P53-dependent Pathway Research Articles

MIA40 circumvents the folding constraints imposed by TRIAP1 function.

The MIA40 relay system mediates the import of small cysteine-rich proteins into the intermembrane mitochondrial space (IMS). MIA40 substrates are synthesized in the cytosol and assumed to be disordered in their reduced state in this compartment. As they cross the outer mitochondrial membrane, MIA40 promotes the oxidation of critical native disulfides to facilitate folding, trapping functional species in the IMS. Here, we study the redox-controlled folding of TRIAP1, a small cysteine-rich protein with moonlighting function: regulating phospholipid trafficking between mitochondrial membranes in the IMS and preventing apoptosis in the cytosol. TRIAP1 dysregulation is connected to oncogenesis. Although TRIAP1 contains a canonical twin CX9C motif, its sequence characteristics and folding pathway deviate from typical MIA40 substrates. In its reduced state, TRIAP1 rapidly populates a hydrophobic collapsed, alpha-helical, and marginally stable molten globule. This intermediate, biases oxidative folding towards a non-native Cys37-Cys47 kinetic trap, slowing the reaction. MIA40 accelerates TRIAP1 folding rate by 30-fold, bypassing the formation of this folding trap. MIA40 drives the oxidation of the inner disulfide bond Cys18-Cys37, and subsequently, it can catalyze the formation of the outer disulfide bond Cys8-Cys47 to attain the native two-disulfide-bridged structure. We demonstrate that, unlike most MIA40 substrates, TRIAP1's folding pathway is strongly constrained by the structural requirements for its function in phospholipid traffic at the IMS. The obligatory population of a reduced, alpha-helical, metastable molten globule in the cytoplasm may explain TRIAP1's connection to the p53-dependent cell survival pathway, constituting a remarkable example of a functional molten globule state.

Anticancer effects of aloe-emodin from Rheum undulatum L. through activation of the p53 pathway in human prostate cancer cells

Aloe-emodin, an anthraquinone compound naturally derived from Rheum undulatum L., has gained extensive research attention owing to its various pharmacological effects, including its potential as an anticancer, antivirus, anti-inflammatory, antibacterial, and anti-parasitic agent. It has demonstrated notable inhibitory effects against various types of cancer and cancer cells. Prostate cancer is among the most commonly identified cancers globally and remains a leading cause of cancer-associated deaths in men, often presenting challenges in early detection due to its asymptomatic nature during initial stages. The aim of present study was to determine the biological activity of aloe-emodin obtained from Rheum undulatum L. involving activation of the p53-dependent pathway in certain human prostate cancer cell lines. We explored the mechanisms underlying the anticancer effects of aloe-emodin using LNCaP cells, which include p53-wild type and phosphatase and tensin homolog-deficient mutated genes, a widely studied model in genomic research. Aloe-emodin induced apoptosis in LNCaP cells through several mechanisms, including upregulation of the cleavage of caspase-8 (a cross-linked promoter of cell death signals), phosphorylation of p53 at serine 15, DNA fragmentation, cleavage of poly [ADP-ribose] polymerase, and promotion of cell death. These findings strongly indicated that aloe-emodin's anticancer properties in human prostate cancer involve the activation of p53-induced cellular senescence. Conclusively, the findings of this study imply that aloe-emodin extracted from Rheum undulatum L. is a potential therapeutic compound for adjuvant chemotherapy that induces apoptosis and pyroptosis, an innate immune response, in preventing the progression of precancerous lesions in patients with prostate cancer.

