The endoplasmic reticulum (ER) lipid raft proteins (Erlins) belong to the stomatin-prohibitin-flotillin-HflC/K (SPFH) family and form highly oligomeric platforms that mediate the degradation of activated inositol 1,4,5-trisphosphate receptors by facilitating their interaction with the E3 ligase RNF170. However, the molecular mechanisms underlying this process remain unclear. Here, we successfully reconstituted the Erlin1-Erlin2 complex and its complex with RNF170 by overexpressing these components in HEK293F cells. We also isolated the Erlin2 oligomer by solely expressing Erlin2 in the cells. Using cryo-EM, we determined the structures of the Erlin1-Erlin2 complex, Erlin1-Erlin2-RNF170 complex, and Erlin2 oligomer at resolutions of 3.29 Å, 3.05 Å, and 2.12 Å, respectively. Both the Erlin1-Erlin2 complex and the Erlin2 oligomer exhibit similar cage-like architectures, with the Erlin1-Erlin2 complex containing 13 pairs of Erlin1 and Erlin2 subunits, whereas the Erlin2 oligomer comprises 26 Erlin2. Although RNF170 was clearly identified during protein purification, it was invisible in the final 3D reconstruction, suggesting a high degree of flexibility between RNF170 and the Erlin complex. Multiple water molecules were identified in the Erlin2 oligomer, underscoring their critical roles in facilitating the high degree of oligomerization of the Erlin2 complex. Taken together, our structural investigation elucidates the molecular basis for the assembly of the Erlin complex and provides a framework for further investigation.

Tumorigenesis exhibits complex interactions with the vascular system. Targeting angiogenesis represents an emerging strategy for remodeling the tumor microenvironment. The Notch signaling pathway, a key regulatory mechanism, orchestrates tumor angiogenesis by modulating endothelial cell differentiation and vascular homeostasis. However, the clinical translation of Notch-targeted therapies is limited by severe toxicities due to lack of tissue specificity. Posttranslational modifications (PTMs) chemically regulate protein functions, thereby influencing multiple signaling cascades including Notch signaling. Notably, Notch-associated PTMs are essential for signal transduction integrity. Some types in PTMs, such as glycosylation and ubiquitination, are the core for maintaining the integrity of the Notch signaling pathway. Dysfunctional Notch-related PTMs disrupt signal fidelity and drive pathological angiogenesis. This review systematically explores: (i) crosstalk between Notch signaling and tumor angiogenesis, (ii) regulatory roles of PTMs on Notch molecules in tumor angiogenesis, and (iii) therapeutic potential of targeting Notch-related PTMs for anti-angiogenic strategies in tumor. We aim to elucidate the molecular nexus of PTMs-Notch-angiogenesis in tumor progression. Furthermore, we discuss therapeutic challenges in modulating Notch signaling pathway-dependent PTMs within tumor angiogenesis, focusing on critical barriers to their clinical translation in oncology.

Metabolic adaptability, controlled by transcription factors or oncogenes, is critical for the survival of cancer cells. However, the mechanism by which the transcription factor forkhead box protein O1 (FOXO1) regulates the proliferation and survival of malignant tumor cells under high levels of reactive oxygen species (ROS) remains poorly understood. Here, we found that FOXO1 endows cancer cells with the strong antioxidative capacity and rapid proliferation. By upregulating the expression of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway, FOXO1 promotes the synthesis of nicotinamide adenine dinucleotide phosphate and ribose 5-phosphate and thus enhances the antioxidative and proliferative capabilities of cancer cells. Induction of G6PD expression in FOXO1-deficient cells mitigates tumor growth inhibition and alleviates ROS level elevation. These results establish a critical role of FOXO1 in the regulation of G6PD during the antioxidative and proliferative processes of cancer cells.

Amyloid precursor protein (APP), a type I transmembrane protein, is closely related to the pathogenesis of Alzheimer’s disease (AD). Amyloid beta (Aβ) is generated by sequential processing of APP in the Golgi apparatus and endosomes, and its toxicity leads to neuron dysfunction and neurodegeneration. APP is selectively shuttled between intracellular membrane compartments and ultimately transported into lysosomes. However, the mechanisms underlying APP sorting signals and lysosomal degradation are largely unclear. In this study, we show that the von Hippel‒Lindau (VHL) protein, a subunit of an E3 ligase, recognizes the cytoplasmic domain of APP and mediates its ubiquitination. VHL-mediated ubiquitination facilitates the sorting of membrane APP into intraluminal vesicles of multivesicular bodies (MVBs) and subsequent degradation in lysosomes. Therefore, the loss of VHL accelerates Aβ plaque deposition and memory deficits in AD model mice. Our findings reveal the role of VHL in restricting AD pathogenesis through ubiquitination-dependent MVB sorting and lysosomal degradation of APP.

