
仮足の分裂競争は、細胞の方向決定メカニズムにおいて重要な役割を果たし、浅い化学勾配下での高精度な走化性を可能にする。


coremsg

化学勾配に対する持続的な仮足分裂は-浅い勾配での効果的な走化性戦略である


化学勾配に対する持続的な仮足分裂は、浅い勾配での効果的な走化性戦略である


title_rewrite


繊毛根は細胞内の膜構造と柔軟に連結しており、その構造的特徴が繊毛の感覚機能と運動機能を支えていることが明らかになった。


Ciliary rootlets are striated bundles of filaments that connect the base of cilia to internal cellular structures. Rootlets are critical for the sensory and motile functions of cilia. However, the mechanisms underlying these functions remain unknown, in part due to a lack of structural information of rootlet organization. In this study, we obtain 3D reconstructions of membrane-associated and purified rootlets using cryo-electron tomography (cryo-ET). We show that flexible protrusions on the rootlet surface, which emanate from the cross-striations, connect to intracellular membranes. In purified rootlets, the striations were classified into amorphous (A)-bands, associated with accumulations on the rootlet surface, and discrete (D)-bands corresponding to punctate lines of density that run through the rootlet. These striations connect a flexible network of longitudinal filaments. Subtomogram averaging suggests the filaments consist of two intertwined coiled coils. The rootlet’s filamentous architecture, with frequent membrane-connecting cross-striations, lends itself well for anchoring large membranes in the cell.

### Competing Interest Statement

The authors have declared no competing interest.

A cryo-ET study of ciliary rootlet organization

光学顕微鏡を用いた繊毛根の組織構造の解析


セプチンは外分泌複合体の細胞膜への局在化を制御し、適切な分泌小胞の標的化と融合を可能にする。


Septins can function as scaffolds for protein recruitment, membrane-bound diffusion barriers, or membrane curvature sensors. Septins are important for cytokinesis, but their exact roles are still obscure. In fission yeast, four septins (Spn1 to Spn4) accumulate at the rim of the division plane as rings. The octameric exocyst complex, which tethers exocytic vesicles to the plasma membrane, exhibits a similar localization and is essential for plasma membrane deposition during cytokinesis. Without septins, the exocyst spreads across the division plane but absent from the rim during septum formation. These results suggest that septins and the exocyst physically interact for proper localization. Indeed, we predicted six pairs of direct interactions between septin and exocyst subunits by AlphaFold2 ColabFold, most of them are confirmed by co-immunoprecipitation and yeast two-hybrid assays. Exocyst mislocalization results in mistargeting of secretory vesicles and their cargos, which leads to cell-separation delay in septin mutants. Our results indicate that septins guide the targeting of exocyst complex on the plasma membrane for vesicle tethering during cytokinesis through direct physical interactions.

### Competing Interest Statement

The authors have declared no competing interest.

*   Co-IP
    :   Co-immunoprecipitation
    EMCCD
    :   Electron-multiplying charge-coupled device
    FPS
    :   Frame per second
    FRAP
    :   Fluorescence recovery after photobleaching
    NA
    :   Numerical aperture
    PB
    :   Phloxin B
    pLDDT
    :   Predicted Local-Distance Difference Test
    ROI
    :   Region of interest
    SPB
    :   Spindle pole body
    TIRF
    :   Total internal reflection fluorescence
    TRAPP-II
    :   Transport particle protein-II
    WT
    :   Wild type

Septins function in exocytosis via physical interactions with the exocyst complex in fission yeast cytokinesis

