Negative Regulatory Mechanism Research Articles

MARCH8 Mediates K27-Linked Polyubiquitination of IL-7 Receptor α to Negatively Regulate IL-7–Triggered T Cell Homeostasis

Abstract IL-7 is a cytokine produced by stromal cells, which binds to IL-7Rα and plays an important role for homeostasis of T lymphocytes. Excessive activities of IL-7–triggered signaling pathways causes autoimmune diseases. How IL-7–triggered signaling and immune effects are regulated is not fully understood. In this study, we show that the membrane-associated RING-CH (MARCH) E3 ligase family member MARCH8 mediates K27-linked polyubiquitination of IL-7Rα, leading to its lysosomal degradation. Site-directed mutagenesis suggests that MARCH8 meditates polyubiquitination of IL-7Rα at K265/K266, and mutation of these residues renders IL-7Rα resistance to MARCH8-mediated polyubiquitination and degradation. MARCH8 deficiency increases IL-7–triggered activation of the downstream transcription factor STAT5 and transcriptional induction of the effector genes in human T lymphoma cells. MARCH8 deficiency also promotes IL-7–triggered T cell proliferation and splenic memory CD8+ T cell differentiation in mice. Our findings suggest that MARCH8 negatively regulates IL-7–triggered signaling by mediating K27-linked polyubiquitination and lysosomal degradation of IL-7Rα, which reveals a negative regulatory mechanism of IL-7–triggered T cell homeostasis.

ING5 inhibits aerobic glycolysis of lung cancer cells by promoting TIE1-mediated phosphorylation of pyruvate dehydrogenase kinase 1 at Y163.

Aerobic glycolysis is critical for tumor growth and metastasis. Previously, we have found that the overexpression of the inhibitor of growth 5 (ING5) inhibits lung cancer aggressiveness and epithelial-mesenchymal transition (EMT). However, whether ING5 regulates lung cancer metabolism reprogramming remains unknown. Here, by quantitative proteomics, we showed that ING5 differentially regulates protein phosphorylation and identified a new site (Y163) of the key glycolytic enzyme PDK1 whose phosphorylation was upregulated 13.847-fold. By clinical study, decreased p-PDK1Y163 was observed in lung cancer tissues and correlated with poor survival. p-PDK1Y163 represents the negative regulatory mechanism of PDK1 by causing PDHA1 dephosphorylation and activation, leading to switching from glycolysis to oxidative phosphorylation, with increasing oxygen consumption and decreasing lactate production. These effects could be impaired by PDK1Y163F mutation, which also impaired the inhibitory effects of ING5 on cancer cell EMT and invasiveness. Mouse xenograft models confirmed the indispensable role of p-PDK1Y163 in ING5-inhibited tumor growth and metastasis. By siRNA screening, ING5-upregulated TIE1 was identified as the upstream tyrosine protein kinase targeting PDK1Y163. TIE1 knockdown induced the dephosphorylation of PDK1Y163 and increased the migration and invasion of lung cancer cells. Collectively, ING5 overexpression-upregulated TIE1 phosphorylates PDK1Y163, which is critical for the inhibition of aerobic glycolysis and invasiveness of lung cancer cells.

STUB1-mediated K63-linked ubiquitination of UHRF1 promotes the progression of cholangiocarcinoma by maintaining DNA hypermethylation of PLA2G2A

