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Nature Communications May 2024Maturation of eukaryotic pre-mRNAs via splicing and polyadenylation is modulated across cell types and conditions by a variety of RNA-binding proteins (RBPs). Although...
Maturation of eukaryotic pre-mRNAs via splicing and polyadenylation is modulated across cell types and conditions by a variety of RNA-binding proteins (RBPs). Although there exist over 1,500 RBPs in human cells, their binding motifs and functions still remain to be elucidated, especially in the complex environment of tissues and in the context of diseases. To overcome the lack of methods for the systematic and automated detection of sequence motif-guided pre-mRNA processing regulation from RNA sequencing (RNA-Seq) data we have developed MAPP (Motif Activity on Pre-mRNA Processing). Applying MAPP to RBP knock-down experiments reveals that many RBPs regulate both splicing and polyadenylation of nascent transcripts by acting on similar sequence motifs. MAPP not only infers these sequence motifs, but also unravels the position-dependent impact of the RBPs on pre-mRNA processing. Interestingly, all investigated RBPs that act on both splicing and 3' end processing exhibit a consistently repressive or activating effect on both processes, providing a first glimpse on the underlying mechanism. Applying MAPP to normal and malignant brain tissue samples unveils that the motifs bound by the PTBP1 and RBFOX RBPs coordinately drive the oncogenic splicing program active in glioblastomas demonstrating that MAPP paves the way for characterizing pre-mRNA processing regulators under physiological and pathological conditions.
Topics: Humans; RNA-Binding Proteins; Polyadenylation; RNA Precursors; RNA Splicing; Gene Expression Regulation, Neoplastic; Neoplasms; Nucleotide Motifs; Polypyrimidine Tract-Binding Protein; RNA Splicing Factors; Heterogeneous-Nuclear Ribonucleoproteins; RNA, Messenger
PubMed: 38750024
DOI: 10.1038/s41467-024-48046-1 -
PLoS Biology May 2024BAK and BAX execute intrinsic apoptosis by permeabilising the mitochondrial outer membrane. Their activity is regulated through interactions with pro-survival BCL-2...
BAK and BAX execute intrinsic apoptosis by permeabilising the mitochondrial outer membrane. Their activity is regulated through interactions with pro-survival BCL-2 family proteins and with non-BCL-2 proteins including the mitochondrial channel protein VDAC2. VDAC2 is important for bringing both BAK and BAX to mitochondria where they execute their apoptotic function. Despite this important function in apoptosis, while interactions with pro-survival family members are well characterised and have culminated in the development of drugs that target these interfaces to induce cancer cell apoptosis, the interaction between BAK and VDAC2 remains largely undefined. Deep scanning mutagenesis coupled with cysteine linkage identified key residues in the interaction between BAK and VDAC2. Obstructive labelling of specific residues in the BH3 domain or hydrophobic groove of BAK disrupted this interaction. Conversely, mutating specific residues in a cytosol-exposed region of VDAC2 stabilised the interaction with BAK and inhibited BAK apoptotic activity. Thus, this VDAC2-BAK interaction site can potentially be targeted to either inhibit BAK-mediated apoptosis in scenarios where excessive apoptosis contributes to disease or to promote BAK-mediated apoptosis for cancer therapy.
Topics: Voltage-Dependent Anion Channel 2; bcl-2 Homologous Antagonist-Killer Protein; Apoptosis; Humans; Protein Binding; Mitochondria; Animals; HEK293 Cells
PubMed: 38696533
DOI: 10.1371/journal.pbio.3002617 -
PLoS Pathogens Apr 2024Apoptosis is a critical host antiviral defense mechanism. But many viruses have evolved multiple strategies to manipulate apoptosis and escape host antiviral immune...