The development and homeostasis of intestinal epithelium are mediated by actively proliferating Lgr5+ stem cells, which possess a remarkable self-renewal and differentiation capacity. Recently, our study demonstrated that N6-methyladenosine (m6A) methylation was essential for the survival of colonic stem cells. Here, we show that methyltransferase-like 3 (METTL3) expression is downregulated in the colon mucosa in ulcerative colitis (UC) patients and strongly associated with the differentiation and maturation of goblet cells during inflammation. In mice, depletion of Mettl3 significantly inhibits the self-renewal and differentiation of Lgr5+ stem cells, especially the differentiation and maturation of goblet cells, resulting in intestinal dysplasia and spontaneous inflammation. Mechanistically, Mettl3 deletion-mediated m6A loss facilitates the expression levels of growth factor receptor binding protein 10 (Grb10) and interferon-related developmental regulator 1 (Ifrd1) via increasing their messenger RNA stability. We further demonstrate that the levels of GRB10 and IFRD1 are negatively correlated with METTL3 level in UC samples. Collectively, our data indicate that METTL3 enhances the self-renewal and differentiation of Lgr5+ stem cells during intestinal development and inflammation, and thus it may be a potential therapeutic target for UC treatment.

Cohesin is a ring complex closed with structural maintenance of chromosome 1 (SMC-1), SMC-3, and a kleisin subunit, mediating sister chromatid cohesion in mitosis and meiosis. Kleisin N- and C-terminal domains interact with SMC-3 and SMC-1, forming two distinct cohesin gates. Whether these gates are specialized for mitosis and meiosis remains elusive. Here, we create Caenorhabditis elegans mutants that express chimeric proteins swapping N- and C-terminal domains between different kleisins to investigate how these gates are specialized for different cell division programs. Replacing the meiotic REC-8N-terminus with that of a cell division-unrelated kleisin COH-1 or the mitotic kleisin sister chromatid cohesion protein 1 (SCC-1) disrupts inter-sister chromatid cohesion and causes severe meiotic defects. Swapping the REC-8 C-terminus with that of COH-1 or SCC-1 largely retains the meiotic functions of REC-8 but causes age-related chromosome abnormalities. A specialized C-terminus is also required for the functions of SCC-1. Furthermore, point mutations in the REC-8 C-terminus cause severe meiotic defects without impairing the SMC-1-kleisin interaction, suggesting an integrated SMC-1-kleisin gate. These findings suggest the requirements for specialized cohesin gates in different biological processes.

Probing centromere-kinetochore core complex CENP-L/M assembly using cenpemlin Dear Editor, Chromosome segregation in eukaryotes relies on intricate interactions between spindle microtubules and centromeres (Liu et al., 2020 ).Recently, using cryo-electron microscopy (cryo-EM) alongside functional analyses, we and other groups unveiled the molecular basis of how human kinetochore constitutive centromere-associated network (CCAN) interacts with duplex DNA and facilitates accurate chromosome segregation

Alternative polyadenylation (APA) is an essential post-transcriptional process that produces mature mRNA isoforms by regulating the usage of polyadenylation sites (PASs). APA is involved in lymphocyte activation; however, its role throughout the entire differentiation trajectory remains elusive. Here, we analyzed single-cell 3'-end transcriptome data from healthy subjects to construct a dynamic-APA landscape from hematopoietic stem and progenitor cells (HSPCs) to terminally differentiated lymphocytes. This analysis covered 19973 cells of 12 clusters from five lineages (B cells, CD4+ T cells, CD8+ T cells, natural killer cells, and plasmacytoid dendritic cells). A total of 2364 genes exhibited differential 3'-untranslated region (3'UTR) PAS usage, and 3021 genes displayed differential intronic cleavage during lymphoid differentiation. We observed a global trend of 3'UTR shortening during lymphoid differentiation. Nevertheless, specific events of both 3'UTR shortening and lengthening were also identified within each cluster. The APA patterns delineated three differentiation stages: HSPCs, precursor cells, and mature cells. Moreover, we demonstrated that the conversion of naïve T cells to memory T cells was accompanied by dynamic APA in transcription factor-encoding genes (TCF7 and NFATC2IP), immune function-related genes (BCL2, CD5, CD28, GOLT1B, and TMEM59), and protein ubiquitination-related genes (UBE2G1, YPEL5, and SUMO3). These findings expand our understanding of the underlying molecular mechanisms of APA and facilitate studies on the regulatory role of APA in lymphoid hematopoiesis.