BackgroundCholangiocarcinoma (CCA) is a highly malignant tumor characterized by a lack of effective targeted therapeutic strategies. The protein UHRF1 plays a pivotal role in the preservation of DNA methylation and works synergistically with DNMT1. Posttranscriptional modifications (PTMs), such as ubiquitination, play indispensable roles in facilitating this process. Nevertheless, the specific PTMs that regulate UHRF1 in CCA remain unidentified.MethodsWe confirmed the interaction between STUB1 and UHRF1 through mass spectrometry analysis. Furthermore, we investigated the underlying mechanisms of the STUB1-UHRF1/DNMT1 axis via co-IP experiments, denaturing IP ubiquitination experiments, nuclear‒cytoplasmic separation and immunofluorescence experiments. The downstream PLA2G2A gene, regulated by the STUB1-UHRF1/DNMT1 axis, was identified via RNA-seq. The negative regulatory mechanism of PLA2G2A was explored via bisulfite sequencing PCR (BSP) experiments to assess changes in promoter methylation. The roles of PLA2G2A and STUB1 in the proliferation, invasion, and migration of CCA cells were assessed using the CCK-8 assay, colony formation assay, Transwell assay, wound healing assay and xenograft mouse model. We evaluated the effects of STUB1/UHRF1 on cholangiocarcinoma by utilizing a primary CCA mouse model.ResultsThis study revealed that STUB1 interacts with UHRF1, resulting in an increase in the K63-linked ubiquitination of UHRF1. Consequently, this facilitates the nuclear translocation of UHRF1 and enhances its binding affinity with DNMT1. The STUB1-UHRF1/DNMT1 axis led to increased DNA methylation of the PLA2G2A promoter, subsequently repressing its expression. Increased STUB1 expression in CCA was inversely correlated with tumor progression and overall survival. Conversely, PLA2G2A functions as a tumor suppressor in CCA by inhibiting cell proliferation, invasion and migration.ConclusionsThese findings suggest that the STUB1-mediated ubiquitination of UHRF1 plays a pivotal role in tumor progression by epigenetically silencing PLA2G2A, underscoring the potential of STUB1 as both a prognostic biomarker and therapeutic target for CCA.Graphical

Single-cell and spatial sequencing identifies senescent and germinal tumor cells in adamantinomatous craniopharyngiomas

Adamantinomatous craniopharyngioma (ACP) is a clinically aggressive tumor without effective treatment method. Previous studies proposed a paracrine tumorigenesis model, in which oncogenic β-catenin induces senescence in pituitary stem cells and the senescent cells lead the formation of paracrine tumors through secretion of pro-tumorigenic factors. However, there lacks characterization on senescent cells in ACPs. Here, we profiled 12 ACPs with single-cell RNA and TCR-sequencing to elucidate the cellular atlas in ACPs and 3 of them were also subject to spatial sequencing to localize different subpopulations of the tumor cells. In total, we obtained the transcriptome profiles of 70,682 cells. Tumor cells, which were unambiguously identified through the cellular mutation status of the driver CTNNB1 mutations, were clustered into 6 subsets. The whorl-like cluster (WC) cells show distinct molecular features from the other tumor cells and the palisading epithelium (PE) cells consists of a proliferating subset. Other than typical PE and WC, we identified two novel subpopulations of the tumor cells. In one subpopulation, the cells express a high level of cytokines, e.g., FDCSP and S100A8/A9, and are enriched with the senescence-associated secretory phenotype (SASP) factors. Hematoxylin and eosin staining reveals that these SASP cells lack an ordered structures and their nuclei are elongated. In the other subpopulation, the cell sizes are small and they are tightly packed together with an unusual high density expressing a high level of mitochondrial genes (median 10.9%). These cells are the origin of the tumor developmental trajectories revealed by RNA velocity and pseudo-time analysis. Single-cell RNA and TCR analysis reveals that some ACPs are infiltrated with clonally expanded cytotoxic T cells. We propose a hypothesis that WC and PE are formed via different negative regulation mechanisms of the overactivated WNT/β-catenin signaling which provides a new understanding on the tumorigenesis of ACPs. The study lays a foundation for future studies on targeting senescent cells in ACPs with senolytic compounds or other therapeutic agents.

Stub1 promotes degradation of the activated Diaph3: A negative feedback regulatory mechanism of the actin nucleator

The formin protein Diaph3 is an actin nucleator that regulates numerous cytoskeleton-dependent cellular processes through the activation of actin polymerization. Expression and activity of Diaph3 is tightly regulated: lack of Diaph3 results in developmental defects and embryonic lethality in mice, while overexpression of Diaph3 causes auditory neuropathy. It is known that Diaph3 homophilic interactions include the intramolecular interaction of its DID-DAD domains and the intermolecular interactions of DD-DD domains or FH2-FH2 domains. However, the physiological significance of these interactions in Diaph3 protein stability and activity is not fully understood. In this study, we show that FH2-FH2 interaction promotes Diaph3 activity, while DID-DAD and DD-DD interactions inhibit Diaph3 activity through distinct mechanisms. DID-DAD interaction is responsible for the autoinhibition of Diaph3 protein, which is disrupted by binding of Rho GTPases. Interestingly, we find that DID-DAD interaction stabilizes the expression of each DID or DAD domain against proteasomal-mediated degradation. Disruption of DID-DAD interaction by RhoA binding or M1041A mutation causes increased Diaph3 activity and accelerated degradation of the activated Diaph3 protein. Further, the activated Diaph3 is ubiquitinated at K1142/1143/1144 lysine residues by the E3 ligase Stub1. Expression of Stub1 is causally related to the stability and activity of Diaph3. Knockdown of Stub1 in mouse cochlea results in hair cell stereocilia defects, neuronal degeneration and hearing loss, resembling the phenotypes of mice overexpressing Diaph3. Thus, our study reports a novel regulatory mechanism of Diaph3 protein expression and activity whereby the active but not inactive Diaph3 is readily degraded to prevent excessive actin polymerization.

