Inhibition of OSBP blocks retrograde trafficking by inducing partial Golgi degradation.

Sterol-binding proteins are important regulators of lipid homeostasis and membrane integrity; however, the discovery of selective modulators can be challenging due to structural similarities in the sterol-binding domains. We report the discovery of potent and selective inhibitors of oxysterol-binding protein (OSBP), which we term oxybipins. Sterol-containing chemical chimeras aimed at identifying new sterol-binding proteins by targeted degradation, led to a significant reduction in levels of Golgi-associated proteins.

Fluorescent probes and degraders of the sterol transport protein Aster-A.

Our understanding of sterol transport proteins (STPs) has increased exponentially in the last decades with advances in the cellular and structural biology of these important proteins. However, small molecule probes have only recently been developed for a few selected STPs. Here we describe the synthesis and evaluation of potential proteolysis-targeting chimeras (PROTACs) based on inhibitors of the STP Aster-A.

A "Three-in-One" Multifunctional Probe for Bcl-2/Mcl-1 Profiling and Visualizing in Situ.

Bcl-2 and Mcl-1, the two arms of the anti-apoptotic Bcl-2 family proteins, have been identified as key regulators of apoptosis and effective therapeutic targets of cancer. However, no small-molecular probe is capable of profiling and visualizing both Bcl-2 and Mcl-1 simultaneously in situ. Herein, we report a multifunctional molecular probe (BnN -OPD-Alk) by a "three-in-one" molecular designing strategy, which integrated the Bcl-2/Mcl-1 binding ligand, fluorescent reporter group and photoreactive group azido into the same scaffold.

Proteolysis Targeting Chimeras for the Selective Degradation of Mcl-1/Bcl-2 Derived from Nonselective Target Binding Ligands.

Proteolysis targeting chimera (PROTAC) recruits an E3 ligase to a target protein to induce its ubiquitination and subsequent degradation. We reported success in the development of two PROTACs ( and ) that potently and selectively induce the degradation of Mcl-1 and Bcl-2 (DC = 0.7 and 3.

A novel turn-on fluorescent probe for selective sensing and imaging of glutathione in live cells and organisms.

We synthesized six 1-oxo-1H-phenalene-2,3-dicarbonitrile (OPD)-based probes with various leaving groups using an arylthioether linker and for the first time identified the probe O-NH2 capable of highly selective detection of glutathione over cysteine/homocysteine in vitro and in vivo based on an aromatic nuclear substitution reaction (SNAr) mechanism. The fluorescence of the probe O-NH2 was quenched because of the photoinduced electron transfer (PET) process, but switched on by a glutathione-triggered specific recognition reaction between the probe O-NH2 and glutathione. The recognition mechanism for glutathione was explored and verified by theoretical calculations and ESI-MS analysis.

Discovery of selective Mcl-1 inhibitors via structure-based design and structure-activity relationship analysis.

Based on Nap-1, a Mcl-1/Bcl-2 dual inhibitor reported by our group, we carried out a structure-guided molecular design and structure-activity relationship (SAR) analysis to study structural features contributing to Mcl-1 binding selectivity and affinity. A series of derivatives of Nap-1 with various pharmacophores were synthesized and among them a dual Mcl-1/Bcl-2 inhibitor A4 with enhanced affinities (IC = 0.15 μM for Mcl-1, 0.

Proteome-Wide Identification of On- and Off-Targets of Bcl-2 Inhibitors in Native Biological Systems by Using Affinity-Based Probes (AfBPs).

Selective inhibition of proteins of the Bcl-2 family by small-molecule inhibitors is a promising new approach in drug discovery. However, information about how these molecules interact with their cellular targets (on- and off-) is highly limited. We have designed and synthesized photoreactive and "clickable" affinity-based probes (AfBPs)-Nap-2 and Nap-5-by introducing photo-crosslinkers onto Nap-1, a fluorescent derivative of small-molecule Bcl-2 inhibitor S1-6.