An arrayed CRISPR screen identifies knockout combinations improving antibody productivity in HEK293 cells
Ontology highlight
ABSTRACT: Mammalian cells are used to express complex biologics such as multispecific antibodies. While multispecifics enable promising new strategies for treating human disease, their production at high expression titer and purity can be challenging. To understand how cells respond to antibody and multispecific expression, five molecules were selected for bulk RNA-seq early after transfection of a HEK293 host. All five molecules shared a differential expression signature of secretory and protein folding stress, but this signature was stronger for molecules with low titer. We then designed an arrayed CRISPR knockout screen of 206 differentially-expressed target genes and 223 literature-motivated targets to identify knockouts that impact antibody productivity. Eight novel knockout targets were identified that increased expression titers by 20 to 80%. Notably, seven of these top eight hits were from the differentially- expressed set of candidate-gene knockouts. The top knockout target, HIST2H3C, showed evidence for additivity with five other hits, including a knockout combination that increased the titer of a difficult-to-express antibody by up to 100%. Findings for both HIST2H3C and INHBE knockout targets generalized to an alternate HEK293 host expressing an additional antibody and a multispecific with no meaningful impact on product purity. Thus, we propose HIST2H3C and INHBE disruption to be a promising and novel strategy for host-cell engineering to improve antibody and multispecific productivity.
Project description:Host cell proteins (HCPs) are process-related impurities generated during biotherapeutic protein production. HCPs can be problematic if they pose a significant metabolic demand, degrade product quality, or contaminate the final product. Here, we present an effort to create a “clean” Chinese hamster ovary (CHO) cell by disrupting multiple genes to eliminate HCPs. Using a model of CHO cell protein secretion, we predicted the elimination of unnecessary HCPs could have a non-negligible impact on protein production. We analyzed the total HCP content of 6-protein, 11-protein, and 14-protein knockout clones and characterized their growth in shake flasks and bioreactors. These cell lines exhibited a substantial reduction in total HCP content (40%-70%). We also observed higher productivity and improved growth characteristics, in specific clones. With the reduced HCP content, protein A and ion exchange chromatography more efficiently purified a monoclonal antibody (mAb) produced in these cells during a three-step purification process. Thus, substantial improvements can be made in protein titer and purity through large-scale HCP deletion, providing an avenue to increased quality and affordability of high-value biopharmaceuticals.
Project description:Chromatin immunoprecipitation (ChIP) is an antibody-based approach that is most frequently utilized in research areas of chromatin biology and epigenetics. The ENCODE Consortium provided guidelines about antibody but the fundamental aspect regarding antibody titer was not addressed. Here, we introduced a simple and quick DNA-based quantification of chromatin input, allowing to normalize the antibody amount in individual ChIP reaction to the optimal titer. We further demonstrated the titration-based normalization of antibody amount generates improved assay outcome with high consistency among samples in an experiment or recurrent experiments for a broad range of chromatin input amount. Chromatin immunoprecipitation-sequencing (ChIP-seq) was performed for histone H3K27ac mark in the conditions of various titer of antibody in ChIP reactions..
Project description:Mdr1a-, Bcrp-, and Mrp2-knockout rats are a more practical species for ADME studies than murine models and previously demonstrated expected alterations in pharmacokinetics of various probe substrates. At present, gene expression and pathology changes were systematically studied in small intestine, liver, kidney, and brain tissue from male SAGE Mdr1a-, Bcrp-, and Mrp2-knockout rats versus wild-type Sprague Dawley controls. Gene expression data supported the relevant knockout genotype. As expected, Mrp2-knockout rats were hyperbilirubinemic and exhibited upregulation of hepatic Mrp3. Overall, few alterations were observed within 137 ADME-relevant genes. The two most consequential changes were upregulation of intestinal carboxylesterase in Mdr1a-knockouts and catechol-O-methyltransferase in all tissues of Bcrp-knockout rats. Previously reported upregulation of hepatic Mdr1b P-glycoprotein in proprietary Wistar Mdr1a-knockout rats was not observed in the SAGE counterpart investigated herein. Relative liver and kidney weights were 22-53% higher in all three knockouts, with microscopic increases in hepatocyte size in Mdr1a- and Mrp2-knockout rats, and glomerular size in Bcrp- and Mrp2-knockouts. Increased relative weight of clearing organs is quantitatively consistent with reported increases in clearance of drugs that are not substrates of the knocked-out transporter. Overall, SAGE knockout rats demonstrated modest compensatory changes, which do not preclude their general application to study transporter-mediated pharmacokinetics. However until future studies elucidate the magnitude of functional change, caution is warranted in rare instances of extensive metabolism by catechol-O-methyltransferase in Bcrp-knockouts and intestinal carboxylesterase in Mdr1a-knockout rats, specifically for molecules with free catechol groups and esters subject to gut wall hydrolysis. 3 groups of knockout animals compared to wild-type male Sprague Dawley control rats. 4 animals per group. Assayed the following tissues: brain, duodenum, ileum, jejunum, kidney (cortex-anterior pole), kidney (medulla), liver. Hybridized to Affymetrix Rat Genome 230 v2 [Rat230_2] arrays.
