Mitochondrial regulation of cell death: a phylogenetically conserved control

Challenges of Regulated Cell Death: Implications for Therapy Resistance in Cancer

Regulated cell death, a regulatory form of cell demise, has been extensively studied in multicellular organisms. It plays a pivotal role in maintaining organismal homeostasis under normal and pathological conditions. Although alterations in various regulated cell death modes are hallmark features of tumorigenesis, they can have divergent effects on cancer cells. Consequently, there is a growing interest in targeting these mechanisms using small-molecule compounds for therapeutic purposes, with substantial progress observed across various human cancers. This review focuses on summarizing key signaling pathways associated with apoptotic and autophagy-dependent cell death. Additionally, it explores crucial pathways related to other regulated cell death modes in the context of cancer. The discussion delves into the current understanding of these processes and their implications in cancer treatment, aiming to illuminate novel strategies to combat therapy resistance and enhance overall cancer therapy.

PA2G4/EBP1 ubiquitination by PRKN/PARKIN promotes mitophagy protecting neuron death in cerebral ischemia

Cerebral ischemia induces massive mitochondrial damage, leading to neuronal death. The elimination of damaged mitochondria via mitophagy is critical for neuroprotection. Here we show that the level of PA2G4/EBP1 (proliferation-associated 2G4) was notably increased early during transient middle cerebral artery occlusion and prevented neuronal death by eliciting cerebral ischemia-reperfusion (IR)-induced mitophagy. Neuron-specific knockout of Pa2g4 increased infarct volume and aggravated neuron loss with impaired mitophagy and was rescued by introduction of adeno-associated virus serotype 2 expressing PA2G4/EBP1. We determined that PA2G4/EBP1 is ubiquitinated on lysine 376 by PRKN/PARKIN on the damaged mitochondria and interacts with receptor protein SQSTM1/p62 for mitophagy induction. Thus, our study suggests that PA2G4/EBP1 ubiquitination following cerebral IR-injury promotes mitophagy induction, which may be implicated in neuroprotection.Abbreviations: AAV: adeno-associated virus; ACTB: actin beta; BNIP3L/NIX: BCL2 interacting protein 3 like; CA1: Cornu Ammonis 1; CASP3: caspase 3; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; DMSO: dimethyl sulfoxide; PA2G4/EBP1: proliferation-associated 2G4; FUNDC1: FUN14 domain containing 1; IB: immunoblotting; ICC: immunocytochemistry; IHC: immunohistochemistry; IP: immunoprecipitation; MCAO: middle cerebral artery occlusion; MEF: mouse embryonic fibroblast; OGD: oxygen-glucose deprivation; PRKN/PARKIN: parkin RBR E3 ubiquitin protein ligase; PINK1: PTEN induced kinase 1; RBFOX3/NeuN: RNA binding fox-1 homolog 3; SQSTM1/p62: sequestosome 1; TIMM23: translocase of inner mitochondrial membrane 23; TOMM20: translocase of outer mitochondrial membrane 20; TUBB: tubulin beta class I; WT: wild-type.

Landscape of molecular crosstalk between SARS-CoV-2 infection and cardiovascular diseases: emphasis on mitochondrial dysfunction and immune-inflammation

BACKGROUND

SARS-CoV-2, the pathogen of COVID-19, is a worldwide threat to human health and causes a long-term burden on the cardiovascular system. Individuals with pre-existing cardiovascular diseases are at higher risk for SARS-CoV-2 infection and tend to have a worse prognosis. However, the relevance and pathogenic mechanisms between COVID-19 and cardiovascular diseases are not yet completely comprehended.

METHODS

Common differentially expressed genes (DEGs) were obtained in datasets of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) infected with SARS-CoV-2 and myocardial tissues from heart failure patients. Further GO and KEGG pathway analysis, protein-protein interaction (PPI) network construction, hub genes identification, immune microenvironment analysis, and drug candidate predication were performed. Then, an isoproterenol-stimulated myocardial hypertrophy cell model and a transverse aortic constriction-induced mouse heart failure model were employed to validate the expression of hub genes.

RESULTS

A total of 315 up-regulated and 78 down-regulated common DEGs were identified. Functional enrichment analysis revealed mitochondrial metabolic disorders and extensive immune inflammation as the most prominent shared features of COVID-19 and cardiovascular diseases. Then, hub DEGs, as well as hub immune-related and mitochondria-related DEGs, were screened. Additionally, nine potential therapeutic agents for COVID-19-related cardiovascular diseases were proposed. Furthermore, the expression patterns of most of the hub genes related to cardiovascular diseases in the validation dataset along with cellular and mouse myocardial damage models, were consistent with the findings of bioinformatics analysis.

CONCLUSIONS

The study unveiled the molecular networks and signaling pathways connecting COVID-19 and cardiovascular diseases, which may provide novel targets for intervention of COVID-19-related cardiovascular diseases.

Cell death classification: A new insight based on molecular mechanisms

Cells tend to disintegrate themselves or are forced to undergo such destructive processes in critical circumstances. This complex cellular function necessitates various mechanisms and molecular pathways in order to be executed. The very nature of cell death is essentially important and vital for maintaining homeostasis, thus any type of disturbing occurrence might lead to different sorts of diseases and dysfunctions. Cell death has various modalities and yet, every now and then, a new type of this elegant procedure gets to be discovered. The diversity of cell death compels the need for a universal organizing system in order to facilitate further studies, therapeutic strategies and the invention of new methods of research. Considering all that, we attempted to review most of the known cell death mechanisms and sort them all into one arranging system that operates under a simple but subtle decision-making (If \ Else) order as a sorting algorithm, in which it decides to place and sort an input data (a type of cell death) into its proper set, then a subset and finally a group of cell death. By proposing this algorithm, the authors hope it may solve the problems regarding newer and/or undiscovered types of cell death and facilitate research and therapeutic applications of cell death.

The delaying effect of Qingxin Zishen decoction on ovarian aging: Examining regulation of ovarian mitochondria apoptosis in aged rats

Ovarian aging is a significant challenge in gynecology, and there is currently no effective treatment for it. However, the medicinal agent Qingxin Zishen decoction (QZD) has shown potential in the treatment of ovarian dysfunction. The present study aimed to evaluate the mitochondrial apoptotic mechanism of delayed ovarian aging in QZD in aging rats. The healthy female Sprague-Dawley (SD) rats (n = 40, 350 ± 20 g) were randomly assigned to different dosage groups and 4-month-old SD rats (n = 10) were assigned to the control group. QZD groups were treated with QZD for four weeks, and ovarian tissues were extracted for mRNA and protein assays to examine the role of the apoptotic pathway in QZD. The results showed that QZD treatment for four weeks significantly increased the mRNA and protein expressions of the anti-apoptotic gene B-cell lymphoma 2 (Bcl-2) and Bcl-2/Bax ratio, as well as downregulated the pro-apoptotic genes Bax, caspase-3, and caspase-9. Moreover, QZD treatment effectively reduced the expression of cytochrome C (cyto-C) and apoptotic protease-activating factor 1 (Apaf-1), both of which are components of the intrinsic apoptotic pathway. These changes exhibited a dose-response manner. The findings suggest that QZD might have therapeutic potential in delaying ovarian mitochondrial function decline and in preventing and treating ovarian aging-related diseases by downregulating and upregulating the pro-apoptotic (Bax, caspase-3, caspase-9, cyto-C, Apaf-1) and anti-apoptotic (Bcl-2 and Bcl-2/Bax ratio) genes, respectively.

