MAPK15 protects from oxidative stress-dependent cellular senescence by inducing the mitophagic process

Design of a prodrug photocage for cancer cells detection and anticancer drug release

Developing probes for simultaneous diagnosis and killing of cancer cells is crucial, yet challenging. This article presents the design and synthesis of a novel Rhodamine B fluorescence probe. The design strategy involves utilizing an anticancer drug (Melphalan) to bind with a fluorescent group (HRhod-OH), forming HRhod-MeL, which is non-fluorescent. However, when exposed to the high levels of reactive oxygen species (ROS) of cancer cells, HRhod-MeL transforms into a red-emitting Photocage (Rhod-MeL), and selectively accumulates in the mitochondria of cancer cells, where, when activated with green light (556 nm), anti-cancer drugs released. The Photocage improve the efficacy of anti-cancer drugs and enables the precise diagnosis and killing of cancer cells. Therefore, the prepared Photocage can detect cancer cells and release anticancer drugs in situ, which provides a new method for the development of prodrugs.

MAPK15 controls cellular responses to oxidative stress by regulating NRF2 activity and expression of its downstream target genes

Oxidation processes in mitochondria and different environmental insults contribute to unwarranted accumulation of reactive oxygen species (ROS). These, in turn, rapidly damage intracellular lipids, proteins, and DNA, ultimately causing aging and several human diseases. Cells have developed different and very effective systems to control ROS levels. Among these, removal of excessive amounts is guaranteed by upregulated expression of various antioxidant enzymes, through activation of the NF-E2-Related Factor 2 (NRF2) protein. Here, we show that Mitogen Activated Protein Kinase 15 (MAPK15) controls the transactivating potential of NRF2 and, in turn, the expression of its downstream target genes. Specifically, upon oxidative stress, MAPK15 is necessary to increase NRF2 expression and nuclear translocation, by inducing its activating phosphorylation, ultimately supporting transactivation of cytoprotective antioxidant genes. Lungs are continuously exposed to oxidative damages induced by environmental insults such as air pollutants and cigarette smoke. Interestingly, we demonstrate that MAPK15 is very effective in supporting NRF2-dependent antioxidant transcriptional response to cigarette smoke of epithelial lung cells. Oxidative damage induced by cigarette smoke indeed represents a leading cause of disability and death worldwide by contributing to the pathogenesis of different chronic respiratory diseases and lung cancer. Therefore, the development of novel therapeutic strategies able to modulate cellular responses to oxidative stress would be highly beneficial. Our data contribute to the necessary understanding of the molecular mechanisms behind such responses and identify new potentially actionable targets.

SIRT2 regulates apoptosis by inducing mitophagy in sheep cumulus cells

Cumulus cells surrounding oocytes furnish nutritional support crucial for oocyte maturation in vitro, and thereby enhance oocyte quality significantly. Our previous studies affirmed the role of SIRT2 in regulation of mitochondrial function in sheep granulosa cells. However, the effect of SIRT2 action on mitophagy in these cells remain unclear. Here, RNA-seq was used to scrutinize pathways where differentially expressed genes (DEGs) are enriched following SIRT2 knockdown in cumulus cells. Prior to SIRT2 knock down, cumulus cells were treated with the mitophagy inhibitor Mdivi-1. Potential mechanisms by which SIRT2 affects apoptosis via mitophagy were explored. Results indicated that DEGs after SIRT2 knockdown were enriched in various pathways including mitochondria, mitophagy, and apoptosis. The expression levels of CASP3/CASP9 were significantly increased after mitophagy activation (P < 0.01), whereas inhibition of mitophagy had no effect on apoptosis (P > 0.05). Pretreatment of cumulus cells with Mdivi-1 prior to SIRT2 knockdown significantly reduced the expression of mitophagy-related genes, the number of autolysosomes, the expression of CASP3/CASP9, and the levels of Ca2+ and cytochrome C (P < 0.05). In addition, an improvement in mitochondrial morphology and increases in ATP levels and mitochondrial DNA (mtDNA) copy numbers were observed. Interestingly, double knockdown of SIRT2 and MAPK15 was found to reverse increased mitophagy and apoptosis activity caused by SIRT2 knockdown. Our findings indicate that SIRT2 modulate apoptosis in cumulus cells by regulating mitophagy, with MAPK15 likely playing a pivotal role in this process.

