ASU SoLS Faculty: Lokesh Joshi

Associate Professor of Bioengineering and The Biodesign Institute, joined Arizona State University in 2000. Received a Ph.D. in biochemistry from Bath University, England in 1994 and then joined Boyce Thompson Institute and Cornell University as post-doctoral fellow and research associate.

There are two major fields of emphasis in Dr. Joshis research group: 1) Post-translational modifications on biomolecules, and 2) Discovery and development of protein-based therapeutics for clinical applications. Some of the projects currently under study are described here.

Post-translational modifications in plants:

Biotechnology is enabling the identification of increasing numbers of bioactive macromolecules that can be applied to control/prevent various diseases. Most human proteins are co- and post-translationally modified and in many cases, these modifications are critical for the structure and biological activity of these molecules. Various recombinant systems are being employed to produce biologically active recombinant molecules. Our current system of choice is plants because plant-derived recombinant proteins are safer, cheaper and plants are natures best bioreactors.

The technology for producing recombinant proteins in plants is relatively well established. However, to make biologically functional molecules in plants, additional knowledge is essential in their ability to perform post-translational modifications. Our research is directed towards understanding these modifications, specifically, glycosylation, hydroxylation and phosphorylation, on recombinant and endogenous proteins. Metabolic engineer techniques are employed to achieve the desired modifications.

We have recently shown that plants produce sialylated glycoconjugates containing both N-acetyl-D-neuraminic acid (Neu5Ac) and N-glycolyl-D-neuraminic acid (Neu5Gc). Our discovery of sialylated glycoconjugates in plants opens new fields of research in plant biochemistry and biotechnology and raises important questions regarding the biosynthesis, regulation, distribution, and function of SAs in plants. This discovery is also of importance for the path to produce sialylated human glycoconjugates in plants for clinical applications.

Discovery and development of protein-based therapeutics for clinical applications:

We are engineering plants to produce 'designer' protein molecules of therapeutic value. Most of these proteins and peptides require specific post-translational modifications for their structural and functional properties. We are also utilizing in silico and molecular modeling tools to generate mini-proteins with optimized physical and biological properties.

Three of these proteins that are currently being studied are:

A novel macrophage activating factor (MAF): Glycosylated form of MAF is required for macrophage and dendritic cells. Cancers and infectious diseases deactivate MAF and therefore prevent its ability to activate phagocytes and the immune response. We are developing recombinant and synthetic versions of MAF as an effective adjuvant for immunotherapy of cancer as well as microbial infections.

HSP20: A small heat shock-like phosphoprotein (SHP20) that has been shown to be responsible for vasorelaxation. This phosphoprotein is primarily being developed for coronary and peripheral revascularization surgeries and subarachnoid vasospasm induced hemorrhage. Various forms of this protein are being produced in plants and E.coli for optimal activity in muscle cells.

Collagen: Collagen is a large family of structural proteins. There are over 25 different types of collagens and currently animal carcasses are the only feasible source of this most prevalent protein in our body. Collagen goes through multiple post-translational events such as, hydroxylation of prolines, hydroxylation of lysine, glycosylation of hydroxylysine, disulfide bond formation, N-glycosylation and N- and C-terminal peptide cleavage. We are collaborating with FibroGen Inc., Medicago Inc. and investigators at the University of Oulu, Finland, to generate human collagen molecules in plants and study their post-translational modifications.

Selected Publications

Joshi, L., Shah, M., Flynn, C.R., and Panitch, A. 2004. Post-Translational modifications and their roles in plant-produced recombinant therapeutics. In Transgenic Crops and Human Health, Encyclopedia of Plant & Crop Science, (Ed. Joshi, L.). Marcel Dekker, Inc. NY. In Press.

Joshi, L., Shah, M., Flynn, C.R., and Panitch, A. 2004. Plant produced recombinant therapeutics. In Transgenic Crops and Human Health, Encyclopedia of Plant & Crop Science, (Ed. Goodman R.). Marcel Dekker, Inc. NY. 969-972.

Joshi, L. Editor 2004. Transgenic Crops and Human Health. Encyclopedia of Plant & Crop Science. Marcel Dekker, Inc. NY.