Mitochondrial Dysfunction-Associated Mechanisms in the Development of Chronic Liver Diseases

The liver is a major metabolic organ that performs many essential biological functions such as detoxification and the synthesis of proteins and biochemicals necessary for digestion and growth. Any disruption in normal liver function can lead to the development of more severe liver disorders. Overall, about 3 million Americans have some type of liver disease and 5.5 million people have progressive liver disease or cirrhosis, in which scar tissue replaces the healthy liver tissue. An estimated 20% to 30% of adults have excess fat in their livers, a condition called steatosis. The most common etiologies for steatosis development are (1) high caloric intake that causes non-alcoholic fatty liver disease (NAFLD) and (2) excessive alcohol consumption, which results in alcohol-associated liver disease (ALD). NAFLD is now termed "metabolic-dysfunction-associated steatotic liver disease" (MASLD), which reflects its association with the metabolic syndrome and conditions including diabetes, high blood pressure, high cholesterol and obesity. ALD represents a spectrum of liver injury that ranges from hepatic steatosis to more advanced liver pathologies, including alcoholic hepatitis (AH), alcohol-associated cirrhosis (AC) and acute AH, presenting as acute-on-chronic liver failure. The predominant liver cells, hepatocytes, comprise more than 70% of the total liver mass in human adults and are the basic metabolic cells. Mitochondria are intracellular organelles that are the principal sources of energy in hepatocytes and play a major role in oxidative metabolism and sustaining liver cell energy needs. In addition to regulating cellular energy homeostasis, mitochondria perform other key physiologic and metabolic activities, including ion homeostasis, reactive oxygen species (ROS) generation, redox signaling and participation in cell injury/death. Here, we discuss the main mechanism of mitochondrial dysfunction in chronic liver disease and some treatment strategies available for targeting mitochondria.

Different types of cell death and their shift in shaping disease

Cell death is the irreversible stop of life. It is also the basic physiological process of all organisms which involved in the embryonic development, organ maintenance and autoimmunity of the body. In recent years, we have gained more comprehension of the mechanism in cell death and have basically clarified the different types of "programmed cell death", such as apoptosis, necroptosis, autophagy, and pyroptosis, and identified some key genes in these processes. However, in these previous studies, the conversion between different cell death modes and their application in diseases are rarely explored. To sum up, although many valued discoveries have been discovered in the field of cell death in recent years, there are still many unknown problems to be solved in this field. Facts have proved that cell death is a very complex game, and a series of core players have the ability to destroy the delicate balance of the cell environment, from survival to death, from anti-inflammatory to pro-inflammatory. With the thorough research of the complex regulatory mechanism of cell death, there will certainly be exciting new research in this field in the next few years. The sake of this paper is to emphasize the complex mechanism of overturning the balance between different cell fates and provide relevant theoretical basis for the connection between cell death transformation and disease treatment in the future.

Houttuynia cordata Thunb. Hexane fraction induces MDA-MB-231 cell apoptosis via caspases, ER stress, cell cycle arrest and attenuated Akt/ERK signaling

Houttuynia cordata Thunb. (HCT) is a perennial plant used in traditional Thai medicine for many centuries. This study aimed to investigate the antiproliferative effect of the hexane fraction, which has not been explored before. HCT ethanol extract (crude extract) was sequentially fractionated to obtain a hexane (H) fraction. GC-MS was used to determine the phytochemicals. The H fraction consisted of lipids, mainly α-linolenic acid and some terpenoids. MTT assay was used to determine the cytotoxic effects of H fraction in MCF-7, MDA-MB-231, NIH3T3 and PBMCs. The mode of cell death and cell cycle analysis were determined by flow cytometry. The mechanisms of cell death were defined by mitochondrial transmembrane potential (MTP) reduction and activation of caspase-3, -8 and -9. The expression levels of the Bcl-2 family, cell cycle-related, endoplasmic reticulum (ER) stress-associated proteins; and Akt/ERK signaling molecules were investigated by immunoblotting. The H fraction was toxic to MDA-MB-231 more than MCF-7 cells but not to NIH3T3 and PBMCs. The growth of MDA-MB-231 cells was inhibited through apoptosis. MTP was disrupted whereas caspase-3, -8 and -9 were activated. The expression of pro-apoptotic Bax and Bak was upregulated, while Bid and anti-apoptotic Bcl-xL proteins were downregulated. Cyclin D1 and CDK4 levels were downregulated. The cell cycle was arrested at G1. Moreover, GRP78 and CHOP elevation indicated ER stress-mediated pathway. The expression ratio of pAkt/Akt and pERK/ERK were reduced. Taken together, the molecular mechanisms of MDA-MB-231 cell apoptosis were via intrinsic/extrinsic pathways, cell cycle arrest, ER stress and abrogation of Akt/ERK survival pathways. According to the most current research, the H fraction may be used as an adjuvant in the BC treatment; however, before the anticancer strategy can be applied to patients, it is important to determine each active compound's effects in cell lines and in vivo when compared with a combined mixture.

Apoptotic cell death in disease-Current understanding of the NCCD 2023

Apoptosis is a form of regulated cell death (RCD) that involves proteases of the caspase family. Pharmacological and genetic strategies that experimentally inhibit or delay apoptosis in mammalian systems have elucidated the key contribution of this process not only to (post-)embryonic development and adult tissue homeostasis, but also to the etiology of multiple human disorders. Consistent with this notion, while defects in the molecular machinery for apoptotic cell death impair organismal development and promote oncogenesis, the unwarranted activation of apoptosis promotes cell loss and tissue damage in the context of various neurological, cardiovascular, renal, hepatic, infectious, neoplastic and inflammatory conditions. Here, the Nomenclature Committee on Cell Death (NCCD) gathered to critically summarize an abundant pre-clinical literature mechanistically linking the core apoptotic apparatus to organismal homeostasis in the context of disease.

A Correlation between 3'-UTR of OXA1 Gene and Yeast Mitochondrial Translation

Mitochondria possess their own DNA (mtDNA) and are capable of carrying out their transcription and translation. Although protein synthesis can take place in mitochondria, the majority of the proteins in mitochondria have nuclear origin. 3' and 5' untranslated regions of mRNAs (3'-UTR and 5'-UTR, respectively) are thought to play key roles in directing and regulating the activity of mitochondria mRNAs. Here we investigate the association between the presence of 3'-UTR from OXA1 gene on a prokaryotic reporter mRNA and mitochondrial translation in yeast. OXA1 is a nuclear gene that codes for mitochondrial inner membrane insertion protein and its 3'-UTR is shown to direct its mRNA toward mitochondria. It is not clear, however, if this mRNA may also be translated by mitochondria. In the current study, using a β-galactosidase reporter gene, we provide genetic evidence for a correlation between the presence of 3'-UTR of OXA1 on an mRNA and mitochondrial translation in yeast.