Prophylactic vitamin C supplementation regulates DNA demethylation to protect against cisplatin-induced acute kidney injury in mice

Cisplatin-induced acute kidney injury (AKI) restricts the use of cisplatin as a first-line chemotherapeutic agent. Our previous study showed that prophylactic vitamin C supplementation may act as an epigenetic modulator in alleviating cisplatin-induced AKI in mice. However, the targets of vitamin C and the mechanisms underlying the epigenetics changes remain largely unknown. Herein, whole-genome bisulfite sequencing and bulk RNA sequencing were performed on the kidney tissues of mice treated with cisplatin with prophylactic vitamin C supplementation (treatment mice) or phosphate-buffered saline (control mice) at 24 h after cisplatin treatment. Ascorbyl phosphate magnesium (APM), an oxidation-resistant vitamin C derivative, was found that led to global hypomethylation in the kidney tissue and regulated different functional genes in the promoter region and gene body region. Integrated evidence suggested that APM enhanced renal ion transport and metabolism, and reduced apoptosis and inflammation in the kidney tissues. Strikingly, Mapk15, Slc22a6, Cxcl5, and Cd44 were the potential targets of APM that conferred protection against cisplatin-induced AKI. Moreover, APM was found to be difficult to rescue cell proliferation and apoptosis caused by cisplatin in the Slc22a6 knockdown cell line. These results elucidate the mechanism by which vitamin C as an epigenetic regulator to protects against cisplatin-induced AKI and provides a new perspective and evidence support for controlling the disease process through regulating DNA methylation.

The HIF-1/ BNIP3 pathway mediates mitophagy to inhibit the pyroptosis of fibroblast-like synoviocytes in rheumatoid arthritis

BACKGROUND

Synovial hypoxia, a critical pathological characteristic of rheumatoid arthritis (RA), significantly contributes to synovitis and synovial hyperplasia. In response to hypoxic conditions, fibroblast-like synoviocytes (FLS) undergo adaptive changes involving gene expression modulation, with hypoxia-inducible factors (HIF) playing a pivotal role. The regulation of BCL2/adenovirus e1B 19 kDa protein interacting protein 3 (BNIP3) and nucleotide-binding oligomerization segment-like receptor family 3 (NLRP3) expression has been demonstrated to be regulated by HIF-1. The objective of this study was to examine the molecular mechanism that contributes to the aberrant activation of FLS in response to hypoxia. Specifically, the interaction between BNIP3-mediated mitophagy and NLRP3-mediated pyroptosis was conjointly highlighted.

METHODS

The research methodology employed Western blot and immunohistochemistry techniques to identify the occurrence of mitophagy in synovial tissue affected by RA. Additionally, the levels of mitophagy under hypoxic conditions were assessed using Western blot, immunofluorescence, quantitative polymerase chain reaction (qPCR), and CUT&Tag assays. Pyroptosis was observed through electron microscopy, fluorescence microscopy, and Western blot analysis. Furthermore, the quantity of reactive oxygen species (ROS) was measured. The silencing of HIF-1α and BNIP3 was achieved through the transfection of short hairpin RNA (shRNA) into cells.

RESULTS

In the present study, a noteworthy increase in the expression of BNIP3 and LC3B was observed in the synovial tissue of patients with RA. Upon exposure to hypoxia, FLS of RA exhibited BNIP3-mediated mitophagy and NLRP3 inflammasome-mediated pyroptosis. It appears that hypoxia regulates the expression of BNIP3 and NLRP3 through the transcription factor HIF-1. Additionally, the activation of mitophagy has been observed to effectively inhibit hypoxia-induced pyroptosis by reducing the intracellular levels of ROS.

CONCLUSION

In summary, the activation of FLS in RA patients under hypoxic conditions involves both BNIP3-mediated mitophagy and NLRP3 inflammasome-mediated pyroptosis. Additionally, mitophagy can suppress hypoxia-induced FLS pyroptosis by eliminating ROS and inhibiting the HIF-1α/NLRP3 pathway.