Apoptosis is a critical host antiviral defense mechanism. But many viruses have evolved multiple strategies to manipulate apoptosis and escape host antiviral immune responses. Herpesvirus infection regulated apoptosis; however, the underlying molecular mechanisms have not yet been fully elucidated. Hence, the present study aimed to study the relationship between herpesvirus infection and apoptosis in vitro and in vivo using the pseudorabies virus (PRV) as the model virus. We found that mitochondria-dependent apoptosis was induced by PRV gM, a late protein encoded by PRV UL10, a virulence-related gene involved in enhancing PRV pathogenicity. Mechanistically, gM competitively combines with BCL-XL to disrupt the BCL-XL-BAK complex, resulting in BCL-2-antagonistic killer (BAK) oligomerization and BCL-2-associated X (BAX) activation, which destroys the mitochondrial membrane potential and activates caspase-3/7 to trigger apoptosis. Interestingly, similar apoptotic mechanisms were observed in other herpesviruses (Herpes Simplex Virus-1 [HSV-1], human cytomegalovirus [HCMV], Equine herpesvirus-1 [EHV-1], and varicella-zoster virus [VZV]) driven by PRV gM homologs. Compared with their parental viruses, the pathogenicity of PRV-ΔUL10 or HSV-1-ΔUL10 in mice was reduced with lower apoptosis and viral replication, illustrating that UL10 is a key virulence-related gene in PRV and HSV-1. Consistently, caspase-3 deletion also diminished the replication and pathogenicity of PRV and HSV-1 in vitro and in mice, suggesting that caspase-3-mediated apoptosis is closely related to the replication and pathogenicity of PRV and HSV-1. Overall, our findings firstly reveal the mechanism by which PRV gM and its homologs in several herpesviruses regulate apoptosis to enhance the viral replication and pathogenicity, and the relationship between gM-mediated apoptosis and herpesvirus pathogenicity suggests a promising approach for developing attenuated live vaccines and therapy for herpesvirus-related diseases.
Topics: Apoptosis; Animals; Herpesvirus 1, Suid; Mice; Mitochondria; Pseudorabies; Viral Proteins; Herpesviridae; Virus Replication; Humans; Mice, Inbred BALB C; Virulence
PubMed: 38669242
DOI: 10.1371/journal.ppat.1012146 -
Iranian Journal of Basic Medical... 2024This study assessed the effects of electroacupuncture (EA) stimulation at different frequencies at the Dazhui and Baihui acupoints in the subacute phase after transient...
Electroacupuncture at the Dazhui and Baihui acupoints and different frequencies (10 and 50 Hz) protects against apoptosis by up-regulating ERK1/2-mediated signaling in rats after global cerebral ischemia.
OBJECTIVES
This study assessed the effects of electroacupuncture (EA) stimulation at different frequencies at the Dazhui and Baihui acupoints in the subacute phase after transient global cerebral ischemia (GCI).
MATERIALS AND METHODS
Rats were subjected to GCI for 25 min, followed by reperfusion for 7 days. EA at acupoints was performed at 10, 30, or 50 Hz, 1 day after reperfusion and then once daily for 6 consecutive days.
RESULTS
EA at acupoints at 10 and 50 Hz effectively down-regulated apoptosis in the hippocampal cornu ammonis 1(CA1) area and ameliorated memory deficits. Moreover, EA treatment at 10 and 50 Hz markedly increased phospho (p)-extracellular signal-regulated protein kinase 1/2 (ERK1/2), p-ERK1/2/neuronal nuclei (NeuN), p-cAMP response element-binding protein (CREB)/p-ERK1/2, B-cell lymphoma-2 (Bcl-2)/p-CREB, and X-linked inhibitor of apoptosis protein/NeuN expression levels and decreased Bcl-2 homologous antagonist/killer, second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI, cytochrome c, cleaved caspase-3, and apoptosis-inducing factor expression levels. Furthermore, 10-Hz EA treatment effectively increased p-p38 mitogen-activated protein kinase (MAPK), p-p38 MAPK/NeuN, and p-CREB/p-p38 MAPK expression levels. Pretreatment with U0126 (ERK1/2 inhibitor) completely abrogated the effects of 10- and 50-Hz EA treatments on the aforementioned protein expression levels. Similarly, pretreatment with SB203580 (p38 MAPK inhibitor) completely abrogated the effects of 10-Hz treatment on the aforementioned protein expression levels.
CONCLUSION
The effects of 10- and 50-Hz EA treatments on mitochondria-related apoptosis can be attributed to the activation of ERK1/2/p38 MAPK/CREB/Bcl-2- and ERK1/2/CREB/Bcl-2-mediated signaling, respectively, in the hippocampal CA1 area at 7 days after transient GCI.
