A one-step specific assay for continuous detection of sirtuin 2 activity

Cuproptosis-a potential target for the treatment of osteoporosis

Osteoporosis is an age-related disease of bone metabolism marked by reduced bone mineral density and impaired bone strength. The disease causes the bones to weaken and break more easily. Osteoclasts participate in bone resorption more than osteoblasts participate in bone formation, disrupting bone homeostasis and leading to osteoporosis. Currently, drug therapy for osteoporosis includes calcium supplements, vitamin D, parathyroid hormone, estrogen, calcitonin, bisphosphates, and other medications. These medications are effective in treating osteoporosis but have side effects. Copper is a necessary trace element in the human body, and studies have shown that it links to the development of osteoporosis. Cuproptosis is a recently proposed new type of cell death. Copper-induced cell death regulates by lipoylated components mediated via mitochondrial ferredoxin 1; that is, copper binds directly to the lipoylated components of the tricarboxylic acid cycle, resulting in lipoylated protein accumulation and subsequent loss of iron-sulfur cluster proteins, leading to proteotoxic stress and eventually cell death. Therapeutic options for tumor disorders include targeting the intracellular toxicity of copper and cuproptosis. The hypoxic environment in bone and the metabolic pathway of glycolysis to provide energy in cells can inhibit cuproptosis, which may promote the survival and proliferation of various cells, including osteoblasts, osteoclasts, effector T cells, and macrophages, thereby mediating the osteoporosis process. As a result, our group tried to explain the relationship between the role of cuproptosis and its essential regulatory genes, as well as the pathological mechanism of osteoporosis and its effects on various cells. This study intends to investigate a new treatment approach for the clinical treatment of osteoporosis that is beneficial to the treatment of osteoporosis.

Development of a single-step fluorogenic sirtuin assay and its applications for high-throughput screening

Sirtuins (SIRTs) are a class of nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylases. Since SIRTs have different subcellular locations and different preferences for deacylation activity, SIRTs are not only highly gaining significance in biological functions but also implications in human diseases. Therefore, it is valuable to establish a high-throughput screening method for the rapid and accurate discovery of SIRT modulators. In this study, we designed and synthesized small molecules 4a-d as fluorogenic probes based on the different lysine substrates of SIRTs, which can be recognized and catalyzed by SIRTs and then spontaneous intramolecular transesterification can give the fluorescence. We have undertaken a comprehensive study of these fluorogenic probes with different SIRTs for assay optimization, validation, kinetics, parameters, and applications of high-throughput screening formats. We envision that these probes will provide useful and powerful tools for the highly efficient discovery of more SIRT inhibitors.

Multi-omics approaches identify SF3B3 and SIRT3 as candidate autophagic regulators and druggable targets in invasive breast carcinoma

Autophagy is a critical cellular homeostatic mechanism, and its dysfunction is linked to invasive breast carcinoma (BRCA). Recently, several omics methods have been applied to explore autophagic regulators in BRCA; however, more reliable and robust approaches for identifying crucial regulators and druggable targets remain to be discovered. Thus, we report here the results of multi-omics approaches to identify potential autophagic regulators in BRCA, including gene expression (EXP), DNA methylation (MET) and copy number alterations (CNAs) from The Cancer Genome Atlas (TCGA). Newly identified candidate genes, such as SF3B3, TRAPPC10, SIRT3, MTERFD1, and FBXO5, were confirmed to be involved in the positive or negative regulation of autophagy in BRCA. SF3B3 was identified firstly as a negative autophagic regulator, and siRNA/shRNA-SF3B3 were shown to induce autophagy-associated cell death in in vitro and in vivo breast cancer models. Moreover, a novel small-molecule activator of SIRT3, 1-methylbenzylamino amiodarone, was discovered to induce autophagy in vitro and in vivo. Together, these results provide multi-omics approaches to identify some key candidate autophagic regulators, such as the negative regulator SF3B3 and positive regulator SIRT3 in BRCA, and highlight SF3B3 and SIRT3 as new druggable targets that could be used to fill the gap between autophagy and cancer drug development.

A Set of Highly Sensitive Sirtuin Fluorescence Probes for Screening Small-Molecular Sirtuin Defatty-Acylase Inhibitors

Human sirtuins (SIRT1-7) regulate not only deacetylation but also deacylation of fatty acid-derived acyl moieties (defatty-acylation) at the ε-amino group of lysine residues. SIRT-subtype-specific defatty-acylase activity modulators are needed for detailed investigation of the biological roles of these enzymes, and to find suitable small molecules, we require appropriate screening systems. Here, we designed and synthesized a set of SIRT defatty-acylase activity probes with various quencher moieties and peptide sequences based on our previously developed one-step FRET-based SIRT probe SFP3, using improved methodology. Scanning of this set of probes with SIRT isozymes revealed that certain probe/isozyme combinations showed especially high responses. To illustrate the utility of the combinations thus identified, we applied compound 18/SIRT2 for inhibitor screening of a large chemical library. This enabled us to discover a new small molecule SIRT2-specific defatty-acylase inhibitor.