Inhibition of nuclear deacetylase Sirtuin-1 induces mitochondrial acetylation and calcium overload leading to cell death

Mitochondrial calcium uniporter complex: Unveiling the interplay between its regulators and calcium homeostasis

The mitochondrial calcium uniporter complex (MCUc), serving as the specific channel for calcium influx into the mitochondrial matrix, is integral to calcium homeostasis and cellular integrity. Given its importance, ongoing research spans various disease models to understand the properties of the MCUc in pathophysiological contexts, but reported a different conclusion. Therefore, this review delves into the profound connection between MCUc-mediated calcium transients and cellular signaling pathways, mitochondrial dynamics, metabolism, and cell death. Additionally, we shed light on the recent advancements concerning the structural intricacies and auxiliary components of the MCUc in both resting and activated states. Furthermore, emphasis is placed on novel extrinsic and intrinsic regulators of the MCUc and their therapeutic implications across a spectrum of diseases. Meanwhile, we employed molecular docking simulations and identified candidate traditional Chinese medicine components with potential binding sites to the MCUc, potentially offering insights for further research on MCUc modulation.

SIRT1: a novel regulator in colorectal cancer

The class-III histone deacetylase SIRT1 is the most extensively investigated sirtuin deacetylase. It is resistant to the broad deacetylase inhibitor trichostatin A and depends on oxidized nicotinamide adenine nucleotide (NAD+). SIRT1 plays a crucial role in the tumorigenesis of numerous types of cancers, including colorectal cancer (CRC). Accumulating evidence indicates that SIRT1 is a therapeutic target for CRC; however, the function and underlying mechanism of SIRT1 in CRC still need to be elucidated. Herein, we provide a detailed and updated review to illustrate that SIRT1 regulates many processes that go awry in CRC cells, such as apoptosis, autophagy, proliferation, migration, invasion, metastasis, oxidative stress, resistance to chemo-radio therapy, immune evasion, and metabolic reprogramming. Moreover, we closely link our review to the clinical practice of CRC treatment, summarizing the mechanisms and prospects of SIRT1 inhibitors in CRC therapy. SIRT1 inhibitors as monotherapy in CRC or in combination with chemotherapy, radiotherapy, and immune therapies are comprehensively discussed. From epigenetic regulation to its potential therapeutic effect, we hope to offer novel insights and a comprehensive understanding of SIRT1's role in CRC.

Emamectin benzoate exposure induced carp kidney injury by triggering mitochondrial oxidative stress to accelerate ferroptosis and autophagy

Emamectin benzoate (EMB), commonly used as an insecticide in fishery production, inevitably leaves residual chemicals in aquatic environments. High-level EMB exposure can cause severe damage to multiple systems of marine animals, potentially through mechanisms involving severe mitochondrial damage and oxidative stress. However, it is not clear yet how EMB exposure at a certain level can cause damage to fish kidney tissue. In this study, we exposed carps to an aquatic environment containing 2.4 μg/L of EMB and cultured carp kidney cells in vitro, established a cell model exposed to EMB. Our findings revealed that EMB exposure resulted in severe kidney tissue damage in carp and compromised the viability of grass carp kidney cells (CIK cells). By RNA-seq analysis, EMB exposure led to significant differences in mitochondrial homeostasis, response to ROS, ferroptosis, and autophagy signals in carp kidney tissue. Mechanistically, EMB exposure induced mitochondrial oxidative stress by promoting the generation of mitochondrial superoxide and reducing the activity of antioxidant enzymes. Additionally, EMB exposure triggered loss of mitochondrial membrane potential, an imbalance in mitochondrial fusion/division homeostasis, and dysfunction in oxidative phosphorylation, ultimately impairing ATP synthesis. Notably, EMB exposure also accelerated excessive autophagy and ferroptosis of cells by contributing to the formation of lipid peroxides and autophagosomes, and the deposition of Fe2+. However, N-acetyl-L-cysteine (NAC) treatment alleviated the damage and death of CIK cells by inhibiting oxidative stress. Overall, our study demonstrated that EMB exposure induced mitochondrial oxidative stress, impaired mitochondrial homeostasis, and function, promoted autophagy and ferroptosis of kidney cells, and ultimately led to kidney tissue damage in carp. Our research enhanced the toxicological understanding on EMB exposure and provides a model reference for comparative medicine.

Icariside I enhances the effects of immunotherapy in gastrointestinal cancer via targeting TRPV4 and upregulating the cGAS-STING-IFN-I pathway

Gastrointestinal cancer is among the most common cancers worldwide. Immune checkpoint inhibitor-based cancer immunotherapy has become an innovative approach in cancer treatment; however, its efficacy in gastrointestinal cancer is limited by the absence of infiltration of immune cells within the tumor microenvironment. Therefore, it is therefore urgent to develop a novel therapeutic drug to enhance immunotherapy. In this study, we describe a previously unreported potentiating effect of Icariside I (ICA I, GH01), the main bioactive compound isolated from the Epimedium species, on anti-tumor immune responses. Mechanistically, molecular docking and SPR assay result show that ICA I binding with TRPV4. ICA I induced intracellular Ca2+ increasing and mitochondrial DNA release by targeting TRPV4, which triggered cytosolic ox-mitoDNA release. Importantly, these intracellular ox-mitoDNA fragments were taken up by immune cells in the tumor microenvironment, which amplified the immune response. Moreover, our study shows the remarkable efficacy of sequential administration of ICA I and anti-α-PD-1 mAb in advanced tumors and provides a strong scientific rationale for recommending such a combination therapy for clinical trials. ICA I enhanced the anti-tumor effects with PD-1 inhibitors by regulating the TRPV4/Ca2+/Ox-mitoDNA/cGAS/STING axis. We expect that these findings will be translated into clinical therapies, which will benefit more patients with cancer in the near future.

