Cellular and Molecular Life Sciences最新文献

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.

Shallow trophoblast invasion and improper maternal spiral artery remodeling are the primary mechanisms underlying the development of preeclampsia (PE). Bone morphogenetic protein 6 (BMP6) is a proinvasive and proangiogenic factor in vitro; however, its regulatory mechanisms in trophoblast behavior and its role in PE development remain unclear. In this study, primary human trophoblasts and the HTR8/SVneo cell line were utilized asin vitrostudy models. Bulk RNA sequencing (RNA-seq) and single-cell RNA sequencing (scRNA-seq) data were analyzed to explore the expression patterns of BMP6-regulated genes. We found that BMP6 treatment significantly upregulated inhibitor of DNA-binding 1 (ID1) in human trophoblasts. ID1 depletion abolished both basal and BMP6-induced trophoblast invasion and vascular mimicry. Mechanistically, ID1-mediated upregulation of serpin family E member 2 (SERPINE2) and placental growth factor (PlGF) was essential for BMP6-induced trophoblast invasion. In third-trimester placentas, BMP6 mRNA and protein levels were significantly elevated in PE compared with controls. In the adenovirus-expressing fms-like tyrosine kinase-1 (Ad Flt1)-induced rat model of PE, both circulating BMP6 and placental Bmp6 expression were increased in PE rats in late pregnancy. Significantly, BMP6 supplementation during early pregnancy (gestational days 10-13) alleviated maternal hypertension and fetal growth restriction in the PE model. These findings suggest BMP6 promotes trophoblast invasion through ID1-mediated upregulation of SERPINE2 and PlGF. The late-gestation upregulation of BMP6 may represent a compensatory response to shallow trophoblast invasion in PE. Early BMP6 supplementation mitigates PE-related phenotypes in a rat model, highlighting BMP6 as a potential therapeutic target for the prevention and management of PE.

The imbalanced expression of interferon regulatory factor (IRF) 4 and IRF8 in activated B cells significantly influences their differentiation and promotes the development of immune-related diseases. Restoring abnormal B cells to appropriate responses may treat these diseases. In this study, an oligodeoxynucleotide (ODN) S2, designed according to the consensus sequence recognized by IRFs in interferon-stimulated response elements, was used as an immunomodulator to investigate its effects on mouse splenic B cells stimulated with the TLR9 agonist CpG ODN, either alone or in combination with antigen, and to explore its underlying mechanisms. The results showed that S2 had a significant negative regulatory effect on CpG ODN induced B cell activation. It also significantly downregulated the production of IL-6 and the percentage of IL-6⁺ B cells in splenocytes stimulated by CpG ODN, but significantly upregulated the percentage of IL-10⁺ B cells. Interestingly, S2 impaired antibody production both in vitro and in vivo, but rescued mice from lethal inflammatory responses. Further studies showed that S2 could bind IRF4 and IRF8 with high affinity, slightly upregulate phosphorylated IRF4, reduce the expression and nuclear translocation of IRF8, and alter the proportion of IRF4⁺, IRF8⁺ or double-positive B cells in spleen cells induced by CpG ODN. These results suggest that S2 acts as a decoy directing some B cells to differentiate into IL-10-producing Breg-like cells rather than plasma cells by restoring the TLR9 signal-induced IRF4 and IRF8 ratio imbalance. This indicates its potential as an immunomodulator for the treatment of diseases associated with B-cell abnormalities.

Background: Premature ovarian insufficiency (POI) profoundly compromises female reproductive health through accelerated follicle depletion and endocrine disruption. Emerging evidence highlights the therapeutic potential of mesenchymal stem cell-derived exosomes (MSC-Exs), particularly when their function is enhanced by hypoxic preconditioning. In this study, the ability of hypoxia-preconditioned MSC-Exs (H-Exs) to ameliorate oxidative damage to granulosa cells (GCs) and restore ovarian function, was systematically evaluated, and a POI rat model was used to investigate the underlying mechanism.

Methods: CircRNAs specifically expressed in H-Exs were identified and validated. The ability of H-Exs and their corresponding circPTP4A2 to repair oxidative damage and restore mitochondrial function were evaluated by antioxidant enzyme assays, reactive oxygen species (ROS) assays, JC-1 staining, ATP level assays, oxygen consumption rate (OCR) measurements and TEM. The interaction between circPTP4A2 and YBX1 was analysed by molecular dynamics simulations, RIP, CHX assays, and MG132 assays, and the restorative effect of the circPTP4A2/YBX1 axis on ovarian function was verified.

Results: Our findings revealed that compared with normoxic MSC-Exs (N-Exs), H-Exs exerted superior protective effects, significantly attenuating oxidative stress and restoring mitochondrial bioenergetics in KGN cells. Mechanistically, circPTP4A2 was identified as a hypoxia-responsive cargo selectively enriched in H-Exs. This circular RNA stabilized Y-box binding protein 1 (YBX1) through direct interaction, increasing its antioxidative capacity and mitochondrial regulatory functions. Hypoxia-inducible factor 1-alpha (HIF-1α) was further shown to transcriptionally upregulate circPTP4A2 via direct binding to the promoter region of its host gene PTP4A2.

