ASU, Joint Appointment: Agriculture and Biology, Arkansas Biosciences Institute
- Plant-made industrial/pharmaceutical proteins
- Protein processing & trafficking
- Transformation technologies
Research Summary | Selected Publications | Lab Members | Key Collaborators | Research Projects | Links
Research within the Cramer group is currently focused in two areas: 1) the development of plants as a bioproduction platform for complex high-value pharmaceutical proteins and vaccines and 2) the development of RTB, the nontoxic carbohydrate binding domain of ricin, for transmucosal delivery, subcellular trafficking, and immune-presentation of associated proteins and drugs. These studies incorporate basic analyses of protein synthesis, processing, trafficking, folding/structure, assembly and stability in plants as well as uptake and bioactivity in target animals and human/animal cells. Although trained in genetics and plant molecular biology, Cramer‘s research has developed a very strong biomedical focus and integrates highly interactive collaborations with bioinformaticists, immunologists, medical biochemists, and infectious disease researchers at University of Arkansas, Fayetteville, UA for Medical Sciences in Little Rock, and University of Georgia as well as colleagues at ASU.
Dr. Cramer’s research has also encompassed a strong entrepreneurial component – she has co-founded and served as chief scientific officer of several biotech start-up companies including Crop Tech Corp (1993-2003) and BioStrategies-LC (2007-present). Her pioneering research on the use of plants to produce human lysosomal enzymes as replacement therapeutics for human lysosomal storage diseases led to the development of one of the first plant-made pharmaceuticals in human use.
Hood, E, CL Cramer, G Medrano, and J Xu. 2012. Protein targeting: Strategic planning for optimizing protein products through plant biotechnology. Chapter 3 in: Plant Biotechnology and Agriculture: Prospects for the 21stCentury, A. Altman, P.M. Hasagawa (eds.), Elsevier, in press. (doi: 10.1016/B978-0-12-381466-1.00003-1).
Medrano, G, MC Dolan, J Condori, DN Radin, and CL Cramer. 2012. Quality assessment of recombinant proteins derived from plants. In: Recombinant Gene Expression: Reviews and Protocols, Third Edition. A. Lorence (eds.) Humana Press/Springer, New York, pp.535-564.
Xu, J, MC Dolan, G Medrano, CL Cramer, and PJ Weathers. 2011. Green factory: Plants as bioproduction platforms for recombinant proteins. Biotechnol. Adv., (doi:10.1016/j.biotechadv. 2011.08.020).
Walker, K, C Cramer, S Jennings, and X Huang. 2011. TERPRED: A dynamic structural data analysis tool, Proceedings of the World Congress on Computer Science and Information Engineering, 2011.
Medrano, G, N Stephens, A McMickle, M Dolan, D Radin, G Erf, and CL Cramer. 2010. Efficient plant-based production of chicken IL-12 yields a strong immunostimulatory cytokine. J. Interferon Cytokine Res., 30(3):143-154.
Medrano, G, MJ Reidy, J Liu, J Ayala, MC Dolan and CL Cramer. 2009. Rapid system for evaluating bioproduction capacity of complex pharmaceutical proteins in plants. In Methods in Biotechnology "Recombinant Pharmaceutical Proteins from Plants", Humana Press, USA, pp.51-68.
Carole L. Cramer, PhD, Arkansas Biosciences Institute
Jorge Ayala, Biostrategies, LC
Jose Condori, PhD, Biostrategies LC
Dr. Maureen Dolan, biotechnology | Arkansas State University, Jonesboro
Dr. Xiuzhen Huang, bioinformatics | Arkansas State University, Jonesboro
Dr. Argelia Lorence, plant biology, metabolic engineering | Arkansas State University, Jonesboro
Dr. David N. Radin, entrepreneur, plant-based bioproduction | BioStrategies LC, Jonesboro, AR
Dr. Ralph Tripp, viral immunology | College of Veterinary Medicine, University of Georgia
Dr. S. Mark Tompkins, influenza, vaccine development | College of Veterinary Medicine, University of Georgia
Dr. Jianfeng (Jay) Yu, biochemical engineer | Arkansas State University, Jonesboro
Dr. Shiguang Yu, immunology, autoimmune disease | Arkansas State University, Jonesboro
Plant-based bioproduction systems for therapeutic proteins. Plants are fully capable of synthesizing complex bioactive foreign proteins including those that require multiple post-translational processing and/or subunit assembly. Plants also provide key advantages of safety, scale, and cost compared to current mammalian cell-based bioproduction systems for commercial pharmaceutical proteins. Dr. Cramer was a pioneer in the development of plant-made pharmaceuticals and is the inventor for key technologies supporting the first commercial PMP – an enzyme replacement therapeutic for Gaucher Disease. The Cramer group is currently exploiting transient expression systems involvingAgrobacterium-mediated transfection of Nicotiana benthamiana. This system enables rapid recombinant protein production (leaves are harvested 2-3 days after vector infiltration), accelerating transgene optimization and quickly providing recombinant proteins for evaluation and bioactivity assessment. In addition to projects targeting specific ‘proteins of interest’, basic studies on mechanism of protein production, processing, and trafficking are also on-going and incorporate a) bioinformatics of protein structure-function relationships, b) transcriptomics to identify key factors supporting or limiting protein production and stability in plants, and c) assessment of product bioactivity in vitro and in animal studies.
Lectin-mediated delivery of therapeutics. Effective delivery of drugs and therapeutic proteins to target tissues, cells, and subcellular locations remain a significant challenge for pharmaceutical and veterinary applications. We are developing RTB (the non-toxic carbohydrate-binding subunit of ricin) and other plant lectins as protein carriers. RTB mediates delivery of associated proteins across mucosal surfaces and utilizes multiple endocytic pathways for efficient uptake into mammalian cells. Within cells, RTB facilitates trafficking to lysosomes, to the ER via the retrograde pathway, or is ‘transcytosed’ for uptake into distal cells. We are exploring the potential of RTB to facilitate delivery of human lysosomal proteins for enzyme replacement therapeutics for lysosomal storages diseases.
Plant-derived vaccines and adjuvants. Plants show significant promise for the bioproduction of vaccine antigens due to their ability to cost-effectively produce complex proteins at large scale. The potential to deliver these plant-derived vaccines directly via feed (e.g., as transgenic seed) is particularly appealing for agricultural or veterinary applications as it eliminates the cost of purifying the protein immunogen. Although subunit vaccines (vaccines based on immunogenic proteins of the disease agent rather than attenuated or inactivated whole organisms) are considered safer, they are often less immunogenic and do not elicit strong cell-mediated immunity. Our research group is addressing these limitations in several ways. We have demonstrated that plants can produce fully bioactive interleukin-12 (IL-12), the key cytokine that triggers induction of the cell-mediated arm of the immune system. We have partnered with BioStrategies-LC to produce chicken and porcine IL-12 targeting avian and swine influenza. We are also testing the potential of the RTB lectin to facilitate antigen presentation. We have modified our RTB carrier for dominant delivery to 1) lysosomal compartments (the site of antigen processing for MHC-II presentation leading to strong antibody-mediated immunity) and 2) the ER/cytosol (site of antigen processing for MHC-I presentation triggering cell-mediated immunity). We hypothesize that differential RTB-mediated targeting of fused vaccine antigens will elicit distinct immune profiles and provide novel approaches to orchestrate protective immunity.
Cramer's P3 YouTube Video: http://youtu.be/DChOVhzTw7Q