Simultaneous measurement of p53:Mdm2 and p53:Mdm4 protein-protein interactions in whole cells using fluorescence labelled foci

Icariin-Mediated miR-875-5p Inhibits Autophagy and Epithelial-Mesenchymal Transition by Regulation of MDM4 in Cervical Cancer

MicroRNAs, one type of non-coding RNA, and Icariin have attracted tremendous attention concerning various diseases, especially cancers. Also, the function of Icariin on malignant behaviors by targeting miR-875-5p/MDM4 axis in cervical cancer remains unknown. MiR-875-5p analogs combined with MDM4 or Icariin were used to explore autophagy and epithelial-mesenchymal transition in cancer cells. Xenograft mice were highlighted to elucidate the influences of Icariin and miR-875-5p in vivo. As a result, miR-875-5p was cut down in cervical cancer cells, which promoted malignant phenotype, autophagy, and limited apoptosis in cervical cancer cells. Contrarily,miR-875-5p overexpression had a contrary performance in cervical cancer cells. miR-875-5p was validated as a sponge of MDM4. Enhanced expression of MDM4 weakened the performance of miR-875-5p mimic on autophagy and epithelial-mesenchymal transition. Moreover, Icariin reversed the stimulative action of the inhibitor on autophagy and xenograft tumor growth. Generally, These findings imply that Icariin could be identified as a curative avenue for cervical cancer via miR-875-5p/MDM4 axis.

Functional display of bioactive peptides on the vGFP scaffold

Grafting bioactive peptides into recipient protein scaffolds can often increase their activities by conferring enhanced stability and cellular longevity. Here, we describe use of vGFP as a novel scaffold to display peptides. vGFP comprises GFP fused to a bound high affinity Enhancer nanobody that potentiates its fluorescence. We show that peptides inserted into the linker region between GFP and the Enhancer are correctly displayed for on-target interaction, both in vitro and in live cells by pull-down, measurement of target inhibition and imaging analyses. This is further confirmed by structural studies highlighting the optimal display of a vGFP-displayed peptide bound to Mdm2, the key negative regulator of p53 that is often overexpressed in cancer. We also demonstrate a potential biosensing application of the vGFP scaffold by showing target-dependent modulation of intrinsic fluorescence. vGFP is relatively thermostable, well-expressed and inherently fluorescent. These properties make it a useful scaffold to add to the existing tool box for displaying peptides that can disrupt clinically relevant protein–protein interactions.

Fluorescence Quantum Yields in Complex Environments from QM-MM TDDFT Simulations: The Case of Indole in Different Solvents

Fluorescence is commonly exploited to probe microscopic properties. An important example is tryptophan in protein environments, where variations in fluorescence quantum yield, and in absorption and emission maxima, are used as indicators of changes in the environment. Modeling the fluorescence quantum yield requires the determination of both radiative and nonradiative decay constants, both on the potential energy surface of the excited fluorophore. Furthermore, the inclusion of complex environments implies their accurate representation as well as extensive configurational sampling. In this work, we present and test various methodologies based on time-dependent density functional theory (TDDFT) and quantum mechanics/molecular mechanics (QM/MM) dynamics that take all of these requirements into account to provide a quantitative prediction of the effect of the environment on the fluorescence quantum yield of indole, a tryptophan fluorophore. This investigation paves the way for applications to the realistic spectroscopic characterization of the local protein environment of tryptophan from computer simulations.