Mitogen-activated Protein Kinase Research Articles

Disruption of cotranscriptional splicing suggests RBM39 is a therapeutic target in acute lymphoblastic leukemia

AbstractThere are only a few options for patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL), thus, this is a major area of unmet medical need. In this study, we reveal that the inclusion of a poison exon in RBM39, which could be induced by both CDK9 or CDK9 independent cyclin-dependent kinases, mitogen-activated protein kinases, glycogen synthase kinases, CDC-like kinases (CMGC) kinase inhibition, is recognized by the nonsense-mediated messenger RNA decay pathway for degradation. Targeting this poison exon in RBM39 with CMGC inhibitors led to protein downregulation and the inhibition of ALL growth, particularly in relapsed/refractory B-ALL. Mechanistically, disruption of cotranscriptional splicing by the inhibition of CMGC kinases, including DYRK1A, or inhibition of CDK9, which phosphorylate the C-terminal domain of RNA polymerase II (Pol II), led to alteration in the SF3B1 and Pol II association. Disruption of SF3B1 and the transcriptional elongation complex altered Pol II pausing, which promoted the inclusion of a poison exon in RBM39. Moreover, RBM39 ablation suppressed the growth of human B-ALL, and targeting RBM39 with sulfonamides, which degrade RBM39 protein, showed strong antitumor activity in preclinical models. Our data reveal that relapsed/refractory B-ALL is susceptible to pharmacologic and genetic inhibition of RBM39 and provide 2 potential strategies to target this axis.

Enhanced activation of signaling pathway by recombinant human adiponectin from genome-edited chickens

Adiponectin (ADPN) exerts various cellular and metabolic functions by activating signaling pathways, including extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) pathways, the protein kinase B (Akt) pathway, and the p38 mitogen-activated protein kinase (MAPK) pathway. However, generating functional recombinant human adiponectin (hADPN) in bacterial or mammalian cells is challenging. Although ADPN agonist peptides have been developed, problems like stability, solubility, and affinity for receptors remain. Recently, a genome-edited chicken bioreactor system was established, ensuring efficient ADPN production with optimal post-transcriptional modifications. We assessed the ability of egg white (EW)-derived hADPN, commercial hADPN, various ADPN agonist peptides, and globular ADPN on activation of the ERK1/2, Akt, and p38 MAPK pathways. EW-derived hADPN, abundant in hexamers and high molecular weight multimers, significantly phosphorylated ERK1/2 in serum-starved HEK293 cells after 15 min of treatment. Comparative analysis revealed that EW-derived hADPN and commercial hADPN induced greater phosphorylation of ERK1/2, Akt, and p38 MAPK than ADPN agonist peptides and globular ADPN, with EW-derived hADPN showing the highest activation. In summary, the finding that EW-derived hADPN strongly activates the ERK1/2, Akt, p38 MAPK signaling pathways highlights that an ADPN production system based on genome-edited chickens is an advantageous alternative to existing methods.

Targeting USP14/UCHL5: A Breakthrough Approach to Overcoming Treatment-Resistant FLT3-ITD-Positive AML.

FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) mutations in acute myeloid leukemia (AML) are associated with poor prognosis and therapy resistance. This study aimed to demonstrate that inhibiting the deubiquitinating enzymes ubiquitin-specific peptidase 14 (USP14) and ubiquitin C-terminal hydrolase L5 (UCHL5) (USP14/UCHL5) with b-AP15 or the organogold compound auranofin (AUR) induces apoptosis in the ITD-transformed human leukemia cell line MV4-11 and mononuclear leukocytes derived from patients with FLT3-ITD-positive AML. This study included patients diagnosed with AML at Tokyo Medical and Dental University Hospital between January 2018 and July 2024. Both treatments blocked downstream FLT3 pathway events, with the effects potentiated by USP14 knockdown. Both treatments inhibited FLT3 deubiquitination via K48 and disrupted translation initiation via 4EBP1, a downstream FLT3 target. FLT3 was downregulated in the leukemic cells, with the associated activation of stress-related MAP kinase pathways and increased NF-E2-related factor 2. Furthermore, the overexpression of B-cell lymphoma-extra-large and myeloid cell leukemia-1 prevented the cell death caused by b-AP15 and AUR. These results suggest that inhibiting USP14/UCHL5, which involves multiple regulatory mechanisms, is a promising target for novel therapies for treatment-resistant FLT3-ITD-positive AML.