Ameliorative Potential of Ursolic Acid Isolated from Morina coulteriana Royle Targeting P53 Gene Mutation Induced by Cyclophosphamide

Objective: More than 50% of human cancers show mutated TP53 gene. Reactivation or restoration of p53 mutations is viewed as a potential approach for treating cancer. The objective of the present study was to determine whether ursolic acid (UA) could effectively restore the p53 mutations to their wild type or normal state and upregulate its expression. Methods: The animals were divided into 3 groups, each with 10 mice. Group I was the negative control which received normal saline with 1% dimethyl sulfoxide (DMSO). Group II was the positive control which received cyclophosphamide (CP) (50mg/kg bw) intrapritonealy for 4 days continuously after which the animals were kept on normal saline for the rest 10 days. The treatment group received cyclophosphamide (CP) initially for the first 4 successive days intraperitoneally (50mg/kg bw) and then ursolic acid (UA) (60 mg/kg bw) orally for the next 10 days (post-treatment). Isolated DNA was used in Sanger sequencing of the polymerase chain reaction (PCR) amplified product of the TP53 gene. Results: Our study demonstrated that UA treatment post CP injection had a restoration efficacy of 89.08%. The molecule, in this investigation, was able to restore the wild type (normal) conformation to the mutations induced by cyclophosphamide in the TP53 gene. 89.08 % mutations converted back to their normal or wild-type forms in the treatment group. Conclusion: Several investigations have been carried out on this molecule and have indicated UA as a promising chemopreventive agent. The most frequently mutated gene in any type of cancer is the tumor suppressor p53 and UA has shown a potential in functional restoration of the mutated p53 protein. p53 is known to play a vital role in apoptosis and the p53 dependent apoptotic pathway is of prime importance in cancer therapy. Though there has been pioneering work on PRIMA-1 and thiosemicarbazones, identification and development of additional molecules is required.

Dynamics of changes in markers of apoptosis, circadian rhythms and antioxidant processes in the model of temporal lobe epilepsy in rats

Temporal lobe epilepsy is a common neurological disorder that in many cases is accompanied by drug resistance. The current approach to the treatment of patients with drug resistance includes surgical intervention, which does not guarantee full recovery. At present, new antiepileptic drugs that affect signaling cascades inherent in epileptogenesis are being developed. The development of such drugs requires knowledge of the basic mechanisms of epilepsy pathogenesis. The aim of the work was to investigate the dynamics of expression of proteins involved in the regulation of apoptosis, circadian rhythms and antioxidant response in the temporal cortex of the brain during prolonged kindling in the Krushinsky-Molodkina (KM) rat model with hereditary audiogenic epilepsy. The dynamics of expression of studied proteins – p53, CLOCK, Nrf2, p105 - was investigated in the temporal cortex (immunohistochemistry, Western blotting). It was found that p53 level was lower in KM control rats than in Wistar rats. In KM rats subjected to 21 days kindling, p53 content is increased compared to KM control. CLOCK level was downregulated in the KM control group compared to the negative control and elevated in the KM group after kindling 21 days relative to the KM group after 7 days kindling. No changes in Nrf2 and p105 production were detected. The data obtained suggest that the changes in the levels of the studied proteins in control KM rats compared to Wistar rats are genetically determined. Induced epileptogenesis (kindling) for 21 days leads to activation of p53-dependent apoptosis pathway and, possibly, to desynchronosis - change of circadian rhythms. The findings contribute to the study of temporal lobe epilepsy mechanisms and require further studies related to mitochondrial apoptosis and sleep-wake cycle shift in the pathogenesis of temporal lobe epilepsy.

Induction of Apoptosis and Antiproliferative Activity of MCF-7 Human Breast Cancer Cells with Sonicated Aqueous Peel Extract of Punica granatum L. (Nimali sp.).

