrosis and fat. Ablation of Osteopontin/Spp1 in a murine model of DMD (mdx) improves the dystrophic phenotype, but the source of Spp1 and its impact on target cells in dystrophic muscles remain unknown. In dystrophic muscles, macrophages are the predominate infiltrating leukocyte and express high levels of Spp1. We used macrophage-specific ablation combined with single-cell transcriptional profiling to uncover the impact of macrophage-derived Spp1 on cell-cell interactions in mdx muscles. Ablation of macrophage-specific Spp1 (cKO) correlated with reduction of 2 PDGFRa+ stromal cell populations, expressing Lifr+ and Procr+. Sorting and transcriptional profiling of these populations confirmed that they are enriched in adipogenesis genes and are highly related to fibroadipogenic precursors (FAPS). These adipogenic stromal cells (ASC) displayed more adipogenic potential in vitro compared with FAPS, likely due to a more differentiated state. Reduction of ASCs correlated with reduced intramuscular diaphragmatic fat and improved diaphragm function. These data suggest a role for myeloid-derived Spp1 in the differentiation of stromal cells towards an adipogenic fate, leading to accumulation of intramuscular fat in dystrophic muscles.
Authors
Philip K. Farahat, Chino Kumagai-Cresse, Raquel L. Aragón, Feiyang Ma, Justin K. Amakor, Alejandro Espinoza, Irina Kramerova, Robert J. Jimenez, Bradley M. Smith, Jesus Perez, Rachelle H. Crosbie, Apoorva H. Nagendra, Jackie McCourt-Towner, Gerald Coulis, Oluwatayo F. Ikotun, April D. Pyle, Matteo Pellegrini, Elizabeth M. McNally, S. Armando Villalta, Melissa J. Spencer
Abstract
Hereditary cardiomyopathies are the prototypic forms of heart failure and major causes of sudden cardiac death. The genome in cardiomyopathies is exposed to internal stressors, which damage the DNA and activate the DNA damage response (DDR) pathways. We set to determine whether the DDR pathways were activated and pathogenic in an established mouse model of desmoplakin (DSP)-cardiomyopathy generated upon deletion of the Dsp gene in cardiac myocytes (Myh6-McmTam:DspF/F). The mice exhibited premature death, cardiac dysfunction, myocardial cell death, fibrosis, and increased expression levels of the pro-inflammatory cytokines, consistent with the phenotype of human DSP-cardiomyopathy. Cytosolic nuclear self-DNA (nDNA) and mitochondrial DNA (mtDNA) were increased in cardiac myocyte cytosol in the Myh6-McmTam:DspF/F mice. Likewise, the DDR pathway proteins, including the cyclic GMP-AMP synthase (CGAS), stimulator of interferon response 1 (STING1) were upregulated as were the transcript levels of interferon response factor 3 (IRF3) and the nuclear factor κB (NFκB) target genes. Deletion of the Mb21d1 gene encoding CGAS in the Myh6-McmTam:DspF/F mice prolonged survival, improved cardiac function, attenuated fibrosis, and reduced cell death. Thus, cytosolic nDNA and mtDNA are increased and the DDR pathways are activated and pathogenic in a mouse model of DSP-cardiomyopathy, whereas genetic blockade of CGAS is salubrious.
Authors
Weiyue Wang, Benjamin Cathcart, Quoc D. Nguyen, Loi Q. Lao, Amelia Bryans, Sara E. Coleman, Leila Rouhi, Priyatansh Gurha, Ali J. Marian
Abstract
β-Thalassemia is a genetic disorder arising from mutations in the β-globin gene, leading to ineffective erythropoiesis and iron overload. Ineffective erythropoiesis, a hallmark of β-thalassemia, is an important driver of iron overload, which contributes to liver fibrosis, diabetes, and cardiac disease. Iron homeostasis is regulated by the hormone hepcidin; BMP6/hemojuvelin–mediated (BMP6/HJV-mediated) signaling induces hepatic hepcidin expression via SMAD1/5, with transmembrane serine protease 6 (TMPRSS6) being a negative regulator of HJV. Individuals with loss-of-function mutations in the TMPRSS6 gene show increased circulating hepcidin and iron-refractory iron-deficiency anemia, suggesting that blocking TMPRSS6 may be a viable strategy to elevate hepcidin levels in β-thalassemia. We generated a human mAb (REGN7999) that inhibits TMPRSS6. In an Hbbth3/+ mouse model of β-thalassemia, REGN7999 treatment led to significant reductions in liver iron, reduced ineffective erythropoiesis, and showed improvements in RBC health, running distance during forced exercise, and bone density. In a phase I, doubleblind, randomized, placebo-controlled study in healthy human volunteers (NCT05481333), REGN7999 increased serum hepcidin and reduced serum iron with an acceptable tolerability profile. Our results suggest that, by both reducing iron and improving RBC function, inhibition of TMPRSS6 by REGN7999 may offer a therapy for iron overload and impaired erythropoiesis in β-thalassemia.