Transcriptome Profiling Revealed ABA Signaling Pathway-Related Genes and Major Transcription Factors Involved in the Response to Water Shock and Rehydration in Ginkgo biloba

To assess the regulatory mechanisms involved in the transcriptomic response of Ginkgo biloba to water shock and rehydration, ginkgo seedlings were subjected to dehydration for 0, 3, 6, 12, and 24 h, followed by rehydration for 12 h (Re12 h). A total of 1388, 1802, 2267, 2667, and 3352 genes were upregulated, whereas 1604, 1839, 1934, 2435, and 3035 genes were downregulated, at 3, 6, 12, 24, and Re12 h, respectively, compared to 0 h. Two KEGG pathways—the plant pathogen interaction pathway and mitogen-activated protein kinase (MAPK) signaling pathway—were enriched under water shock but not under rehydration. Moreover, plant hormone signal transduction was enriched under both water shock and rehydration. Differentially expressed genes (DEGs) involved in the ABA signaling pathway (PYR/PYLs, PP2Cs, and SnRK2s) and major differentially expressed transcription factors (MYB, bHLH, AP2/ERF, NAC, WRKY, and bZIP TFs) were identified. qRT-PCR analysis further revealed GbWRKY3 as a negative regulator of the water shock response in G. biloba. The subcellular localization results revealed GbWRKY3 as a nuclear protein. These phenotype-related DEGs, pathways, and TFs provide valuable insight into the water shock and rehydration response in G. biloba.

Targeting mast cell activation alleviates anti-MHC I antibody and LPS-induced TRALI in mice by pharmacologically blocking the TLR3 and MAPK pathway

Transfusion-related lung injury (TRALI) poses a significant risk following blood transfusion and remains the primary cause of transfusion-related morbidity and mortality, primarily driven by the activation of immune cells through anti-major histocompatibility complex class I (anti-MHC I) antibody. However, it remains to be defined how immune microenvironmental cue contributes to TRALI. Here, we uncover that activated mast cells within the immune microenvironment promote lung inflammation and injury in antibody-mediated TRALI, both in vitro and in vivo. This was demonstrated by co-culturing lipopolysaccharide (LPS)-pretreated mast cell line with anti-MHC I antibody and establishing a “two-hit” TRALI mouse model through intratracheal injection of LPS followed by tail-vein injection of anti-MHC I antibody. Importantly, mast cell-deficient KitW-sh/W-sh mice exhibited markedly reduced lung inflammation and injury responses in antibody-mediated TRALI compared with wild-type mice. Mechanistically, activation of toll-like receptor 3 (TLR3)/mitogen-activated protein kinase (MAPK) signaling pathway in mast cells contributes to the enhanced production of proinflammatory factors. These excessive proinflammatory factors produced by activated mast cells contribute to lung inflammation and injury in antibody-mediated TRALI. Pharmacologically targeting the TLR3/MAPK pathway to inhibit mast cell activation normalizes the proinflammatory microenvironment and alleviates lung inflammation and injury in the preclinical TRALI mouse model. Overall, we find that activation of mast cells via the TLR3/MAPK pathway contributes to lung inflammation and injury in antibody-mediated TRALI, providing novel insights into its underlying mechanisms. Furthermore, targeting activated mast cells and the associated pathway offers potential therapeutic strategies for antibody-mediated TRALI.

Genetic evidence for a regulated cysteine protease catalytic triad in LegA7, a Legionella pneumophila protein that impinges on a stress response pathway.