Si-Wu-Tang attenuates hepatocyte PANoptosis and M1 polarization of macrophages in non-alcoholic fatty liver disease by influencing the intercellular transfer of mtDNA

ETHNOPHARMACOLOGICAL RELEVANCE

Non-alcoholic fatty liver disease (NAFLD) represents a burgeoning challenge for public health with potential progression to malignant liver diseases. PANoptosis, an avant-garde conceptualization of cell deaths, is closely associated with mitochondrial damage and linked to multiple liver disorders. Si-Wu-Tang (SWT), a traditional Chinese herbal prescription renowned for regulating blood-related disorders and ameliorating gynecological and hepatic diseases, has been demonstrated to alleviate liver fibrosis by regulating bile acid metabolism and immune responses.

AIM OF THE STUDY

However, the mechanisms by which mtDNA is released from PANoptotic hepatocytes, triggering macrophage activation and hepatitis and whether this process can be reversed by SWT remain unclear.

MATERIALS AND METHODS

Here, sophisticated RNA-sequencing complemented by molecular approaches were applied to explore the underlying mechanism of SWT against NAFLD in methionine/choline-deficient diet (MCD)-induced mice and relative in vitro models.

RESULTS

We revealed that SWT profoundly repaired mitochondrial dysfunction, blocked mitochondrial permeability transition and mtDNA released to the cytoplasm, subsequently reversing hepatocyte PANoptosis and macrophage polarization both in MCD-stimulated mice and in vitro. Mechanically, loaded lipids dramatically promoted the opening of mPTP and oligomerization of VDAC2 to orchestrate mtDNA release, which was combined with ZBP1 to promote hepatocyte PANoptosis and also taken by macrophages to trigger M1 polarization via the FSTL1 and PKM2 combination. SWT effectively blocked NOXA signaling and reversed all these detrimental outcomes.

CONCLUSION

Our findings show that SWT protects against hepatitis-mediated hepatocyte PANoptosis and macrophage M1 polarization by influencing intrahepatic synthesis, release and intercellular transfer of mtDNA, suggesting a potential therapeutic strategy for ameliorating NAFLD.

Effect of MEHP on testosterone synthesis via Sirt1/Foxo1/Rab7 signaling pathway inhibition of lipophagy in TM3 cells

Mono-2-ethylhexyl phthalic acid (MEHP) is the most toxic metabolite of the plasticizer di-2-ethylhexyl phthalic acid (DEHP), and studies have shown that MEHP causes serious reproductive effects. However, its exact mechanisms of action remain elusive. In this study, we aimed to investigate the reproductive effects of MEHP and preliminarily explore its underlying molecular mechanisms. We found that TM3 cells gradually secreted less testosterone and intracellular free cholesterol with increasing MEHP exposure. MEHP exposure inhibited lipophagy and the Sirt1/Foxo1/Rab7 signaling pathway in TM3 cells, causing aberrant accumulation of intracellular lipid droplets. Addition of the Sirt1 agonist SRT1720 and Rab7 agonist ML-098 alleviated the inhibition of lipophagy and increased free cholesterol and testosterone contents in TM3 cells. SRT1720 alleviated the inhibitory effect of MEHP on the Sirt1/Foxo1/Rab7 signaling pathway, whereas ML-098 only alleviated the inhibition of Rab7 protein expression by MEHP and had no effect on Sirt1 and Foxo1 protein expression. This suggests that MEHP inhibits lipophagy in TM3 cells by suppressing the Sirt1/Foxo1/Rab7 signaling pathway, ultimately leading to a further decrease in cellular testosterone secretion. This study improves our current understanding of the toxicity and molecular mechanisms of action of MEHP and provides new insights into the reproductive effects of phthalic acid esters.

Conserved role of hnRNPL in alternative splicing of epigenetic modifiers enables B cell activation

The multifunctional RNA-binding protein hnRNPL is implicated in antibody class switching but its broader function in B cells is unknown. Here, we show that hnRNPL is essential for B cell activation, germinal center formation, and antibody responses. Upon activation, hnRNPL-deficient B cells show proliferation defects and increased apoptosis. Comparative analysis of RNA-seq data from activated B cells and another eight hnRNPL-depleted cell types reveals common effects on MYC and E2F transcriptional programs required for proliferation. Notably, while individual gene expression changes are cell type specific, several alternative splicing events affecting histone modifiers like KDM6A and SIRT1, are conserved across cell types. Moreover, hnRNPL-deficient B cells show global changes in H3K27me3 and H3K9ac. Epigenetic dysregulation after hnRNPL loss could underlie differential gene expression and upregulation of lncRNAs, and explain common and cell type-specific phenotypes, such as dysfunctional mitochondria and ROS overproduction in mouse B cells. Thus, hnRNPL is essential for the resting-to-activated B cell transition by regulating transcriptional programs and metabolism, at least in part through the alternative splicing of several histone modifiers.

Mitochondrial fusion-fission dynamics and its involvement in colorectal cancer

The incidence and mortality rates of colorectal cancer have elevated its status as a significant public health concern. Recent research has elucidated the crucial role of mitochondrial fusion-fission dynamics in the initiation and progression of colorectal cancer. Elevated mitochondrial fission or fusion activity can contribute to the metabolic reprogramming of tumor cells, thereby activating oncogenic pathways that drive cell proliferation, invasion, migration, and drug resistance. Nevertheless, excessive mitochondrial fission can induce apoptosis, whereas moderate mitochondrial fusion can protect cells from oxidative stress. This imbalance in mitochondrial dynamics can exert dual roles as both promoters and inhibitors of colorectal cancer progression. This review provides an in-depth analysis of the fusion-fission dynamics and the underlying pathological mechanisms in colorectal cancer cells. Additionally, it offers partial insights into the mitochondrial kinetics in colorectal cancer-associated cells, such as immune and endothelial cells. This review is aimed at identifying key molecular events involved in colorectal cancer progression and highlighting the potential of mitochondrial dynamic proteins as emerging targets for pharmacological intervention.