Authors
Heinrich E. Lob, Nikhil Singh, Kusha Mohammadi, Larisa Ivanova, Beth Crowell, Hyon J. Kim, Leah Kravets, Nanditha M. Das, Yonaton Ray, Jee Hae Kim, Sylvie Rottey, Emily Labriola-Tompkins, Hazem E. Hassan, Lorna Farrelly, Harvey F. Chin, Marilena Preda, Leigh Spencer Noakes, Kei Saotome, Matthew Franklin, Marc W. Retter, Elif Karayusuf, John J. Flanagan, William Olson, Kalyan C. Nannuru, Vincent Idone, Michael E. Burczynski, Olivier A. Harari, Lorah Perlee, Griet Van Lancker, Andrew J. Murphy, Aris N. Economides, Sarah J. Hatsell
Abstract
The gain-of-function MUC5B promoter variant is the dominant risk factor for the development of idiopathic pulmonary fibrosis (IPF). However, its impact on protein expression in both non-fibrotic control and IPF lung specimens have not been well characterized. Utilizing laser capture microdissection coupled to mass spectrometry (LCM-MS), we investigated the proteomic profiles of airway and alveolar epithelium in non-fibrotic controls (n = 12) and IPF specimens (n = 12), stratified by the MUC5B promoter variant. Through qualitative and quantitative analyses, as well as pathway analysis and immunohistological validation, we have identified a distinct MUC5B-associated protein profile. Notably, the non-fibrotic control alveoli exhibited substantial MUC5B-associated protein changes, with an increase of IL-3 signaling. Additionally, we found that epithelial cells overlying IPF fibroblastic foci cluster closely to alveolar epithelia and express proteins associated with cellular stress pathways. In conclusion, our findings suggest that the MUC5B promoter variant leads to protein changes in alveolar and airway epithelium that appears to be associated with initiation and progression of lung fibrosis.
Authors
Jeremy A. Herrera, Mark Maslanka, Rachel Z. Blumhagen, Rachel Blomberg, Nyan Ye Lwin, Janna Brancato, Carlyne D. Cool, Jonathan P. Huber, Jonathan S. Kurche, Chelsea M. Magin, Kirk C. Hansen, Ivana V. Yang, David A. Schwartz
Abstract
Loss-of-function (LOF) variants in IL6ST, encoding GP130, can cause hyper-IgE syndrome (HIES). Monoallelic LOF variants in IL6ST lead to HIES when located in the intracellular domain downstream of box 1/2 and upstream of the STAT3 phosphorylation sites and the recycling motif, due to their dominant negative (DN) activity. In this region, two previously unreported IL6ST variants, p.K702Sfs7* and p.Y759Wfs26*, were identified in two families with autosomal dominant (AD) HIES. Both variants were LOF, exhibited DN effects, leading to the accumulation of mutant GP130 on the cell surface. The p.K702Sfs7* mutation was the most upstream N-terminal mutation linked to HIES caused by heterozygous IL6ST variants. Comprehensive screening of IL6ST mutants revealed that most premature terminations downstream of amino acid F641, at the end of the transmembrane domain, resulted in LOF and DN effects via GP130 accumulation on the cell surface. The absence of the recycling motif (positions 782-787) in surface-expressed LOF GP130 led to its accumulation, contributing to the DN effect. The importance of intracellular truncating IL6ST variants can possibly be predicted based on the location of the premature stop codon. GP130 accumulation on the cell surface is a characteristic and potentially diagnostic finding in HIES patients with heterozygous IL6ST variants.
