Production of recombinant human glucocerebrosidase in Escherichia coli

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DESCRIPTION (provided by applicant): Gaucher's disease is the most common lysosomal storage disease in humans resulting in the harmful accumulation of fatty glucocerebroside in the spleen, liver, lungs, bone marrow, and brain. Gaucher patients exhibit a hereditary deficiency of glucocerebrosidase (GCase), but effective enzyme replacement therapy is available for most patients with Gaucher's disease. Recombinant GCase currently generates over $1 billion in annual revenue, but production of GCase is expensive. The resulting cost leaves many patients unable to afford treatment and health carriers reluctant to underwrite lifelong treatment. Currently, the glycoprotein GCase is expressed in Chinese Hamster ovary (CHO) cells and further processed in vitro to expose requisite terminal mannose residues for biological uptake in human patients. In addition to being expensive, mammalian cell culture is susceptible to viral contamination. In fact, viral contamination has resulted in a severe shortage of GCase that has set back revenues and endangered patients who depend on regular intravenous administration of the drug. This has opened the market for alternative industrial scale GCase expression platforms that are well-characterized, not susceptible to viral contamination, and do not require intricate in vitro chemical modification. Glycobia specializes in glycoengineering bacteria as a platform for the stereospecific biosynthesis of therapeutic glycoproteins. The specific hypothesis of these proposed studies is that glycoengineered Escherichia coli can be used to produce active recombinant GCase without the need for in vitro chemical modification. The advantage of E. coli as a host for GCase expression is that - unlike yeast, CHO, plant or all other eukaryote cells - there are no native glycosylation pathways to result in uncontrolled glycoforms. We anticipate that an E. coli expression platform will be capable of producing active GCase in a controlled, rapid, and cost-effective manner. The objective of this proposal is to generate GCase by cloning and expressing the genetic machinery for mannose oligosaccharide synthesis in E. coli (Aim 1) and expressing active GCase in glycoengineered E. coli (Aim 2). This bacterial expression platform represents a transformative solution to the unanswered biomedical challenge of delivering a cost-effective GCase enzyme replacement therapy to patients. PUBLIC HEALTH RELEVANCE: Glucocerebrosidase enzyme replacement therapy has revolutionized the clinical treatment of Gaucher's disease, but inefficiencies in the production platform have resulted in prohibitive costs to the healthcare consumer. Recombinant glucocerebrosidase is expressed in mammalian cell culture making the process expensive, susceptible to viral contamination, and subject to further in vitro processing of uncontrollable glycoforms. The proposed studies focus on producing active glucocerebrosidase in Escherichia coli fermentation without the need for mammalian cell culture or in vitro chemical modification.