Regeneration and anti-inflammatory effects of stem cells and their extracellular vesicles in gynecological diseases

There are many gynecological diseases, among which breast cancer (BC), cervical cancer (CC), endometriosis (EMs), and polycystic ovary syndrome (PCOS) are common and difficult to cure. Stem cells (SCs) are a focus of regenerative medicine. They are commonly used to treat organ damage and difficult diseases because of their potential for self-renewal and multidirectional differentiation. SCs are also commonly used for difficult-to-treat gynecological diseases because of their strong directional differentiation ability with unlimited possibilities, their tendency to adhere to the diseased tissue site, and their use as carriers for drug delivery. SCs can produce exosomes in a paracrine manner. Exosomes can be produced in large quantities and have the advantage of easy storage. Their safety and efficacy are superior to those of SCs, which have considerable potential in gynecological treatment, such as inhibiting endometrial senescence, promoting vascular reconstruction, and improving anti-inflammatory and immune functions. In this paper, we review the mechanisms of the regenerative and anti-inflammatory capacity of SCs and exosomes in incurable gynecological diseases and the current progress in their application in genetic engineering to provide a foundation for further research.

Autophagy-mediated control of ribosome homeostasis in oncogene-induced senescence

Oncogene-induced senescence (OIS) is a persistent anti-proliferative response that acts as a barrier against malignant transformation. During OIS, cells undergo dynamic remodeling, which involves alterations in protein and organelle homeostasis through autophagy. Here, we show that ribosomes are selectively targeted for degradation by autophagy during OIS. By characterizing senescence-dependent alterations in the ribosomal interactome, we find that the deubiquitinase USP10 dissociates from the ribosome during the transition to OIS. This release of USP10 leads to an enhanced ribosome ubiquitination, particularly of small subunit proteins, including lysine 275 on RPS2. Both reinforcement of the USP10-ribosome interaction and mutation of RPS2 K275 abrogate ribosomal delivery to lysosomes without affecting bulk autophagy. We show that the selective recruitment of ubiquitinated ribosomes to autophagosomes is mediated by the p62 receptor. While ribophagy is not required for the establishment of senescence per se, it contributes to senescence-related metabolome alterations and facilitates the senescence-associated secretory phenotype.

Highly-sensitive and homogenous detection of 8-oxoguanine based DNA oxidative damage by a CRISPR-enhanced structure-switching aptamer assay

8-oxoguanine (8-oxoG) based DNA damage is the most common type of DNA damage which greatly affect gene expression. Therefore, accurate quantification of 8-oxoG based DNA damage is of high clinical significance. However, current methods for 8-oxoG detection struggle to balance convenience, low cost, and sensitivity. Herein, we have proposed and investigated the shortened crRNA mode of CRISPR-Cas12a system and greatly enhanced its signal-to-noise ratio. Taking advantages of the shortened crRNA mode, we further developed a CRISPR-enhanced structure-switching aptamer assay (CESA) for 8-oxoG. The analytical performance of CESA was thoroughly investigated via detecting free 8-oxoG and 8-oxoG on gDNA. The CESA displayed impressive sensitivity for free 8-oxoG, with detection and quantification limits of 32.3 pM and 0.107 nM. These limits modestly rose to 64.5 pM and 0.215 nM when examining 8-oxoG on gDNA. To demonstrate the clinical practicability and significance of the CESA system, we further applied it to measuring 8-oxoG levels in 7 plasma samples (Cervical carcinoma, 11.87 ± 0.69 nM VS. Healthy control, 2.66 ± 0.42 nM), 24 seminal plasma samples (Asthenospermia, 22.29 ± 7.48 nM VS. Normal sperm, 9.75 ± 3.59 nM), 10 breast-tissue gDNA samples (Breast cancer, 2.77 ± 0.63 nM/μg VS. Healthy control, 0.41 ± 0.09 nM/μg), and 24 sperm gDNA samples (Asthenospermia, 28.62 ± 4.84 VS. Normal sperm, 16.67 ± 3.31). This work not only proposes a novel design paradigm of shortened crRNA for developing CRISPR-Cas12a based biosensors but also offers a powerful tool for detecting 8-oxoG based DNA damage.