The antioxidant and antiproliferative activities of various parts of the Punica granatum L. fruit (Nimali variety) on MCF-7 human breast cancer cells have been investigated. The analysis of the effect on gene regulation and apoptosis induction compared to different extraction methods, was carried out highlighting the fruit's potential anticancer properties attributed to polyphenol-rich composition. This study analyzed alterations in radical scavenging capacity (RSC), phenol (TPC), and flavonoid contents (FC) of pomegranate fruit parts, and antiproliferative activity towards MCF-7 cancer cells using different extraction methods. Most effective peel extract/s were analyzed for total protein content, nitric oxide production, LDH, and Caspase 3 and 8 activities. RT-qPCR was performed with intact RNA to examine the apoptotic pathway and gene expression, and western blot analysis confirmed the presence of tumor suppressor protein/s. The sonicated peel extract (SPL) exhibited the highest RSC, TPC, and FC. Fermented juice displayed higher RSC, TPC, and FC compared to fresh juice. Sonicated peel extract showed an IC50 value of 130±4.5 μg mL-1 against MCF-7 cells, while VERO (healthy) cells had values >1,000 μg mL-1. Sonication was identified as the most effective extraction method for the antiproliferative activity of pomegranate fruit. The study revealed that SPL induced apoptosis via the p21, p53-dependent, caspase 8 pathways, and caspase 3-independent mechanisms in MCF-7 cells. Findings emphasize the potential therapeutic effects of SPL in the antiproliferative effect of MCF-7 cells by modulating caspase 8, p53, and p21-dependent pathways, without activating caspase 3.

SF3B4 Regulates Cellular Senescence and Suppresses Therapy-induced Senescence of Cancer Cells.

Cellular senescence is a state in which cells permanently exit the cell cycle, preventing tumor growth, but it can also contribute to aging and chronic inflammation. Senescence induced by cancer therapies, known as therapy-induced senescence (TIS), halts cancer cell proliferation and prevents metastasis. TIS has been investigated as an important therapeutic approach that could minimize cytotoxicity effects. This study aimed to elucidate the role of splicing factor 3B subunit 4 (SF3B4) in cellular senescence and TIS in cancer cells. β-galactosidase staining was used to examine senescence induction. SF3B4 and p21 expression were determined by RT-qPCR and western blot. Cell proliferation and cell death were evaluated. SF3B4 expression decreases in replicative senescent human fibroblasts and its knockdown induces senescence via a p21-dependent pathway. In A549 non-small cell lung cancer (NSCLC) cells, SF3B4 knockdown also increased senescence markers. Notably, SF3B4 overexpression mitigated doxorubicin-induced senescence in A549 cells. SF3B4 regulates senescence, and this study highlights its potential as a therapeutic target for developing better cancer treatment strategies by leveraging TIS to suppress tumor growth and enhance treatment efficacy.

The N-terminal fragment of histone deacetylase 4 (1-669aa) promotes chondrocyte apoptosis via the p53-dependent endoplasmic reticulum stress pathway.

Exogenous administration of the histone deacetylation 4 (HDAC4) protein can effectively delay osteoarthritis (OA) progression. However, HDAC4 is unstable and easily degrades into N-terminal (HDAC4-NT) and C-terminal fragments, and the HDAC4-NT can exert biological effects, but little is known about its role in chondrocytes and cartilage. Thus, the roles of HDAC4-NT fragments (1-289aa, 1-326aa and 1-669aa) in chondrocytes and cartilage were evaluated via real-time cell analysis (RTCA), safranin O staining, Sirius Red staining and nanoindentation. Molecular mechanisms were profiled via whole-transcriptome sequencing (RNA-seq) and verified invitro and invivo by a live cell real-time monitoring system, flow cytometry, western blotting and immunohistochemistry. The results showed that 1-669aa induced chondrocyte death and cartilage injury significantly, and the differentially expressed genes (DEGs) were enriched mainly in the apoptotic term and p53 signalling pathway. The validation experiments showed that 1-669aa induced chondrocyte apoptosis via the endoplasmic reticulum stress (ERS) pathway, and up-regulated p53 expression was essential for this process. Thus, we concluded that the HDAC4-NT fragment 1-669aa induces chondrocyte apoptosis via the p53-dependent ERS pathway, suggesting that in addition to overexpressing HDAC4, preventing it from degradation may be a new strategy for the treatment of OA.

