Daiwen Yang (Professor)
1. Mechanism of silk fiber formation and production of engineered spider silk and functionalized fibers
Spider silk is orderly assembled from one or more silk proteins. Due to its outstanding mechanical property, lightness, biodegradability and biocompatibility, spider silk is a super material with substantial potential in medicine and industry. Unfortunately, spider silk is not available commercially because spiders are cannibalistic and territorial and thus cannot be farmed. To make spider silk available on a large scale, various recombinant methods have been attempted but with limited success due to our poor understanding of the molecular mechanism of silk fiber formation and the silk structure-property relationship.
We focus on the structures of silk proteins, production of spider silk from recombinant silk proteins, and generation of silk fibers with various biochemical functions. To reveal the fiber formation mechanism and silk property-structure relationship, we have been studying the structures of silk proteins at different stages of fiber formation using biophysical techniques such as nuclear magnetic resonance spectroscopy (NMR), electron microscopy (EM), X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), and mass spectrometry (MS). It is noteworthy that silk formation involves dramatic changes from water-soluble proteins with dominant random-coil or α-helical structures to insoluble silk fibers with dominant β-sheet structures. In order to produce super silk, we have been engineering silk proteins by molecular biology techniques for high yield production and developing microfluidic device for spinning protein solution into strong silk. Silk proteins can be easily modified by fusing with enzymes or other proteins with various functions or by chemical modification. Using such modified proteins, we are producing functional biomaterials.
2. Fatty acid binding proteins and structure-based drug design
Fatty acid binding proteins (FABPs) are a cluster of specific carrier proteins that actively facilitate the transport of fatty acids to specific organelles in the cell for metabolism, storage, and signalling. They are critical meditators of metabolism and inflammatory processes and are considered as promising therapeutic targets for metabolic diseases. Nine types of FABPs (FABP1-9) are found in the cytosol of a variety of mammalian tissues and some are detected in human serum. Besides the common role as fatty acid carriers, FABPs may play other roles in different biological processes since FABP4 (adipocyte FABP) is implicated in diabetes, FABP1 (liver FABP) is related to kidney and non-alcoholic liver diseases, and FABP3 (heart FABP) is associated with neurodegenerative diseases such as Alzheimer’s.
Because the differential functional roles of different FABPs cannot be explained by the structures alone, we have been studying the dynamics that is currently the missing link between the protein structure and function using mutagenesis, NMR, MS and molecular dynamics simulation. We aim to understand how different FABPs play differential functions and to design inhibitors and antibodies that selectively target one FABP. Identification of true inhibitors and antibodies is achieved using bioassays and animal models, while functional tests are performed on animal models.
3. Stem cell reprogramming factors
Induced pluripotent stem cells (iPSCs) have been generated from somatic cells using a set of reprogramming factors (either [Oct4, Sox2, Klf4 and c-Myc] or [Oct4, Sox2, Nanog and Lin28]). iPSCs generated from patients can differentiate into various cell types, which suggests that iPSCs could provide an unlimited cell resource for regenerative medicine, transgenic breeding, and understanding disease mechanisms. Unfortunately, the efficiency of reprogramming somatic cells into iPSCs is still very low, and this is a large obstacle hindering the utility of reprogramming technology. It has long been hypothesized that cancer arises from a subpopulation of tumor cells with stem cell properties. Indeed, the elevated expressions of Oct4 and Nanog have been detected in many types of cancers.
Key reprogramming factors (including Oct4, Sox2 and Nanog) are dominated by intrinsically disordered regions that account for about 62%-80% of their amino acid sequences. The disordered regions are essential for the functions, but they have received little attention. To improve the reprogramming efficiency and provide a method to suppress tumorigenesis, we are studying the structures and functions of the disordered regions of Oct4, Sox2 and Nanog using NMR and mutagenesis. We aim to identify residues or regions critical for enhancing reprogramming efficiency and tumorigenesis. Experiments on reprogramming efficiency and tumorigenesis are done in collaboration with stem cell biologists.
4. Development of NMR and computational methods for protein structure determination and dynamics characterization
To overcome difficulties encountered in our characterization of protein structures and dynamics, we develop novel NMR experiments and new computational methods.
- 2011 – present: Professor, Department of Biological Sciences, National University of Singapore.
- 2005 – 2011: Associate professor, Department of Biological Sciences, National University of Singapore.
- 2001 – 2005: Assistant professor, Department of Biological Sciences and Department of Chemistry, National University of Singapore.
- 1997 – 2000: Research associate, Department of Medical Genetics, University of Toronto, Canada.
- 1995 – 1997: Postdoctoral research fellow, Department of Medical Genetics, University of Toronto, Canada.
- 1992 – 1995: Postdoctoral research fellow, Nagayama protein array project, ERATO, JRDC, Japan.
- Department of Biological Sciences, National University of Singapore
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- Tel: 65-65161014. Fax: 65-67792486. E – mail: email@example.com