SIRT1: Harnessing multiple pathways to hinder NAFLD

Non-alcoholic fatty liver disease (NAFLD) encompasses hepatic steatosis, non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. It is the primary cause of chronic liver disorders, with a high prevalence but no approved treatment. Therefore, it is indispensable to find a trustworthy therapy for NAFLD. Recently, mounting evidence illustrates that Sirtuin 1 (SIRT1) is strongly associated with NAFLD. SIRT1 activation or overexpression attenuate NAFLD, while SIRT1 deficiency aggravates NAFLD. Besides, an array of therapeutic agents, including natural compounds, synthetic compounds, traditional Chinese medicine formula, and stem cell transplantation, alleviates NALFD via SIRT1 activation or upregulation. Mechanically, SIRT1 alleviates NAFLD by reestablishing autophagy, enhancing mitochondrial function, suppressing oxidative stress, and coordinating lipid metabolism, as well as reducing hepatocyte apoptosis and inflammation. In this review, we introduced the structure and function of SIRT1 briefly, and summarized the effect of SIRT1 on NAFLD and its mechanism, along with the application of SIRT1 agonists in treating NAFLD.

Autophagy-dependent lysosomal calcium overload and the ATP5B-regulated lysosomes-mitochondria calcium transmission induce liver insulin resistance under perfluorooctane sulfonate exposure

Perfluorooctane sulfonate (PFOS), an officially listed persistent organic pollutant, is a widely distributed perfluoroalkyl substance. Epidemiological studies have shown that PFOS is intimately linked to the occurrence of insulin resistance (IR). However, the detailed mechanism remains obscure. In previous studies, we found that mitochondrial calcium overload was concerned with hepatic IR induced by PFOS. In this study, we found that PFOS exposure noticeably raised lysosomal calcium in L-02 hepatocytes from 0.5 h. In the PFOS-cultured L-02 cells, inhibiting autophagy alleviated lysosomal calcium overload. Inhibition of mitochondrial calcium uptake aggravated the accumulation of lysosomal calcium, while inhibition of lysosomal calcium outflowing reversed PFOS-induced mitochondrial calcium overload and IR. Transient receptor potential mucolipin 1 (TRPML1), the calcium output channel of lysosomes, interacted with voltage-dependent anion channel 1 (VDAC1), the calcium intake channel of mitochondria, in the PFOS-cultured cells. Moreover, we found that ATP synthase F1 subunit beta (ATP5B) interacted with TRPML1 and VDAC1 in the L-02 cells and the liver of mice under PFOS exposure. Inhibiting ATP5B expression or restraining the ATP5B on the plasma membrane reduced the interplay between TRPML1 and VDAC1, reversed the mitochondrial calcium overload and deteriorated the lysosomal calcium accumulation in the PFOS-cultured cells. Our research unveils the molecular regulation of the calcium crosstalk between lysosomes and mitochondria, and explains PFOS-induced IR in the context of activated autophagy.

By regulating the IP3R/GRP75/VDAC1 complex to restore mitochondrial dynamic balance, selenomethionine reduces lipopolysaccharide-induced neuronal apoptosis

Selenium (Se), as one of the essential trace elements, plays an anti-inflammatory, antioxidation, and immune-enhancing effect in the body. In addition, Se can also improve nervous system damage induced by various factors. Earlier studies have described the important role of mitochondrial dynamic imbalance in lipopolysaccharide (LPS)-induced nerve injury. The inositol 1,4,5-triphosphate receptor (IP3R)/glucose-regulated protein 75 (GRP75)/voltage-dependent anion channel 1 (VDAC1) complex is considered to be the key to regulating mitochondrial dynamics. However, it is not clear whether Selenomethionine (SeMet) has any influence on the IP3R/GRP75/VDAC1 complex. Therefore, the aim of this investigation was to determine whether SeMet can alleviate LPS-induced brain damage and to elucidate the function of the IP3R/GRP75/VDAC1 complex in it. We established SeMet and/or LPS exposure models in vivo and in vitro using laying hens and primary chicken nerve cells. We noticed that SeMet reversed endoplasmic reticulum stress (ERS) and the imbalance in mitochondrial dynamics and significantly prevented the occurrence of neuronal apoptosis. We made this finding by morphological observation of the brain tissue of laying hens and the detection of related genes such as ERS, the IP3R/GRP75/VDAC1 complex, calcium signal (Ca2+), mitochondrial dynamics, and apoptosis. Other than that, we also discovered that the IP3R/GRP75/VDAC1 complex was crucial in controlling Ca2+ transport between the endoplasmic reticulum and the mitochondrion when SeMet functions as a neuroprotective agent. In summary, our results revealed the specific mechanism by which SeMet alleviated LPS-induced neuronal apoptosis for the first time. As a consequence, SeMet has great potential in the treatment and prevention of neurological illnesses (like neurodegenerative diseases).

Glsirt1-mediated deacetylation of GlCAT regulates intracellular ROS levels, affecting ganoderic acid biosynthesis in Ganoderma lucidum

Lysine acetylation is a reversible, dynamic protein modification regulated by lysine acetyltransferases and deacetylases. However, in Basidiomycetes, the extent of lysine acetylation of nonhistone proteins remains largely unknown. Recently, we identified the deacetylase Glsirt1 as a key regulator of the biosynthesis of ganoderic acid (GA), a key secondary metabolite of Ganoderma lucidum. To gain insight into the characteristics, extent, and biological function of Glsirt1-mediated lysine acetylation in G. lucidum, we aimed to identify additional Glsirt1 substrates via comparison of acetylomes between wild-type (WT) and Glsirt1-silenced mutants. A large amount of Glsirt1-dependent lysine acetylation occurs in G. lucidum according to the results of this omics analysis, involving energy metabolism, protein synthesis, the stress response and other pathways. Our results suggest that GlCAT is a direct target of Glsirt1 and that the deacetylation of GlCAT by Glsirt1 reduces catalase activity, thereby leading to the accumulation of intracellular reactive oxygen species (ROS) and positively regulating the biosynthesis of GA. Our findings provide evidence for the involvement of nonhistone lysine acetylation in the biological processes of G. lucidum and help elucidate the involvement of important ROS signaling molecules in regulating physiological and biochemical processes in this organism. In conclusion, this proteomic analysis reveals a striking breadth of cellular processes affected by lysine acetylation and provides new nodes of intervention in the biosynthesis of secondary metabolites in G. lucidum.

