Structure, Function, and Inhibitors of the Mitochondrial Chaperone TRAP1

Targeting HSP90 for Cancer Therapy: Current Progress and Emerging Prospects

Heat shock protein 90 (HSP90), a highly conserved member of the heat shock protein family, regulates various proteins and signaling pathways involved in cancer, making it a promising target for cancer therapy. Traditional HSP90 inhibitors have demonstrated significant antitumor potential in preclinical trials, with over 20 compounds advancing to clinical trials and showing promising results. However, the limited clinical efficacy and shared toxicity of these inhibitors restrict their further clinical use. Encouragingly, developing novel inhibitors using conventional medicinal chemistry approaches─such as selective inhibitors, dual inhibitors, protein-protein interaction inhibitors, and proteolysis-targeting chimeras─is expected to address these challenges. Notably, the selective inhibitor TAS-116 has already been successfully marketed. In this Perspective, we summarize the structure, biological functions, and roles of HSP90 in cancer, analyze the clinical status of HSP90 inhibitors, and highlight the latest advancements in novel strategies, offering insights into their future development.

Mitochondrial Chaperone Code: Just warming up

More than 99% of the mitochondrial proteome is encoded by the nucleus and requires refolding following import. Therefore, mitochondrial proteins require the coordinated action of molecular chaperones for their folding and activation. Several heat shock protein (Hsp) molecular chaperones, including members of the Hsp27, Hsp40/70, and Hsp90 families, as well as the chaperonin complex Hsp60/10 have an established role in mitochondrial protein import and folding. The "Chaperone Code" describes the regulation of chaperone activity by dynamic post-translational modifications; however, little is known about the post-translational regulation of mitochondrial chaperones. Dissecting the regulation of chaperone function is essential for understanding their differential regulation in pathogenic conditions and the potential development of efficacious therapeutic strategies. Here, we summarize the recent literature on post-translational regulation of mitochondrial chaperones, the consequences for mitochondrial function, and potential implications for disease.

Targeting the Mitochondrial Chaperone TRAP1 Alleviates Vascular Pathologies in Ischemic Retinopathy

Activation of hypoxia-inducible factor 1α (HIF1α) contributes to blood-retinal barrier (BRB) breakdown and pathological neovascularization responsible for vision loss in ischemic retinal diseases. During disease progression, mitochondrial biology is altered to adapt to the ischemic environment created by initial vascular dysfunction, but the mitochondrial adaptive mechanisms, which ultimately contribute to the pathogenesis of ischemic retinopathy, remain incompletely understood. In the present study, it is identified that expression of mitochondrial chaperone tumor necrosis factor receptor-associated protein 1 (TRAP1) is essential for BRB breakdown and pathologic retinal neovascularization in mouse models mimicking ischemic retinopathies. Genetic Trap1 ablation or treatment with small molecule TRAP1 inhibitors, such as mitoquinone (MitoQ) and SB-U015, alleviate retinal pathologies via proteolytic HIF1α degradation, which is mediated by opening of the mitochondrial permeability transition pore and activation of calcium-dependent protease calpain-1. These findings suggest that TRAP1 can be a promising target for the development of new treatments against ischemic retinopathy, such as retinopathy of prematurity and proliferative diabetic retinopathy.

The development of cancers research based on mitochondrial heat shock protein 90

Mitochondrial heat shock protein 90 (mtHsp90), including Tumor necrosis factor receptor-associated protein 1 (TRAP1) and Hsp90 translocated from cytoplasm, modulating cellular metabolism and signaling pathways by altering the conformation, activity, and stability of numerous client proteins, and is highly expressed in tumors. mtHsp90 inhibition results in the destabilization and eventual degradation of its client proteins, leading to interference with various tumor-related pathways and efficient control of cancer cell development. Among these compounds, gamitrinib, a specific mtHsp90 inhibitor, has demonstrated its safety and efficacy in several preclinical investigations and is currently undergoing evaluation in clinical trials. This review aims to provide a comprehensive overview of the present knowledge pertaining to mtHsp90, encompassing its structure and function. Moreover, our main emphasis is on the development of mtHsp90 inhibitors for various cancer therapies, to present a thorough overview of the recent pre-clinical and clinical advancements in this field.

Recent Advances in Synthetic Routes to Azacycles

A heterocycle is an important structural scaffold of many organic compounds found in pharmaceuticals, materials, agrochemicals, and biological processes. Azacycles are one of the most common motifs of a heterocycle and have a variety of applications, including in pharmaceuticals. Therefore, azacycles have received significant attention from scientists and a variety of methods of synthesizing azacycles have been developed because their efficient synthesis plays a vital role in the production of many useful compounds. In this review, we summarize recent approaches to preparing azacycles via different methods as well as describe plausible reaction mechanisms.