Legionella pneumophila grows in a membrane-bound compartment in macrophages during disease. Construction of the compartment requires a dedicated secretion system that translocates virulence proteins into host cells. One of these proteins, LegA7, is shown to activate a stress response pathway in host cells called the mitogen-activated protein kinase (MAPK) pathway. The effects on the mammalian MAPK pathway were reconstructed in yeast, allowing the development of a strategy to identify the role of individual domains of LegA7. A domain similar to cysteine proteases is demonstrated to be critical for impinging on the MAPK pathway, and the catalytic activity of this domain is required for targeting this path. In addition, a conserved series of repeats, called ankyrin repeats, controls this activity. Data are provided that argue the interaction of the ankyrin repeats with unknown targets probably results in activation of the cysteine protease domain.

A Comparative Genomic Study of Conventional and Undifferentiated Melanoma

Undifferentiated melanoma, defined as melanoma that has lost all usual phenotypic and immunohistochemical characteristics of conventional melanoma, can pose significant diagnostic challenges. Molecular studies have advanced our understanding of undifferentiated melanoma by demonstrating that a subset of these tumors harbors known melanoma driver alterations in genes such as BRAF, NRAS, and NF1. However, there is a paucity of data describing genetic alterations that may distinguish undifferentiated melanoma from conventional melanoma. In this study, we directly compared the genomic profiles of undifferentiated melanoma to a cohort of conventional melanomas, including 14 undifferentiated melanoma cases (comprised of 2 primary cases, 2 cutaneous recurrences, and 10 metastases) and a cohort of 127 conventional melanomas including primary, recurrent, and metastatic cases. Targeted sequencing of 447 cancer-associated genes was performed, including identification of mutations and copy number alterations. NRAS was the most frequent melanoma driver in undifferentiated melanoma (8/14 cases, 57%), although notably, only 1 undifferentiated melanoma harbored an NRAS Q61R mutation. Compared with the conventional melanoma cohort, undifferentiated melanoma demonstrated statistically significant enrichment of pathogenic activating RAC1 mutations (6/14 total cases, 43%), including P29S (4/6 cases), P29L (1/6 cases), and D11E (1/6 cases). In addition to providing insight into the molecular pathogenesis of undifferentiated melanoma, these findings also suggest that RAS Q61R immunohistochemistry may have limited utility for its diagnosis. The presence of recurrent RAC1 mutations in undifferentiated melanoma is also notable as these alterations may contribute to mitogen-activated protein kinase pathway–targeted therapy resistance. Furthermore, the RAC1 alterations identified in this cohort have been shown to drive a melanocytic to mesenchymal switch in melanocytes, offering a possible explanation for the undifferentiated phenotype of these melanomas.

Tamarixetin Protects Chondrocytes against IL-1β-Induced Osteoarthritis Phenotype by Inhibiting NF-κB and Activating Nrf2 Signaling.

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage breakdown and chronic inflammation in joints. As the most prevalent form of arthritis, OA affects around 600 million people globally. Despite the increasing number of individuals with OA risk factors, such as aging and obesity, there is currently no effective cure for the disease. In this context, this study investigated the therapeutic effects of tamarixetin, a flavonoid with antioxidative and anti-inflammatory properties, against OA pathology and elucidated the underlying molecular mechanism. In interleukin-1β (IL-1β)-treated chondrocytes, tamarixetin inhibited the OA phenotypes, restoring cell viability and chondrogenic properties while reducing hypertrophic differentiation and dedifferentiation. Tamarixetin alleviated oxidative stress via the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway activation and inhibited mitogen-activated protein kinase and nuclear factor-κB (NF-κB). Furthermore, tamarixetin attenuated pyroptosis, a programmed cell death caused by excessive inflammation, by suppressing inflammasome activation. We confirmed that the chondroprotective effects of tamarixetin are mediated by the concurrent upregulation of Nrf2 signaling and downregulation of NF-κB signaling, which are key players in balancing antioxidative and inflammatory responses. Overall, our study demonstrated that tamarixetin possesses chondroprotective properties by alleviating IL-1β-induced cellular stress in chondrocytes, suggesting its therapeutic potential to relieve OA phenotype.

