Targeted Degradation of Proteins by Small Molecules: A Novel Tool for Functional Proteomics†

D.      Zhang; S.-   H.   Baek; A.      Ho; H.      Lee; Y.   S.   Jeong; K.      Kim

Abstract

A novel strategy that targets protein for degradation has recently been developed by exploiting a protein-targeting chimeric molecule (‘Protac’). Typically, the chimeric Protac is composed of a small-molecule ligand (‘bait’) on one end and a synthetic octapeptide on the other. This octapeptide is recognized by E3 ubiquitin ligase pVHL (von Hippel Lindau tumor suppressor protein), thereby recruiting a small moleculebound protein (‘prey’) to pVHL for ubiquitination and degradation. Since selective degradation of a cellular protein generates a “loss of function” mutation, this protein knock-out strategy may be useful to study the function of a given protein or to evaluate whether a cellular protein is a potential target for drug intervention, in a manner reminiscent of gene knock-out or siRNA approaches. Herein, we show that a synthetic pentapeptide is sufficient to interact with pVHL E3 ligase, and that the pentapeptide-based Protac efficiently induces ubiquitination and degradation of target protein. Our results also demonstrate that the pentapeptide-based Pr otac can enter cells efficiently to exerts its biological activity effectively. These results suggest that the synthetic pentapeptide can be used either directly in the preparation of cell-permeable Protacs or as a template to develop peptidomimetic or non-peptide Protacs.

Keywords: protein-targeting chimeric molecule (protac), ubiquitin, e3 ubiquitin ligase, post-genomic era, hypoxia-inducing factor, von hippel lindau tumor suppressor protein (pvhl), proteasome, estrogen receptor (er), estradiol (e2)