Cellular and Molecular Life Sciences最新文献

Pathogenic variants in GRIN2B, encoding the NMDA receptor (NMDAR) GluN2B subunit, are linked to intellectual disability (ID) and related neurodevelopmental disorders. While most disease-associated variants are missense, protein-truncating variants (PTVs) may cause haploinsufficiency with less severe phenotypes. Here, we characterize a knock-in mouse model carrying the GluN2B-L825Ffs*15 PTV (Grin2b^+/Δ). Proteomic analysis revealed markedly reduced full-length GluN2B protein and no detectable truncated GluN2B, accompanied by a small compensatory increase in GluN2A. Electrophysiology in hippocampal neurons demonstrated reduced NMDA-induced currents, diminished ifenprodil sensitivity, and accelerated NMDAR-mediated EPSC deactivation, consistent with a shift toward GluN2A-containing receptors. AMPAR-mEPSC amplitudes were increased, indicating altered excitatory synaptic function. Behaviorally, Grin2b^+/Δ mice exhibited hypoactivity, increased anxiety in males, and impaired sensorimotor gating in both sexes, while learning, memory, and social behaviors remained largely intact. These results demonstrate that a monoallelic GluN2B PTV alters NMDAR subunit composition and function, producing moderate behavioral effects, and provide insight into mechanisms underlying GRIN2B-associated ID.

Toxoplasma gondii chronically infects the central nervous system (CNS), but the mechanisms enabling its traversal of the blood-brain barrier (BBB) remain unclear. Here, we investigated BBB penetration using brain endothelial spheroids and cerebral tissue-derived organoids that recapitulate three-dimensional barrier features. We show that T. gondii tachyzoites efficiently colonize spheroids, without detectable barrier disruption or obligatory parasite replication. Following direct transmigration, tachyzoites invaded and replicated within deeper cell layers. Type I strains (RH, CPS) exhibited higher colonization efficiency than type II strains (PRU, ME49), independent of replication. In contrast, when spheroids were exposed to T. gondii-infected dendritic cells (DCs), both strain types were transported similarly into deep cellular layers. Infected DCs adopted an amoeboid-like migratory phenotype that facilitated parasite transport and subsequent dissemination after egress. Colonization was attenuated by ICAM-1 blockade or heparin treatment, while the parasite effector GRA15, despite modulating DC-endothelial adhesion, did not significantly impact intratissue migration. In contrast, deletion of the effector TgWIP markedly reduced the number of infected DCs entering the spheroids. Similar colonization dynamics were observed in murine cerebral organoids. Collectively, these findings highlight spheroid and organoid models as robust systems for uncovering the cellular and molecular mechanisms underlying T. gondii BBB traversal and CNS colonization.

ZDHHC4, a palmitoyl transferase belonging to the DHHC family, is crucial in cells by catalyzing palmitoylation of proteins, thereby regulating their function and localization. However, its role in melanoma is not well understood. Here, our research determined that ZDHHC4 expression was upregulation in human melanoma specimens and cells. Functional studies reveal that knocking down ZDHHC4 inhibits cell proliferation, migration and invasion of melanoma cells. Moreover, we performed mass spectrometry analysis and found that ZEB-2 is a substrate of ZDHHC4. ZEB-2 interacted with ZDHHC4 through its N-terminal sequences, which promotes the ZDHHC4-mediated palmitoylation of ZEB-2 at C478, facilitating ZEB-2 deubiquitination and its protein stability. This key modification is required for epithelial-to-mesenchymal transition (EMT) in melanoma cells. Furthermore, we found a positive correlation between the expression levels of ZDHHC4 and ZEB-2 in clinical melanoma samples. In summary, our results provide a deeper understanding of mechanism regulating ZDHHC4 in melanoma, suggesting that targeting ZDHHC4 may offer novel therapeutic strategies by suppressing tumor growth and metastasis through the disruption of ZEB-2 palmitoylation process.