Integrating network pharmacology, molecular docking and non-targeted serum metabolomics to illustrate pharmacodynamic ingredients and pharmacologic mechanism of Haizao Yuhu Decoction in treating hyperthyroidism.

To explore the pharmacodynamic ingredients and pharmacologic mechanism of Haizao Yuhu Decoction (HYD) in treating hyperthyroidism via an analysis integrating network pharmacology, molecular docking, and non-targeted serum metabolomics. Therapeutic targets of hyperthyroidism were searched through multi-array analyses in the Gene Expression Omnibus (GEO) database. Hub genes were subjected to the construction of a protein-protein interaction (PPI) network, and GO and KEGG enrichment analyses. Targets of active pharmaceutical ingredients (APIs) in HYD and those of hyperthyroidism were intersected to yield hub genes, followed by validations via molecular docking and non-targeted serum metabolomics. 112 hub genes were identified by intersecting APIs of HYD and therapeutic targets of hyperthyroidism. Using ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) in both negative and positive ion polarity modes, 279 compounds of HYD absorbed in the plasma were fingerprinted. Through summarizing data yielded from network pharmacology and non-targeted serum metabolomics, 214 common targets were identified from compounds of HYD absorbed in the plasma and therapeutic targets of hyperthyroidism, including PTPN11, PIK3CD, EGFR, HRAS, PIK3CA, AKT1, SRC, PIK3CB, and PIK3R1. They were mainly enriched in the biological processes of positive regulation of gene expression, positive regulation of MAPK cascade, signal transduction, protein phosphorylation, negative regulation of apoptotic process, positive regulation of protein kinase B signaling and positive regulation of MAP kinase activity; and molecular functions of identical protein binding, protein serine/threonine/tyrosine kinase activity, protein kinase activity, RNA polymerase II transcription factor activity, ligand-activated sequence-specific DNA binding and protein binding. A total of 185 signaling pathways enriched in the 214 common targets were associated with cell proliferation and angiogenesis. HYD exerts a pharmacological effect on hyperthyroidism via inhibiting pathological angiogenesis in the thyroid and rebalancing immunity.

Supercritical CO2 extracts of propolis inhibits tumor proliferation and Enhances the immunomodulatory activity via activating the TLR4-MAPK/NF-κB signaling pathway

Propolis is a natural immunomodulator with anticancer activity. This study investigated the immunomodulatory mechanism and anti-tumor activity of supercritical CO2 extracts of propolis (SEP) in tumor-bearing immunosuppression mice. We used cyclophosphamide (CTX) to construct the immunosuppressive mice model and then inoculated them with CT26 cells to build the CT26 tumor-bearing immunosuppression mice model. Upon treatment with SEP, tumor proliferation in mice was markedly suppressed, with tumor volumes decreasing from 1881.43 mm3 to 1049.95 mm3 and weights reducing from 2.07 g to 1.13 g. Concurrently, the immune system recovered well, and the spleen and thymus indexes increased significantly. The total T lymphocyte (CD3+ T cell) contents in the spleen and blood recovered from 11.88 % to 21.19 % and 15.32 % to 22.19 %, respectively. In addition, the CD4+ /CD8+ ratio has returned to a healthy level, 3.12 in the spleen and 5.42 in the blood. The levels of IL-1β, IL-6, and TNF-α were increased by 2.17, 2.76, and 7.15 times in the spleen, 2.76, 1.92, and 3.02 times in the serum. Moreover, the western blot results showed that SEP treatment increased the expression of toll-like receptor 4 (TLR4) and the phosphorylation of p38, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p65. These results indicated that SEP activated the immune activity of RAW 264.7 macrophages through the TLR4-mitogen-activated protein kinase (MAPK)/nuclear factor kappa B (NF-κB) signaling pathway to exert immunomodulatory function and inhibit tumor proliferation. This study facilitated the further application of SEP as a potential immunomodulatory and anti-tumor functional food.

Therapeutic effects of paeonol on non‑small cell lung cancer cells via regulation of the MAPK pathway.