MCU complex: Exploring emerging targets and mechanisms of mitochondrial physiology and pathology

BACKGROUND

Globally, the onset and progression of multiple human diseases are associated with mitochondrial dysfunction and dysregulation of Ca2+ uptake dynamics mediated by the mitochondrial calcium uniporter (MCU) complex, which plays a key role in mitochondrial dysfunction. Despite relevant studies, the underlying pathophysiological mechanisms have not yet been fully elucidated.

AIM OF REVIEW

This article provides an in-depth analysis of the current research status of the MCU complex, focusing on its molecular composition, regulatory mechanisms, and association with diseases. In addition, we conducted an in-depth analysis of the regulatory effects of agonists, inhibitors, and traditional Chinese medicine (TCM) monomers on the MCU complex and their application prospects in disease treatment. From the perspective of medicinal chemistry, we conducted an in-depth analysis of the structure-activity relationship between these small molecules and MCU and deduced potential pharmacophores and binding pockets. Simultaneously, key structural domains of the MCU complex in Homo sapiens were identified. We also studied the functional expression of the MCU complex in Drosophila, Zebrafish, and Caenorhabditis elegans. These analyses provide a basis for exploring potential treatment strategies targeting the MCU complex and provide strong support for the development of future precision medicine and treatments.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The MCU complex exhibits varying behavior across different tissues and plays various roles in metabolic functions. It consists of six MCU subunits, an essential MCU regulator (EMRE), and solute carrier 25A23 (SLC25A23). They regulate processes, such as mitochondrial Ca2+ (mCa2+) uptake, mitochondrial adenosine triphosphate (ATP) production, calcium dynamics, oxidative stress (OS), and cell death. Regulation makes it a potential target for treating diseases, especially cardiovascular diseases, neurodegenerative diseases, inflammatory diseases, metabolic diseases, and tumors.

Novel indocyanine green-loaded photothermal nanoparticles targeting TRPV1 for thermal ablation treatment of severe murine asthma induced by ovalbumin and lipopolysaccharide

To identify a replacement strategy for bronchial thermoplasty (BT) with non-invasive and free-of-severe side effect is urgently needed in the clinic for severe asthma treatment. In this study, PLGA-PEG@ICG@TRPV1 pAb (PIT) photothermal nanoparticles targeting bronchial TRPV1 were designed for photothermal therapy (PTT) against severe murine asthma induced by ovalbumin and lipopolysaccharide. PIT was formulated with a polyethylene glycol (PEG)-grafted poly (lactic-co-glycolic) acid (PLGA) coating as a skeleton structure to encapsulate indocyanine green (ICG) and was conjugated to the polyclonal antibody against transient receptor potential vanilloid 1 (TRPV1 pAb). The results revealed that PIT held good druggability due to its electronegativity and small diameter. PIT demonstrated great photothermal effects both in vivo and in vitro and exhibited good ability to target TRPV1 in vitro because of its selective cell uptake and specific cell toxicity toward TRPV1-overexpressing cells. The PIT treatment effectively reduced asthma symptoms in mice. This is evident from improvements in expiratory airflow limitation, significant decreases in inflammatory cell infiltration in the airways, and increases in goblet cell and columnar epithelial cell proliferation. In conclusion, PIT alleviates severe murine asthma symptoms through a combination of TRPV1 targeting and photothermal effects.

Application of calcium overload-based ion interference therapy in tumor treatment: strategies, outcomes, and prospects

Low selectivity and tumor drug resistance are the main hinderances to conventional radiotherapy and chemotherapy against tumor. Ion interference therapy is an innovative anti-tumor strategy that has been recently reported to induce metabolic disorders and inhibit proliferation of tumor cells by reordering bioactive ions within the tumor cells. Calcium cation (Ca2+) are indispensable for all physiological activities of cells. In particular, calcium overload, characterized by the abnormal intracellular Ca2+ accumulation, causes irreversible cell death. Consequently, calcium overload-based ion interference therapy has the potential to overcome resistance to traditional tumor treatment strategies and holds promise for clinical application. In this review, we 1) Summed up the current strategies employed in this therapy; 2) Described the outcome of tumor cell death resulting from this therapy; 3) Discussed its potential application in synergistic therapy with immunotherapy.

Mitochondrial dynamics and colorectal cancer biology: mechanisms and potential targets

Colorectal cancer (CRC) is a significant public health concern, and its development is associated with mitochondrial dysfunction. Mitochondria can adapt to the high metabolic demands of cancer cells owing to their plasticity and dynamic nature. The fusion-fission dynamics of mitochondria play a crucial role in signal transduction and metabolic functions of CRC cells. Enhanced mitochondrial fission promotes the metabolic reprogramming of CRC cells, leading to cell proliferation, metastasis, and chemoresistance. Excessive fission can also trigger mitochondria-mediated apoptosis. In contrast, excessive mitochondrial fusion leads to adenosine triphosphate (ATP) overproduction and abnormal tumor proliferation, whereas moderate fusion protects intestinal epithelial cells from oxidative stress-induced mitochondrial damage, thus preventing colitis-associated cancer (CAC). Therefore, an imbalance in mitochondrial dynamics can either promote or inhibit CRC progression. This review provides an overview of the mechanism underlying mitochondrial fusion-fission dynamics and their impact on CRC biology. This revealed the dual role of mitochondrial fusion-fission dynamics in CRC development and identified potential drug targets. Additionally, this study partially explored mitochondrial dynamics in immune and vascular endothelial cells in the tumor microenvironment, suggesting promising prospects for targeting key fusion/fission effector proteins against CRC.

miR-135a Mediates Mitochondrial Oxidative Respiratory Function through SIRT1 to Regulate Atrial Fibrosis

INTRODUCTION

This study aimed to explore the function of miR-135a in the progress of atrial fibrosis and the mechanism of miR-135a/SIRT1 (sirtuin 1) in human cardiac fibroblasts and mouse cardiac fibroblasts (MCFs) mediating the regulation of atrial fibrosis by mitochondrial oxidative respiration function.

