Publications by authors named "Zion Lee"

The augmentation of transgene copy numbers is a prevalent approach presumed to enhance transcriptional activity and product yield. CHO cell lines engineered via targeted integration (TI) offer an advantageous platform for investigating the interplay between gene copy number, mRNA abundance, product yield, and product quality. Our investigation revealed that incrementally elevating the gene copy numbers of both IgG heavy chain (HC) and light chain (LC) concurrently resulted in the attainment of plateaus in mRNA levels and product titers, notably occurring beyond four to five gene copies integrated at the same TI site.

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Recombinant adeno-associated virus (rAAV) is among the most commonly used vectors for gene therapy. It is commonly produced by transfection of HEK293 cells with three plasmids each containing the vector genome including gene of interest (GOI), helper functions, and rep and cap genes for genome replication and capsid formation. To meet the potential clinical needs, the productivity of the production system needs to be enhanced.

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The timing of floral transition is determined by both endogenous molecular pathways and external environmental conditions. Among these environmental conditions, photoperiod acts as a cue to regulate the timing of flowering in response to seasonal changes. Additionally, it has become clear that various environmental factors also control the timing of floral transition.

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Recombinant adeno-associated virus (rAAV) is among the most commonly used in vivo gene delivery vehicles and has seen a number of successes in clinical application. Current manufacturing processes of rAAV employ multiple plasmid transfection or rely on virus infection and face challenges in scale-up. A synthetic biology approach was taken to generate stable cell lines with integrated genetic modules, which produced rAAV upon induction albeit at a low productivity.

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Tubulin glutamylation is a reversible modification of the microtubules that regulates cilia stability and function. The addition of glutamates to the microtubule is catalyzed by members of the TTLL family of enzymes, while the removal is carried out by a family of cytosolic carboxypeptidase (CCP) enzymes. has two deglutamylating enzymes, CCPP-1 and CCPP-6 .

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Lignin is a complex polymer that is embedded in plant cell walls to provide physical support and water protection. For these reasons, the production of lignin is closely linked with plant adaptation to terrestrial regions. In response to developmental cues and external environmental conditions, plants use an elaborate regulatory network to determine the timing and location of lignin biosynthesis.

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Nitrogen (N) is an essential macronutrient required for plant growth and crop production. However, N in soil is usually insufficient for plant growth. Thus, chemical N fertilizer has been extensively used to increase crop production.

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An important quality attribute of a recombinant adeno-associated virus (rAAV) as a therapeutic vector is its infectivity. Current assays to quantify infectious rAAV rely on coinfection with a helper virus such as adenovirus (Ad), which requires helper virus preparation and introduces additional variability. A simple method that has high sensitivity and removes the need for helper virus would improve assay consistency and facilitate high-throughput applications such as rAAV producer cell line development.

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Recombinant adeno-associated viruses (rAAV) are important gene delivery vehicles for gene therapy applications. Their production relies on plasmid transfection or virus infection of producer cells, which pose a challenge in process scale-up. Here, we describe a template for a transfection-free, helper virus-free rAAV producer cell line using a synthetic biology approach.

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Influenza A virus (IAV) is a segmented negative-sense RNA virus and is the cause of major epidemics and pandemics. The replication of IAV is complex, involving the production of three distinct RNA species; mRNA, cRNA, and vRNA for all eight genome segments. While understanding IAV replication kinetics is important for drug development and improving vaccine production, current methods for studying IAV kinetics has been limited by the ability to detect all three different RNA species in a scalable manner.

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Different regions of a mammalian genome have different accessibilities to transcriptional machinery. The integration site of a transgene affects how actively it is transcribed. Highly accessible genomic regions called super-enhancers have been recently described as strong regulatory elements that shape cell identity.

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For the biomanufacturing of protein biologics, establishing stable cell lines with high transgene transcription is critical for high productivity. Modern genome engineering tools can direct transgene insertion to a specified genomic locus and can potentially become a valuable tool for cell line generation. In this study, the authors survey transgene integration sites and their transcriptional activity to identify characteristics of desirable regions.

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The facilitated glucose transporter GLUT1 (SLC2A1) is an important mediator of glucose homeostasis in humans. Though it is found in most cell types to some extent, the level of GLUT1 expression across different cell types can vary dramatically. Prior studies in erythrocytes-which express particularly high levels of GLUT1-have suggested that GLUT1 is able to form tetrameric complexes with enhanced transport activity.

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