The present study aimed to investigate the molecular mechanisms by which paeonol impedes DNA damage repair, induces apoptosis and inhibits cell viability via the mitogen-activated protein kinase (MAPK) pathway. Firstly, normal human bronchial epithelial cells (BEAS-2B) and non-small cell lung cancer cells (H1299) were employed in the study as cellular models. Following cultivation, the cells were divided into experimental and control groups, and were treated with different concentrations of paeonol. Subsequently, various techniques, including western blotting, Cell Counting Kit-8, colony formation, TUNEL and comet assays were conducted to evaluate the effects of paeonol on cell viability, colony-forming ability, apoptosis levels and DNA damage in H1299 cells. According to the experimental results, paeonol significantly reduced the viability and colony formation ability of H1299 cells, but substantially increased apoptosis and DNA damage. These effects were enhanced in response to higher concentrations of paeonol. Furthermore, western blot analysis revealed that paeonol treatment decreased the protein levels of B-cell lymphoma 2 and breast cancer susceptibility gene 1, while it increased the expression levels of cleaved-PARP, cleaved-caspase 3, γH2AX and P21. Additionally, the phosphorylated levels of extracellular signal-regulated kinase 1, c-Jun N-terminal kinase and P38 within the MAPK signaling pathway were diminished. Collectively, the present study demonstrated that paeonol may inhibit the metabolic activity and proliferative capability of H1299 cells, and that it could promote apoptosis and obstruct DNA damage repair by modulating the MAPK signaling pathway.

Consensus QTL map deciphered genes and pathways regulating tolerance to post‐flowering diseases in maize

AbstractPost‐flowering diseases (PFDs), such as ear rot, stalk rot and smut, affect maize yield and quality by damaging the reproductive organs, stalks and seeds. We hypothesized that quantitative trait loci (QTL) associated with different PFDs colocalize and share similar defence mechanisms. Hence, to find a stable consensus meta‐QTL (MQTL) for single or multiple PFDs, MQTL analysis was performed. QTL conferring resistance to PFD reported in 31 independent studies were collated to develop a consensus map. As many as 49 MQTL conferring PFD resistance were projected using appropriate algorithms. Most MQTL regions encompass genes encoding a wide range of defence‐related proteins. MQTL1.1 and MQTL10.5 included QTL/genes for resistance to all PFDs, which supported our hypothesis. Candidate genes for PFDs in MQTL7.1 were associated with pathogenesis‐related 1 protein and mitogen‐activated protein kinase (MAPK) signalling. MQTL5.2 encompassed chalcone flavanone isomerase and cinnamoyl coenzyme A (CoA) reductase genes involved in flavonoid and phenylpropanoid biosynthesis, respectively. Furthermore, MQTL10.4 was found to harbour genes encoding E3 ubiquitin ligase, WRKY‐TF11, calcium‐binding domains and zinc finger motifs. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis reiterated the role of genes within MQTL7.1 in the MAPK signalling pathway, phytohormone signal transduction and plant–pathogen interaction. Hence, we propose that these genes are potential candidates for PFD resistance. Furthermore, 75% of the genes within the MQTL showed orthology with sorghum and rice, indicating that these genes were conserved across species. The role of 27 MQTL, including the six most significant MQTL, was confirmed with reported genome‐wide association study (GWAS) results. Thus, the hotspots associated with PFDs identified in our study could be reliably used in marker‐assisted breeding for PFD resistance.

MAP2K1 dampens cigarette smoke-induced inflammation via suppression of type I interferon pathway activation.

