Summary of the Overall Laboratory Research Interests

The Overall Lab founded the field of ‘degradomics’. Degradomics is the application of genomic and proteomic techniques to determine protease and protease-substrate repertoires—or ‘degradomes’—on an cell, tissue and organism-wide scale. The Overall Lab has developed world-leading innovative quantitative proteomic techniques to enrich and identify proteolysis products in vivo. This awareness and understanding derived from application of “omics” technologies to complex biological systems has revolutionized the understanding of the roles of proteases and matrix metalloproteinases (MMP) in particular, in physiological and pathological processes in vivo.

For technical reasons protein cleavage is opaque to conventional proteomics, which limits functional insight. Therefore, to specifically enrich for mature protein N-termini and neo-N-termini of proteins we utilize 4-8plex iTRAQ and 10plex TMT TAILS (Terminal Amine Isotopic Labeling of Substrates) (Nature Biotech 28, 281-288 (2010); Nature Protocols 6, 1578-1611 (2011). Using quantitative proteomics information determined through TAILS, our lab’s signature approach, the protein substrate and the exact cleavage site are determined in the same analysis. By analyzing all N-termini, the original mature N terminus of a protein together with protease generated neo-N termini, the N-terminome of the tissue is elucidated. By then analyzing all quantifiable peptides that change in abundance significantly between samples, protein expression and new protease substrates are identified. On a global scale this generates the proteolytic signature of the tissue. The proteolytic signature can be used to identify protease networks in vivo that are operative in the system under study and to identify new disease biomarkers, with the advantage of being mechanistically informative. Resultant new drug targets and new clinical tests for early, accurate patient diagnosis can thereby by translated. [read more …]

Research Highlights

The Overall Laboratory has helped shape the current view of MMPs as key regulators of multiple signaling pathways that are integral to innate immunity rather than just dowdy degraders of the extracellular matrix (Butler & Overall 09 Nature Rev Drug Disc). We were at the forefront in this revision of in vivo roles for MMP with the first use of yeast 2-hybrid substrate screens for protease substrate discovery, that identified chemokines and CCN cytokines as novel MMP substrates (McQuibban et al 00 Science). Next we adapted proteomics for substrate discovery, but soon recognized inadequacies for the specialized tasks of substrate and cleavage site identification (López-Otín & Overall 02 Nature Rev Mol Cell Biol; Overall & Blobel 07 Nature Rev Mol Cell Biol). So, we initiated the new field of degradomics in 2000 to describe all genomic and proteomic investigations of proteases, their inhibitors and substrates. Following this paper in Science (McQuibban et al 00 Science) Dr. Carlos López-Otín (Chair of the 2007 MMP Gordon Research Conference) and Dr. Chris Overall wrote an invited review in Nature Reviews Molecular Cell Biology formally introducing the term degradomics and describing approaches to study proteolysis on a system-wide scale (López-Otín & Overall 02 Nature Rev Mol Cell Biol). This was updated by another paper in Nature Reviews Molecular Cell Biology, co-authored with Dr. Carl Blobel (Chair of the 2009 MMP Gordon Research Conference), describing proteomic and other innovative techniques to link proteases with substrates (Overall & Blobel 07 Nature Rev Mol Cell Biol). In Nature Reviews Genetics we annotated the complete human and mouse protease and inhibitor degradomes (Puente et al 2003 Nature Rev Genetics)[read more …]