Hsin-Yao Tang, Ph.D.

The Tang laboratory is actively involved in multiple collaborative projects that focus on defining disease-related cellular mechanisms and discovering therapeutic targets of diseases. These projects involve diverse experimental strategies that include global proteome profiling, quantification of disease biomarkers, characterization of protein post-translational modifications, identification of protein interactomes, and global polar metabolite and lipid profiling. Results from these analyses have provided insights into mechanisms underlying different cancers such as melanoma, prostate cancer, and ovarian cancer, as well as identified putative biomarkers for disease states.

The Tang laboratory is also involved in improving proteomics technologies in key areas including:

• Chemical crosslink-MS. Chemical crosslinking combined with mass spectrometry (MS) analysis is a powerful method to study protein-protein interaction networks and to obtain valuable structural information from protein complexes. Both traditional non-cleavable and MS-cleavable cross-linkers can be used for identification of protein-protein interaction sites, but MS-cleavable crosslinkers are advantageous because of their ability to generate distinguishing fragment ions during MS/MS that greatly improve identification of crosslinked peptides and crosslinked sites. These diagnostic fragment ions will also reduce the search space during data analysis, allowing the crosslinkers to be used in whole proteome labeling studies. We are interested in developing a robust and reliable workflow for efficient identification of crosslinked sites on proteins using MS-cleavable cross-linkers, such as DSSO and DSBU.
• MS-based glycomics and glycoproteomics. Glycosylation is one of the most abundant post-translational modifications (PTMs) in mammalian cells and is crucial for a wide range of biofunctions. Aberrant glycosylation of proteins has been linked to various diseases, including cancers. The major strength of MS-based analyses is the isolation and fragmentation of analytes to obtain structural information. MS-based glycomics typically consists of the following steps: glycan release by either PNGase F treatment (for N-linked glycans) or β-elimination (for O-linked glycans), glycan enrichment using solid phase separation techniques, glycan derivatization, and LC-MS/MS identification. Global profiling of released glycans has been used to distinguish healthy and disease states. However, information on the protein carriers of glycans and residue site localization is lost after glycan release. The more powerful MS-based glycoproteomics approach that we plan to focus on involves structural analysis of glycopeptides. Protein extracts are proteolytically digested followed by glycopeptide enrichment with subsequent LC-MS/MS analysis. Since the glycan is left intact on the peptide, this method allows the identification of the glycosylated proteins and quantitation of the glycan structures on the glycoproteins.