The OsGAPC1-OsSGL module negatively regulates salt tolerance by mediating abscisic acid biosynthesis in rice.

Plants frequently encounter adverse conditions and stress during their lives. Abscisic acid (ABA) plays a crucial role in response to salt stress, and dynamic regulation of ABA levels is essential for plant growth and stress resistance. In this study, we identified a transcription factor, OsSGL (Oryza sativa Stress tolerance and Grain Length), which acts as a negative regulator in salt stress, controlling ABA synthesis. OsSGL-overexpressing and mutant materials exhibited sensitivity and tolerance to salt stress, respectively. Notably, under salt treatment, several ABA-related genes, including the ABA synthesis enzyme OsNCED3 and the ABA response gene OsRAB21, were bound by OsSGL, leading to the inhibition of their transcription. Additionally, we found that a key enzyme involved in glycolysis, OsGAPC1, interacted with OsSGL and enhanced the inhibitory effect of OsSGL on OsNCED3. Upon salt stress, OsGAPC1 underwent acetylation and then translocated from the nucleus to the cytoplasm, partially alleviating the inhibitory effect of OsSGL on OsNCED3. Identification of the OsGAPC1-OsSGL module revealed a negative regulatory mechanism involved in the response of rice to salt stress. This discovery provides insight into the dynamic regulation of ABA synthesis in plants under salt stress conditions, highlighting the delicate balance between stress resistance and growth regulation.

NLRP3 Negative Regulation Mechanisms in the Resting State and Its Implications for Therapeutic Development.

The NACHT-, leucine-rich-repeat-, and pyrin domain-containing protein 3 (NLRP3) is a critical intracellular sensor of the innate immune system that detects various pathogen- and danger-associated molecular patterns, leading to the assembly of the NLRP3 inflammasome and release of interleukin (IL) 1β and IL-18. However, the abnormal activation of the NLRP3 inflammasome has been implicated in the pathogenesis of autoinflammatory diseases such as cryopyrin-associated autoinflammatory syndromes (CAPS) and common diseases such as Alzheimer's disease and asthma. Recent studies have revealed that pyrin functions as an indirect sensor, similar to the plant guard system, and is regulated by binding to inhibitory 14-3-3 proteins. Upon activation, pyrin transitions to its active form. NLRP3 is predicted to follow a similar regulatory mechanism and maintain its inactive form in the cage model, as it also acts as an indirect sensor. Additionally, newly developed NLRP3 inhibitors have been found to inhibit NLRP3 activity by stabilizing its inactive form. Most studies and reviews on NLRP3 have focused on the activation of the NLRP3 inflammasome. This review highlights the molecular mechanisms that regulate NLRP3 in its resting state, and discusses how targeting this inhibitory mechanism can lead to novel therapeutic strategies for NLRP3-related diseases.

MdSINA2-MdNAC104 Module Regulates Apple Alkaline Resistance by Affecting γ-Aminobutyric Acid Synthesis and Transport.