Atypical MAP kinases - new insights and directions from amoeba

Mitogen-activated protein kinases (MAPKs) have been the focus of many studies over the past several decades, but the understanding of one subgroup of MAPKs, orthologs of MAPK15, known as atypical MAPKs, has lagged behind others. In most organisms, specific activating signals or downstream responses of atypical MAPK signaling pathways have not yet been identified even though these MAPKs are associated with many eukaryotic processes, including cancer and embryonic development. In this Review, we discuss recent studies that are shedding new light on both the regulation and function of atypical MAPKs in different organisms. In particular, the analysis of the atypical MAPK in the amoeba Dictyostelium discoideum has revealed important roles in chemotactic responses and gene regulation. The rapid and transient phosphorylation of the atypical MAPK in these responses suggest a highly regulated activation mechanism in vivo despite the ability of atypical MAPKs to autophosphorylate in vitro. Atypical MAPK function can also impact the activation of other MAPKs in amoeba. These advances are providing new perspectives on possible MAPK roles in animals that have not been previously considered, and this might lead to the identification of potential targets for regulating cell movement in the treatment of diseases.

Cellular and physiological roles of the conserved atypical MAP kinase ERK7

Extracellular signal-regulated kinase 7 (ERK7), also known as ERK8 and MAPK15, is an atypical member of the MAP kinase family. Compared with other MAP kinases, the biological roles of ERK7 remain poorly understood. Recent work, however, has revealed several novel functions for ERK7. These include a highly conserved essential role in ciliogenesis, the ability to control cell growth, metabolism and autophagy, as well as the maintenance of genomic integrity. ERK7 functions through phosphorylation-dependent and -independent mechanisms and it is activated by cellular stressors, including DNA-damaging agents, and nutrient deprivation. Here, we summarize recent developments in understanding ERK7 function, emphasizing its conserved roles in cellular and physiological regulation.

Natural Morin-Based Metal Organic Framework Nanoenzymes Modulate Articular Cavity Microenvironment to Alleviate Osteoarthritis

Osteoarthritis (OA) is always characterized as excessive reactive oxygen species (ROS) inside articular cavity. Mimicking natural metalloenzymes with metal ions as the active centers, stable metal organic framework (MOF) formed by natural polyphenols and metal ions shows great potential in alleviating inflammatory diseases. Herein, a series of novel copper-morin-based MOF (CuMHs) with different molar ratios of Cu²⁺ and MH were employed to serve as ROS scavengers for OA therapy. As a result, CuMHs exhibited enhanced dispersion in aqueous solution, improved biocompatibility, and efficient ROS-scavenging ability compared to MH. On the basis of H₂O₂-stimulated chondrocytes, intracellular ROS levels were efficiently declined and cell death was prevented after treated by Cu₆MH (Cu²⁺ and MH molar ratio of 6:1). Meanwhile, Cu₆MH also exhibited efficient antioxidant and anti-inflammation function by down-regulating the expression of IL6, MMP13, and MMP3, and up-regulating cartilage specific gene expression as well. Importantly, Cu₆MH could repair mitochondrial function by increasing mitochondrial membrane potential, reducing the accumulation of calcium ions, as well as promoting ATP content production. In OA joint model, intra-articular (IA) injected Cu₆MH suppressed the progression of OA. It endowed that Cu₆MH might be promising nanoenzymes for the prevention and treatment of various inflammatory diseases.

Assessing Drug-Induced Mitochondrial Toxicity in Cardiomyocytes: Implications for Preclinical Cardiac Safety Evaluation

Drug-induced cardiotoxicity not only leads to the attrition of drugs during development, but also contributes to the high morbidity and mortality rates of cardiovascular diseases. Comprehensive testing for proarrhythmic risks of drugs has been applied in preclinical cardiac safety assessment for over 15 years. However, other mechanisms of cardiac toxicity have not received such attention. Of them, mitochondrial impairment is a common form of cardiotoxicity and is known to account for over half of cardiovascular adverse-event-related black box warnings imposed by the U.S. Food and Drug Administration. Although it has been studied in great depth, mitochondrial toxicity assessment has not yet been incorporated into routine safety tests for cardiotoxicity at the preclinical stage. This review discusses the main characteristics of mitochondria in cardiomyocytes, drug-induced mitochondrial toxicities, and high-throughput screening strategies for cardiomyocytes, as well as their proposed integration into preclinical safety pharmacology. We emphasize the advantages of using adult human primary cardiomyocytes for the evaluation of mitochondrial morphology and function, and the need for a novel cardiac safety testing platform integrating mitochondrial toxicity and proarrhythmic risk assessments in cardiac safety evaluation.