MDM2 Is Essential to Maintain the Homeostasis of Epithelial Cells by Targeting p53

Introduction: MDM2 is known as the primary negative regulator of p53, and MDM2 promotes lung cancer fibrosis and lung injury through p53-dependent and p53-independent pathways. However, the mechanism by which MDM2 influences the pathogenesis of asthma is unknown. In this study, we investigated the function of MDM2 in lung epithelial cells in type 2 lung inflammation. Methods: We used type II alveolar epithelial cell-specific heterozygous knockout of Mdm2 mice to validate its function. Then papain-induced asthma model was established, and changes in inflammation were observed by measuring immunohistochemistry and flow cytometry analysis. Results: In this study, we knockdown the mouse Mdm2 gene in type 2 alveolar epithelial cells. We demonstrated that heterozygous Mdm2 gene-deleted mice were highly susceptible to protease allergen papain-induced pulmonary inflammation characterized by increased ILC2 numbers, IL-5 and IL-13 cytokine levels, and lung pathology. A mechanistic study showed that following the decreased expression of Mdm2 in lung epithelial cells and A549 cell line, p53 was overactivated, and the expression of its downstream genes p21, Puma, and Noxa was elevated, which resulted in apoptosis. After Mdm2 knockdown, the mRNA expression of inflammation-related gene IL-25, HMGB1, and TNF-α were increased, which further amplified the downstream ILC2 response and lung inflammation. Conclusion: These results indicate that Mdm2 maintains the homeostasis of lung epithelial cells by targeting P53 and regulates the function of lung epithelial cells under type 2 lung inflammation.

A novel variant in GAS2 is associated with autosomal dominant nonsyndromic hearing impairment in a Chinese family

Knockout of GAS2 (growth arrest-specific protein 2), causes disorganization and destabilization of microtubule bundles in supporting cells of the cochlear duct, leading to hearing loss in vivo. However, the molecular mechanism through which GAS2 variant results in hearing loss remains unknown. By Whole-exome sequencing, we identified a novel heterozygous splicing variant in GAS2 (c.616–2 A > G) as the only candidate mutation segregating with late-onset and progressive nonsyndromic hearing loss (NSHL) in a large dominant family. This splicing mutation causes an intron retention and produces a C-terminal truncated protein (named GAS2mu). Mechanistically, the degradation of GAS2mu via the ubiquitin-proteasome pathway is enhanced, and cells expressing GAS2mu exhibit disorganized microtubule bundles. Additionally, GAS2mu further promotes apoptosis by increasing the Bcl-xS/Bcl-xL ratio instead of through the p53-dependent pathway as wild-type GAS2 does, indicating that GAS2mu acts as a toxic molecule to exacerbate apoptosis. Our findings demonstrate that this novel variant of GAS2 promotes its own protein degradation, microtubule disorganization and cellular apoptosis, leading to hearing loss in carriers. This study expands the spectrum of GAS2 variants and elucidates the underlying pathogenic mechanisms, providing a foundation for future investigations of new therapeutic strategies to prevent GAS2-associated progressive hearing loss.

Astaxanthin Induces Apoptosis in MCF-7 Cells through a p53-Dependent Pathway.

Astaxanthin (3,3'-dihydroxy-β,β-carotene-4,4'-dione; AXT) is a xanthophyll β-carotenoid found in microalgae, seafood, fungi, complex plants, flamingos, and quail. It is well known that AXT plays a role as a drug with antioxidant and antitumor properties. Furthermore, several studies have reported that the reagent shows anti-inflammatory and neuroprotective effects. Recently, it was found that AXT acts as a peroxisome proliferator-activated receptor γ (PPARγ) modulator. To investigate the effect of AXT on MCF-7 cells (a human breast cancer cell line), the cells were treated with various concentrations of AXT. The treatment induced the decrease in cell number in a dose-dependent manner. Additionally, the Annexin V-positive cells were increased by the AXT treatment. These results indicated that apoptosis was induced in the tumor cells through the treatment of AXT. To elucidate the connection between apoptosis and p53, the levels of p53 and p21 proteins were assessed. Consequently, it was observed that the expression of p53 and p21 increased proportionally to the concentration of the AXT treatment. These findings suggest that the apoptosis of MCF-7 cells induced by AXT operates through a p53-dependent pathway, implying that AXT could potentially have a beneficial role in future breast cancer treatments. Thus, our results will provide a direction for future cancer challenges.