METHODS

Using Ang II (angiotensin II) to induce fibrosis in HCFs (human corneal fibroblasts) and MCF (Michigan Cancer Foundation, MCF) cells in vitro, the miRNA-seq results of previous studies were validated. Proliferative and invasive ability of HCFs and MCFs was detected by Cell Counting Kit-8 assay (CCK-8) and scratch experiment after overexpressing miR-135a in HCFs and MCF cells. Protein and mRNA expression was tested using Western blot and qPCR. The target of miR-135a was verified as SIRT1 by a luciferase reporter assay and the activities of the mitochondrial respiratory enzyme complexes I, II, III, and IV were determined colorimetrically. The activities of malondialdehyde, reactive oxygen species, and superoxide dismutase in cells were detected with enzyme-linked immunosorbent assay (ELISA).

RESULTS

miR-135a expression was elevated in HCFs and MCFs cells in the Ang II group than control group. Overexpression of miR-135a could promote the proliferation, migration, oxidative stress, as well as fibrosis of cardiac fibroblasts and suppresses mitochondrial activity. In addition, we found SIRT1 was a target gene of miR-135a. What is more, the findings showed miR-135a promoted fibrosis in HCFs and MCFs cells acting through regulation of SIRT1.

CONCLUSIONS

miR-135a mediates mitochondrial oxidative respiratory function through SIRT1 to regulate atrial fibrosis.

Tranexamic Acid Causes Chondral Injury Through Chondrocytes Apoptosis Induced by Activating Endoplasmic Reticulum Stress

PURPOSE

To investigate whether tranexamic acid (TXA) is cytotoxic in chondrocyte and cartilage tissues, as well as explore the mechanisms behind the possible toxicity in detail.

METHODS

We detected the cell viability of chondrocytes in vitro and the change of morphology and specific in vivo contents of cartilage after TXA treatment. Furthermore, we detected apoptosis in cartilage. We used apoptosis-specific staining, reactive oxygen species detection, mitochondrial membrane potential detection, flow cytometry, and western blot for apoptosis detection. Finally, we detected the activation of endoplasmic reticulum stress (ERS) in TXA-treated chondrocytes to clarify the mechanism behind chondrocyte apoptosis.

RESULTS

TXA presented an increasing toxic effect with increasing concentrations, especially in the 100 mg/mL group. In addition, we found that 50 mg/mL and 100 mg/mL TXA significantly increased apoptosis in cartilage and subchondral bone. TXA could induce chondrocyte apoptosis in cell and protein levels with reactive oxygen species generation and mitochondrial membrane depolarization. An apoptosis inhibitor could inhibit the induced apoptosis. Next, TXA induced calcium overload in chondrocytes and increased ERS-specific protein expression, whereas ERS inhibitor blocked ERS activation and further inhibited chondrocyte apoptosis.

CONCLUSIONS

We concluded that TXA had a toxic effect on chondrocytes by inducing apoptosis through ERS activation, especially in 50 mg/mL and 100 mg/mL groups. We recommend TXA concentrations of less than 50 mg/mL in joint surgeries.

CLINICAL RELEVANCE

It is still unclear whether TXA has a toxic effect on cartilage when topically used in joint surgeries. The concentration also varies. This study provides additional evidence that TXA at high concentrations will cause cartilage damage, which will help to provide a new understanding of the clinical administration of TXA.

Histone deacetylase inhibitor pracinostat suppresses colorectal cancer by inducing CDK5-Drp1 signaling-mediated peripheral mitofission

Divisions at the periphery and midzone of mitochondria are two fission signatures that determine the fate of mitochondria and cells. Pharmacological induction of excessively asymmetric mitofission-associated cell death (MFAD) by switching the scission position from the mitochondrial midzone to the periphery represents a promising strategy for anticancer therapy. By screening a series of pan-inhibitors, we identified pracinostat, a pan-histone deacetylase (HDAC) inhibitor, as a novel MFAD inducer, that exhibited a significant anticancer effect on colorectal cancer (CRC) in vivo and in vitro. Pracinostat increased the expression of cyclin-dependent kinase 5 (CDK5) and induced its acetylation at residue lysine 33, accelerating the formation of complex CDK5/CDK5 regulatory subunit 1 and dynamin-related protein 1 (Drp1)-mediated mitochondrial peripheral fission. CRC cells with high level of CDK5 (CDK5-high) displayed midzone mitochondrial division that was associated with oncogenic phenotype, but treatment with pracinostat led to a lethal increase in the already-elevated level of CDK5 in the CRC cells. Mechanistically, pracinostat switched the scission position from the mitochondrial midzone to the periphery by improving the binding of Drp1 from mitochondrial fission factor (MFF) to mitochondrial fission 1 protein (FIS1). Thus, our results revealed the anticancer mechanism of HDACi pracinostat in CRC via activating CDK5-Drp1 signaling to cause selective MFAD of those CDK5-high tumor cells, which implicates a new paradigm to develop potential therapeutic strategies for CRC treatment.

Quercetin and Related Analogs as Therapeutics to Promote Tissue Repair

Quercetin is a polyphenol of the flavonoid class of secondary metabolites that is widely distributed in the plant kingdom. Quercetin has been found to exhibit potent bioactivity in the areas of wound healing, neuroprotection, and anti-aging research. Naturally found in highly glycosylated forms, aglycone quercetin has low solubility in aqueous environments, which has heavily limited its clinical applications. To improve the stability and bioavailability of quercetin, efforts have been made to chemically modify quercetin and related flavonoids so as to improve aqueous solubility while retaining bioactivity. In this review, we provide an updated overview of the biological properties of quercetin and proposed mechanisms of actions in the context of wound healing and aging. We also provide a description of recent developments in synthetic approaches to improve the solubility and stability of quercetin and related analogs for therapeutic applications. Further research in these areas is expected to enable translational applications to improve ocular wound healing and tissue repair.

Targeting ARF1-IQGAP1 interaction to suppress colorectal cancer metastasis and vemurafenib resistance

INTRODUCTION

Acquired resistance to BRAF inhibitor vemurafenib is frequently observed in metastatic colorectal cancer (CRC), and it is a thorny issue that results in treatment failure. As adaptive responses for vemurafenib treatment, a series of cellular bypasses are response for the adaptive feedback reactivation of ERK signaling, which warrant further investigation.