Multiple Actions of Telomerase Reverse Transcriptase in Cell Death Regulation

Telomerase reverse transcriptase (TERT), a core part of telomerase, has been known for a long time only for its telomere lengthening function by reverse transcription of RNA template. Currently, TERT is considered as an intriguing link between multiple signaling pathways. The diverse intracellular localization of TERT corresponds to a wide range of functional activities. In addition to the canonical function of protecting chromosome ends, TERT by itself or as a part of the telomerase complex participates in cell stress responses, gene regulation and mitochondria functioning. Upregulation of TERT expression and increased telomerase activity in cancer and somatic cells relate to improved survival and persistence of such cells. In this review, we summarize the data for a comprehensive understanding of the role of TERT in cell death regulation, with a focus on the interaction of TERT with signaling pathways involved in cell survival and stress response.

Association between oxidative stress, mitochondrial function of peripheral blood mononuclear cells and gastrointestinal cancers

BACKGROUND

The incidence and mortality rate of gastrointestinal cancers are high worldwide. Increasing studies have illustrated that the occurrence, progression, metastasis and prognosis of cancers are intimately linked to the immune system. Mitochondria, as the main source of cellular energy, play an important role in maintaining the physiological function of immune cells. However, the relationship between mitochondrial function of immune cells and tumorigenesis has not yet been systematically investigated.

METHODS

A total of 150 cases, including 60 healthy donors and 90 primary gastrointestinal cancer patients without anti-tumor treatments (30 with gastric cancer, 30 with liver cancer and 30 with colorectal cancer) were involved in our study. The oxidant/antioxidant and cytokine levels in plasma, the ROS level, mitochondrial function and apoptosis ratio of peripheral blood mononuclear cells (PBMCs) were evaluated.

RESULTS

The imbalance between oxidant and antioxidant in plasma was discovered in the primary gastrointestinal cancer patients. The levels of cell reactive oxygen species (ROS) and mitochondrial ROS in PBMCs of primary gastrointestinal cancers were significantly increased compared with that in healthy donors. Meanwhile, the ATP content, the mtDNA copy number and the mitochondrial membrane potential (MMP) in PBMCs of patients with primary gastrointestinal cancers were lower than those in control group. The decreased MMP also occurred in immune cells of gastrointestinal cancers, including T cell, B cell, NK cell and monocyte. Furthermore, the PBMCs apoptosis ratio of primary gastrointestinal cancer patients was significantly higher than that of control group. Importantly, an increase of IL-2 and IL-6 and a decrease of IgG in plasma were found in the patients with primary gastrointestinal cancers. These changes of mitochondrial function in immune cells were consistent among primary gastrointestinal cancers without anti-tumor treatments, such as liver cancer, gastric cancer and colorectal cancer.

CONCLUSION

Our study demonstrated that the imbalance of oxidation/antioxidation in primary gastrointestinal cancer patients without anti-tumor treatments results in excessive ROS. The oxidative stress was associated to the mitochondrial dysfunction, the apoptosis of immune cells and eventually the abnormal immune function in primary gastrointestinal cancers. The application of immune cell mitochondrial dysfunction into clinical evaluation is anticipated.

Mechanisms of Myofibre Death in Muscular Dystrophies: The Emergence of the Regulated Forms of Necrosis in Myology

Myofibre necrosis is a central pathogenic process in muscular dystrophies (MD). As post-lesional regeneration cannot fully compensate for chronic myofibre loss, interstitial tissue accumulates and impairs muscle function. Muscle regeneration has been extensively studied over the last decades, however, the pathway(s) controlling muscle necrosis remains largely unknown. The recent discovery of several regulated cell death (RCD) pathways with necrotic morphology challenged the dogma of necrosis as an uncontrolled process, opening interesting perspectives for many degenerative disorders. In this review, we focus on how cell death affects myofibres in MDs, integrating the latest research in the cell death field, with specific emphasis on Duchenne muscular dystrophy, the best-known and most common hereditary MD. The role of regulated forms of necrosis in myology is still in its infancy but there is increasing evidence that necroptosis, a genetically programmed form of necrosis, is involved in muscle degenerating disorders. The existence of apoptosis in myofibre demise will be questioned, while other forms of non-apoptotic RCDs may also have a role in myonecrosis, illustrating the complexity and possibly the heterogeneity of the cell death pathways in muscle degenerating conditions.

Tat-hspb1 Suppresses Clear Cell Renal Cell Carcinoma (ccRCC) Growth via Lysosomal Membrane Permeabilization

Clear cell renal cell carcinoma (ccRCC) is the most prevalent kidney cancer, of which the incidence is increasing worldwide with a high mortality rate. Bioactive peptides are considered a significant class of natural medicines. We applied mass spectrometry-based peptidomic analysis to explore the peptide profile of human renal clear cell carcinoma and adjacent normal tissues. A total of 18,031 peptides were identified, of which 105 unique peptides were differentially expressed (44 were up-regulated and 61 were down-regulated in ccRCC tissues). Through bioinformatic analysis, we finally selected one peptide derived from the HSPB1 protein (amino acids 12-35 of the N-terminal region of HSPB1). Next, we fused this peptide to the HIV-Tat, generated a novel peptide named Tat-hspb1, and found that Tat-hspb1 inhibited ccRCC cells' viability while being less cytotoxic to normal epithelial cells. Furthermore, Tat-hspb1 induced apoptosis and inhibited the proliferation and migration of ccRCC cells. Furthermore, we demonstrated that Tat-hspb1 was predominantly localized in lysosomes after entering the ccRCC cell and induced lysosomal membrane permeabilization (LMP) and the release of cathepsin D from lysosomes. Taken together, Tat-hspb1 has the potential to serve as a new anticancer drug candidate.

Porcine cGAS-STING signaling induced autophagy inhibits STING downstream IFN and apoptosis

The innate immune DNA sensing cGAS-STING signaling pathway has been widely recognized for inducing interferons (IFNs) and subsequent antiviral state. In addition to IFN, the cGAS-STING pathway also elicits other cell autonomous immunity events including autophagy and apoptosis. However, the downstream signaling events of this DNA sensing pathway in livestock have not been well defined. Here, we systematically analyzed the porcine STING (pSTING) induced IFN, autophagy and apoptosis, revealed the distinct dynamics of three STING downstream events, and established the IFN independent inductions of autophagy and apoptosis. Further, we investigated the regulation of autophagy on pSTING induced IFN and apoptosis. Following TBK1-IRF3-IFN activation, STING induced Atg5/Atg16L1 dependent autophagy through LIR motifs. In turn, the autophagy likely promoted the pSTING degradation, inhibited both IFN production and apoptosis, and thus restored the cell homeostasis. Therefore, this study sheds lights on the molecular mechanisms of innate immunity in pigs.