AGEs induce MMP-9 promoter demethylation through the GADD45α-mediated BER pathway to promote breast cancer metastasis in patients with diabetes.

Scientific evidence has linked diabetes to a higher incidence and increased aggressiveness of breast cancer; however, mechanistic studies of the numerous regulators involved in this process are insufficiently thorough. Advanced glycation end products (AGEs) play an important role in the chronic complications of diabetes, but the mechanisms of AGEs in breast cancer are largely unexplored. In this study, we first demonstrate that high AGE levels in breast cancer tissues are associated with the diabetic state and poor patient outcomes. Furthermore, AGEs interact with the receptor for AGEs (RAGE) to promote breast cancer cell migration and invasion. Mechanistically, based on RNA sequencing (RNA-seq) analysis, we reveal that growth arrest and DNA damage gene 45α (GADD45α) is a vital protein upregulated by AGEs through a P53-dependent pathway. Next, GADD45α recruits thymine DNA glycosylase for base excision repair to form the demethylation complex at the promoter region of MMP-9 and enhance MMP-9 transactivation through DNA demethylation. Overall, our results indicate a critical regulatory role of AGEs in patients with breast cancer and diabetes and reveal a novel mechanism of epigenetic modification in promoting breast cancer metastasis.

Mitochondria-targeted catalase induced cell malignant transformation by the downregulation of p53 protein stability via USP28/miR-200b/PP2A-Cα axis

Antioxidants exert a paradoxical influence on cancer prevention. The latest explanation for this paradox is the different target sites of antioxidants. However, it remains unclear how mitochondria-targeted antioxidants trigger specific p53-dependent pathways in malignant transformation models. Our study revealed that overexpression of mitochondria-targeted catalase (mCAT) instigated such malignant transformation via mouse double minute 2 homolog (MDM2) -mediated p53 degradation. In mouse epithelial JB6 Cl41 cells, the stable expression of mCAT resulted in MDM2-mediated p53 degradation, unlike in catalase-overexpressed Cl41 cells. Further, we demonstrated that mCAT overexpression upregulated ubiquitin-specific protease 28 (USP28) expression, which in turn stabilized c-Jun protein levels. This alteration initiated the activation of the miR-200b promoter transcription activity and a subsequent increase in miR-200b expression. Furthermore, elevated miR-200b levels then promoted its binding to the 3′-untranslated region of protein phosphatase 2A catalytic subunit (PP2A-C) α-isoform mRNA, consequently resulting in PP2A-C protein downregulation. This cascade of events ultimately contributed to increased MDM2 phosphorylation and p53 protein degradation. Thus, the mCAT overexpression triggers MDM2/p53-dependent malignant transformation through USP28/miR-200b/PP2A-Cα pathway, which may provide a new information for understanding mitochondria-targeted antioxidants facilitate the progression to the tumorigenic state.

Self-assembled IR dye/mitoxantrone loaded Porphysomes nanosystem for enhanced combinatorial chemo-photothermal cancer therapy