Soil alkalization is an adverse factor limiting plant growth and yield. As a signaling molecule and secondary metabolite, γ-aminobutyric acid (GABA) responds rapidly to alkaline stress and enhances the alkaline resistance of plants. However, the molecular mechanisms by which the GABA pathway adapts to alkaline stress remain unclear. In this study, a transcription factor, MdNAC104 is identified, from the transcriptome of the alkaline-stressed roots of apple, which effectively reduces GABA levels and negatively regulates alkaline resistance. Nevertheless, applying exogenous GABA compensates the negative regulatory mechanism of overexpressed MdNAC104 on alkaline resistance. Further research confirms that MdNAC104 repressed the GABA biosynthetic gene MdGAD1/3 and the GABA transporter gene MdALMT13 by binding to their promoters. Here, MdGAD1/3 actively regulates alkaline resistance by increasing GABA synthesis, while MdALMT13 promotes GABA accumulation and efflux in roots, resulting in an improved resistance to alkaline stress. This subsequent assays reveal that MdSINA2 interacts with MdNAC104 and positively regulates root GABA content and alkaline resistance by ubiquitinating and degrading MdNAC104 via the 26S proteasome pathway. Thus, the study reveals the regulation of alkaline resistance and GABA homeostasis via the MdSINA2-MdNAC104-MdGAD1/3/MdALMT13 module in apple. These findings provide novel insight into the molecular mechanisms of alkaline resistance in plants.

DIPG-92. IMMUNE ACTIVATION STUDIES WITH THE NEOANTIGEN-BASED PEPTIDE VACCINE RHSC-DIPGVAX DEMONSTRATE ANTIBODY-MEDIATED RESPONSES AND EPITOPE SPREADING IN PEDIATRIC PATIENTS WITH DIFFUSE INTRINSIC PONTINE GLIOMAS (DIPG)

Abstract BACKGROUND Approximately 80% of DIPGs carry gain-of-function lysine-to-methionine (K27M) mutations in histone H3 proteins that frequently co-occur with other protein aberrations, including p53, ACVR1, and PDGFRA. Because the DIPG microenvironment has few infiltrating immune cells, resolution of negative regulatory mechanisms through checkpoint blockade may be necessary to promote vaccine-induced anti-tumor responses. Accordingly, rHSC-DIPGVax is a neoantigen-based peptide vaccine combined with checkpoint inhibitors currently under investigation in clinical trial, NCT04943848. The vaccine contains 16 neoantigen peptides, QS-21 adjuvant, and recombinant heat shock protein, Hsc70. In this study, we investigate vaccine-induced antibody-mediated immunity and the phenomenon of epitope spreading, an extension of the immune response to secondary epitopes not directly targeted by the therapy, thus promoting distinct, individualized responses. METHODS rHSC-DIPGVax is administered every two weeks to patients with DIPG and blood is collected pre-treatment and prior to each dose. To investigate vaccine-induced immunoreactivity to neoantigens targeted by rHSC-DIPGVax, DIPG lysates resolved by two-dimensional gel electrophoresis are immunoblotted with pre- and post-vaccine patient plasma containing antibodies against vaccine antigens. Proteins are immunoprecipitated (IP) from DIPG lysates, followed by mass spectrometry (MS) identification and validation. RESULTS In eight subjects to date, vaccination with rHSC-DIPGVax consistently induces IgM and IgG antibodies against proteins directly targeted by the vaccine, including strong immunoreactivity to ACVR1. Furthermore, antibodies against several secondary proteins are also detected in post-vaccination plasma. Immunoblotting and IP-MS analysis identified several distinct candidates of epitope spreading, including the tumor antigens CEP290, DNAH3, HRNR, KDM6B, LAMA5, and TRPA1. CONCLUSIONS rHSC-DIPGVax induces antibody-mediated tumor-specific responses to DIPG neoantigens, including direct vaccine targets and secondary targets via intra- and inter-molecular epitope spreading. We also present an experimental protocol to investigate vaccine-induced immune activation. Our ongoing studies aim to validate epitope spreading candidates and determine the important biological correlates between antibody responses and clinical outcomes.

Oligomerization-mediated autoinhibition and cofactor binding of a plant NLR

Nucleotide-binding leucine-rich repeat (NLR) proteins play a pivotal role in plant immunity by recognizing pathogen effectors1,2. Maintaining a balanced immune response is crucial, as excessive NLR expression can lead to unintended autoimmunity3,4. Unlike most NLRs, the plant NLR required for cell death 2 (NRC2) belongs to a small NLR group characterized by constitutively high expression without self-activation5. The mechanisms underlying NRC2 autoinhibition and activation are not yet understood. Here we show that Solanum lycopersicum (tomato) NRC2 (SlNRC2) forms dimers and tetramers and higher-order oligomers at elevated concentrations. Cryo-electron microscopy shows an inactive conformation of SlNRC2 in these oligomers. Dimerization and oligomerization not only stabilize the inactive state but also sequester SlNRC2 from assembling into an active form. Mutations at the dimeric or interdimeric interfaces enhance pathogen-induced cell death and immunity in Nicotianabenthamiana. The cryo-electron microscopy structures unexpectedly show inositol hexakisphosphate (IP6) or pentakisphosphate (IP5) bound to the inner surface of the C-terminal leucine-rich repeat domain of SlNRC2, as confirmed by mass spectrometry. Mutations at the inositol phosphate-binding site impair inositol phosphate binding of SlNRC2 and pathogen-induced SlNRC2-mediated cell death in N. benthamiana. Our study indicates a negative regulatory mechanism of NLR activation and suggests inositol phosphates as cofactors of NRCs.

