Lysosome signaling in cell survival and programmed cell death for cellular homeostasis

Anticancer efficacy triggered by synergistically modulating the homeostasis of anions and iron: Design, synthesis and biological evaluation of dual-functional squaramide-hydroxamic acid conjugates

Targeting the homeostasis of anions and iron has emerged as a promising therapeutic approach for the treatment of cancers. However, single-targeted agents often fall short of achieving optimal treatment efficacy. Herein we designed and synthesized a series of novel dual-functional squaramide-hydroxamic acid conjugates that are capable of synergistically modulating the homeostasis of anions and iron. Among them, compound 16 exhibited the most potent antiproliferative activity against a panel of selected cancer cell lines, and strong in vivo anti-tumor efficacy. This compound effectively elevated lysosomal pH through anion transport, and reduced the levels of intracellular iron. Compound 16 could disturb autophagy in A549 cells and trigger robust apoptosis. This compound caused cell cycle arrest at the G1/S phase, altered the mitochondrial function and elevated ROS levels. The present findings clearly demonstrated that synergistic modulation of anion and iron homeostasis has high potentials in the development of promising chemotherapeutic agents with dual action against cancers.

Application of covalent modality in proximity-induced drug pharmacology: Early development, current strategy, and feature directions

With a growing number of covalent drugs securing FDA approval as successful therapies across various indications, particularly in the realm of cancer treatment, the covalent modulating strategy is undergoing a resurgence. The renewed interest in covalent bioactive compounds has captured significant attention from both the academic and biopharmaceutical industry sectors. Covalent chemistry presents several advantages over traditional noncovalent proximity-induced drugs, including heightened potency, reduced molecular size, and the ability to target "undruggable" entities. Within this perspective, we have compiled a comprehensive overview of current covalent modalities applied to proximity-induced molecules, delving into their advantages and drawbacks. Our aim is to stimulate more profound insights and ideas within the scientific community, guiding future research endeavors in this dynamic field.

A mechanism that transduces lysosomal damage signals to stress granule formation for cell survival

Lysosomal damage poses a significant threat to cell survival. Our previous work has reported that lysosomal damage induces stress granule (SG) formation. However, the importance of SG formation in determining cell fate and the precise mechanisms through which lysosomal damage triggers SG formation remains unclear. Here, we show that SG formation is initiated via a novel calcium-dependent pathway and plays a protective role in promoting cell survival in response to lysosomal damage. Mechanistically, we demonstrate that during lysosomal damage, ALIX, a calcium-activated protein, transduces lysosomal damage signals by sensing calcium leakage to induce SG formation by controlling the phosphorylation of eIF2α. ALIX modulates eIF2α phosphorylation by regulating the association between PKR and its activator PACT, with galectin-3 exerting a negative effect on this process. We also found this regulatory event of SG formation occur on damaged lysosomes. Collectively, these investigations reveal novel insights into the precise regulation of SG formation triggered by lysosomal damage, and shed light on the interaction between damaged lysosomes and SGs. Importantly, SG formation is significant for promoting cell survival in the physiological context of lysosomal damage inflicted by SARS-CoV-2 ORF3a, adenovirus infection, Malaria hemozoin, proteopathic tau as well as environmental hazard silica.

Targeting the organelle for radiosensitization in cancer radiotherapy

Radiotherapy is a well-established cytotoxic therapy for local solid cancers, utilizing high-energy ionizing radiation to destroy cancer cells. However, this method has several limitations, including low radiation energy deposition, severe damage to surrounding normal cells, and high tumor resistance to radiation. Among various radiotherapy methods, boron neutron capture therapy (BNCT) has emerged as a principal approach to improve the therapeutic ratio of malignancies and reduce lethality to surrounding normal tissue, but it remains deficient in terms of insufficient boron accumulation as well as short retention time, which limits the curative effect. Recently, a series of radiosensitizers that can selectively accumulate in specific organelles of cancer cells have been developed to precisely target radiotherapy, thereby reducing side effects of normal tissue damage, overcoming radioresistance, and improving radiosensitivity. In this review, we mainly focus on the field of nanomedicine-based cancer radiotherapy and discuss the organelle-targeted radiosensitizers, specifically including nucleus, mitochondria, endoplasmic reticulum and lysosomes. Furthermore, the organelle-targeted boron carriers used in BNCT are particularly presented. Through demonstrating recent developments in organelle-targeted radiosensitization, we hope to provide insight into the design of organelle-targeted radiosensitizers for clinical cancer treatment.