High mobility group A1 (HMGA1), a non-histone chromatin structural protein encoded by the HMGA1 gene, plays a critical role in cancer. Recent studies have increasingly focused on its functions in genomic stability and cell death, revealing its involvement in tumorigenesis, cancer progression, and chemotherapy resistance. Consequently, inhibiting HMGA1 represents a promising strategy for developing novel cancer therapies. This review summarizes the cellular and molecular functions of HMGA1 in regulating genomic integrity and cell death in cancer. Furthermore, we discuss current HMGA1-targeting strategies, with emphasis on approaches leveraging its structural and functional characteristics, aiming to provide new insights for future research on HMGA1-targeted cancer therapies.

Background: Immunosuppression is a distinctive condition resulting from sepsis, marked by impaired immune response and immune dysregulation, with a poor prognosis. PRC1, a mitotic regulatory protein, is associated with immune suppression within the tumor microenvironment. However, the role of PRC1 in septic immunosuppression remains unclear. This research aimed to explore the implication and potential mechanism of PRC1 in septic immunosuppression.

Methods: Dataset GSE95233 and GSE65682 were used to validate the expression and prognostic value of PRC1 in sepsis patients. LPS was used to stimulate naïve or endotoxin-tolerant THP-1 and BMDMs. PRC1 expression was measured in by RT-qPCR and Western blot. Small interfering RNA was used for PRC1 knockdown in THP-1. The phosphorylated STAT3 and active β-catenin was detected by Western blot. The expression levels of cytokines and surface markers of macrophages were validated by RT-qPCR. β-catenin inhibitor MSAB and agonist SKL2001 were used to explore the functional relationship among relevant molecules.

Results: PRC1 expression was increased in sepsis non-survivors in both dataset GSE95233 and GSE65682, and increased PRC1 expression was associated with increased 28-days septic mortality. PRC1 expression was elevated in endotoxin-tolerant macrophages rather than naïve macrophages. Sustained phosphorylation of STAT3 was detected in endotoxin-tolerant macrophages. Increased PRC1 expression maintained the phosphorylated STAT3 level via a β-catenin-dependent mechanism, which was reversed by β-catenin inhibitor MSAB. PRC1 knockdown could reduce STAT3 phosphorylation and restore inflammatory responses in endotoxin-tolerant macrophages, while this effect was eliminated by β-catenin agonist SKL2001. Septic microenvironment promoted the expression of PRC1 in endotoxin-tolerant macrophages.

Conclusion: Our data demonstrated that PRC1 is upregulated in endotoxin-tolerant macrophages, and that increased PRC1 expression maintains STAT3 activation via a β-catenin-dependent mechanism and impairs inflammatory response of macrophages during septic immunosuppression. Targeting PRC1/β-catenin/ STAT3 could represent a novel strategy for the management of septic immunosuppression and restore the inflammatory response of endotoxin-tolerant macrophages.

The African swine fever virus (ASFV) -encoded late structural protein pA104R is a putative histone-like protein, which is also a DNA-binding related protein required for ASFV DNA replication, transcription, and genome packaging. However, the molecular mechanism underlying pA104R-host protein interactions remain unknown. To identify proteins potentially interacting with ASFV-pA104R, a primary porcine alveolar macrophage (PAM) cDNA yeast two-hybrid library was constructed, and the pig E3 ubiquitin ligase RING-finger protein 2 (RNF2) was identified, which specifically negatively regulates the proliferation of ASFV. Mechanistically, RNF2 inhibits ASFV replication by promoting the proteasomal degradation of ASFV-pA104R through K48-linked ubiquitination at pA104R lysine 5 (K5). Further studies showed that the K5R mutation impairs the interaction between pA104R and RNF2 and antagonizes for pA104R degradation by RNF2. An ASFV mutant carrying a pA104R point mutation (ASFV CN/SC/2019 pA104R-K5R) was generated based on the ASFV CN/SC/2019 (wild-type) strain. Furthermore, our findings indicate that ASFV CN/SC/2019 pA104R-K5R enhances viral replication and virulence, potentially by increasing viral transcription and/or modulating the host immune response. Accordingly, compared with the parental strain, ASFV CN/SC/2019 pA104R-K5R was more pathogenic and severe lesions in swine. Collectively, our study identifies an intrinsic antiviral protein RNF2 that mediates ASFV CN/SC/2019 pA104R-K5 site ubiquitination emerges as a potential determinant of viral replication and pathogenicity.