Browsing by Author "Konkle, Barbara A."

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    Cryptic resolution sites in the vector plasmid lead to the heterogeneities in the rAAV vectors
    (Wiley, 2023) Zhang, Junping; Chrzanowski, Matthew; Frabutt, Dylan A.; Lam, Anh K.; Mulcrone, Patrick L.; Li, Lei; Konkle, Barbara A.; Miao, Carol H.; Xiao, Weidong; Pediatrics, School of Medicine
    Recombinant adeno-associated virus (rAAV) vectors carry a cassette of interest retaining only the inverted terminal repeats (ITRs) from the wild-type virus. Conventional rAAV production primarily uses a vector plasmid as well as helper genes essential for AAV replication and packaging. Nevertheless, plasmid backbone related contaminants have been a major source of vector heterogeneity. The mechanism driving the contamination phenomenon has yet to be elucidated. Here we identified cryptic resolution sites in the plasmid backbone as a key source for producing snapback genomes, which leads to the increase of vector genome heterogeneity in encapsidated virions. By using a single ITR plasmid as a model molecule and mapping subgenomic particles, we found that there exist a few typical DNA break hotspots in the vector DNA plasmid backbone, for example, on the ampicillin DNA element, called aberrant rescue sites. DNA around these specific breakage sites may assume some typical secondary structures. Similar to normal AAV vectors, plasmid DNA with a single ITR was able to rescue and replicate efficiently. These subgenomic DNA species significantly compete for trans factors required for rAAV rescue, replication, and packaging. The replication of single ITR contaminants during AAV production is independent of size. Packaging of these species is greatly affected by its size. A single ITR and a cryptic resolution site in the plasmid work synergistically, likely causing a source of plasmid backbone contamination.
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    Influence of N-glycosylation in the A and C domains on the immunogenicity of factor VIII
    (American Society of Hematology, 2022) Vander Kooi, Amber; Wang, Shuaishuai; Fan, Meng-Ni; Chen, Alex; Zhang, Junping; Chen, Chun-Yu; Cai, Xiaohe; Konkle, Barbara A.; Xiao, Weidong; Li, Lei; Miao, Carol H.; Pediatrics, School of Medicine
    The most significant complication in hemophilia A treatment is the formation of inhibitors against factor VIII (FVIII) protein. Glycans and glycan-binding proteins are central to a properly functioning immune system. This study focuses on whether glycosylation of FVIII plays an important role in induction and regulation of anti-FVIII immune responses. We investigated the potential roles of 4 N-glycosylation sites, including N41 and N239 in the A1 domain, N1810 in the A3 domain, and N2118 in the C1 domain of FVIII, in moderating its immunogenicity. Glycomics analysis of plasma-derived FVIII revealed that sites N41, N239, and N1810 contain mostly sialylated complex glycoforms, while high mannose glycans dominate at site N2118. A missense variant that substitutes asparagine (N) to glutamine (Q) was introduced to eliminate glycosylation on each of these sites. Following gene transfer of plasmids encoding B domain deleted FVIII (BDD-FVIII) and each of these 4 FVIII variants, it was found that specific activity of FVIII in plasma remained similar among all treatment groups. Slightly increased or comparable immune responses in N41Q, N239Q, and N1810Q FVIII variant plasmid-treated mice and significantly decreased immune responses in N2118Q FVIII plasmid-treated mice were observed when compared with BDD-FVIII plasmid-treated mice. The reduction of inhibitor response by N2118Q FVIII variant was also demonstrated in AAV-mediated gene transfer experiments. Furthermore, a specific glycopeptide epitope surrounding the N2118 glycosylation site was identified and characterized to activate T cells in an FVIII-specific proliferation assay. These results indicate that N-glycosylation of FVIII can have significant impact on its immunogenicity.
