Theoretical study of the intermolecular recognition mechanism between Survivin and substrate based on conserved binding mode analysis

Tanshinol alleviates ischemia-induced myocardial fibrosis via targeting ERK2 and disturbing the intermolecular autophosphorylation of ERK2Thr188

Myocardial fibrosis is the fundamental remodeling process in myocardial ischemia (MI) and also the major contributor of heart failure and death. Tanshinol (Danshensu in Chinese, DSS), a major ingredient of salvia mitiorrhiza Bunge (Lamiaceae) root, exerted significant cardio protection effects. In this study, we aimed to identify the action target and then uncover the mechanism of DSS alleviating myocardial fibrosis. The pharmacological activities of DSS protecting ischemic cardiac was assessed and the myocardial proteomics was carried out. To identify the target of DSS, a cellular thermal shift assay combined with LC-MS identification was conducted. Surface plasmon resonance assay, molecular dynamics simulation and pharmacological and molecular biology approaches were adopted to explore the action mechanisms of DSS. Our results revealed that DSS effectively alleviated MI-induced left ventricle dysfunctions and the increasements of circulating myocardial markers. Besides, DSS significantly reversed the proteomic profile related to myocardial fibrotic processes and the ERK2 was identified as a crucial cellular target of DSS. DSS abated the temperature-dependent denaturation of ERK2 in a dose-dependent manner and the KD value of DSS and ERK2 was 60.19 μM. After Ang II stimulation, DSS suppressed the phosphorylation of Thr188 rather than the classic residues in TEY motif. DSS interfered the ERK2 homo-dimerization and then blocked the intermolecular autophosphorylation at Thr188 site. Thereout, DSS inhibited the nuclear translocation of ERK2 and the expression of downstream fibrotic biomolecules. Collectively, our results demonstrated that DSS targeted ERK2 and suppressed the intermolecular autophosphorylation at Thr188 residue, thus protecting ischemic myocardia from fibrosis remodeling.

Synthetic Antibodies Detect Distinct Cellular States of Chromosome Passenger Complex Proteins

High performance affinity reagents are essential tools to enable biologists to profile the cellular location and composition of macromolecular complexes undergoing dynamic reorganization. To support further development of such tools, we have assembled a high-throughput phage display pipeline to generate Fab-based affinity reagents that target different dynamic forms of a large macromolecular complex, using the Chromosomal Passenger Complex (CPC), as an example. The CPC is critical for the maintenance of chromosomal and cytoskeleton processes during cell division. The complex contains 4 protein components: Aurora B kinase, survivin, borealin and INCENP. The CPC acts as a node to dynamically organize other partnering subcomplexes to build multiple functional structures during mitotic progression. Using phage display mutagenesis, a cohort of synthetic antibodies (sABs) were generated against different domains of survivin, borealin and INCENP. Immunofluorescence established that a set of these sABs can discriminate between the form of the CPC complex in the midbody versus the spindle. Others localize to targets, which appear to be less organized, in the nucleus or cytoplasm. This differentiation suggests that different CPC epitopes have dynamic accessibility depending upon the mitotic state of the cell. An Immunoprecipitation/Mass Spectrometry analysis was performed using sABs that bound specifically to the CPC in either the midbody or MT spindle macromolecular assemblies. Thus, sABs can be exploited as high performance reagents to profile the accessibility of different components of the CPC within macromolecular assemblies during different stages of mitosis suggesting this high throughput approach will be applicable to other complex macromolecular systems.

Notoginsenoside R1 Regulates Ischemic Myocardial Lipid Metabolism by Activating the AKT/mTOR Signaling Pathway

Ischemic heart diseases are responsible for more than one-third of all deaths worldwide. Radix notoginseng is widely used to treat ischemic heart disease in China and other Asian countries, and notoginsenoside R1 (NGR1) is its characteristic and large-amount ingredient. However, the potential molecular mechanisms of NGR1 in improving ischemic heart diseases are unclear. In this study, we combined pharmacological evaluation with network pharmacology, myocardial proteomics, and conventional molecular dynamics (MD) simulation to explore the cardio-protection mechanisms of NGR1. Our results revealed that NGR1 improved the echocardiographic, tissue pathological, and serum biochemical perturbations in myocardial ischemic rats. The network pharmacology studies indicated that NGR1 mainly regulated smooth muscle cell proliferation, vasculature development, and lipid metabolism signaling, especially in the PI3K/AKT pathway. Myocardial proteomics revealed that the function of NGR1 was focused on regulating metabolic and energy supply processes. The research combined reverse-docked targets with differential proteins and demonstrated that NGR1 modulated lipid metabolism in ischemic myocardia by interacting with mTOR and AKT. Conventional MD simulation was applied to investigate the influence of NGR1 on the structural stabilization of the mTOR and AKT complex. The results suggested that NGR1 can strengthen the affinity stabilization of mTOR and AKT. Our study first revealed that NGR1 enhanced the affinity stabilization of mTOR and AKT, thus promoting the activation of the AKT/mTOR pathway and improving lipid metabolic abnormity in myocardial ischemic rats.

The survivin molecule as a double-edged sword in cellular physiologic and pathologic conditions and its role as a potential biomarker and therapeutic target in cancer

Survivin is a member of the family of apoptosis inhibitory proteins with increased expression level in most cancerous tissues. Evidence shows that survivin plays regulatory roles in proliferation or survival of normal adult cells, principally vascular endothelial cells, T lymphocytes, primitive hematopoietic cells, and polymorphonuclear neutrophils. Survivin antiapoptotic role is, directly and indirectly, related to caspase proteins and shows its role in cell division through the chromosomal passenger complex. Survivin contains many genetic polymorphisms that the role of some variations has been proven in several cancers. The -31G/C polymorphism is one of the most important survivin mutations which is located in the promoter region on a CDE/CHR motif. This polymorphism can upregulate the survivin messenger RNA. In addition, its allele C can increase the risk of cancers in 1.27-fold than allele G. Considering the fundamental role of survivin in different cancers, this protein could be considered as a new therapeutic target in cancer treatment. For this purpose, various strategies have been designed including the prevention of survivin expression through inhibition of mRNA translation using antagonistic molecules, inhibition of survivin gene function through small inhibitory molecules, gene therapy, and immunotherapy. In this study, we describe the structure, played roles in physiological and pathological states and genetic polymorphisms of survivin. Finally, the role of survivin as a potential target in cancer therapy given challenges ahead has been discussed.