Project description:Myotonic dystrophy (DM) is a multi-systemic disease that severely impacts cardiac and skeletal muscle functions as well as the central nervous system. DM is unusual because it is RNA-mediated disease due to the expression of C(C)UG expansion RNAs that inhibit the activities of the muscleblind-like (MBNL) proteins. In mice, studies using Mbnl1 and Mbnl2 single knockouts have revealed that Mbnl1 plays a predominant role in skeletal and heart muscle alternative splicing regulation while Mbnl2 performs an analogous splicing function in the brain. However, Mbnl single knockout models fail to recapitulate the full-range of adult-onset DM muscle symptoms. Here, we report that Mbnl1; Mbnl2 double knockouts are embryonic lethal while Mbnl1-/-; Mbnl2+/- mice, which express no Mbnl1 and reduced levels of Mbnl2, are viable but develop cardinal features of adult-onset DM cardiac and skeletal muscle disease including reduced lifespan, heart conduction block, severe myotonia and progressive skeletal muscle weakness. Mbnl2 protein levels are elevated in both Mbnl1-/- and Mbnl1-/-; Mbnl2+/- knockouts where Mbnl2 targets Mbnl1-regulated exons. These findings support the MBNL loss-of-function model for DM and provide novel Mbnl compound knockout models to investigate the molecular pathways disrupted by RNA-mediated disease. Mbnl2 protein-RNA interactions were assessed in 4-month-old WT and Mbnl1-/- quadriceps muscles in triplicates by HITS-CLIP.
Project description:This study characterizes gene and enhancer knockout phenotypes of 30 genes in a human pluripotent stem cell (hPSC)-directed islet differentiation system. Samples were collected at five differentiation stages from hPSCs to SC-islet cells for scRNA-seq to examine transcriptional impact of the knockouts over time.
Project description:Mdr1a-, Bcrp-, and Mrp2-knockout rats are a more practical species for ADME studies than murine models and previously demonstrated expected alterations in pharmacokinetics of various probe substrates. At present, gene expression and pathology changes were systematically studied in small intestine, liver, kidney, and brain tissue from male SAGE Mdr1a-, Bcrp-, and Mrp2-knockout rats versus wild-type Sprague Dawley controls. Gene expression data supported the relevant knockout genotype. As expected, Mrp2-knockout rats were hyperbilirubinemic and exhibited upregulation of hepatic Mrp3. Overall, few alterations were observed within 137 ADME-relevant genes. The two most consequential changes were upregulation of intestinal carboxylesterase in Mdr1a-knockouts and catechol-O-methyltransferase in all tissues of Bcrp-knockout rats. Previously reported upregulation of hepatic Mdr1b P-glycoprotein in proprietary Wistar Mdr1a-knockout rats was not observed in the SAGE counterpart investigated herein. Relative liver and kidney weights were 22-53% higher in all three knockouts, with microscopic increases in hepatocyte size in Mdr1a- and Mrp2-knockout rats, and glomerular size in Bcrp- and Mrp2-knockouts. Increased relative weight of clearing organs is quantitatively consistent with reported increases in clearance of drugs that are not substrates of the knocked-out transporter. Overall, SAGE knockout rats demonstrated modest compensatory changes, which do not preclude their general application to study transporter-mediated pharmacokinetics. However until future studies elucidate the magnitude of functional change, caution is warranted in rare instances of extensive metabolism by catechol-O-methyltransferase in Bcrp-knockouts and intestinal carboxylesterase in Mdr1a-knockout rats, specifically for molecules with free catechol groups and esters subject to gut wall hydrolysis.
2013-04-08 | GSE44962 | GEO
Project description:Investigation of intrahost diversity by vaccine status and antibody titer
Project description:mbnl knockout Danio rerio were created using CRISPR-Cas9, including single mbnl paralog knockouts, double mbnl paralog knockouts, and a triple mbnl paralog knockout. RNA-Seq was performed using skeletal muscle of three biological replicates of four month old fish.
Project description:Traditional treatments for bacterial infection have focused upon directly inhibiting growth of the pathogen. However, an equally important determinant of infection outcome is the host defense response. We previously performed a high-throughput chemical screen to identify small molecules that rescued the nematode Caenorhabditis elegans from infection by Pseudomonas aeruginosa. Over 20 of the hits stimulated host defense gene expression. During in-depth studies of five such molecules using microarray analysis, bioinformatic clustering, and RNAi knockdown of candidate gene targets, we identified PMK-1/p38 MAPK and SKN-1/Nrf2 as two key pathways modulated by these hits. Interestingly, the molecules studied did not depend on a single pathway for ameliorating P. aeruginosa pathogenesis in liquid-based assay, but did rely on the PMK-1/p38 MAPK pathway during a colonization-based infection assay on agar. A subset of these molecules was also protective against Enterococcus faecalis and Staphylococcus aureus. In general, the compounds showed little toxicity against mammalian cells or worms, consistent with their identification in a phenotypic, high-content screen. These molecules possess significant potential for use as tools to study innate immune processes