Cell reports最新文献

During cell division, faithful chromosome segregation is ensured by the mitotic spindle. van Toorn et al.¹ uncovered that Cdk1-mediated phosphorylation of the dynein-activating adaptor NuMA promotes the timely assembly of dynein/dynactin/NuMA complexes, essential for correct mitotic progression and genome integrity.

The epitope that monoclonal CR3022 binds to represents a promising target for broad protection against a wide range of human and zoonotic coronaviruses. We develop a powerful model to evaluate antibody affinity maturation in vivo using immunoglobulin (Ig)-humanized mice that express the predicted germline heavy chain of antibody CR3022. Severe acute respiratory syndrome coronavirus (SARS-CoV)/SARS-CoV-2 sequential immunization leads to the convergent evolution of the germline CR3022 through somatic hypermutation (SHM), resembling the affinity-matured CR3022 from a human but now also adapting to key variants and divergent sarbecoviruses. While simple prime-boost strategies drive CR3022-epitope targeting, an intensive vaccination protocol elicits dominant responses to other epitopes. X-ray crystal structures reveal that SARS-CoV-2-neutralizing CR3022-like antibodies exhibit enhanced affinity by increasing polar and electrostatic interactions. Overall, these findings show that CR3022-like clones can be readily adapted through SHM to increase breadth and potency to sarbecoviruses by relatively minor shifts in affinity with appropriate vaccination strategies.

The circadian and immune systems are important for tissue homeostasis, yet their integration in the brain remains understudied. The olfactory bulb, a brain region that exhibits robust circadian rhythms and is regularly exposed to inflammatory stimuli, provides an optimal locus to probe the interaction of these two systems. We find that the murine olfactory bulb rhythmically expresses immune-related transcripts, with antiviral transcripts peaking around dusk. This is accompanied by distinct transcriptional responses to intranasal poly(I:C) (a virus-like immune stimulus) at dusk versus dawn, suggesting that time of day primes the olfactory bulb's response to inflammatory challenges. Using imaging and spectral flow cytometry, we detect and characterize distinct subpopulations of microglia, the resident macrophages of the brain, which differentially respond to intranasal poly(I:C) depending on time of day. This unveils a clear relationship between time of day and olfactory bulb immune processes, suggesting time is an important dimension to consider when studying the olfactory pathway into the brain.

Mapping hippocampal connectivity is essential to understand the neural mechanisms of learning and memory, yet interhemispheric connections between hippocampal formations remain poorly defined. In rodents, two main commissural pathways are known: dentate gyrus hilar mossy cells project to the inner molecular layer of the contralateral dentate gyrus, and CA2/CA3 pyramidal neurons send collaterals to contralateral CA3, CA2, and CA1 regions. By contrast, commissural outputs from CA1 remain largely unexplored. Here, we show that dorsal CA1 (dCA1) pyramidal neurons located in the right hemisphere project to contralateral dorsal subiculum (dSUB) in addition to contralateral dCA1. We then assess the function of the projection from the right dCA1 to the left dSUB and find that this interhemispheric pathway supports spatial memory and spatial working memory, two cognitive functions altered in the Df16(A)^+/- mouse model of 22q11.2 deletion syndrome (22q11.2DS) associated with schizophrenia. Notably, the right-to-left dCA1 interhemispheric projections are disrupted in Df16(A)^+/- mice, suggesting that dysregulation of this circuit may contribute to 22q11.2DS-related cognitive deficits.

Ubiquitination plays a crucial role in the tumor necrosis factor (TNF)-α signaling pathway. To identify mechanisms by which ubiquitination regulates TNF-α signaling, we perform a screen using a gene expression library of ubiquitination-modifying enzymes. We find that the deubiquitinating enzyme MINDY2 inhibits TNF-α-induced cell death. MINDY2 modulates ubiquitination at the K612 site of RIPK1, which in turn attenuates RIPK1 recruitment by TNFR1, thereby influencing the complex 1 signaling pathway and RIPK1-dependent cell death. To investigate the in vivo function of MINDY2, we generate MINDY2-knockout mice. Compared to wild-type mice, MINDY2-deficient mice exhibit more severe hypothermia, mortality, and intestinal damage after TNF-α challenge. Collectively, our work reveals that MINDY2 is a checkpoint in RIPK1-dependent cell death, and that its deficiency exacerbates TNF-mediated tissue damage in vivo.