OBJECTIVES

We identified ARF1 (ADP-ribosylation factor 1) as a novel regulator of both vemurafenib resistance and cancer metastasis, its molecular mechanism and potential inhibitor were investigated in this study.

METHODS

DIA-based quantitative proteomics and RNA-seq were performed to systematic analyze the profiling of vemurafenib-resistant RKO cells (RKO-VR) and highly invasive RKO cells (RKO-I8), respectively. Co‑immunoprecipitation assay was performed to detect the interaction of ARF1 and IQGAP1 (IQ-domain GTPase activating protein 1). An ELISA-based drug screen system on FDA-approved drug library was established to screen the compounds against the interaction of ARF1-IQGAP1.The biological functions of ARF1 and LY2835219 were determined by transwell, western blotting, Annexin V-FITC/PI staining and in vivo experimental metastasis assays.

RESULTS

We found that ARF1 strongly interacted with IQGAP1 to activate ERK signaling in VR and I8 CRC cells. Deletion of IQGAP1 or inactivation of ARF1 (ARF-T48S) restored the invasive ability induced by ARF1. As ARF1-IQGAP1 interaction is essential for ERK activation, we screened LY2835219 as novel inhibitor of ARF1-IQGAP1 interaction, which inactivated ERK signaling and suppressed CRC metastasis and vemurafenib-resistance in vitro and in vivo with no observed side effect. Furthermore, LY2835219 in combined treatment with vemurafenib exerted significantly inhibitory effect on ARF1-mediated cancer metastasis than used independently.

CONCLUSION

This study uncovers that ARF1-IQGAP1 interaction-mediated ERK signaling reactivation is critical for vemurafenib resistance and cancer metastasis, and that LY2835219 is a promising therapeutic agent for CRC both as a single agent and in combination with vemurafenib.

Polyphyllin D punctures hypertrophic lysosomes to reverse drug resistance of hepatocellular carcinoma by targeting acid sphingomyelinase

Hypertrophic lysosomes are critical for tumor progression and drug resistance; however, effective and specific lysosome-targeting compounds for cancer therapy are lacking. Here we conducted a lysosomotropic pharmacophore-based in silico screen in a natural product library (2,212 compounds), and identified polyphyllin D (PD) as a novel lysosome-targeted compound. PD treatment was found to cause lysosomal damage, as evidenced by the blockade of autophagic flux, loss of lysophagy, and the release of lysosomal contents, thus exhibiting anticancer effects on hepatocellular carcinoma (HCC) cell both in vitro and in vivo. Closer mechanistic examination revealed that PD suppressed the activity of acid sphingomyelinase (SMPD1), a lysosomal phosphodieserase that catalyzes the hydrolysis of sphingomyelin to produce ceramide and phosphocholine, by directly occupying its surface groove, with Trp148 in SMPD1 acting as a major binding residue; this suppression of SMPD1 activity irreversibly triggers lysosomal injury and initiates lysosome-dependent cell death. Furthermore, PD-enhanced lysosomal membrane permeabilization to release sorafenib, augmenting the anticancer effect of sorafenib both in vivo and in vitro. Overall, our study suggests that PD can potentially be further developed as a novel autophagy inhibitor, and a combination of PD with classical chemotherapeutic anticancer drugs could represent a novel therapeutic strategy for HCC intervention.

LINC00493-encoded microprotein SMIM26 exerts anti-metastatic activity in renal cell carcinoma

Human microproteins encoded by long non-coding RNAs (lncRNA) have been increasingly discovered, however, complete functional characterization of these emerging proteins is scattered. Here, we show that LINC00493-encoded SMIM26, an understudied microprotein localized in mitochondria, is tendentiously downregulated in clear cell renal cell carcinoma (ccRCC) and correlated with poor overall survival. LINC00493 is recognized by RNA-binding protein PABPC4 and transferred to ribosomes for translation of a 95-amino-acid protein SMIM26. SMIM26, but not LINC00493, suppresses ccRCC growth and metastatic lung colonization by interacting with acylglycerol kinase (AGK) and glutathione transport regulator SLC25A11 via its N-terminus. This interaction increases the mitochondrial localization of AGK and subsequently inhibits AGK-mediated AKT phosphorylation. Moreover, the formation of the SMIM26-AGK-SCL25A11 complex maintains mitochondrial glutathione import and respiratory efficiency, which is abrogated by AGK overexpression or SLC25A11 knockdown. This study functionally characterizes the LINC00493-encoded microprotein SMIM26 and establishes its anti-metastatic role in ccRCC, and therefore illuminates the importance of hidden proteins in human cancers.

SIRT1 mediated gastric cancer progression under glucose deprivation through the FoxO1-Rab7-autophagy axis

Purpose

Silent mating type information regulator 2 homolog 1 (SIRT1) and autophagy have a two-way action (promoting cell death or survival) on the progression and treatment of gastric cancer (GC) under different conditions or environments. This study aimed to investigate the effects and underlying mechanism of SIRT1 on autophagy and the malignant biological behavior of GC cells under conditions of glucose deprivation (GD).

Materials and methods

Human immortalized gastric mucosal cell GES-1 and GC cell lines SGC-7901, BGC-823, MKN-45 and MKN-28 were utilized. A sugar-free or low-sugar (glucose concentration, 2.5 mmol/L) DMEM medium was used to simulate GD. Additionally, CCK8, colony formation, scratches, transwell, siRNA interference, mRFP-GFP-LC3 adenovirus infection, flow cytometry and western blot assays were performed to investigate the role of SIRT1 in autophagy and malignant biological behaviors (proliferation, migration, invasion, apoptosis and cell cycle) of GC under GD and the underlying mechanism.