Conclusion: These results establish the circPTP4A2/YBX1 axis as a critical mediator of the therapeutic efficacy of H-Exs for POI, providing both mechanistic insights and a translational framework for exosome-based regenerative strategies.

Retinal ganglion cell (RGC) degeneration caused by optic nerve injury and diseases such as glaucoma leads to irreversible vision loss, yet effective neuroprotective treatments remain elusive. Secondary degeneration driven by astrocytic gliosis and neuroinflammation contributes substantially to neuronal death. Connexin 43 (Cx43), a gap junction protein abundantly expressed in astrocytes, is a key mediator of these secondary responses. Using an optic nerve crush (ONC) mouse model that recapitulates traumatic optic neuropathy, we found that Cx43 haploinsufficiency significantly preserved visual function, limited inner retina thinning, and protected RGCs from apoptosis and macrophage infiltration. Mechanistically, cytokine stimulation of astrocytes triggered Cx43 hemichannel opening and the release of inflammatory ATP and neurotoxic glutamate, which in turn promote RGC apoptosis. A novel Cx43(M1) antibody selectively inhibited astrocytic hemichannels, prevented the release of these factors, and reduced RGC death. Remarkably, a single administration of Cx43(M1) 30 min after ONC improved visual function and RGC survival for at least four weeks, accompanied by attenuated gliosis and reduced Cx43 expression. Together, these findings identify astrocytic Cx43 hemichannels as key mediators of secondary RGC neurodegeneration and demonstrate that their targeted inhibition confers sustained neuroprotection following optic nerve injury.

TLR-targeted immunotherapy represents a promising strategy for combating infectious diseases by initiating or enhancing protective antimicrobial immunity. Here, we identified the first frog-derived TLR2 and TLR4 agonist, Cathelicidin-Ka (Cath-Ka), from the skin of Kaloula pulchra. The presence of Cath-Ka significantly enhanced proliferation, cytokine production, polarization, chemotaxis, phagocytosis, and intracellular bacterial killing of macrophages and peritoneal cells by targeting TLR2 and TLR4, rather than other pattern recognition receptors, and subsequently activated the downstream MyD88-MAPKs pathway. Cath-Ka also promoted macrophage polarization towards the M1 rather than M2 phenotype, and its intraperitoneal injection significantly promoted the chemotaxis of pro-inflammatory monocytes/macrophages into the peritoneal cavity. Finally, the mutant of Cath-Ka with amination at C-terminus had stronger effects on macrophage function modulation than the original peptide. These findings suggest that Cath-Ka and its amidated mutant are promising candidates for the treatment of TLR2 and TLR4-related diseases, including infections.

Autophagy, the process for recycling cytoplasm in the lysosome, relies on tightly regulated membrane trafficking. During autophagy, autophagosomes either fuse with endosomes generating amphisomes and then lysosomes, or directly fuse with lysosomes, in both cases generating autolysosomes that degrade their contents. It remains unclear whether specific mechanisms or conditions determine these alternate routes. Here, we demonstrate that the endosomal regulator SNX3 specifically regulates basal autophagy under nutrient-adequate conditions in both Caenorhabditis elegans (C. elegans) and cultured mammalian cells. In C. elegans, SNX-3 depletion elevates autophagy independently of the UNC-51/ULK1 complex and leads to the accumulation of both autophagosomes and amphisomes, which consequently impairs the clearance of autophagic cargo, including SQST-1/p62 and protein aggregates. Mechanistically, SNX-3 depletion differentially regulates the machineries required for autophagosome-lysosome fusion. In snx-3 mutants, the Q-SNARE components SYX-17 and SNAP-29 translocate to autophagosomes, where they assemble with the endosomal R-SNAREs VAMP-7 and VAMP-8 to promote amphisome formation. Conversely, loss of SNX-3 impairs the lysosomal delivery of VAMP-8 and RAB-7, both essential for autophagosome/amphisome-lysosome fusion, thereby generating fusion-incompetent lysosomes. However, starvation restores the lysosomal fusion capability compromised by snx-3 depletion. Our findings reveal that autophagosome-lysosome fusion is preferentially regulated by nutrient status, and identify an endosomal regulator that tunes membrane trafficking with changing autophagy demands.

Aberrant protein regulatory pathways disrupt bone development and contribute to skeletal diseases. The cysteine protease family of deubiquitinating enzymes (DUBs) are critical for regulation of bone-resorbing osteoclasts and bone-forming osteoblasts. Here, we demonstrate that the DUB ubiquitin-specific protease 8 (USP8) is highly expressed in osteoclasts and its deletion impairs osteoclast development and bone resorption activity. Deletion of Usp8 in osteoclasts (Usp8^Ctsk) results in low trabecular bone mass due to defective endochondral bone formation and short stature resulting from abnormal growth plate structure. Usp8 deficiency in osteoclasts reduces the number of mitochondrial, mitochondrial activity, oxidative phosphorylation, and mitophagy, while ROS production and inflammatory responses increased. USP8 mediates the regulation of mitophagy in osteoclasts through the stabilization of Parkin. Moreover, Usp8-deficient osteoclasts in metaphysis secrete factors that impair both growth plate development and trabecular bone formation. Collectively, these findings identify USP8 as a key regulator of osteoclast development and secretory factor production, shaping the microenvironment essential for skeletal development.