Sirtuin 1 in osteoarthritis: Perspectives on regulating glucose metabolism

Osteoarthritis (OA) is a degenerative disease characterised by articular cartilage destruction, and its complex aetiology contributes to suboptimal clinical treatment outcomes. A close association exists between glucose metabolism dysregulation and OA pathogenesis. Owing to the unique environment of low oxygen and glucose concentrations, chondrocytes rely heavily on their glycolytic capacity, exhibiting distinct spatiotemporal differences. However, under pathological stimulation, chondrocytes undergo excessive glycolytic activity while mitochondrial respiration and other branches of glucose metabolism are compromised. This metabolic change induces cartilage degeneration by reprogramming the inflammatory responses. Sirtuins, a highly conserved family of nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases, regulate glucose metabolism in response to energy fluctuations in different cellular compartments，alleviating metabolic stress. SIRT1, the most extensively studied sirtuin, participates in maintaining glucose homeostasis in almost all key metabolic tissues. While actively contributing to the OA progression and displaying diverse biological effects in cartilage protection, SIRT1's role in regulating glucose metabolism in chondrocytes has not received sufficient attention. This review focuses on discussing the beneficial role of SIRT1 in OA progression from a metabolic regulation perspective based on elucidating the primary characteristics of chondrocyte glucose metabolism. We also summarise the potential mechanisms and therapeutic strategies targeting SIRT1 in chondrocytes to guide clinical practice and explore novel therapeutic directions.

Low expression of lysosome-related genes KCNE1, NPC2, and SFTPD promote cancer cell proliferation and tumor associated M2 macrophage polarization in lung adenocarcinoma

Background

Recent research has shown that lysosomes play a critical role in the onset and progression of malignancy by regulating tumor cell death through several mechanisms. Nevertheless, the involvement of lysosome-associated genes (LSAGs) in lung adenocarcinoma (LUAD) is still not well understood.

Methods

LSAGs were identified in malignant lung epithelial cells, as well as biologically and functionally annotated by the comprehensive integration of single-cell and bulk RNA-sequencing data. Prognostic characterization of LSAGs was established, of which the accuracy and reliability were assessed by one-way Cox and LASSO regression. Correlations between LSAG properties and immune cell infiltration, chemotherapy, and immunotherapy were analyzed by integrated omics data. Finally, we characterized the expression of three LSAGs (KCNE1, NPC2, and SFTPD) in malignant lung epithelium and assessed their impact on tumor malignancy related phenotypes.

Results

We identified 18 LSAGs associated with prognosis, of which 3 LSAGs were used to construct prognostic models. High-risk patients had worse survival and the model predicted it better than other clinical indicators. Based on the functional enrichment analyses, LSAGs were associated with binding and molecular activity functions, inhibition of DNA damage repair and tumor growth, IL7 signaling pathway, and glycolysis. M0 macrophages and M1 macrophages were substantially enriched in high-risk patients. Conversely, there was a considerable enrichment of resting dendritic cells and M2 macrophages in patients at low risk. We also found that risk scores predicted the outcome of immunotherapy. In vitro, we found that KCNE1, NPC2, and SFTPD were lowly expressed in malignant epithelial cells and patients with low expression of KCNE1, NPC2, and SFTPD had a higher percentage of M2 macrophage infiltration. Overexpression of KCNE1, NPC2, and SFTPD suppressed the proliferation and invasion of malignant cells, and M0 macrophages remarkably reduced M2 macrophage polarization and cellular secretion of pro-tumor cytokines.

Conclusions

We used three LASGs-KCNE1, NPC2, and SFTPD-to develop and validate a predictive signature for LUAD patients. Furthermore, we found that low expression of KCNE1, NPC2, and SFTPD promotes lung cancer cell proliferation and invasion and M2 macrophage polarization. Our study may provide fresh perspectives for customized immunotherapy.

NLRP3 Inhibition Leads to Impaired Mucosal Fibroblast Function in Patients with Inflammatory Bowel Diseases

BACKGROUND AND AIMS

Inflammatory bowel diseases (IBD) are characterized by mucosal inflammation and sequential fibrosis formation, but the exact role of the hyperactive NLRP3 inflammasome in these processes is unclear. Thus, we studied the expression and function of the NLRP3 inflammasome in the context of inflammation and fibrosis in IBD.