Authors
Kosuke Ashihara, Takaki Asano, Kanako Takeuchi, Kosuke Noma, Miyuki Tsumura, Wenjie Wang, Wei-Te Lei, Hisao Higo, Toshio Kubo, Yoko Mizoguchi, Shuhei Karakawa, Aurélie Cobat, Clément Conil, Etsushi Toyofuku, Akimasa Sekine, Kohsuke Imai, Dusan Bogunovic, Jean-Laurent Casanova, Cheng-Lung Ku, Vivien Béziat, Satoshi Okada
Abstract
Human Caspase Recruitment Domain Containing Protein 9 (CARD9) deficiency predisposes to invasive fungal disease, particularly by Candida spp. Distinctly, CARD9-deficiency causes chronic central nervous system (CNS) candidiasis. Currently, no animal model recapitulates the chronicity of disease, precluding a better understanding of immunopathogenesis. We established a knock-in mouse homozygous for the recurring p.Y91H mutation (Y91HKI) and, in parallel to Card9-/- mice, titrated the intravenous fungal inoculum to the CARD9-genotype to develop a model of chronic invasive candidiasis. Strikingly, CARD9-deficient mice had predominantly CNS involvement, with neurological symptoms appearing late during infection and progressive brain fungal burden in the absence of fulminant sepsis, reflecting the human syndrome. Mononuclear cell aggregation at fungal lesions in the brain correlated with increased MHCII+Ly6C+ monocyte numbers at day 1 post-infection in WT and Y91HKI mice, but not in Card9-/- mice. At day 4 post-infection, neutrophils and additional Ly6C+ monocytes were recruited to the CARD9-deficient brain. As in humans, Y91HKI mutant mice demonstrated cerebral multinucleated giant cells and granulomata. Subtle immunologic differences between the hypomorphic (p.Y91H) and null mice were noted, perhaps explaining some of the variability seen in humans. Our work established a disease-recapitulating animal model to specifically decipher chronic CNS candidiasis due to CARD9 deficiency.
Authors
Marija Landekic, Isabelle Angers, Yongbiao Li, Marie-Christine Guiot, Marc-André Déry, Annie Beauchamp, Lucie Roussel, Annie Boisvert, Wen Bo Zhou, Christina Gavino, Julia Luo, Stéphane Bernier, Makayla Kazimerczak-Brunet, Yichun Sun, Brendan Snarr, Michail S. Lionakis, Robert T. Wheeler, Irah L. King, Salman Qureshi, Maziar Divangahi, Donald C. Vinh
Abstract
Many chemotherapeutic agents impair cancer growth by inducing DNA damage. The impact of these agents on mutagenesis in normal cells, including sperm, is largely unknown. Here, we applied high-fidelity duplex sequencing to 94 samples from 36 individuals exposed to diverse chemotherapies and 32 controls. We found that many of the sperm samples from men exposed to chemotherapy, the mutation burden was elevated as compared to controls and the expected burden based on trio studies, with one subject having >10-fold increase over expected for age. Saliva from this same individual also had a markedly higher mutation burden. We then validated this finding using other tissues, also finding an increased mutation burden in the blood and liver of many subjects exposed to chemotherapy as compared to unexposed controls. Similarly, mice treated with three cycles of cisplatin had an increased mutation burden in sperm but also in the liver, and hematopoietic progenitor cells. These results suggest an association between cancer therapies and mutation burden, with implications for counseling cancer patients considering banking sperm prior to therapy and for cancer survivors considering the tradeoffs of using banked sperm as compared to conceiving naturally.
Authors
Shany Picciotto, Camilo Arenas-Gallo, Amos Toren, Ruty Mehrian-Shai, Bryan Daly, Stephen Rhodes, Megan Prunty, Ruolin Liu, Anyull Bohorquez, Marta Grońska-Pęski, Shana Melanaphy, Pamela Callum, Emilie Lassen, Anne-Bine Skytte, Rebecca C. Obeng, Christopher Barbieri, Molly Gallogly, Brenda Cooper, Katherine Daunov, Lydia Beard, Koen Van-Besien, Joshua Halpern, Quintin Pan, Gilad D. Evrony, Viktor A. Adalsteinsson, Jonathan E. Shoag
No posts were found with this tag.