A Synthetic Small RNA Homologous to the D-Loop Transcript of mtDNA Enhances Mitochondrial Bioenergetics

Mitochondrial malfunction is a hallmark of many diseases, including neurodegenerative disorders, cardiovascular and lung diseases, and cancers. We previously found that alveolar progenitor cells, which are more resistant to cigarette smoke-induced injury than the other cells of the lung parenchyma, upregulate the mtDNA-encoded small non-coding RNA mito-ncR-805 after exposure to smoke. The mito-ncR-805 acts as a retrograde signal between the mitochondria and the nucleus. Here, we identified a region of mito-ncR-805 that is conserved in the mammalian mitochondrial genomes and generated shorter versions of mouse and human transcripts (mmu-CR805 and hsa-LDL1, respectively), which differ in a few nucleotides and which we refer to as the "functional bit". Overexpression of mouse and human functional bits in either the mouse or the human lung epithelial cells led to an increase in the activity of the Krebs cycle and oxidative phosphorylation, stabilized the mitochondrial potential, conferred faster cell division, and lowered the levels of proapoptotic pseudokinase, TRIB3. Both oligos, mmu-CR805 and hsa-LDL1 conferred cross-species beneficial effects. Our data indicate a high degree of evolutionary conservation of retrograde signaling via a functional bit of the D-loop transcript, mito-ncR-805, in the mammals. This emphasizes the importance of the pathway and suggests a potential to develop this functional bit into a therapeutic agent that enhances mitochondrial bioenergetics.

Necroptosis in Solid Organ Transplantation: A Literature Overview

Ischemia-reperfusion injury (IRI) is encountered in various stages during solid organ transplantation (SOT). IRI is known to be a multifactorial inflammatory condition involving hypoxia, metabolic stress, leukocyte extravasation, cellular death (including apoptosis, necrosis and necroptosis) and an activation of immune response. Although the cycle of sterile inflammation during IRI is consistent among different organs, the underlying mechanisms are poorly understood. Receptor-interacting protein kinase 3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL) are thought to be crucial in the implementation of necroptosis. Moreover, apart from “silent” apoptotic death, necrosis also causes sterile inflammation—necroinflammation, which is triggered by various damage-associated molecular patterns (DAMPs). Those DAMPs activate the innate immune system, causing local and systemic inflammatory responses, which can result in graft failure. In this overview we summarize knowledge on mechanisms of sterile inflammation processes during SOT with special focus on necroptosis and IRI and discuss protective strategies.

Extracellular and Intracellular Skeletons: How Do They Involve in Apoptosis

Apoptosis plays a key role in removing abnormal or senescent cells, maintaining the overall health of the tissue, and coordinating individual development. Recently, it has been discovered that the intracellular cytoskeleton plays a role in the apoptotic process. In addition, the regulatory role of extracellular matrix (ECM) fibrous proteins, which can be considered as the extracellular skeleton, in the process of apoptosis is rarely summarized. In this review, we collect the latest knowledge about how fibrous proteins inside and outside cells regulate apoptosis. We describe how ECM fibrous proteins participate in the regulation of death receptor and mitochondrial pathways through various signaling cascades mediated by integrins. We then explore the molecular mechanisms by which intracellular intermediate filaments regulate cell apoptosis by regulating death receptors on the cell membrane surface. Similarly, we report on novel supporting functions of microtubules in the execution phase of apoptosis and discuss their formation mechanisms. Finally, we discuss that the polypeptide fragments formed by caspase degradation of ECM fibrous proteins and intracellular intermediate filament act as local regulatory signals to play different regulatory roles in apoptosis.

Oxypeucedanin and isoimperatorin extracted from Prangos ferulacea (L.) Lindl protect PC12 pheochromocytoma cells from oxidative stress and apoptosis induced by doxorubicin

Background and purpose:

Doxorubicin (DOX) as a chemotherapeutic agent has been widely used in the treatment of various types of cancer. However, DOX exerts a toxic effect on normal tissues such as the brain. Furanocoumarins reduce the risk of cardiovascular and brain diseases because of their antioxidant activities. This study has been designed, for the first time, to evaluate the effect of known furanocoumarins oxypeucedanin and isoimperatorin extracted from Prangos ferulacea (L.) Lindl on oxidative stress and apoptosis induced by DOX toward pheochromocytoma cell line (PC12).

Experimental approach:

NMR and MASS spectrometers were used to characterize the isolated compounds. The protective effects of isolated compounds on DOX-induced cytotoxicity in PC12 cells were examined by MTT assay. PC12 cells were pretreated with oxypeucedanin and isoimperatorin for 2 and 21 h, respectively, subsequently exposure to DOX at IC₅₀ concentration. Then, mitochondrial membrane potential (MMP), Bax and Bcl2 mRNA expressions, caspase-3 activation, and the generation of intracellular reactive oxygen species (ROS) were measured after 24 h.

Findings/Results:

Pretreatment with oxypeucedanin and isoimperatorin significantly decreased DOX-induced apoptosis through reduction of caspase-3 activity and ROS generation and an increase in MMP. In addition, our finding showed pretreatment with these compounds leads to regulation of Bcl-2.

Conclusion and implications:

Taken together our observation indicated that oxypeucedanin and isoimperatorin have a protective effect against apoptosis induced by DOX in PC12 cells by inhibition of ROS production.

Role of Autophagy in Cardiovascular Disease and Aging

Cardiovascular disease is the leading cause of death worldwide and is expected to further increase as people continue to live even longer. Although the life span of the general population is increasing, the con of such a prolonged life span is that aging has certain detrimental effects on the molecular, structural, and functional elements of the cardiovascular system. This review will discuss various molecular pathways linked to longevity, most notably autophagy and its associated mechanisms, and how these pathways can be targeted to promote cardiovascular health through the process of aging. It is to be noted that the process of autophagy decreases with aging; hence, this review concludes that the promotion of autophagy, through implementation of caloric restriction, intermittent fasting, and pharmacologic agents, has proven to be an efficacious means of stimulating cardiovascular health. Therefore, autophagy is an important target for prevention and procrastination of cardiovascular pathologies in the geriatric population.

Photodynamic Therapy Induced Cell Death Mechanisms in Breast Cancer

Breast cancer is the second most common cancer globally and the pioneering cause of mortality among women. It usually begins from the ducts or lobules, referred to as ductal carcinoma in situ, or lobular carcinoma in situ. Age, mutations in Breast Cancer Gene 1 or 2 (BRCA1 or BRCA2) genes, and dense breast tissue are the highest risk factors. Current treatments are associated with various side effects, relapse, and a low quality of life. Although conventional treatments, such as surgery and chemotherapy, have been used for decades, their adverse side effects on normal cells and tissues pose a major weakness, which calls for a non-invasive treatment option. Photodynamic therapy (PDT) has proven to be a promising form of cancer therapy. It is less invasive, target-specific, and with reduced cytotoxicity to normal cells and tissues. It involves the use of a photosensitizer (PS) and light at a specific wavelength to produce reactive oxygen species. One of the reasons for the target specificity is associated with the dense vascularization of cancer tissues, which tends to increase the surface area for the PS uptake. Photosensitizers are light-sensitive molecules, which result in cancer cell destruction followed by light irradiation. Depending on the localization of the PS within the cancer cell, its destruction may be via apoptosis, necrosis, or autophagy. This review focuses on the breast cancer etiopathology and PDT-induced cell death mechanisms in breast cancer cells.

