A ligand discovery toolbox for the WWE domain family of human E3 ligases.

The WWE domain is a relatively under-researched domain found in twelve human proteins and characterized by a conserved tryptophan-tryptophan-glutamate (WWE) sequence motif. Six of these WWE domain-containing proteins also contain domains with E3 ubiquitin ligase activity. The general recognition of poly-ADP-ribosylated substrates by WWE domains suggests a potential avenue for development of Proteolysis-Targeting Chimeras (PROTACs).

Development of Selective ADAMTS-5 Peptide Substrates to Monitor Proteinase Activity.

The dysregulation of proteinase activity is a hallmark of osteoarthritis (OA), a disease characterized by progressive degradation of articular cartilage by catabolic proteinases such as a disintegrin and metalloproteinase with thrombospondin type I motifs-5 (ADAMTS-5). The ability to detect such activity sensitively would aid disease diagnosis and the evaluation of targeted therapies. Förster resonance energy transfer (FRET) peptide substrates can detect and monitor disease-related proteinase activity.

Imaging articular cartilage in osteoarthritis using targeted peptide radiocontrast agents.

Background: Established MRI and emerging X-ray contrast agents for non-invasive imaging of articular cartilage rely on non-selective electrostatic interactions with negatively charged proteoglycans. These contrast agents have limited prognostic utility in diseases such as osteoarthritis (OA) due to the characteristic high turnover of proteoglycans. To overcome this limitation, we developed a radiocontrast agent that targets the type II collagen macromolecule in cartilage and used it to monitor disease progression in a murine model of OA.

Single Amino Acid Replacement in G-7039 Leads to a 70-fold Increase in Binding toward GHS-R1a.

The growth hormone secretagogue receptor type 1a (GHS-R1a) is a class A rhodopsin-like G protein coupled receptor (GPCR) that is expressed in a variety of human tissues and is differentially expressed in benign and malignant prostate cancer. Previously, the peptidomimetic [1-Nal ,Lys (4-fluorobenzoyl)]G-7039 was designed as a molecular imaging tool for positron emission tomography (PET). However, this candidate was a poor binder (IC =69 nm), required a lengthy four-step radiosynthesis, and had a cLogP above 8.

Purification and Activity Determination of ADAMTS-4 and ADAMTS-5 and Their Domain Deleted Mutants.

A disintegrin-like and metalloproteinase with thrombospondin type-1 motifs-4 (ADAMTS-4) and ADAMTS-5 are zinc-dependent metalloproteinases that are involved in the maintenance of cartilage extracellular matrix (ECM) and are currently considered the major aggrecanases in the development of osteoarthritis. In this chapter we describe the establishment and cultivation of cell lines expressing ADAMTS-4,-5 and their domain deletion mutants; the collection of medium containing expressed ADAMTS-4,-5; the subsequent purification of this medium through anti-FLAG affinity chromatography; and the characterization of ADAMTS-4,-5 activity using synthetic Förster resonance energy transfer (FRET) peptide substrates.

Peptidomimetic growth hormone secretagogue derivatives for positron emission tomography imaging of the ghrelin receptor.

The ghrelin receptor is a seven-transmembrane (7-TM) receptor known to have an increased level of expression in human carcinoma and heart failure. Recent work has focused on the synthesis of positron emission tomography (PET) probes designed to target and image this receptor for disease diagnosis and staging. However, these probes have been restricted to small-molecule quinalizonones and peptide derivatives of the endogenous ligand ghrelin.

Bridging computational modeling with amino acid replacements to investigate GHS-R1a-peptidomimetic recognition.

The ghrelin receptor, also referred to as the growth hormone secretagogue receptor 1a (GHS-R1a), is a G protein-coupled receptor (GPCR) primarily expressed in the brain and pituitary. The wide spectrum of biological functions of GHS-R1a has rendered it a target for therapeutic drugs and for molecular imaging agents, for a variety of diseases. An improved understanding of the binding mechanism of a ligand to GHS-R1a would provide guidance on ligand design.