METHODS

We analysed intestinal NLRP3 expression in mucosal immune cells and fibroblasts from IBD patients and NLRP3-associated gene expression via single-cell RNA sequencing and microarray analyses. Furthermore, cytokine secretion of NLRP3 inhibitor treated blood and mucosal cells, as well as proliferation, collagen production, and cell death of NLRP3 inhibitor treated intestinal fibroblasts from IBD patients were studied.

RESULTS

We found increased NLRP3 expression in the inflamed mucosa of IBD patients and NLRP3 inhibition led to reduced IL-1β and IL-18 production in blood cells and diminished the bioactive form of mucosal IL-1β. Single cell analysis identified overlapping expression patterns of NLRP3 and IL-1β in classically activated intestinal macrophages and we also detected NLRP3 expression in CD163+ macrophages. In addition, NLRP3 expression was also found in intestinal fibroblasts from IBD patients. Inhibition of NLRP3 led to reduced proliferation of intestinal fibroblasts, which was associated with a marked decrease in production of collagen type I and type VI in IBD patients. Moreover, NLRP3 inhibition in intestinal fibroblasts induced autophagy, a cellular process involved in collagen degradation.

CONCLUSIONS

In the presented study, we demonstrate that inhibiting NLRP3 might pave the way for novel therapeutic approaches in IBD, especially to prevent the severe complication of intestinal fibrosis formation.

A single fluorescent probe to examine the dynamics of mitochondria-lysosome interplay and extracellular vesicle role in ferroptosis

Ferroptosis is a non-apoptotic form of cell death characterized by iron-dependent lipid peroxidation and glutathione (GSH) depletion. Despite recent advances, challenges remain in understanding the bidirectional interactions or interplay between organelles during ferroptosis. In this study, we aimed to understand the interplay between mitochondria (Mito) and lysosomes (Lyso) in cell homeostasis and ferroptosis. For this purpose, we designed a single fluorescent probe that marks GSH in Mito and hypochlorous acid (HOCl) in Lyso with two distinct emissions. Using this dual-targeted single fluorescent probe (9-morphorino pyronine), we detected Mito-Lyso interplay in ferroptosis. We disclosed differences in Mito-Lyso interplay depending on the induction of ferroptosis. Although erastin treatment decreased GSH, RSL3 triggered a HOCl burst, and FIN56- and FINO2-induced ferroptosis increased GSH and HOCl. Additionally, we showed that only extracellular vesicles generated during erastin-induced ferroptosis could spontaneously move and dock to neighboring cells, resulting in accelerated cell death.

Teratogenic Effects of Drugs on Primary Lymphocytes Assessed by Flow Cytometry

Peripheral blood lymphocytes as primary cells can be isolated from human, animal, fetus, and placenta. These cells are an excellent cellular model for the assessment of cytotoxicity, genotoxicity, oxidative stress, and mitochondrial and lysosomal dysfunction induced by drug and chemicals. Moreover, peripheral blood lymphocytes are an easily available source of primary cells appropriate for basic research and in cellular studies regarding teratogenic, genotoxic, and cytotoxic effect of drugs and chemicals. Most drugs and other chemicals that produce birth defects, known as teratogenic agents, produce reactive oxygen species (ROS) formation and mitochondrial and lysosomal dysfunction. It seems that there is an important mechanistic link between oxidative stress, mitochondrial damages, lysosomal integrity, and teratogenic drug-induced birth defects. One of the most sensitive periods in the embryo is transition from an important developmental event to another such as transition from proliferation to differentiation. Mitochondria, lysosomes, and cellular ROS have an important role in proliferative, differentiative, and apoptotic activities during the development. Therefore, disruption of the function of mitochondria, lysosomes, oxidative stress, and redox imbalance leads to cellular dysfunctions and subsequently poor developmental outcomes in the fetus. In this chapter, we will focus on evaluation of mitochondrial/lysosomal functions and estimation of ROS formation using flow cytometry methods in isolated lymphocytes and their isolated mitochondria.