Gallic acid for cancer therapy: Molecular mechanisms and boosting efficacy by nanoscopical delivery

Cancer is the second leading cause of death worldwide. Majority of recent research efforts in the field aim to address why cancer resistance to therapy develops and how to overcome or prevent it. In line with this, novel anti-cancer compounds are desperately needed for chemoresistant cancer cells. Phytochemicals, in view of their pharmacological activities and capacity to target various molecular pathways, are of great interest in the development of therapeutics against cancer. Plant-derived-natural products have poor bioavailability which restricts their anti-tumor activity. Gallic acid (GA) is a phenolic acid exclusively found in natural sources such as gallnut, sumac, tea leaves, and oak bark. In this review, we report on the most recent research related to anti-tumor activities of GA in various cancers with a focus on its underlying molecular mechanisms and cellular pathwaysthat that lead to apoptosis and migration of cancer cells. GA down-regulates the expression of molecular pathways involved in cancer progression such as PI3K/Akt. The co-administration of GA with chemotherapeutic agents shows improvements in suppressing cancer malignancy. Various nano-vehicles such as organic- and inorganic nano-materials have been developed for targeted delivery of GA at the tumor site. Here, we suggest that nano-vehicles improve GA bioavailability and its ability for tumor suppression.

Host cell death during infection with Chlamydia: a double-edged sword

The phylum Chlamydiae constitutes a group of obligate intracellular bacteria that infect a remarkably diverse range of host species. Some representatives are significant pathogens of clinical or veterinary importance. For instance, Chlamydia trachomatis is the leading infectious cause of blindness and the most common bacterial agent of sexually transmitted diseases. Chlamydiae are exceptionally dependent on their eukaryotic host cells as a consequence of their developmental biology. At the same time, host cell death is an integral part of the chlamydial infection cycle. It is therefore not surprising that the bacteria have evolved exquisite and versatile strategies to modulate host cell survival and death programs to their advantage. The recent introduction of tools for genetic modification of Chlamydia spp., in combination with our increasing awareness of the complexity of regulated cell death in eukaryotic cells, and in particular of its connections to cell-intrinsic immunity, has revived the interest in this virulence trait. However, recent advances also challenged long-standing assumptions and highlighted major knowledge gaps. This review summarizes current knowledge in the field and discusses possible directions for future research, which could lead us to a deeper understanding of Chlamydia's virulence strategies and may even inspire novel therapeutic approaches.

Flow cytometric detection of hyper-polarized mitochondria in regulated and accidental cell death processes

Shikonin induced necroptosis in Jurkat cells were identified flow cytometrically by the up-regulation of RIP3 in live cells and that a proportion of these cells underwent other forms of regulated cell death (RCD) which included parthanatos (< 10%), or cleaved PARP (< 10%) and DNA Damage (> 30%). Live necroptotic cells also possessed functioning mitochondria with hyper-polarized mitochondria membrane potential and generated a fivefold increase in cellular reactive oxygen species (ROS) which was resistant to inhibition by zVAD and necrostatin-1 (Nec-1). After loss of plasma membrane integrity these dead necroptotic cells then showed a higher incidence of parthanatos (> 40%), or cleaved PARP (> 15%) but less DNA Damage (< 15%). Inhibition of shikonin induced apoptosis and necroptosis by zVAD and Nec-1 respectively resulted in live necroptotic cells with an increased incidence of cleaved PARP and reduced levels of DNA Damage respectively. Dead necroptotic cells then showed a reduced incidence of parthanatos and DNA Damage after inhibition by zVAD and Nec-1 respectively. A high proportion of these dead necroptotic cells (30%) which lacked plasma membrane integrity also displayed functioning hyper-polarized mitochondria with high levels of cellular ROS and thus had the capacity to influence the outcome of RCD processes rather than just been the end product of cell death, the necrotic cell. Flow cytometry can thus measure multiple forms of RCD and the level of cellular ROS and MMP which highlights the inter-connection between cell death processes and that a single cell may simultaneously display multiple forms of RCD.

Mechanisms of Regulated Cell Death: Current Perspectives

Balancing cell survival and cell death is fundamental to development and homeostasis. Cell death is regulated by multiple interconnected signaling pathways and molecular mechanisms. Regulated cell death (RCD) is implicated in fundamental processes such as organogenesis and tissue remodeling, removal of unnecessary structures or cells, and regulation of cell numbers. RCD can also be triggered by exogenous perturbations of the intracellular or extracellular microenvironment when the adaptive processes that respond to stress fail. During the past few years, many novel forms of non-apoptotic RCD have been identified, and the characterization of RCD mechanisms at a molecular level has deepened our understanding of diseases encountered in human and veterinary medicine. Given the complexity of these processes, it has become clear that the identification of RCD cannot be based simply on morphologic characteristics and that descriptive and diagnostic terms presently used by pathologists-such as individual cell apoptosis or necrosis-appear inadequate and possibly misleading. In this review, the current understanding of the molecular machinery of each type of non-apoptotic RCD mechanisms is outlined. Due to the continuous discovery of new mechanisms or nuances of previously described processes, the limitations of the terms apoptosis and necrosis to indicate microscopic findings are also reported. In addition, the need for a standard panel of biomarkers and functional tests to adequately characterize the underlying RCD and its role as a mechanism of disease is considered.

Mild hypothermia facilitates mitochondrial transfer from astrocytes to injured neurons during oxygen-glucose deprivation/reoxygenation

Mitochondrial dysfunction is now considered an important sign of neuronal death during cerebral ischemia/reperfusion (I/R) injury. Studies have shown that the transfer of mitochondria from astrocytes to injured neurons contributes to endogenous neuroprotection after stroke. Basic and clinical studies have shown that mild hypothermia exerts a clear protective effect on neurons after cerebral ischemic injury, but the role of mild hypothermia in this endogenous neuroprotective mechanism remains unclear. Here, we established a neuronal cell oxygen-glucose deprivation (OGD)/reoxygenation (OGD/R)-induced injury model and explored the effect of mild hypothermia on the transfer of mitochondria from astrocytes to injured neurons. Astrocytes in the hypothermia group (33 °C) released more functional mitochondria into the extracellular medium than those in the normal temperature group (37 °C). Compared with cells in the normal temperature group, OGD-injured neuronal cells in the mild hypothermia group exhibited an increased intracellular ATP content, mitochondrial membrane potential (MMP) and cellular viability and a decreased death rate after the addition of astrocyte-derived conditioned medium. Based on the results of this study, mild hypothermia promotes endogenous neuroprotective effects through a mechanism related to functional mitochondria released from astrocytes into the extracellular space and transferred into injured neurons.

Alternative approaches to overcome chemoresistance to apoptosis in cancer

Apoptosis, or programmed cell death, is a form of regulated cell death (RCD) that is essential for organogenesis and homeostatic maintenance of normal cell populations. Apoptotic stimuli activate the intrinsic and/or extrinsic pathways to induce cell death due to perturbations in the intracellular and extracellular microenvironments, respectively. In patients with cancer, the induction of apoptosis by anticancer drugs and radiation can produce cancer cell death. However, tumor cells can adapt and become refractory to apoptosis-inducing therapies, resulting in the development of clinical resistance to apoptosis. Drug resistance facilitates the development of aggressive primary tumors that eventually metastasize, leading to therapy failure and mortality. To overcome the resistance to apoptosis to neoadjuvant chemotherapy or targeted therapy, alternative targets of RCD can be induced in apoptosis-resistant cancer cells. Alternatively, cell death can be independent of apoptosis and this strategy could be utilized to develop novel anti-cancer therapies. This chapter discusses approaches that could be employed to overcome clinical resistance to apoptosis in cancer cells.