Keloids are pathological scars caused by dysregulated wound healing, characterized by fibroblast hyperproliferation and excessive extracellular matrix deposition. Natural killer (NK) cells restrain aberrant cell growth through IFN-γ but also produce amphiregulin (AREG), which promotes tissue repair and cell survival. The role of NK cells in keloid pathogenesis remains unclear. Here, we identify functional alterations in NK cells in lesional skin and peripheral blood from people with keloids. In lesions, NK cell-derived IFN-γ limits fibroblast survival and matrix production, whereas NK cell-derived AREG counteracts these effects. Fibroblast-derived TGF-β further suppresses NK cell IFN-γ production, forming a local immunoregulatory loop. Systemically, people with keloids exhibit increased plasma IFN-β, which induces a distinct circulating NK cell subset with elevated IFN-stimulated genes and reduced IFN-γ production. Elevated IFN-β suppresses PI3K-AKT signaling and promotes NK cell exhaustion through mitochondrial and metabolic dysfunction, linking local and systemic NK cell dysregulation in keloids.

Necroptotic cell death triggers the release of inflammatory mediators but the exact mechanisms controlling its activation are not fully understood. Previous studies have identified key steps during necroptosis, which are believed to be coupled: MLKL phosphorylation by RIPK3, release of N-terminal autoinhibition, and MLKL oligomerization. Yet, ectopic expression of phosphomimetic MLKL is insufficient to induce necroptosis in human cells. Here, we employ five different pharmacological, biological, and genetic methods to demonstrate that inhibiting the MLKL N terminus prevents both phosphorylation and oligomerization. Conversely, loss of interaction between the N-terminal four-helical bundle and brace domains demonstrates basal MLKL phosphorylation, even in the absence of necroptotic stimuli. Moreover, we show that MLKL phosphorylation is not necessary for maintaining MLKL oligomer stability. We propose that MLKL is released from autoinhibition prior to phosphorylation, explaining why phosphomimetic MLKL lacks cytotoxic activity.

Rapid recall is the hallmark of memory T cells. While naive cells require days to mount effector responses to new threats, antigen-experienced memory cells produce cytokines within hours of a repeat encounter. Compared to naive cells, memory cells exhibit enhanced chromatin accessibility proximal to rapid-recall genes, but the transcription factors (TFs) that establish, maintain, and utilize these putative regulatory elements are unknown. We leverage single-nuclei multiome sequencing (gene expression and chromatin accessibility) to characterize the dynamic activation responses of CD4⁺ T cells and reconstruct the underlying gene regulatory networks. Memory-associated TFs (MAF, PRDM1, RUNX2, SMAD3, and KLF6) are predicted to orchestrate rapid recall. KLF6 binding to its predicted target genes is confirmed by chromatin immunoprecipitation sequencing, while the memory-associated activities of all five factors replicate in independent single-cell RNA sequencing studies. Integrating genome-wide association study data, we nominate CD4⁺ T cell populations and gene regulatory mechanisms that might underlie genetic risk to immune-mediated diseases.

The α3β4 nicotinic acetylcholine receptor (nAChR) is a heteropentameric ligand-gated channel whose distribution includes reward circuits of the brain, where it regulates expression of drug withdrawal symptoms. α3β4 nAChRs form two stoichiometries in the absence of other subunits, containing orthosteric binding sites between the primary α3 and the adjacent β4 subunit. The identity of the fifth (accessory) subunit is different between the two stoichiometries, but it is unknown whether this structural nuance yields any biophysical differences. To investigate this, we constrained receptor stoichiometry by engineering an α3β4 tandem dimer and co-expressing it in HEK293T cells with a select fifth subunit. We then used substituted-cysteine accessibility to covalently modify the primary and accessory binding sites. This approach revealed a functional "accessory orthosteric" site at the α3-α3 interface of (α3)₃(β4)₂ nAChRs. Understanding the stoichiometric differences in α3β4 nAChRs will inform future therapeutic strategies to target nicotine withdrawal.

Activating mutations in BRAF are common in cutaneous melanoma, yet mutational inactivation of the tumor suppressor TP53 is relatively rare despite widespread attenuation of TP53 function, suggesting alternate mechanisms of TP53 inhibition. Using proximity-dependent proteomic mapping, we define a BRAF^V600E-specific interactome and identify a selective interaction between oncogenic BRAF and TP53. We demonstrate that BRAF^V600E engages the DNA-binding domain of TP53, drives its localization from the nucleus to the cytoplasm, and suppresses TP53 activity. This functional inhibition persists following DNA damage or pharmacologic disruption of TP53 pathways, demonstrating that oncogenic BRAF constrains TP53 activity. These findings establish a protein interaction through which BRAF^V600E functionally inactivates TP53 and reveal a mechanism by which melanoma bypasses TP53-mediated tumor suppression without requiring genetic alteration.