Application of Traditional Chinese Medicine in Inhibiting the PD-1/PD-L1 Pathway in the Treatment of Gastric and Colon Cancers

Immune checkpoint regulation is a negative feedback regulatory mechanism in the body, and sequential death receptor-1 (PD-1) and programmed death receptor ligand-1 (PD-L1) are known as immune checkpoints. The PD-1/PD-L1 pathway inhibits the activity of effector T cells through a negative regulatory mechanism to avoid excessive response-induced body damage. PD-L1 is highly expressed in many tumor tissues, and high PD-L1 expression can ultimately lead to tumor immune escape. Therefore, immune checkpoint blockade with inhibition of negative immune regulation therapy has become a cutting-edge hot spot for antitumor therapy, with the main target molecules being PD-1 and PD-L1. Recent years have seen promising progress in the study of traditional Chinese medicines and their effects on gastric and colon cancers, particularly in relation to the PD-1/PD-L1 pathway mechanisms. This review specifically examines the modulation of the PD-L1 pathway by certain traditional Chinese medicines in gastric and colon cancers, aiming to provide insights for the development of innovative drugs for these types of digestive cancers.

The impact of negative cognitive bias on NSSI: mediating non-adaptive cognitive emotion regulation strategies

BackgroundIndividuals may be more likely to engage in NSSI due to negative cognitive bias, while the use of negative emotional regulation mechanisms may further contribute to NSSI. Currently, there is a dearth of studies regarding the correlation among the three variables.MethodThe study employed convenience sampling to collect data via online platforms from a total of 572 college students in Harbin, Heilongjiang Province, China, over the period of January 2024 to February 2024. The questionnaires comprise the Non-Adaptive Cognitive Emotion Srategy Regulation Subscale, the Negative Cognitive Processing Bias Questionnaire, and the NSSI Questionnaire.OutcomeNegative cognitive bias significantly and directly influences NSSI, as indicated by a beta coefficient of 0.3788 and a confidence interval of [0.2878, 0.4698]. The existence of negative cognitive bias significantly enhances the impact of non-adaptive cognitive emotion control approaches (β = 0.5613, CI [0.4808, 0.6418]). Non-adaptive cognitive emotion regulation strategies showed a significant effect on NSSI, as indicated by a beta coefficient of 0.2033 and a confidence interval of [0.0942, 0.3125]. The non-adaptive cognitive emotion control strategy serves as an intermediary between negative cognitive bias and NSSI, explaining 30.12% of the overall impact.In conclusionThe results demonstrate that non-adaptive cognitive emotion regulation strategies play a partially moderating role in the relationship between negative cognitive bias and NSSI among nursing students. We emphasize the importance of non-adaptive cognitive emotion regulation strategies, negative cognitive biases, and NSSI among nursing students. In order to reduce the occurrence of NSSI, it is important for schools, families, and teachers to work together closely and implement a well-organized and efficient intervention to protect the mental well-being of nursing students.

The heparin-binding domain of VEGF165 directly binds to integrin αvβ3 and VEGFR2/KDR D1: a potential mechanism of negative regulation of VEGF165 signaling by αvβ3.