Shah, M.M., Fujiyama, K., Flynn, C.R. and Joshi, L. 2003. Presence of sialylated endogenous glycoconjugates in plant cells. Nature Biotechnology. 21(12):1470-1471.

Joshi, L. and Panitch, A. Post-Translational Modifications: Branches on the Tree. 2003. Journal of Vascular Biology. In Press.

Tessier D., Komalavilas P., Panitch A., Joshi L., Brophy C.M. 2003. The small heat shock protein (HSP) 20 is dynamically associated with the actin cross-linking protein actinin. J Surg Res. 111(1):152-7.

Flynn, C.R., Komalavilas, P., Tessier, D., Thresher, J., Niederkofler, E.E., Parmiter, C., Nelson, R.W., Panitch, A., Joshi, L., Brophy, C.M. 2003. Transduction of Biologically-Active Motifs of the Small Heat Shock-related Protein, HSP20, Leads to Relaxation of Vascular Smooth Muscle. Faseb J Express. 17(10):1358-60. Epub 2003 May 08.

Joshi, L., Shah, M., Flynn, C.R., and Panitch, A. 2003. Development of bioengineered plants as a source of protein/peptide Pharmaceuticals. In Transgenic Crops and Human Health, Encyclopedia of Plant & Crop Science, (Ed. Joshi, L.). Marcel Dekker, Inc. NY. In Press.

Joshi, L, JM Van Eck, K Mayo, R Di Silverstro, ME Blake (Nieto), T Ganapathi, V Haridas, JU Gutterman and CJ Arntzen. (2002) Metabolomics of plant saponins; Bioprospecting triterpene glycoside diversity with respect to mammalian cell targets. OMICS: Journal of Integrative Biology. 6(3), 235-245.

Joshi, L, MJ Shuler, and HA Wood. (2001). Production of a Sialylated N-linked Glycoprotein in Insect cells. Biotechnology Progress 17:822-827.

Kalidas, C, L Joshi, and C Batt. (2001). Characterization of glycosylated variants of beta-lactoglobulin expressed in Pichia pastoris. Protein Engineering 14(3):201-207.

Joshi, L, TR Davis, TS Mattu, PM Rudd, RA Dwek, ML Shuler, and HA Wood. (2000). The influence of baculovirus host cell interaction on glycosylation of a recombinant protein. Biotechnology Progress 16:650-656.

Wood, HA, ML Shuler, and L Joshi. (2000). On earth and in space: Insect cell glycosylation pathway. In Vitro Cellular and Developmental Biology-Animal 36 (3 Part 2):4.A..

Joshi, L, ML Shuler, and HA Wood. (1999). Insecta can Perform Human-Type Glycosylation. Glycobiology 9 (10), 1126. Abstract.

Joshi, L and RJ St. Leger. (1999). Cloning, functional expression and substrate specificity of carboxypeptidase A secreted by the pathogenic fungus Metarhizium anisopliae. Journal of Biological Chemistry 274(14):9803-9811.

St. Leger, RJ, L Joshi, and DW Roberts. (1998). Ambient pH is a major determinant in the expression of cuticle degrading enzymes and hydrophobin by Metarhizium anisopliae. Applied and Environmental Microbiology 64(2):709-713.

St. Leger, RJ, L Joshi, and DW Roberts. (1998). Adaptation of proteases and carbohydrates of saprophytic, phytopathogenic and entomopathogenic fungi to the requirements of their ecological niches. Microbiology 1997 Jun 143 ( Pt 6):1983-92.

St. Leger, RJ and L Joshi. (1997). Molecular methods for studying entomopathogenic fungi. IN: Practical guides to New Methods in Modern Biology - Manual of techniques in insect pathology (ed. LA Lacey). Academic Press. 367-394.

Joshi, L, RJ St. Leger, and DW Roberts. (1997). Isolation of a cDNA encoding a novel subtilisin-like protease (Pr1B) from the entomopathogenic fungus, Metarhizium anisopliae using differential display-RT-PCR. Gene 197:1-8.