PubMed: 38645497
DOI: 10.22038/IJBMS.2024.72279.15716 -
Cell Death Discovery Apr 2024Mitochondrial permeability transition (mPT)-mediated mitochondrial dysfunction plays a pivotal role in various human diseases. However, the intricate details of its...
Mitochondrial permeability transition (mPT)-mediated mitochondrial dysfunction plays a pivotal role in various human diseases. However, the intricate details of its mechanisms and the sequence of events remain elusive, primarily due to the interference caused by Bax/Bak-induced mitochondrial outer membrane permeabilization (MOMP). To address these, we have developed a methodology that utilizes nano-flow cytometry (nFCM) to quantitatively analyze the opening of mitochondrial permeability transition pore (mPTP), dissipation of mitochondrial membrane potential ( Ψ), release of cytochrome c (Cyt c), and other molecular alternations of isolated mitochondria in response to mPT induction at the single-mitochondrion level. It was identified that betulinic acid (BetA) and antimycin A can directly induce mitochondrial dysfunction through mPT-mediated mechanisms, while cisplatin and staurosporine cannot. In addition, the nFCM analysis also revealed that BetA primarily induces mPTP opening through a reduction in Bcl-2 and Bcl-xL protein levels, along with an elevation in ROS content. Employing dose and time-dependent strategies of BetA, for the first time, we experimentally verified the sequential occurrence of mPTP opening and Ψ depolarization prior to the release of Cyt c during mPT-mediated mitochondrial dysfunction. Notably, our study uncovers a simultaneous release of cell-death-associated factors, including Cyt c, AIF, PNPT1, and mtDNA during mPT, implying the initiation of multiple cell death pathways. Intriguingly, BetA induces caspase-independent cell death, even in the absence of Bax/Bak, thereby overcoming drug resistance. The presented findings offer new insights into mPT-mediated mitochondrial dysfunction using nFCM, emphasizing the potential for targeting such dysfunction in innovative cancer therapies and interventions.
PubMed: 38622121
DOI: 10.1038/s41420-024-01947-y -
Cell Death & Disease Apr 2024BH3-mimetics represent promising anti-cancer agents in tumors that rely on the anti-apoptotic function of B-Cell Lymphoma 2 (BCL2) proteins, particularly in leukemia and...
BH3-mimetics represent promising anti-cancer agents in tumors that rely on the anti-apoptotic function of B-Cell Lymphoma 2 (BCL2) proteins, particularly in leukemia and lymphoma cells primed for apoptosis. Mechanistically, BH3-mimetics may displace pro-apoptotic binding partners thus inducing BAX/BAK-mediated mitochondrial permeabilization followed by cytochrome c release, activation of the caspase cascade and apoptosis. Here, we describe a novel mode of caspase-independent cell death (CICD) induced by BH3-mimetics in a subset of diffuse large B-cell lymphoma (DLBCL) cells. Of note, rather than occurring via necroptosis, CICD induced immediately after mitochondrial permeabilization was associated with transcriptional reprogramming mediated by activation of c-Jun N-terminal Kinase (JNK) signaling and Activator Protein 1 (AP1). Thereby, CICD resulted in the JNK/AP1-mediated upregulation of inflammatory chemokines and increased migration of cytotoxic Natural Killer (NK) cells. Taken together, our study describes a novel mode of CICD triggered by BH3-mimetics that may alter the immune response towards dying cells.
Topics: Humans; bcl-2-Associated X Protein; bcl-2 Homologous Antagonist-Killer Protein; Apoptosis; Antineoplastic Agents; Caspases; Lymphoma, Large B-Cell, Diffuse; Cell Line; Proto-Oncogene Proteins c-bcl-2
PubMed: 38622118
DOI: 10.1038/s41419-024-06652-3 -
Poultry Science Mar 2024Heat shock proteins (HSP) are a group of highly conserved molecular chaperones found in various organisms and have been associated with tumorigenesis, tumor progression,...