Chemo-photothermal therapy (PTT) is an emerging non-invasive cancer treatment modality. Light-responsive porphysomes (DPP IR Mtx @Lipo NPs) nanosystems ablate breast cancer cells upon oxidative stress and hyperthermia. The unique self-assembled porphysomes were formed spherical shape in the size range of 150 ± 30 nm formed by the co-assembly of porphyrins along with IR 775 and chemotherapeutic drug, Mitoxantrone (Mtx), forming a camouflaged nanosystem (DPP IR Mtx @Lipo NPs, porphysomes). The advent of the prepared porphysomes aids in proper tuning of NIR absorbance improving singlet oxygen species generation among other anticancer drugs. The eminent release of DPP and adjuvant chemo-drug, Mitoxantrone from the self-assembled porphysomes is triggered by IR 775, a NIR photosensitizer upon laser irradiation. These multifunctional DPP IR Mtx @Lipo NPs have an efficient photothermal conversion efficiency of 65.8% as well as bioimaging properties. In-vitro studies in 2D and 3D models showed a significant cell death of 4T1 cells via the apoptotic pathway when irradiated with NIR laser, causing minimal damage to nearby healthy cells. DPP IR Mtx @Lipo NPs exhibited commingled PDT/PTT interdependent via NIR laser exposure, leading to mitochondrial disruption. Interestingly, the transient transfection using p53-GFP in cancer cells followed by DPP IR Mtx @Lipo NPs treatment causes rapid cell death. The activation of p53-dependent apoptosis pathways was vividly expressed, evidenced by the upregulation of Bax and increased pattern of Caspase-3 cleavage. This effect was pronounced upon transfection and induction with DPP IR Mtx @Lipo NPs, particularly in comparison to non-transfected malignant breast cancer 4T1 cells.

ФУНКЦИОНАЛЬНЫЕ И СТРУКТУРНЫЕ ИЗМЕНЕНИЯ ТИМУСА КРЫС ПРИ ВОЗДЕЙСТВИИ РАЗЛИЧНЫХ ДОЗ ЭНДОКРИННОГО ДИСРАПТОРА

In recent years, there has been a significant increase in the number of diseases associated with impaired functioning of the immune system in the world. One of the main reasons for this can be considered environmental pollution by endocrine disruptors. The most common disruptor on the planet is DDT. Its ubiquitous content in food, water and soil is noted, which makes the study of the effect of its background doses on the body extremely relevant. Systemic consumption of low doses of the disruptor DDT leads to significant changes in the structural and functional characteristics of the rat thymus, which are manifested by increased death of lymphocytes and reticuloepitheliocytes, in the mechanisms of death of which the p53-dependent pathway of apoptosis is involved, as well as a decrease in the proliferative activity of thymocytes, i.e., it is capable of having an immunotoxic effect on the body. These data show that the maximum permissible levels of DDT in food are not safe for the body's immune system.

Anticancer Activity and Molecular Mechanisms of Acetylated and Methylated Quercetin in Human Breast Cancer Cells

Quercetin, a flavonoid polyphenol found in many plants, has garnered significant attention due to its potential cancer chemoprevention. Our previous studies have shown that acetyl modification of the hydroxyl group of quercetin altered its antitumor effects in HepG2 cells. However, the antitumor effect in other cancer cells with different gene mutants remains unknown. In this study, we investigated the antitumor effect of quercetin and its methylated derivative 3,3′,4′,7-O-tetramethylquercetin (4Me-Q) and acetylated derivative 3,3′,4′,7-O-tetraacetylquercetin (4Ac-Q) on two human breast cancer cells, MCF-7 (wt-p53, caspase-3-ve) and MDA-MB-231 (mt-p53, caspase-3+ve). The results demonstrated that 4Ac-Q exhibited significant cell proliferation inhibition and apoptosis induction in both MCF-7 and MDA-MB-231 cells. Conversely, methylation of quercetin was found to lose the activity. The human apoptosis antibody array revealed that 4Ac-Q might induce apoptosis in MCF-7 cells via a p53-dependent pathway, while in MDA-MB-231 cells, it was induced via a caspase-3-dependent pathway. Furthermore, an evaluation using a superoxide inhibitor, MnTBAP, revealed 4Ac-Q-induced apoptosis in MCF-7 cells in a superoxide-independent manner. These findings provide valuable insights into the potential of acetylated quercetin as a new approach in cancer chemoprevention and offer new avenues for health product development.