Bisphenol A induced neuronal apoptosis and enhanced autophagy in vitro through Nrf2/HO-1 and Akt/mTOR pathways

Bisphenol A (BPA) was traditionally used in epoxy resins and polycarbonate plastics, but it was found to be harmful to human health due to its endocrine-disrupting effects. It can affect various biological functions of human beings and interfere with brain development. However, the neurotoxic mechanisms of BPA on brain development and associated neurodegeneration remain poorly understood. Here, we reported that BPA (100, 250, 500 μM) inhibited cell viability of neural cells PC12, SH-SY5Y and caused dose-dependent cell death. In addition, BPA exposure increased intracellular reactive oxygen species (ROS) and mitochondrial ROS (mtROS) levels, decreased mitochondrial membrane potential, reduced the expression of cytochrome c oxidase IV (COX4), downregulated Bcl-2, and initiated apoptosis. Moreover, BPA treatment resulted in the accumulation of intracellular acidic vacuoles and increased the autophagy marker LC3 II to LC3 I ratio. Furthermore, BPA exposure inhibited Nrf2/ HO-1 and AKT/mTOR pathways and mediated cellular oxidative stress, apoptosis, and excessive autophagy, leading to neuronal degeneration. The interactions between oxidative stress, autophagy, and apoptosis during BPA-induced neurotoxicity remain unclear and require further in vivo confirmation.

Revealing Mitochondrion-Lysosome Dynamic Interactions and pH Variations in Live Cells with a pH-Sensitive Fluorescent Probe

Mitochondrion-lysosome interactions have garnered significant attention in recent research. Numerous studies have shown that mitochondrion-lysosome interactions, including mitochondrion-lysosome contact (MLC) and mitophagy, are involved in various biological processes and pathological conditions. Single fluorescent probes are termed a pivotal chemical tool in unraveling the intricate spatiotemporal interorganelle interplay in live cells. However, current chemical tools are insufficient to deeply understand mitochondrion-lysosome dynamic interactions and related diseases, Moreover, the rational design of mitochondrion-lysosome dual-targeting fluorescent probes is intractable. Herein, we designed and synthesized a pH-sensitive fluorescent probe called INSA, which could simultaneously light up mitochondria (red emission) and lysosomes (green emission) for their internal pH differences. Employing INSA, we successfully recorded long-term dynamic interactions between lysosomes and mitochondria. More importantly, the increasing mitochondrion-lysosome interactions in ferroptotic cells were also revealed by INSA. Further, we observed pH variations in mitochondria and lysosomes during ferroptosis for the first time. In brief, this work not only introduced a pH-sensitive fluorescent probe INSA for the disclosure of the mitochondrion-lysosome dynamic interplays but also pioneered the visualization of the organellar pH alternation in a specific disease model.

Pathophysiology of Lysosomes in a Nutshell

Lysosomes are acidic organelles present in all nucleated mammalian cells [...].

Role of Microbiota-Modified Bile Acids in the Regulation of Intracellular Organelles and Neurodegenerative Diseases

Bile acids (BAs) are amphiphilic steroidal molecules generated from cholesterol in the liver and facilitate the digestion and absorption of fat-soluble substances in the gut. Some BAs in the intestine are modified by the gut microbiota. Because BAs are modified in a variety of ways by different types of bacteria present in the gut microbiota, changes in the gut microbiota can affect the metabolism of BAs in the host. Although most BAs absorbed from the gut are transferred to the liver, some are transferred to the systemic circulation. Furthermore, BAs have also been detected in the brain and are thought to migrate into the brain through the systemic circulation. Although BAs are known to affect a variety of physiological functions by acting as ligands for various nuclear and cell-surface receptors, BAs have also been found to act on mitochondria and autophagy in the cell. This review focuses on the BAs modified by the gut microbiota and their roles in intracellular organelles and neurodegenerative diseases.

Genetic Evidence for Endolysosomal Dysfunction in Parkinson’s Disease: A Critical Overview

Parkinson’s disease (PD) is the second most common neurodegenerative disorder in the aging population, and no disease-modifying therapy has been approved to date. The pathogenesis of PD has been related to many dysfunctional cellular mechanisms, however, most of its monogenic forms are caused by pathogenic variants in genes involved in endolysosomal function (LRRK2, VPS35, VPS13C, and ATP13A2) and synaptic vesicle trafficking (SNCA, RAB39B, SYNJ1, and DNAJC6). Moreover, an extensive search for PD risk variants revealed strong risk variants in several lysosomal genes (e.g., GBA1, SMPD1, TMEM175, and SCARB2) highlighting the key role of lysosomal dysfunction in PD pathogenesis. Furthermore, large genetic studies revealed that PD status is associated with the overall “lysosomal genetic burden”, namely the cumulative effect of strong and weak risk variants affecting lysosomal genes. In this context, understanding the complex mechanisms of impaired vesicular trafficking and dysfunctional endolysosomes in dopaminergic neurons of PD patients is a fundamental step to identifying precise therapeutic targets and developing effective drugs to modify the neurodegenerative process in PD.