Heat shock proteins (HSP) are a group of highly conserved molecular chaperones found in various organisms and have been associated with tumorigenesis, tumor progression, and metastasis. However, the relationship between HSP60 and apoptosis remains elusive. The aim of this study was to explore the role and regulatory mechanisms of apoptosis in response to altered HSP60 expression. We generated DF-1 cell lines of both HSP60 overexpression and knockdown and assessed their impact on apoptosis levels using ELISA and flow cytometry analyses. Additionally, we examined the transcription and protein expression levels of apoptosis-related signaling factors using fluorescence quantitative PCR (qPCR) and Western blotting analyses. Heat shock proteins 60 overexpression led to a significant decrease in apoptosis levels in DF-1 cells, which could be attributed to the downregulation of BAX and BAK expression, the upregulation of Bcl-2, and the decreased expression of Caspase 3. Conversely, HSP60 knockdown led to a substantial increase in apoptosis levels in DF-1 cells, facilitated by the downregulation of BAX and Bcl-2 expression, and the upregulation of BAK expression, which increased Caspase 3 levels, thereby promoting apoptosis. The findings of our study provide the first evidence of the inhibitory effect of HSP60 on apoptosis in DF-1 cells. These observations have significant implications for disease progression and cancer research, with potential medical applications.
PubMed: 38603929
DOI: 10.1016/j.psj.2024.103619 -
Biomedicine & Pharmacotherapy =... May 2024Hepatocellular carcinoma (HCC) stands as a leading cause of mortality, and despite recent advancements in the overall survival rates, the prognosis remains dismal....
Hepatocellular carcinoma (HCC) stands as a leading cause of mortality, and despite recent advancements in the overall survival rates, the prognosis remains dismal. Prunetin 4-O-glucoside (Prunetrin or PUR), an active compound derived from Prunus sp., was explored for its impact on HepG2 and Huh7 cells. The cytotoxicity assessment revealed a notable reduction in cell viability in both cell lines, while exhibiting non-toxicity towards HaCaT cells. Colony formation studies underscored PUR's inhibitory effect on cell proliferation, dose-dependently. Mechanistically, PUR downregulated cell cycle proteins (CDC25c, Cdk1/CDC2, and Cyclin B1), inducing G2/M phase arrest, corroborated by flow cytometry. Western blot analyses exhibited dose-dependent cleavages of PARP and caspase 3, indicative of apoptosis. Treatment with the apoptotic inhibitor z-vmd-fmk provided evidence of PUR-induced apoptosis. Annexin V and PI flow cytometry further affirmed apoptotic induction. Enhanced expression of cleaved-caspase 9 and the pro-apoptotic protein Bak, coupled with reduced anti-apoptotic Bcl-xL, and affirmed PUR's induction of intrinsic apoptosis. Additionally, PUR activated the MAPK pathway, evidenced by elevated phospho p38 and phospho ERK expressions in both cell lines. Notably, a concentration-dependent decrease in mTOR and Akt expressions indicated PUR's inhibition of the Akt/mTOR pathway in HepG2 and Huh7 cells. These findings illuminate PUR's multifaceted impact, revealing its potential as a promising therapeutic agent against HepG2 and Huh7 cells through modulation of cell cycle, apoptosis, and key signaling pathways.
Topics: Humans; Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Cell Survival; G2 Phase Cell Cycle Checkpoints; Hep G2 Cells; Liver Neoplasms; MAP Kinase Signaling System; Proto-Oncogene Proteins c-akt; Signal Transduction; TOR Serine-Threonine Kinases; Isoflavones; Cell Cycle Checkpoints
PubMed: 38552440
DOI: 10.1016/j.biopha.2024.116483 -
Asian Pacific Journal of Cancer... Mar 2024Brucein D (BrD), a quassinoid isolated from Brucea javanica fruit, reportedly demonstrates anti-cancer activity. This study's objective is to evaluate the cytotoxicity...
OBJECTIVE
Brucein D (BrD), a quassinoid isolated from Brucea javanica fruit, reportedly demonstrates anti-cancer activity. This study's objective is to evaluate the cytotoxicity of Brucein D and its ability to induce apoptosis in T24 bladder cancer cells.
METHODS
We investigated the cytotoxic activity of BrD against the T24 cell through the induction of apoptosis in vitro. This cytotoxic activity was evaluated with ΜΤΤ assay and followed by Calcein-AM/PI viability staining. Apoptotic activity was determined with Hoechst 33342 nuclear staining and DNA fragmentation. Doxorubicin and docetaxel were used as a positive control. Evaluation of apoptotic-related gene expression, Bax, Bak, Bcl2, and p53 was also performed using semi-quantitative PCR analysis. Statistical analysis was conducted using One-way ANOVA followed by post hoc test Turkey's HSD (Honestly Significance Difference).