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    Sequencing of 53,831 diverse genomes from the NHLBI TOPMed Program
    (Springer Nature, 2021) Taliun, Daniel; Harris, Daniel N.; Kessler, Michael D.; Carlson, Jedidiah; Szpiech, Zachary A.; Torres, Raul; Gagliano Taliun, Sarah A.; Corvelo, André; Gogarten, Stephanie M.; Kang, Hyun Min; Pitsillides, Achilleas N.; LeFaive, Jonathon; Lee, Seung-Been; Tian, Xiaowen; Browning, Brian L.; Das, Sayantan; Emde, Anne-Katrin; Clarke, Wayne E.; Loesch, Douglas P.; Shetty, Amol C.; Blackwell, Thomas W.; Smith, Albert V.; Wong, Quenna; Liu, Xiaoming; Conomos, Matthew P.; Bobo, Dean M.; Aguet, François; Albert, Christine; Alonso, Alvaro; Ardlie, Kristin G.; Arking, Dan E.; Aslibekyan, Stella; Auer, Paul L.; Barnard, John; Barr, R. Graham; Barwick, Lucas; Becker, Lewis C.; Beer, Rebecca L.; Benjamin, Emelia J.; Bielak, Lawrence F.; Blangero, John; Boehnke, Michael; Bowden, Donald W.; Brody, Jennifer A.; Burchard, Esteban G.; Cade, Brian E.; Casella, James F.; Chalazan, Brandon; Chasman, Daniel I.; Chen, Yii-Der Ida; Cho, Michael H.; Choi, Seung Hoan; Chung, Mina K.; Clish, Clary B.; Correa, Adolfo; Curran, Joanne E.; Custer, Brian; Darbar, Dawood; Daya, Michelle; de Andrade, Mariza; DeMeo, Dawn L.; Dutcher, Susan K.; Ellinor, Patrick T.; Emery, Leslie S.; Eng, Celeste; Fatkin, Diane; Fingerlin, Tasha; Forer, Lukas; Fornage, Myriam; Franceschini, Nora; Fuchsberger, Christian; Fullerton, Stephanie M.; Germer, Soren; Gladwin, Mark T.; Gottlieb, Daniel J.; Guo, Xiuqing; Hall, Michael E.; He, Jiang; Heard-Costa, Nancy L.; Heckbert, Susan R.; Irvin, Marguerite R.; Johnsen, Jill M.; Johnson, Andrew D.; Kaplan, Robert; Kardia, Sharon L. R.; Kelly, Tanika; Kelly, Shannon; Kenny, Eimear E.; Kiel, Douglas P.; Klemmer, Robert; Konkle, Barbara A.; Kooperberg, Charles; Köttgen, Anna; Lange, Leslie A.; Lasky-Su, Jessica; Levy, Daniel; Lin, Xihong; Lin, Keng-Han; Liu, Chunyu; Loos, Ruth J. F.; Garman, Lori; Gerszten, Robert; Lubitz, Steven A.; Lunetta, Kathryn L.; Mak, Angel C. Y.; Manichaikul, Ani; Manning, Alisa K.; Mathias, Rasika A.; McManus, David D.; McGarvey, Stephen T.; Meigs, James B.; Meyers, Deborah A.; Mikulla, Julie L.; Minear, Mollie A.; Mitchell, Braxton D.; Mohanty, Sanghamitra; Montasser, May E.; Montgomery, Courtney; Morrison, Alanna C.; Murabito, Joanne M.; Natale, Andrea; Natarajan, Pradeep; Nelson, Sarah C.; North, Kari E.; O'Connell, Jeffrey R.; Palmer, Nicholette D.; Pankratz, Nathan; Peloso, Gina M.; Peyser, Patricia A.; Pleiness, Jacob; Post, Wendy S.; Psaty, Bruce M.; Rao, D. C.; Redline, Susan; Reiner, Alexander P.; Roden, Dan; Rotter, Jerome I.; Ruczinski, Ingo; Sarnowski, Chloé; Schoenherr, Sebastian; Schwartz, David A.; Seo, Jeong-Sun; Seshadri, Sudha; Sheehan, Vivien A.; Sheu, Wayne H.; Shoemaker, M. Benjamin; Smith, Nicholas L.; Smith, Jennifer A.; Sotoodehnia, Nona; Stilp, Adrienne M.; Tang, Weihong; Taylor, Kent D.; Telen, Marilyn; Thornton, Timothy A.; Tracy, Russell P.; Van Den Berg, David J.; Vasan, Ramachandran S.; Viaud-Martinez, Karine A.; Vrieze, Scott; Weeks, Daniel E.; Weir, Bruce S.; Weiss, Scott T.; Weng, Lu-Chen; Willer, Cristen J.; Zhang, Yingze; Zhao, Xutong; Arnett, Donna K.; Ashley-Koch, Allison E.; Barnes, Kathleen C.; Boerwinkle, Eric; Gabriel, Stacey; Gibbs, Richard; Rice, Kenneth M.; Rich, Stephen S.; Silverman, Edwin K.; Qasba, Pankaj; Gan, Weiniu; NHLBI Trans-Omics for Precision Medicine (TOPMed) Consortium; Papanicolaou, George J.; Nickerson, Deborah A.; Browning, Sharon R.; Zody, Michael C.; Zöllner, Sebastian; Wilson, James G.; Cupples, L. Adrienne; Laurie, Cathy C.; Jaquish, Cashell E.; Hernandez, Ryan D.; O'Connor, Timothy D.; Abecasis, Gonçalo R.; Epidemiology, Richard M. Fairbanks School of Public Health