VEGF-A is a key cytokine in tumor angiogenesis and a major therapeutic target for cancer. VEGF165 is the predominant isoform of VEGF-A, and it is the most potent angiogenesis stimulant. VEGFR2/KDR domains 2 and 3 (D2D3) bind to the N-terminal domain (NTD, residues 1-110) of VEGF165. Since removal of the heparin-binding domain (HBD, residues 111-165) markedly reduced the mitogenic activity of the growth factor, it has been proposed that the HBD plays a critical role in the mitogenicity of VEGF165. Here, we report that αvβ3 specifically bound to the isolated VEGF165 HBD but not to VEGF165 NTD. Based on docking simulation and mutagenesis, we identified several critical amino acid residues within the VEGF165 HBD required for αvβ3 binding, i.e., Arg123, Arg124, Lys125, Lys140, Arg145, and Arg149. We discovered that VEGF165 HBD binds to the KDR domain 1 (D1) and identified that Arg123 and Arg124 are critical for KDR D1 binding by mutagenesis, indicating that the KDR D1-binding and αvβ3-binding sites overlap in the HBD. Full-length VEGF165 mutant (R123A/R124A/K125A/K140A/R145A/R149A) defective in αvβ3 and KDR D1 binding failed to induce ERK1/2 phosphorylation, integrin β3 phosphorylation, and KDR phosphorylation and did not support proliferation of endothelial cells, although the mutation did not affect the KDR D2D3 interaction with VEGF165. Since β3-knockout mice are known to show enhanced VEGF165 signaling, we propose that the binding of KDR D1 to the VEGF165 HBD and KDR D2D3 binding to the VEGF165 NTD are critically involved in the potent mitogenicity of VEGF165. We propose that binding competition between KDR and αvβ3 to the VEGF165 HBD endows integrin αvβ3 with regulatory properties to act as a negative regulator of VEGF165 signaling.

Targeting TRIM29 As a Negative Regulator of CAR-NK Cell Effector Function to Improve Antitumor Efficacy of these Cells: A Perspective.

Natural killer (NK) cells are among the most important cells in innate immune defense. In contrast to T cells, the effector function of NK cells does not require prior stimulation and is not MHC restricted. Therefore, chimeric antigen receptor (CAR)-NK cells are superior to CAR-T cells. The complexity of the tumor microenvironment (TME) makes it necessary to explore various pathways involved in NK cell negative regulation. CAR-NK cell effector function can be improved by inhibiting the negative regulatory mechanisms. In this respect, the E3 ubiquitin ligase tripartite motif containing 29 (TRIM29) is known to be involved in reducing NK cell cytotoxicity and cytokine production. Also, targeting TRIM29 may enhance the antitumor efficacy of CAR-NK cells. The present study discusses the negative effects of TRIM29 on NK cell activity and proposes genomic deletion or suppression of the expression of TRIM29 as a novel approach to optimize CAR-NK cell-based immunotherapy.

G-quadruplexes on chromosomal DNA negatively regulates topoisomerase 1 activity.

Human DNA topoisomerase 1 (Top1) is a crucial enzyme responsible for alleviating torsional stress on DNA during transcription and replication, thereby maintaining genome stability. Previous researches had found that non-working Top1 interacted extensively with chromosomal DNA in human cells. However, the reason for its retention on chromosomal DNA remained unclear. In this study, we discovered a close association between Top1 and chromosomal DNA, specifically linked to the presence of G-quadruplex (G4) structures. G4 structures, formed during transcription, trap Top1 and hinder its ability to relax neighboring DNAs. Disruption of the Top1-G4 interaction using G4 ligand relieved the inhibitory effect of G4 on Top1 activity, resulting in a further reduction of R-loop levels in cells. Additionally, the activation of Top1 through the use of a G4 ligand enhanced the toxicity of Top1 inhibitors towards cancer cells. Our study uncovers a negative regulation mechanism of human Top1 and highlights a novel pathway for activating Top1.

Immune Cells in the Spleen of Mice Mediate the Inflammatory Response Induced by Mannheimia haemolytica A2 Serotype.

(1) Background: Mannheimia haemolytica (M. haemolytica) is an opportunistic pathogen and is mainly associated with respiratory diseases in cattle, sheep, and goats. (2) Methods: In this study, a mouse infection model was established using a M. haemolytica strain isolated from goats. Histopathological observations were conducted on various organs of the mice, and bacterial load determination and RNA-seq analysis were specifically performed on the spleens of the mice. (3) Results: The findings of this study suggest that chemokines, potentially present in the spleen of mice following a M. haemolytica challenge, may induce the migration of leukocytes to the spleen and suppress the release of pro-inflammatory factors through a negative feedback regulation mechanism. Additionally, an interesting observation was made regarding the potential of hematopoietic stem/progenitor cells congregating in the spleen to differentiate into immune cells, which could potentially collaborate with leukocytes in their efforts to counteract M. haemolytica invasion. (4) Conclusions: This study revealed the immune regulation mechanism induced by M. haemolytica in the mouse spleen, providing valuable insights into host-pathogen interactions and offering a theoretical basis for the prevention, control, and treatment of mannheimiosis.