RESULTS
Results show that BrD had high toxicity against T24 bladder cancer cells with an IC50 value of 7.65 ± 1.2 µg/mL but relatively less toxic to 1BR3 normal skin fibroblast cells compared to the doxorubicin and docetaxel treated cells. The viability assay shows that BrD significantly increases the percentage of dead cells relative to control in a dose-dependent manner. Furthermore, the percentage of cells with apoptotic appearance was significantly higher in group treated with BrD IC50 (56.04±3.09%) compared to control (9.42±2.88). The result was similar to doxorubicin IC50 (58.97±12.31) but lower than docetaxel IC50 (74.42±9.79). DNA fragmentation in gel electrophoresis was also observed in T24 cells treated with BrD. Apoptosis was also verified by an alteration in the expression of apoptosis-related genes, upregulation of Bax, Bak, and p53, and downregulation of Bcl-2.
CONCLUSION
BrD has shown a cytotoxic effect against T24 bladder cancer cells. Hence, it is a promising natural compound for the management of bladder cancer by induction of apoptosis through activation of the intrinsic pathway, with low toxicity to normal cells.
Topics: Humans; Docetaxel; Tumor Suppressor Protein p53; bcl-2-Associated X Protein; Urinary Bladder Neoplasms; Apoptosis; Antineoplastic Agents; Doxorubicin; Cell Line, Tumor
PubMed: 38546074
DOI: 10.31557/APJCP.2024.25.3.921 -
Poultry Science May 2024Cadmium (Cd) and high molybdenum (Mo) are injurious to the body. Previous research has substantiated that Cd and Mo exposure caused testicular injury of ducks, but...
Cadmium (Cd) and high molybdenum (Mo) are injurious to the body. Previous research has substantiated that Cd and Mo exposure caused testicular injury of ducks, but concrete mechanism is not fully clarified. To further survey the toxicity of co-exposure to Cd and Mo in testis, 40 healthy 8-day-old Shaoxing ducks (Anas platyrhyncha) were stochasticly distributed to 4 groups and raised with basic diet embracing Cd (4 mg/kg Cd) or Mo (100 mg/kg Mo) or both. At the 16th wk, testis tissues were gathered. The characteristic ultrastructural changes related to apoptosis and ferroptosis were observed in Mo or Cd or both groups. Besides, Mo or Cd or both repressed nuclear factor erythroid 2-related factor 2 (Nrf2) pathway via decreasing Nrf2, Heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase 1 (NQO1), Glutamate-cysteine ligase catalytic subunit (GCLC) and Glutamate-cysteine ligase modifier subunit (GCLM) mRNA expression of and Nrf2 protein expression, then stimulated apoptosis by elevating Bcl-2 antagonist/killer-1 (Bak-1), Bcl-2-associated X-protein (Bax), Cytochrome complex (Cyt-C), caspase-3 mRNA expression, cleaved-caspase-3 protein expression and apoptosis rate, as well as reducing B-cell lymphoma-2 (Bcl-2) mRNA expression and ratio of Bcl-2 to Bax, and triggered ferroptosis by upregulating Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4), transferrin receptor (TFR1) and Prostaglandin-Endoperoxide Synthase 2 (PTGS2) expression levels, and downregulating ferritin heavy chain 1 (FTH1), ferritin light chain 1 (FTL1), ferroportin 1 (FPN1), solute carrier family 7 member 11 (SCL7A11) and glutathione peroxidase 4 (GPX4) expression levels. The most obvious changes of these indexes were observed in co-treated group. Altogether, the results announced that Mo or Cd or both evoked apoptosis and ferroptosis by inhibiting Nrf2 pathway in the testis of ducks, and co-exposure to Mo and Cd exacerbated these variations.
Topics: Animals; Male; Ducks; Cadmium; Testis; Apoptosis; Ferroptosis; NF-E2-Related Factor 2; Signal Transduction; Molybdenum; Avian Proteins
PubMed: 38537407
DOI: 10.1016/j.psj.2024.103653