    The Trans-Omics for Precision Medicine (TOPMed) programme seeks to elucidate the genetic architecture and biology of heart, lung, blood and sleep disorders, with the ultimate goal of improving diagnosis, treatment and prevention of these diseases. The initial phases of the programme focused on whole-genome sequencing of individuals with rich phenotypic data and diverse backgrounds. Here we describe the TOPMed goals and design as well as the available resources and early insights obtained from the sequence data. The resources include a variant browser, a genotype imputation server, and genomic and phenotypic data that are available through dbGaP (Database of Genotypes and Phenotypes)1. In the first 53,831 TOPMed samples, we detected more than 400 million single-nucleotide and insertion or deletion variants after alignment with the reference genome. Additional previously undescribed variants were detected through assembly of unmapped reads and customized analysis in highly variable loci. Among the more than 400 million detected variants, 97% have frequencies of less than 1% and 46% are singletons that are present in only one individual (53% among unrelated individuals). These rare variants provide insights into mutational processes and recent human evolutionary history. The extensive catalogue of genetic variation in TOPMed studies provides unique opportunities for exploring the contributions of rare and noncoding sequence variants to phenotypic variation. Furthermore, combining TOPMed haplotypes with modern imputation methods improves the power and reach of genome-wide association studies to include variants down to a frequency of approximately 0.01%.
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    Site-Specific N- and O-Glycosylation Analysis of Human Plasma Fibronectin
    (Frontiers Media, 2021-06-15) Liu, Ding; Wang, Shuaishuai; Zhang, Junping; Xiao, Weidong; Miao, Carol H.; Konkle, Barbara A.; Wan, Xiu-Feng; Li, Lei; Pediatrics, School of Medicine
    Human plasma fibronectin is an adhesive protein that plays a crucial role in wound healing. Many studies had indicated that glycans might mediate the expression and functions of fibronectin, yet a comprehensive understanding of its glycosylation is still missing. Here, we performed a comprehensive N- and O-glycosylation mapping of human plasma fibronectin and quantified the occurrence of each glycoform in a site-specific manner. Intact N-glycopeptides were enriched by zwitterionic hydrophilic interaction chromatography, and N-glycosite sites were localized by the 18O-labeling method. O-glycopeptide enrichment and O-glycosite identification were achieved by an enzyme-assisted site-specific extraction method. An RP–LC–MS/MS system functionalized with collision-induced dissociation and stepped normalized collision energy (sNCE)-HCD tandem mass was applied to analyze the glycoforms of fibronectin. A total of 6 N-glycosites and 53 O-glycosites were identified, which were occupied by 38 N-glycoforms and 16 O-glycoforms, respectively. Furthermore, 77.31% of N-glycans were sialylated, and O-glycosylation was dominated by the sialyl-T antigen. These site-specific glycosylation patterns on human fibronectin can facilitate functional analyses of fibronectin and therapeutics development.