%0 Journal Article
%T Development of Small Molecular Proteasome Inhibitors Using a Caenorhabditis elegans Screen
%A Sudhir Nayak
%A Michela Fiaschi
%A Dana King
%A Erica R. Tabakin
%A Lyndsay Wood
%A David A. Hunt
%J International Journal of Medicinal Chemistry
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/237286
%X We have developed a screening protocol to identify compounds with characteristics of small molecule proteasome inhibitors using the real-time analysis of the Caenorhabditis elegans germ line. This screen is able to identify compounds that induce germ line phenotypes characteristic of a reduction in proteasome function such as changes in polarity, aberrant nuclear morphology, and stimulation of apoptosis. This basic protocol is amenable to a high throughput (96-well) format and has been used successfully to identify multiple compounds for further analysis based on structural elements from the naturally occurring compounds lactacystin and the ¦Â-lactone homologs omuralide and salinosporamide A. The further development of this assay system should allow for the generation of novel small molecule proteasome inhibitors in a genetically tractable whole animal amenable to biochemical analysis. 1. Introduction The controlled turnover of proteins is essential for the majority of cellular processes, including cell proliferation and cell death. The bulk of protein turnover in the cell is governed by the 26S proteasome, a highly conserved multisubunit protease complex with essential roles in regulating proteins levels in the cytoplasm and nucleus of all eukaryotes [1¨C5]. In addition to the well-studied roles of 26S in cell cycle regulation and removal of misfolded proteins, proteasome activity has also been implicated stress response, gene expression, DNA repair, immune regulation, and carcinogenesis [6]. The central role of the 26S proteasome in the selective degradation of intracellular proteins involved in the cell cycle has made it a target of considerable interest in the development of novel anticancer therapeutics. Over the last 15 years, a variety of synthetic and natural compounds have been characterized that selectively inhibit the proteasome and fall into seven major categories (aldehydes, ¦Â-lactones, epoxyketones, boronates, vinyl sulfones, cyclic peptides, and macrocyclic vinyl ketones) [7]. Other than cyclic peptides, both synthetic and natural inhibitors have a small molecule backbone with a reactive pharmacophore that is able to interact with the N-terminal threonine of the catalytic ¦Â-subunits and interfere with proteolytic activity [8]. All categories of synthetic and natural proteasome inhibitors have been useful in elucidating the role of the 26S proteasome in normal cellular processes. Importantly, the dipeptidyl boronic acid Bortezomib (MG-341, PS-341, Velcade) has also been approved as a therapeutic in the treatment of multiple myeloma [9]. The
%U http://www.hindawi.com/journals/ijmc/2014/237286/