Results

SGC-7901 cells had the longest tolerance time to GD culture conditions, which had the highest expression of SIRT1 protein and the level of basal autophagy. With the extension of GD time, the autophagy activity in SGC-7901 cells also increased. Under GD conditions, we found a close relationship between SIRT1, FoxO1 and Rab7 in SGC-7901 cells. SIRT1 regulated the activity of FoxO1 and upregulated the expression of Rab7 through deacetylation, which ultimately affected autophagy in GC cells. In addition, changing the expression of FoxO1 provided feedback on the expression of SIRT1 in the cell. Reducing SIRT1, FoxO1 or Rab7 expression significantly inhibited the autophagy levels of GC cells under GD conditions, decreased the tolerance of GC cells to GD, enhanced the inhibition of GD in GC cell proliferation, migration and invasion and increased apoptosis induced by GD.

Conclusion

The SIRT1-FoxO1-Rab7 pathway is crucial for the autophagy and malignant biological behaviors of GC cells under GD conditions, which could be a new target for the treatment of GC.

Mitochondrial Ion Channels

Mitochondria are involved in multiple cellular tasks, such as ATP synthesis, metabolism, metabolite and ion transport, regulation of apoptosis, inflammation, signaling, and inheritance of mitochondrial DNA. The majority of the correct functioning of mitochondria is based on the large electrochemical proton gradient, whose component, the inner mitochondrial membrane potential, is strictly controlled by ion transport through mitochondrial membranes. Consequently, mitochondrial function is critically dependent on ion homeostasis, the disturbance of which leads to abnormal cell functions. Therefore, the discovery of mitochondrial ion channels influencing ion permeability through the membrane has defined a new dimension of the function of ion channels in different cell types, mainly linked to the important tasks that mitochondrial ion channels perform in cell life and death. This review summarizes studies on animal mitochondrial ion channels with special focus on their biophysical properties, molecular identity, and regulation. Additionally, the potential of mitochondrial ion channels as therapeutic targets for several diseases is briefly discussed.

Transient receptor potential channel stimulation induced oxidative stress and apoptosis in the colon of mice with colitis-associated colon cancer: modulator role of Sambucus ebulus L

BACKGROUND

Increased Ca²⁺ entry causes an increase in tumor cell proliferation, apoptosis, cytosolic reactive free oxygen species (cyROS), and mitochondrial ROS (miROS) in tumor cells. The cyROS and miROS stimulate the cation channels, including the TRPA1, TRPM2, and TRPV1. Sambucus ebulus L (SEB) (Dwarf Elder) induced both antioxidant and anticancer effects in the human hepatocarcinoma and human colon carcinoma cancer cell lines. We investigated the etiology of colorectal cancer and the impact of three channels, as well as the protective effects of SEB on apoptosis, cyROS, and miROS in the colon of mice with colitis-associated colon cancer (AOM/DSS).

METHODS

A total 28 mice were equally divided into four groups as control, SEB (100 mg/kg/day for 14 days), AOM/DSS, and SEB + AOM/DSS. Azoxymethane/dextran sulfate sodium-induced colon cancer associated with colitis was induced in the AOM/DSS groups within 10 weeks. At the end of the experiments, the colon samples were removed from the mice.

RESULTS

The protein bands of caspase - 3, TRPA1, TRPM2, and TRPV1 were increased by the treatments of AOM/DSS. The levels of apoptosis, cyROS, cleaved caspase - 3, and cleaved caspase - 9, as well as the depolarization of the mitochondrial membrane, all increased in the AOM/DSS group. Although they were reduced in the SEB and AOM/DSS + SEB groups by the treatments of SEB, TRPA1 (AP18), TRPM2 (ACA), and TRPV1 (capsazepine) antagonists, the apoptotic and oxidant values were further elevated in the AOM/DSS group by the treatments of TRPA1 (cinnamaldehyde), TRPM2 (H₂O₂), and TRPV1 (capsaicin) agonists.

CONCLUSION

The activations of TRPA1, TRPM2, and TRPV1 channels induced the increase of apoptotic and oxidant actions in the colon cancer cells, although their inhibition via SEB treatment decreased the actions. Hence, TRPA1, TRPM2, and TRPV1 activations could be used as effective agents in the treatment of colon tumors.

Activation of the sirtuin silent information regulator 1 pathway inhibits pathological myocardial remodeling

Myocardial remodeling refers to structural and functional disorders of the heart caused by molecular biological changes in the cardiac myocytes in response to neurological and humoral factors. A variety of heart diseases, such as hypertension, coronary artery disease, arrhythmia, and valvular heart disease, can cause myocardial remodeling and eventually lead to heart failure. Therefore, counteracting myocardial remodeling is essential for the prevention and treatment of heart failure. Sirt1 is a nicotinamide adenine dinucleotide⁺-dependent deacetylase that plays a wide range of roles in transcriptional regulation, energy metabolism regulation, cell survival, DNA repair, inflammation, and circadian regulation. It positively or negatively regulates myocardial remodeling by participating in oxidative stress, apoptosis, autophagy, inflammation, and other processes. Taking into account the close relationship between myocardial remodeling and heart failure and the involvement of SIRT1 in the development of the former, the role of SIRT1 in the prevention of heart failure via inhibition of myocardial remodeling has received considerable attention. Recently, multiple studies have been conducted to provide a better understanding of how SIRT1 regulates these phenomena. This review presents the progress of research involving SIRT1 pathway involvement in the pathophysiological mechanisms of myocardial remodeling and heart failure.