Age Peculiarities of Respiratory Activity and Membrane Microviscosity of Mitochondria from Rat Cardiomyocytes

We studied respiratory activity and microviscosity of mitochondrial membranes from the left ventricular myocardium of 2-month-old (n=8) and 15-month-old (n=8) rats. The respiratory control (RC) during substrate phosphorylation was calculated as the ratio of oxygen absorption rates in the presence of ADP and after its utilization. In 2-month-old rats, RC was 4.66 (4.56; 4.71); in 15-month-old animals, it was significantly (р<0.05) lower: 3.57 (3.50; 3.62). Pyrene probe eximerization indices for regions of protein-lipid and lipid-lipid interactions in mitochondria of 2-month-old animals were significantly lower than in the group of 15-month-old rats, which indicated reduced microviscosity of the lipid environment of proteins. Thus, the decrease in RC of mitochondria from the left ventricle of 15-month-old animals and the increase in the microviscosity coefficients of their membranes indicate age-related changes in the structural and functional activity of mitochondria.

Mitochondrial Ion Channels of the Inner Membrane and Their Regulation in Cell Death Signaling

Mitochondria are bioenergetic organelles with a plethora of fundamental functions ranging from metabolism and ATP production to modulation of signaling events leading to cell survival or cell death. Ion channels located in the outer and inner mitochondrial membranes critically control mitochondrial function and, as a consequence, also cell fate. Opening or closure of mitochondrial ion channels allow the fine-tuning of mitochondrial membrane potential, ROS production, and function of the respiratory chain complexes. In this review, we critically discuss the intracellular regulatory factors that affect channel activity in the inner membrane of mitochondria and, indirectly, contribute to cell death. These factors include various ligands, kinases, second messengers, and lipids. Comprehension of mitochondrial ion channels regulation in cell death pathways might reveal new therapeutic targets in mitochondria-linked pathologies like cancer, ischemia, reperfusion injury, and neurological disorders.

In-vitro Chemopreventive Potential of a Chromone from Bomarea setacea (ALSTROEMERIACEAE) against Colorectal Cancer

Chemoprevention with natural products may provide important alternatives in the search for new drugs to treat cancer. Thus, the ethanol extract of Bomarea setacea and its secondary metabolite (chromone) were evaluated in-vitro in SW480 and SW620 human adenocarcinoma colon cells to identify a possible effect on cell growth, antiproliferative and/or proapoptotic activity. The ethanol extract did not show growth inhibition of these cell lines 48 h after treatment; besides, it required higher concentration and time to have an antiproliferative effect. On the other hand, although the chromone was not as active as the reference drug (5-FU), it displayed a greater selectivity, being 156-fold more selective against SW480 cells (SI => 100) and 255-fold against SW620 cells (SI => 86,9). Additionally, the chromone caused an important arrest in G2/M (44.18%) with an important accumulation in subG0/G1 phase in SW620 cells, inducing loss in mitochondrial membrane potential and damage in the cell membrane of both cell lines, with activation of caspase 3, suggesting an apoptotic process independent of ROS production and p53 activation.

BCL-2 Inhibitor Venetoclax Induces Autophagy-Associated Cell Death, Cell Cycle Arrest, and Apoptosis in Human Breast Cancer Cells

Introduction

Venetoclax (VCX) is a selective BCL-2 inhibitor approved for the treatment of leukemia and lymphoma. However, the mechanisms of anti-cancer effect of VCX either as a monotherapy or in combination with other chemotherapeutic agents against breast cancer need investigation.

Methods

Breast cancer cell lines with different molecular subtypes (MDA-MB-231, MCF-7, and SKBR-3) were treated with different concentrations of VCX for indicated time points. The expression of cell proliferative, apoptotic, and autophagy genes was determined by qRT-PCR and Western blot analyses. In addition, the percentage of MDA-MB-231 cells underwent apoptosis, expressed higher oxidative stress levels, and the changes in the cell cycle phases were determined by flow cytometry.

Results

Treatment of human breast cancer cells with increasing concentrations of VCX caused a significant decrease in cells growth and proliferation. This effect was associated with a significant increase in the percentage of apoptotic MDA-MB-231 cells and in the expression of the apoptotic genes, caspase 3, caspase 7, and BAX, with inhibition of anti-apoptotic gene, BCL-2 levels. Induction of apoptosis by VCX treatment induced cell cycle arrest at G0/G1 phase with inhibition of cell proliferator genes, cyclin D1 and E2F1. Furthermore, VCX treatment increased the formation of reactive oxygen species and the expression level of autophagy markers, Beclin 1 and LC3-II. Importantly, these cellular changes by VCX increased the chemo-sensitivity of MDA-MB-231 cells to doxorubicin.

Discussion

The present study explores the molecular mechanisms of VCX-mediated inhibitory effects on the growth and proliferation of TNBC MDA-MB-231 cells through the induction of apoptosis, cell cycle arrest, and autophagy. The study also explores the role of BCL-2 as a novel targeted therapy for breast cancer.

Altered mitochondrial calcium handling and cell death by necroptosis: An emerging paradigm

The classical necroptosis signaling is mediated by death receptors (DRs) that work in synergy with traditional caspase inhibitory signals. Currently, potential therapeutic molecules are in various phases of clinical trials for a spectrum of pathological conditions associated with necroptosis. However, a non-classical model of necroptosis has also emerged over the last decade with a relatively unexplored molecular mechanism. Although in vitro studies and preclinical models have shown its close association with mitochondrial dysfunction (mito-dysfunction), contradictory reports have emerged which complicate its definitiveness. Though impaired mitochondrial calcium ([Ca²⁺]_m) handling is established in necrotic cell death, how this interplay regulates necroptosis is yet to be elucidated. Taking these questions into consideration, we have discussed various molecular aspects of necroptosis with the emerging role of mito-dysfunction. Based on the central role of altered [Ca²⁺]_m handling in mito-dysfunction mediated necroptosis, we have provided a comprehensive molecular insight into this emerging paradigm. Potential reasons for the contradictory findings regarding the role of mito-dysfunction in necroptosis in general and mitochondrial-dependent necroptosis in specific are discussed. We also provide insights into the current understanding of how [Ca²⁺]_m can be a critical determinant in deciding the cell fate under certain pathological conditions, while under others it may be dispensable. Lastly, we have highlighted the key molecular targets which have a direct implication for therapeutic intervention in conditions that are associated with impaired [Ca²⁺]_m handling and cell death by necroptosis.

Resolving the Paradox of Colon Cancer Through the Integration of Genetics, Immunology, and the Microbiota

While colorectal cancers (CRC) are paradigmatic tumors invaded by effector memory lymphocytes, the mechanisms accounting for the relative resistance of MSI negative CRC to immunogenic cell death mediated by oxaliplatin and immune checkpoint inhibitors has remained an open conundrum. Here, we propose the viewpoint where its microenvironmental contexture could be explained -at least in part- by macroenvironmental cues constituted by the complex interplay between the epithelial barrier, its microbial ecosystem, and the local immune system. Taken together this dynamic ménage-à-trois offers novel coordinated actors of the humoral and cellular immune responses actionable to restore sensitivity to immune checkpoint inhibition. Solving this paradox involves breaking tolerance to crypt stem cells by inducing the immunogenic apoptosis of ileal cells in the context of an ileal microbiome shifted towards immunogenic bacteria using cytotoxicants. This manoeuver results in the elicitation of a productive Tfh and B cell dialogue in mesenteric lymph nodes culminating in tumor-specific memory CD8+ T cell responses sparing the normal epithelium.