Synthesis, structure, and mechanism of action of a unique mixed-ligand nickel (II)-complex of tetra-dentate phenol-based ligand with di-aquo co-ligands with significant pro-apoptotic and anti-metastatic effect against malignant human cancer cells

From the discovery of the anticancer activity of “cisplatin”, various type of numerous mononuclear platinum (II) complexes has been evaluated for antitumor activities, though therapeutic use is limited due to side effects and resistance. In this study, A unique mixed ligand mono nuclear octahedral Ni (II) complex [NiL(H2O)2].0·.5H2O (1) [H2L = N,Nʹ-dimethyl-N,Nʹ-bis (2-hydroxy-3,5-di methyl benzyl)-ethylenediamine] with tetra dentate phenol based ligand with N2O2 donor environment along with two labile water molecules was synthesised. The complex (1) is structurally characterized by spectroscopic tools including single-crystal X-ray diffractometer. Complex (1) crystallizes in monoclinic space group P21/n with a = 10.4871(17) Å, b = 20.860 (4) Å and c = 20.955(4) Å. The UV – visible spectra show two peaks around 507 nm and 367 nm due to spin-allowed 1A1g → 1A2g and 1A1g → 1B1g transitions respectively as expected for a square planar d8 system. Mixed ligand octahedral nickel (II) complex with facially coordinating tetra dentate phenol-based ligand (H2L) is in association with two water molecule as ancillary ligand. Two water molecules associated with coordination zone of nickel (II) centre is loosely bound. In this present study, we have evaluated the anti-cancer properties of Complex (1). We found that Complex (1) show potent cancer cell killing activity in case of poorly invasive mice and human cancer cell lines. Complex (1) trigger apoptosis chiefly via p53 dependent pathway. Complex (1) also inhibits cancer cell migration and epithelial to mesenchymal transition in case of metastatic breast cancer cells suggesting potent anti-cancer properties of complex (1).

Identification of Prominin-2 as a new player of cardiomyocyte senescence in the aging heart.

The aging heart is characterized by a number of structural changes leading to ventricular stiffness, impaired resistance to stress and increased risk of developing heart failure (HF). Genetic or pharmacological removal of senescent cells has recently demonstrated the possibility to relieve some cardiac aging features such as hypertrophy and fibrosis. However, the contribution of the different cell types in cardiac aging remains fragmentary due to a lack of cell-specific markers. Cardiomyocytes undergo post-mitotic senescence in response to telomere damage, characterized by persistent DNA damage response and expression of the classical senescence markers p21 and p16, which are shared by many other cell types. In the present study, we used transcriptomic approaches to discover new markers specific for cardiomyocyte senescence. We identified Prominin2 (Prom2), encoding a transmembrane glycoprotein, as the most upregulated gene in cardiomyocytes of aged mice compared to young mice. We showed that Prom2 was upregulated by a p53-dependent pathway in stress-induced premature senescence. Prom2 expression correlated with cardiomyocyte hypertrophy in the hearts of aged mice and was increased in atrial samples of patients with HF with preserved ejection fraction. Consistently, Prom2 overexpression was sufficient to drive senescence, hypertrophy and resistance to cytotoxic stress while Prom2 shRNA silencing inhibited these features in doxorubicin-treated cardiac cells. In conclusion, we identified Prom2 as a new player of cardiac aging, linking cardiomyocyte hypertrophy to senescence. These results could provide a better understanding and targeting of cell-type specific senescence in age-associated cardiac diseases.