The CUL5 E3 ligase complex negatively regulates central signaling pathways in CD8+ T cells

CD8+ T cells play an important role in anti-tumor immunity. Better understanding of their regulation could advance cancer immunotherapies. Here we identify, via stepwise CRISPR-based screening, that CUL5 is a negative regulator of the core signaling pathways of CD8+ T cells. Knocking out CUL5 in mouse CD8+ T cells significantly improves their tumor growth inhibiting ability, with significant proteomic alterations that broadly enhance TCR and cytokine signaling and their effector functions. Chemical inhibition of neddylation required by CUL5 activation, also enhances CD8 effector activities with CUL5 validated as a major target. Mechanistically, CUL5, which is upregulated by TCR stimulation, interacts with the SOCS-box-containing protein PCMTD2 and inhibits TCR and IL2 signaling. Additionally, CTLA4 is markedly upregulated by CUL5 knockout, and its inactivation further enhances the anti-tumor effect of CUL5 KO. These results together reveal a negative regulatory mechanism for CD8+ T cells and have strong translational implications in cancer immunotherapy.

Regulatory function of the endogenous hormone in the germination process of quinoa seeds.

The economic and health significance of quinoa is steadily growing on a global scale. Nevertheless, the primary obstacle to achieving high yields in quinoa cultivation is pre-harvest sprouting (PHS), which is intricately linked to seed dormancy. However, there exists a dearth of research concerning the regulatory mechanisms governing PHS. The regulation of seed germination by various plant hormones has been extensively studied. Consequently, understanding the mechanisms underlying the role of endogenous hormones in the germination process of quinoa seeds and developing strategies to mitigate PHS in quinoa cultivation are of significant research importance. This study employed the HPLC-ESI-MS/MS internal standard and ELISA method to quantify 8 endogenous hormones. The investigation of gene expression changes before and after germination was conducted using RNA-seq analysis, leading to the discovery of 280 differentially expressed genes associated with the regulatory pathway of endogenous hormones. Additionally, a correlation analysis of 99 genes with significant differences identified 14 potential genes that may act as crucial "transportation hubs" in hormonal interactions. Through the performance of an analysis on the modifications in hormone composition and the expression of associated regulatory genes, we posit a prediction that implies the presence of a negative feedback regulatory mechanism of endogenous hormones during the germination of quinoa seeds. This mechanism is potentially influenced by the unique structure of quinoa seeds. To shed light on the involvement of endogenous hormones in the process of quinoa seed germination, we have established a regulatory network. This study aims to offer innovative perspectives on the breeding of quinoa varieties that exhibit resistance to PHS, as well as strategies for preventing PHS.

E3 ubiquitin ligases: key regulators of osteogenesis and potential therapeutic targets for bone disorders.

Ubiquitination is a crucial post-translational modification of proteins that mediates the degradation or functional regulation of specific proteins. This process participates in various biological processes such as cell growth, development, and signal transduction. E3 ubiquitin ligases play both positive and negative regulatory roles in osteogenesis and differentiation by ubiquitination-mediated degradation or stabilization of transcription factors, signaling molecules, and cytoskeletal proteins. These activities affect the proliferation, differentiation, survival, and bone formation of osteoblasts (OBs). In recent years, advances in genomics, transcriptomics, and proteomics have led to a deeper understanding of the classification, function, and mechanisms of action of E3 ubiquitin ligases. This understanding provides new insights and approaches for revealing the molecular regulatory mechanisms of bone formation and identifying therapeutic targets for bone metabolic diseases. This review discusses the research progress and significance of the positive and negative regulatory roles and mechanisms of E3 ubiquitin ligases in the process of osteogenic differentiation. Additionally, the review highlights the role of E3 ubiquitin ligases in bone-related diseases. A thorough understanding of the role and mechanisms of E3 ubiquitin ligases in osteogenic differentiation could provide promising therapeutic targets for bone tissue engineering based on stem cells.

Negative regulation mechanisms of arbuscular mycorrhizal symbiosis in plants

Negative regulation mechanisms of arbuscular mycorrhizal symbiosis in plants