Infection of Mammals and Mosquitoes by Alphaviruses: Involvement of Cell Death

Alphaviruses, such as the chikungunya virus, are emerging and re-emerging viruses that pose a global public health threat. They are transmitted by blood-feeding arthropods, mainly mosquitoes, to humans and animals. Although alphaviruses cause debilitating diseases in mammalian hosts, it appears that they have no pathological effect on the mosquito vector. Alphavirus/host interactions are increasingly studied at cellular and molecular levels. While it seems clear that apoptosis plays a key role in some human pathologies, the role of cell death in determining the outcome of infections in mosquitoes remains to be fully understood. Here, we review the current knowledge on alphavirus-induced regulated cell death in hosts and vectors and the possible role they play in determining tolerance or resistance of mosquitoes.

Deregulation of Cell Death in Cancer: Recent Highlights

The aim of this Special Issue on the deregulation of cell death in cancer is to bring together recent perspectives on the relationship between tumorigenesis and programmed cell death (PCD) [...].

The Distribution of Genes Associated With Regulated Cell Death Is Decoupled From the Mitochondrial Phenotypes Within Unicellular Eukaryotic Hosts

Genetically regulated cell death (RCD) occurs in all domains of life. In eukaryotes, the evolutionary origin of the mitochondrion and of certain forms of RCD, in particular apoptosis, are thought to coincide, suggesting a central general role for mitochondria in cellular suicide. We tested this mitochondrial centrality hypothesis across a dataset of 67 species of protists, presenting 5 classes of mitochondrial phenotypes, including functional mitochondria, metabolically diversified mitochondria, functionally reduced mitochondria (Mitochondrion Related Organelle or MRO) and even complete absence of mitochondria. We investigated the distribution of genes associated with various forms of RCD. No homologs for described mammalian regulators of regulated necrosis could be identified in our set of 67 unicellular taxa. Protists with MRO and the secondarily a mitochondriate Monocercomonoides exilis display heterogeneous reductions of apoptosis gene sets with respect to typical mitochondriate protists. Remarkably, despite the total lack of mitochondria in M. exilis, apoptosis-associated genes could still be identified. These same species of protists with MRO and M. exilis harbored non-reduced autophagic cell death gene sets. Moreover, transiently multicellular protist taxa appeared enriched in apoptotic and autophagy associated genes compared to free-living protists. This analysis suggests that genes associated with apoptosis in animals and the presence of the mitochondria are significant yet non-essential biological components for RCD in protists. More generally, our results support the hypothesis of a selection for RCD, including both apoptosis and autophagy, as a developmental mechanism linked to multicellularity.

Membrane-tethering of cytochrome c accelerates regulated cell death in yeast

Intrinsic apoptosis as a modality of regulated cell death is intimately linked to permeabilization of the outer mitochondrial membrane and subsequent release of the protein cytochrome c into the cytosol, where it can participate in caspase activation via apoptosome formation. Interestingly, cytochrome c release is an ancient feature of regulated cell death even in unicellular eukaryotes that do not contain an apoptosome. Therefore, it was speculated that cytochrome c release might have an additional, more fundamental role for cell death signalling, because its absence from mitochondria disrupts oxidative phosphorylation. Here, we permanently anchored cytochrome c with a transmembrane segment to the inner mitochondrial membrane of the yeast Saccharomyces cerevisiae, thereby inhibiting its release from mitochondria during regulated cell death. This cytochrome c retains respiratory growth and correct assembly of mitochondrial respiratory chain supercomplexes. However, membrane anchoring leads to a sensitisation to acetic acid-induced cell death and increased oxidative stress, a compensatory elevation of cellular oxygen-consumption in aged cells and a decreased chronological lifespan. We therefore conclude that loss of cytochrome c from mitochondria during regulated cell death and the subsequent disruption of oxidative phosphorylation is not required for efficient execution of cell death in yeast, and that mobility of cytochrome c within the mitochondrial intermembrane space confers a fitness advantage that overcomes a potential role in regulated cell death signalling in the absence of an apoptosome.

Multiple roles of caspase-8 in cell death, inflammation, and innate immunity

Caspase-8 is an apical caspase involved in the programmed form of cell death called apoptosis that is critically important for mammalian development and immunity. Apoptosis was historically described as immunologically silent in contrast to other types of programmed cell death such as necroptosis or pyroptosis. Recent reports suggest considerable crosstalk between these different forms of cell death. It is becoming increasingly clear that caspase-8 has many non-apoptotic roles, participating in multiple processes including regulation of necroptosis (mediated by receptor-interacting serine/threonine kinases, RIPK1-RIPK3), inflammatory cytokine expression, inflammasome activation, and cleavage of IL-1β and gasdermin D, and protection against shock and microbial infection. In this review, we discuss the involvement of caspase-8 in cell death and inflammation and highlight its role in innate immune responses and in the relationship between different forms of cell death. Caspase-8 is one of the central components in this type of crosstalk.

Transcriptional and epigenetic control of regulated cell death in yeast

Unicellular organisms like yeast can undergo controlled demise in a manner that is partly reminiscent of mammalian cell death. This is true at the levels of both mechanistic and functional conservation. Yeast offers the combination of unparalleled genetic amenability and a comparatively simple biology to understand both the regulation and evolution of cell death. In this minireview, we address the capacity of the nucleus as a regulatory hub during yeast regulated cell death (RCD), which is becoming an increasingly central question in yeast RCD research. In particular, we explore and critically discuss the available data on stressors and signals that specifically impinge on the nucleus. Moreover, we also analyze the current knowledge on nuclear factors as well as on transcriptional control and epigenetic events that orchestrate yeast RCD. Altogether we conclude that the functional significance of the nucleus for yeast RCD in undisputable, but that further exploration beyond correlative work is necessary to disentangle the role of nuclear events in the regulatory network.

Cancer Treatment Goes Viral: Using Viral Proteins to Induce Tumour-Specific Cell Death

Cell death is a tightly regulated process which can be exploited in cancer treatment to drive the killing of the tumour. Several conventional cancer therapies including chemotherapeutic agents target pathways involved in cell death, yet they often fail due to the lack of selectivity they have for tumour cells over healthy cells. Over the past decade, research has demonstrated the existence of numerous proteins which have an intrinsic tumour-specific toxicity, several of which originate from viruses. These tumour-selective viral proteins, although from distinct backgrounds, have several similar and interesting properties. Though the mechanism(s) of action of these proteins are not fully understood, it is possible that they can manipulate several cell death modes in cancer exemplifying the intricate interplay between these pathways. This review will discuss our current knowledge on the topic and outstanding questions, as well as deliberate the potential for viral proteins to progress into the clinic as successful cancer therapeutics.

Targeting mitochondria for cardiovascular disorders: therapeutic potential and obstacles

A large body of evidence indicates that mitochondrial dysfunction has a major role in the pathogenesis of multiple cardiovascular disorders. Over the past 2 decades, extraordinary efforts have been focused on the development of agents that specifically target mitochondria for the treatment of cardiovascular disease. Despite such an intensive wave of investigation, no drugs specifically conceived to modulate mitochondrial functions are currently available for the clinical management of cardiovascular disease. In this Review, we discuss the therapeutic potential of targeting mitochondria in patients with cardiovascular disease, examine the obstacles that have restrained the development of mitochondria-targeting agents thus far, and identify strategies that might empower the full clinical potential of this approach.