VP5 protein of oncolytic herpes simplex virus type 2 induces apoptosis in A549 cells through TP53I3 protein

Oncolytic virotherapy stands out as a burgeoning and promising therapeutic paradigm, harnessing the intrinsic cytotoxicity of oncolytic viruses for selective replication and dissemination within tumors. The primary mode of action revolves around the direct eradication of tumor cells. In our previous investigations, we formulated an oncolytic herpes simplex virus type 2 (OH2) and substantiated its anti-tumor efficacy both in vivo and in vitro. Subsequently, we embarked on a phase I/II clinical trial in China (NMPA, 2018L02743) and the USA (FDA, IND 27137) to assess OH2's safety, biodistribution, and anti-tumor activity as a standalone agent in patients with advanced solid tumors. In this investigation, our primary focus was to comprehend the influence of the major capsid protein VP5 of OH2 on its efficacy as an antitumor agent. Our findings underscore that the VP5 protein significantly amplifies OH2's oncolytic impact on A549 cells. Additionally, we observed that VP5 actively promotes the induction of apoptosis in A549 cells, both in vivo and in vitro. Through comprehensive transcriptional sequencing, we further authenticated that the VP5 protein triggers apoptosis-related signaling pathways and Gene Ontology (GO) terms in A549 cells. Moreover, we scrutinized differentially expressed genes in the p53-dependent apoptosis pathway and conducted meticulous in vitro validation of these genes. Subsequently, we delved deeper into unraveling the functional significance of the TP53I3 gene and conclusively affirmed that the VP5 protein induces apoptosis in A549 cells through the TP53I3 gene. These revelations illuminate the underlying mechanisms of OH2's antitumor activity and underscore the pivotal role played by the VP5 protein. The outcomes of our study harbor promising implications for the formulation of effective oncolytic virotherapy strategies in cancer treatment.

Deoxynivalenol Induces Intestinal Epithelial Barrier Damage through RhoA/ROCK Pathway-Mediated Apoptosis and F-Actin-Associated Tight Junction Disruption.

Deoxynivalenol (DON) poses a serious global food safety risk due to its high toxicity and contamination rate. It disrupts the intestinal epithelial barrier, allowing exogenous toxins to enter the circulation and resulting in sepsis and systemic toxicity. In this research, 32 male Kunming mice and Porcine Small Intestinal Epithelial (IPEC-J2) cells were treated with DON at 0-4.8 mg/kg (7 d) and 0-12 μM (24 h), respectively. Histopathological results revealed that DON disrupted the intestinal epithelial barrier, causing apoptosis and tight junction (TJ) injury. Immunofluorescence and protein expression results showed that DON-induced p53-dependent mitochondrial pathway apoptosis and fibrillar actin (F-actin)-associated TJ injury and that the RhoA/ROCK pathway were activated in mice jejunal tissue and IPEC-J2 cells. Pretreatment with RhoA or ROCK inhibitors (Rosin or Y-27632) maintained DON-induced apoptosis and F-actin-associated TJ injury in IPEC-J2 cells. Thus, DON induces damage to the intestinal epithelial barrier through the RhoA/ROCK pathway-mediated apoptosis and F-actin-associated TJ disruption.

Phosphoproteomic investigation of targets of protein phosphatases in EGFR signaling.

Receptor tyrosine kinases (RTKs) initiate cellular signaling pathways, which are regulated through a delicate balance of phosphorylation and dephosphorylation events. While many studies of RTKs have focused on downstream-activated kinases catalyzing the site-specific phosphorylation, few studies have focused on the phosphatases carrying out the dephosphorylation. In this study, we analyzed six protein phosphatase networks using chemical inhibitors in context of epidermal growth factor receptor (EGFR) signaling by mass spectrometry-based phosphoproteomics. Specifically, we focused on protein phosphatase 2C (PP2C), involved in attenuating p38-dependent signaling pathways in various cellular responses, and confirmed its effect in regulating p38 activity in EGFR signaling. Furthermore, utilizing a p38 inhibitor, we classified phosphosites whose phosphorylation status depends on PP2C inhibition into p38-dependent and p38-independent sites. This study provides a large-scale dataset of phosphatase-regulation of EGF-responsive phosphorylation sites, which serves as a useful resource to deepen our understanding of EGFR signaling.