Chronic obstructive pulmonary disease (COPD), comprised of chronic bronchitis and emphysema, is a leading cause of morbidity and mortality worldwide. Mitogen-activated protein 2 kinase (MAP2K) pathway activation is present in COPD lung tissue and a genetic polymorphism in Map2k1 associates with FEV1 decline in COPD, suggesting it may contribute to disease pathogenesis. To test the functional contribution of Map2k1 in cigarette smoke (CS)-induced lung inflammation, we used a short-term CS exposure model in mice deficient in myeloid Map2k1 (LysmCre+Mek1fl) and wild-type mice (Mek1fl). Mice deficient in myeloid Map2k1 had enhanced CS-induced lung inflammation characterized by increased neutrophil recruitment, vascular leak, augmented expression of elastolytic matrix metalloproteinases, and increased type I interferon-stimulated gene expression. The augmented neutrophilic inflammatory response could be abrogated by IFNAR1 blockade. These findings indicate that myeloid Map2k1 regulates the immune response to CS via inhibition of the type I interferon pathway. Overall, these results suggest that Map2k1 is a critical determinant in modulating the severity of CS-induced lung inflammation and its expression is protective.NEW & NOTEWORTHY Activation of the mitogen-activated protein kinases (MAPK)-ERK1/2 pathway is present in COPD lung tissue compared with healthy lungs. Our study using mice deficient in myeloid Map2k1 reveals that Map2k1 is a critical determinant in modulating the severity of CS-induced lung inflammation via suppression of type I interferon responses, and its expression is protective.

Comprehensive Analysis of Phycoerythrin 545 Stability and the Apoptotic Impact of Its Degradation Products on HT29 Cells.

This study investigates the properties and potential applications of phycoerythrin 545, a naturally occurring light-harvesting pigment protein from Rhodomonas salina. Phycoerythrin 545, characterized by its bright red color and maximum absorption wavelength at 545 nm, was extracted using freeze-thawing methods, further purified, and analyzed using chromatographic, spectroscopic techniques, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Phycoerythrin 545 consists of two subunits, primarily α and β, but lacks the γ subunit, and is stable at 4 °C within a pH range of 3-10. To further characterize it, its susceptibility to degradation by trypsin was assessed. The biological activity of phycoerythrin 545 and its degradation products were investigated in HT29 human colon cancer cells. The results showed that the degradation products, particularly those within 3-10 kDa, significantly decreased the viability of HT29 cells by inducing apoptosis. Mechanistic studies indicated these effects were mediated through the activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinases and MAPK/c-Jun N-terminal Kinase signaling pathways and involved the regulation of key apoptotic proteins such as p53, Bim, Bad, Bak, and Bax, leading to the activation of the Caspase-3 apoptotic pathway. These findings contribute to understanding the structural and functional properties of phycoerythrin 545, laying a foundation for its exploration in food industry applications and cancer therapy supplementation.

Downregulation of microRNA-29b in cancer and fibrosis: molecular insights and clinical implications

MicroRNA-29b (miR-29b) is known for its therapeutic potential as an antifibrotic and anticancer agent. In fibrotic conditions, miR-29b inhibits fibrogenesis by downregulating crucial regulators such as collagens, extracellular matrix proteins and the transforming growth factor-β pathway. Similarly, in cancer, it acts as a tumor suppressor by downregulating various oncogenes and signaling pathways involved in cancer progression, such as Wnt-β-catenin, p38-mitogen-activated protein kinase and nuclear factor-κB. However, the upregulation of these pathways suppresses miR-29b, contributing to fibrosis and cancer development. Preclinical research and clinical trials have shown that delivering exogenous miR-29b mimics can restore its expression, attenuating tumorigenesis and fibrogenesis. This review discusses miR-29b's potential and its possible therapeutic development for cancer and fibrotic disorders.

Mathematical Modeling and Inference of Epidermal Growth Factor-Induced Mitogen-Activated Protein Kinase Cell Signaling Pathways.

The mitogen-activated protein kinase (MAPK) pathway is an important intracellular signaling cascade that plays a key role in various cellular processes. Understanding the regulatory mechanisms of this pathway is essential for developing effective interventions and targeted therapies for related diseases. Recent advances in single-cell proteomic technologies have provided unprecedented opportunities to investigate the heterogeneity and noise within complex, multi-signaling networks across diverse cells and cell types. Mathematical modeling has become a powerful interdisciplinary tool that bridges mathematics and experimental biology, providing valuable insights into these intricate cellular processes. In addition, statistical methods have been developed to infer pathway topologies and estimate unknown parameters within dynamic models. This review presents a comprehensive analysis of how mathematical modeling of the MAPK pathway deepens our understanding of its regulatory mechanisms, enhances the prediction of system behavior, and informs experimental research, with a particular focus on recent advances in modeling and inference using single-cell proteomic data.