Proteome-Wide Analysis Reveals TFEB Targets for Establishment of a Prognostic Signature to Predict Clinical Outcomes of Colorectal Cancer

Dephosphorylation of transcription factor EB (TFEB) at Ser142 and Ser138 determines its nuclear localization and transcriptional activity. The link between TFEB-associated genes and colorectal cancer (CRC) progression and prognosis remains unclear. To systematically identify the targets of TFEB, we performed data-independent acquisition (DIA)-based quantitative proteomics to compare global protein changes in wild-type (WT) DLD1 cells and TFEB^WT- or TFEB^S142A/S138A (activated status)-expressing DLD1 cells. A total of 6048 proteins were identified and quantified in three independent experiments. The differentially expressed proteins in TFEB^S142A/S138A versus TFEB^WT and TFEB^WT versus control groups were compared, and 60 proteins were identified as products of TFEB transcriptional regulation. These proteins were significantly associated with vesicular endocytic trafficking, the HIF-1 signaling pathway, and metabolic processes. Furthermore, we generated a TFEB-associated gene signature using a univariate and LASSO Cox regression model to screen robust prognostic markers. An eight-gene signature (PLSCR3, SERPINA1, ATP6V1C2, TIMP1, SORT1, MAP2, KDM4B, and DDAH2) was identified. According to the signature, patients were assigned to high-risk and low-risk groups. Higher risk scores meant worse overall survival and higher epithelial-mesenchymal transition (EMT) scores. Additionally, as per the clinicopathological parameters and gene signature, a nomogram was constructed that was utilized to enhance the quantification capacity in risk assessment for individual patients. This research shows that TFEB directly mediates network effects in CRC, and the identified TFEB gene signature-based model may provide important information for the clinical judgment of prognosis.

Why Is Longevity Still a Scientific Mystery? Sirtuins-Past, Present and Future

The sirtuin system consists of seven highly conserved regulatory enzymes responsible for metabolism, antioxidant protection, and cell cycle regulation. The great interest in sirtuins is associated with the potential impact on life extension. This article summarizes the latest research on the activity of sirtuins and their role in the aging process. The effects of compounds that modulate the activity of sirtuins were discussed, and in numerous studies, their effectiveness was demonstrated. Attention was paid to the role of a caloric restriction and the risks associated with the influence of careless sirtuin modulation on the organism. It has been shown that low modulators' bioavailability/retention time is a crucial problem for optimal regulation of the studied pathways. Therefore, a detailed understanding of the modulator structure and potential reactivity with sirtuins in silico studies should precede in vitro and in vivo experiments. The latest achievements in nanobiotechnology make it possible to create promising molecules, but many of them remain in the sphere of plans and concepts. It seems that solving the mystery of longevity will have to wait for new scientific discoveries.

Puerarin prevents cadmium-induced mitochondrial fission in AML-12 cells via Sirt1-dependent pathway

Recent investigations have revealed that puerarin (PU) alleviates cadmium (Cd)-caused hepatic damage via inhibiting oxidative stress. Mitochondria are dynamic organelles and play a critical part in regulating the occurrence of oxidative stress, but the role of mitochondria in the protection of PU against hepatocellular damage caused by Cd exposure remains unknown. Thus, this study was aimed to clarify this issue using mouse hepatocyte AML-12 cell line. Transmission electron microscopy analysis firstly showed that PU prevents Cd-induced mitochondrial ultrastructure damage. Mitochondrial network image analysis by confocal microscopy revealed that PU exerts the protection against Cd-induced cytotoxicity via restoring mitochondrial network fragmentation. Also, mitochondrial dynamic protein expression profiles showed that enhanced fission protein levels and inhibited fusion protein levels in Cd-treated cells were significantly reversed by PU, suggesting the protective effect of PU against Cd-induced mitochondrial fission. Moreover, changes of intracellular ATP level and protein levels of key regulators involving in mitochondrial biogenesis indicated that Sirtuin-1(Sirt1) pathway may be involved in the protection of Cd-impaired mitochondrial function by PU. Next, Sirt1 protein levels in treated cells were effectively regulated by genetic knockdown or chemical agonist SRT1720. Accordingly, alleviation of Cd-induced mitochondrial fission assays and cell viability by PU was markedly regulated by SRT1720 or Sirt1 knockdown, suggesting the indispensable role of Sirt1 in this process. Collectively, these findings highlight that PU prevents Cd-induced mitochondrial fission to alleviate cytotoxicity via Sirt1-dependent pathway, which provide novel evidences to fully understand the hepatoprotective action of PU against heavy metal toxicity.

Whole-transcriptome sequencing identifies neuroinflammation, metabolism and blood-brain barrier related processes in the hippocampus of aged mice during perioperative period

AIM

Perioperative neurocognitive disorders (PND) occur frequently after surgery and anesthesia, especially in aged patients. Previous studies have shown multiple PND related mechanisms in the hippocampus; however, their relationships remain unclear. Meanwhile, the perioperative neuropathological processes are sophisticated and changeable, single period study could not reveal the accurate mechanisms. Thus, multiperiod whole-transcriptome study is necessary to elucidate the gene expression patterns during perioperative period.

METHODS

Aged C57BL/6 mice were subjected to exploratory laparotomy under sevoflurane anesthesia. Whole-transcriptome sequencing (RNA-seq analysis) was performed on the hippocampi from control condition (Con), 30 min (Day0), 2 days (Day2), and 7 days (Day7) after surgery. Gene Ontology/Kyoto Encyclopedia of Genes and Genomes analyses, quantitative real-time PCR, immunofluorescence, and fear conditioning test were also performed to elucidate the pathological processes and modulation networks during the period.

RESULTS

Through RNA-seq analysis, 328, 3597, and 4179 differentially expressed genes (DEGs) were screened out in intraoperative period (Day0 vs. Con), early postoperative period (Day2 vs. Day0), and late postoperative period (Day7 vs. Day2). The involved GO biological processes were divided into 9 categories, and positive-regulated processes were more than negative-regulated ones. Seventy-four transcription factors were highlighted. The potential synaptic and neuroinflammatory pathways were constructed for Neurotransmitter, Synapse and Neuronal alteration categories with 9 genes (Htr1a, Rims1, and Ezh2, etc.). The metabolic and mitochondrial pathways were constructed for metabolism, oxidative stress, and biological rhythm categories with 9 genes (Gpld1, Sirt1, and Cry2, etc.). The blood-brain barrier and neurotoxicity related pathways were constructed for blood-brain barrier, neurotoxicity, and cognitive function categories with 10 genes (Mmp2, Itpr1, and Nrf1, etc.).

CONCLUSION

The results revealed gene expression patterns and modulation networks in the aged hippocampus during perioperative period, which provide insights into overall mechanisms and potential therapeutic targets for prevention and treatment of perioperative central nervous system diseases, such as PND, from the genetic level.