PGC-1α, Sirtuins and PARPs in Huntington's Disease and Other Neurodegenerative Conditions: NAD+ to Rule Them All

In this review, we summarize the available published information on the neuroprotective effects of increasing nicotinamide adenine dinucleotide (NAD+) levels in Huntington's disease models. We discuss the rationale of potential therapeutic benefit of administering nicotinamide riboside (NR), a safe and effective NAD+ precursor. We discuss the agonistic effect on the Sirtuin1-PGC-1α-PPAR pathway as well as Sirtuin 3, which converge in improving mitochondrial function, decreasing ROS production and ameliorating bioenergetics deficits. Also, we discuss the potential synergistic effect of increasing NAD+ combined with PARPs inhibitors, as a clinical therapeutic option not only in HD, but other neurodegenerative conditions.

Autophagy in Cardiovascular Aging

Cardiovascular diseases are the most prominent maladies in aging societies. Indeed, aging promotes the structural and functional declines of both the heart and the blood circulation system. In this review, we revise the contribution of known longevity pathways to cardiovascular health and delineate the possibilities to interfere with them. In particular, we evaluate autophagy, the intracellular catabolic recycling system associated with life- and health-span extension. We present genetic models, pharmacological interventions, and dietary strategies that block, reduce, or enhance autophagy upon age-related cardiovascular deterioration. Caloric restriction or caloric restriction mimetics like metformin, spermidine, and rapamycin (all of which trigger autophagy) are among the most promising cardioprotective interventions during aging. We conclude that autophagy is a fundamental process to ensure cardiac and vascular health during aging and outline its putative therapeutic importance.

Medicinal Plants from Brazilian Cerrado: Antioxidant and Anticancer Potential and Protection against Chemotherapy Toxicity

The use of natural antioxidants in cancer therapy has increased: first, due to the potential of natural antioxidants to kill tumour cells and second, because of their capacity to protect healthy cells from the damage caused by chemotherapy. This review article discusses the antioxidant properties of extracts obtained from medicinal plants from the Brazilian Cerrado and the cell death profile induced by each of these extracts in malignant cells. Next, we describe the capacity of other medicinal plants from the Cerrado to protect against chemotherapy-induced cell toxicity. Finally, we focus on recent insights into the cell death profile induced by extracts from Cerrado plants and perspectives for future therapeutic approaches.

Cell Death in the Kidney

Apoptotic cell death is usually a response to the cell's microenvironment. In the kidney, apoptosis contributes to parenchymal cell loss in the course of acute and chronic renal injury, but does not trigger an inflammatory response. What distinguishes necrosis from apoptosis is the rupture of the plasma membrane, so necrotic cell death is accompanied by the release of unprocessed intracellular content, including cellular organelles, which are highly immunogenic proteins. The relative contribution of apoptosis and necrosis to injury varies, depending on the severity of the insult. Regulated cell death may result from immunologically silent apoptosis or from immunogenic necrosis. Recent advances have enhanced the most revolutionary concept of regulated necrosis. Several modalities of regulated necrosis have been described, such as necroptosis, ferroptosis, pyroptosis, and mitochondrial permeability transition-dependent regulated necrosis. We review the different modalities of apoptosis, necrosis, and regulated necrosis in kidney injury, focusing particularly on evidence implicating cell death in ectopic renal calcification. We also review the evidence for the role of cell death in kidney injury, which may pave the way for new therapeutic opportunities.

Contribution of Mitochondrial Ion Channels to Chemo-Resistance in Cancer Cells

Mitochondrial ion channels are emerging oncological targets, as modulation of these ion-transporting proteins may impact on mitochondrial membrane potential, efficiency of oxidative phosphorylation and reactive oxygen production. In turn, these factors affect the release of cytochrome c, which is the point of no return during mitochondrial apoptosis. Many of the currently used chemotherapeutics induce programmed cell death causing damage to DNA and subsequent activation of p53-dependent pathways that finally leads to cytochrome c release from the mitochondrial inter-membrane space. The view is emerging, as summarized in the present review, that ion channels located in this organelle may account in several cases for the resistance that cancer cells can develop against classical chemotherapeutics, by preventing drug-induced apoptosis. Thus, pharmacological modulation of these channel activities might be beneficial to fight chemo-resistance of different types of cancer cells.

Regulation of mitochondrial function as a promising target in platelet activation-related diseases

Platelets are anucleated cell elements produced by fragmentation of the cytoplasm of megakaryocytes and have a unique metabolic phenotype compared with circulating leukocytes, exhibiting a high coupling efficiency to mitochondrial adenosine triphosphate production with reduced respiratory reserve capacity. Platelet mitochondria are well suited for ex vivo analysis of different diseases. Even some diseases induce mitochondrial changes in platelets without reflecting them in other organs. During platelet activation, an integrated participation of glycolysis and oxidative phosphorylation is mediated by oxidative stress production-dependent signaling. The platelet activation-dependent procoagulant activity mediated by collagen, thrombin and hyperglycemia induce mitochondrial dysfunction to promote thrombosis in oxidative stress-associated pathological conditions. Interestingly, some compounds exhibit a protective action on platelet mitochondrial dysfunction through control of mitochondrial oxidative stress production or inhibition of respiratory complexes. They can be grouped in a) Natural source-derived compounds (e.g. Xanthohumol, Salvianoloc acid A and Sila-amide derivatives of NAC), b) TPP⁺-linked small molecules (e.g. mitoTEMPO and mitoQuinone) and c) FDA-approved drugs (e.g. metformin and statins), illustrating the wide range of molecular structures capable of effectively interacting with platelet mitochondria. The present review article aims to discuss the mechanisms of mitochondrial dysfunction and their association with platelet activation-related diseases.

Aspirin impairs acetyl-coenzyme A metabolism in redox-compromised yeast cells

Aspirin is a widely used anti-inflammatory and antithrombotic drug also known in recent years for its promising chemopreventive antineoplastic properties, thought to be mediated in part by its ability to induce apoptotic cell death. However, the full range of mechanisms underlying aspirin's cancer-preventive properties is still elusive. In this study, we observed that aspirin impaired both the synthesis and transport of acetyl-coenzyme A (acetyl-CoA) into the mitochondria of manganese superoxide dismutase (MnSOD)-deficient Saccharomyces cerevisiae EG110 yeast cells, but not of the wild-type cells, grown aerobically in ethanol medium. This occurred at both the gene level, as indicated by microarray and qRT-PCR analyses, and at the protein level as indicated by enzyme assays. These results show that in redox-compromised MnSOD-deficient yeast cells, but not in wild-type cells, aspirin starves the mitochondria of acetyl-CoA and likely causes energy failure linked to mitochondrial damage, resulting in cell death. Since acetyl-CoA is one of the least-studied targets of aspirin in terms of the latter's propensity to prevent cancer, this work may provide further mechanistic insight into aspirin's chemopreventive behavior with respect to early stage cancer cells, which tend to have downregulated MnSOD and are also redox-compromised.