Mitochondrial genome-derived circRNAs: Orphan epigenetic regulators in molecular biology

Mitochondria are vital for cellular activities, influencing ATP production, Ca2+ signaling, and reactive oxygen species generation. It has been proposed that nuclear genome-derived circular RNAs (circRNAs) play a role in biological processes. For the first time, this study aims to comprehensively explore experimentally confirmed human mitochondrial genome-derived circRNAs (mt-circRNAs) via in-silico analysis. We utilized wide-ranging bioinformatics tools to anticipate their roles in molecular biology, involving miRNA sponging, protein antagonism, and peptide translation. Among five well-characterized mt-circRNAs, SCAR/mc-COX2 stands out as particularly significant with the potential to sponge around 41 different miRNAs, which target several genes mostly involved in endocytosis, MAP kinase, and PI3K-Akt pathways. Interestingly, circMNTND5 and mecciND1 specifically interact with miRNAs through their unique back-splice junction sequence. These exclusively targeted miRNAs (has-miR-5186, 6888-5p, 8081, 924, 672-5p) are predominantly associated with insulin secretion, proteoglycans in cancer, and MAPK signaling pathways. Moreover, all mt-circRNAs intricately affect the P53 pathway through miRNA sequestration. Remarkably, mc-COX2 and circMNTND5 appear to be involved in the RNA’s biogenesis by antagonizing AGO1/2, EIF4A3, and DGCR8. All mt-circRNAs engaged with IGF2BP proteins crucial in redox signaling, and except mecciND1, they all potentially generate at least one protein resembling the immunoglobulin heavy chain protein. Given P53′s function as a redox-sensitive transcription factor, and insulin’s role as a crucial regulator of energy metabolism, their indirect interplay with mt-circRNAs could influence cellular outcomes. However, due to limited attention and infrequent data availability, it is advisable to conduct more thorough investigations to gain a deeper understanding of the functions of mt-circRNA.

ALKBH5 Regulates Osteogenic Differentiation via the lncRNA/mRNA Complex

Human adipose-derived stem cells (hASCs) are commonly used in bone tissue regeneration. The N6-methyladenosine (m6A) modification has emerged as a novel regulatory mechanism for gene expression, playing a critical role in osteogenic differentiation of stem cells. However, the precise role and mechanism of alkylation repair homolog 5 (ALKBH5) in hASC osteogenesis remain incompletely elucidated and warrant further investigation. Herein, we employed methylated RNA immunoprecipitation sequencing, RNA sequencing, and weighted gene coexpression network analysis to identify a key long noncoding RNA (lncRNA) in hASCs: lncRNA AK311120. Functional experiments demonstrated that lnc-AK311120 promoted the osteogenic differentiation of hASCs, while a mutation at the m6A central site A of lnc-AK311120 was found to decrease the level of m6A modification. The osteogenic effect of ALKBH5 was confirmed both in vitro and in vivo using a mandibular defect model in nude mice. Subsequent investigations revealed that knockdown of ALKBH5 resulted in a significant increase in the m6A modification level of lnc-AK311120, accompanied by a downregulation in the expression level of lnc-AK311120. Additional rescue experiments demonstrated that overexpression of lnc-AK311120 could restore the phenotype after ALKBH5 knockdown. We observed that AK311120 interacted with the RNA-binding proteins DExH-Box helicase 9 (DHX9) and YTH domain containing 2 (YTHDC2) to form a ternary complex, while mitogen-activated protein kinase kinase 7 (MAP2K7) served as the shared downstream target gene of DHX9 and YTHDC2. Knockdown of AK311120 led to a reduction in the binding affinity between DHX9/YTHDC2 and the target gene MAP2K7. Furthermore, ALKBH5 facilitated the translation of MAP2K7 and activated the downstream JNK signaling pathway through the AK311120–DHX9–YTHDC2 complex, without affecting its messenger RNA level. Collectively, we have investigated the regulatory effect and mechanism of ALKBH5-mediated demethylation of lncRNA in hASC osteogenesis for the first time, offering a promising approach for bone tissue engineering.

Clarithromycin Modulates Neutrophilic Inflammation Induced by Prevotella intermedia in Human Airway Epithelial Cells.

Objectives: In the present study, we aimed to clarify the mechanisms by which periodontal pathogens, particularly Prevotella intermedia, induce severe neutrophilic inflammation. In addition, we aimed to test the efficacy of macrolides, which has not been resolved in the neutrophilic inflammation induced by P. intermedia. Methods: NCl-H292 human airway epithelial cells were pre-incubated with clarithromycin for 2 h before incubation with P. intermedia supernatants. Then, C-X-C motif chemokine ligand 8 (CXCL8) transcription and interleukin (IL)-8 production were measured. To elucidate the signaling pathway, mitogen-activated protein kinase inhibitors were added to the cell culture, and the cells were subjected to Western blotting. Results:P. intermedia supernatants promoted CXCL8 transcription and IL-8 production, and the reactions were significantly suppressed by clarithromycin pretreatment. Only trametinib, the selective mitogen-activated extracellular signal-regulated kinase inhibitor, downregulated CXCL8 transcription and IL-8 production. Furthermore, Western blotting revealed that stimulation with P. intermedia supernatants specifically induces extracellular signal-regulated kinases (ERK) 1/2 phosphorylation, which is suppressed by clarithromycin pretreatment. Notably, the interference analysis revealed that ERK3 might be dispensable for IL-8 production under the stimulation of P. intermedia supernatants. Conclusions: Our results provide new insight into the mechanism underlying P. intermedia-induced production of IL-8 from human airway epithelial cells. Furthermore, macrolides might have therapeutic potential in regulating periodontal pathogen-induced neutrophilic inflammation in the lungs.

Inhibition of the long non-coding RNA MALAT1 downregulates MAP2K1 to suppress the progression of hypopharyngeal squamous cell carcinoma.

This study aimed to explore the role of lncRNA MALAT1 (Long non-coding RNAs metastasis-associated lung adenocarcinoma transcript), and its underlying mechanisms in Hypopharyngeal Squamous Cell Carcinoma (HSCC). Quantitative real-time PCR (qRT-PCR) was employed to measure lncRNA MALAT1 expression in HSCC and adjacent non-cancerous tissues, along with the expression of the downstream target mitogen-activated protein kinase kinase 1 (MAP2K1). The independent prognostic significance of lncRNA MALAT1 was assessed using Cox regression analysis. Potential downstream targets of MALAT1 were identified through PRM analysis and validated using the TCGA-HNSC database, Western blotting, and immunohistochemistry. CCK-8, flow cytometry, and Transwell assays were conducted to assess the effects of the lncRNA MALAT1/MAP2K1 axis on FaDu cells. Additionally, a nude mouse xenograft model was used to confirm the role of lncRNA MALAT1/MAP2K1 in tumor growth. LncRNA MALAT1 was significantly upregulated in HSCC tissues and closely associated with poor prognosis. Bioinformatics analysis, including parallel reaction monitoring (PRM) screening and TCGA-HNSC data, identified FERMT2, CSNK2A2, and MAP2K1 as potential downstream targets of MALAT1. Validation through qPCR, Western blotting, and immunohistochemistry confirmed MAP2K1 as a downstream target. In vitro and in vivo experiments demonstrated that inhibiting lncRNA MALAT1 suppressed cell proliferation, migration, and epithelial-to-mesenchymal transition (EMT) by downregulating MAP2K1 expression. Additionally, it induced apoptosis, affected the cell cycle, and inhibited tumor growth. Our study uniquely demonstrates that targeting MALAT1 significantly impedes HSCC progression by downregulating its novel downstream target, MAP2K1, offering new insights into potential therapeutic strategies.