細胞分裂時のエキソサイトにおける細胞分裂装置タンパク質セプチンと外分泌複合体の物理的相互作用


Sox9は角膜幹細胞を示す遺伝子であり、その発現の減少が角膜上皮の非対称な細胞運命の切り替えに必要不可欠である。


Adult tissues with high cellular turnover require a balance between stem cell renewal and differentiation, yet the mechanisms underlying this equilibrium are unclear. The cornea exhibits a polarized lateral flow of progenitors from the peripheral stem cell niche to the center; attributed to differences in cellular fate. To identify genes that are critical for regulating the asymmetric fates of limbal stem cells and their transient amplified progeny in the central cornea, we utilized an in vivo cell cycle reporter to isolate proliferating basal cells across the anterior ocular surface epithelium and performed single-cell transcriptional analysis. This strategy greatly increased the resolution and revealed distinct basal cell identities with unique expression profiles of structural genes and transcription factors. We focused on Sox9; a transcription factor implicated in stem cell regulation across various organs. Sox9 was found to be differentially expressed between limbal stem cells and their progeny in the central corneal. Lineage tracing analysis confirmed that Sox9 marks long-lived limbal stem cells and conditional deletion led to abnormal differentiation and squamous metaplasia in the central cornea. These data suggest a requirement for Sox9 for the switch to asymmetric fate and commitment toward differentiation, as transient cells exit the limbal niche. By inhibiting terminal differentiation of corneal progenitors and forcing them into perpetual symmetric divisions, we replicated the Sox9 loss-of-function phenotype. Our findings reveal an essential role for Sox9 for the spatial regulation of asymmetric fate in the corneal epithelium that is required to sustain tissue homeostasis.

### Competing Interest Statement

The authors have declared no competing interest.

Sox9 marks limbal stem cells and is required for asymmetric cell fate switch in the corneal epithelium

角膜上皮の非対称な細胞運命の切り替えに必要なsox9は-角膜幹細胞を示す


角膜上皮の非対称な細胞運命の切り替えに必要なSox9は、角膜幹細胞を示す



サイクリンD1の過剰発現とp27Kip1のノックダウンを同時に行うことで、ミュラー膠細胞の細胞周期再活性化が強力に促進され、網膜再生につながる可能性がある。


Harnessing the regenerative potential of endogenous stem cells to restore lost neurons is a promising strategy for treating neurodegenerative disorders. Müller glia (MG), the primary glial cell type in the retina, exhibit remarkable regenerative abilities in lower vertebrate species, such as zebrafish and amphibians, where injury induces MG to proliferate and differentiate into various retinal neuron types. The regenerative potential of mammalian MG is constrained by their inherent inability to re-enter the cell cycle, likely due to high levels of the cell cycle inhibitor p27Kip1 and low levels of cyclin D1 observed in adult mouse MG. In this study, we found that adeno-associated virus (AAV)-mediated cyclin D1 overexpression and p27Kip1 knockdown exerts a strong synergistic effect on MG proliferation. MG proliferation induced by this treatment was potent but self-limiting, as MG did not undergo uncontrolled proliferation or lead to retinal neoplasia. Single-cell RNA sequencing (scRNA-seq) revealed that cell cycle reactivation leads to immunosuppression and dedifferentiation of MG. Notably, scRNA-seq analysis identified a new cluster of rod-like MG cells expressing both rod and MG genes, which was further validated by RNA in situ hybridization. Cell cycle reactivation also led to de novo genesis of bipolar- and amacrine-like cells from MG. Overall, our findings suggest that AAV- mediated cyclin D1 overexpression and p27Kip1 knockdown stimulate MG proliferation and promote MG reprogramming. This approach may be a promising strategy, especially when combined with other regeneration-promoting factors, to enhance MG-mediated retinal repair.

### Competing Interest Statement

The authors have declared no competing interest.

Müller glia cell cycle re-activation by simultaneous cyclin D1 overexpression and p27kip1 knockdown promotes retinal regeneration in mice

成体マウスの網膜再生を促進するためのミュラー膠細胞の細胞周期再活性化


単一細胞は自律的なタイミング機構を持ち、分節時計の振動の減速と停止を引き起こし、組織レベルの波パターンを生み出す。


Rhythmic and sequential segmentation of the growing vertebrate body relies on the segmentation clock, a multi-cellular oscillating genetic network. The clock is visible as tissue-level kinematic waves of gene expression that travel through the pre-somitic mesoderm (PSM) and arrest at the position of each forming segment. Here we test how this hallmark wave pattern is driven by culturing single maturing PSM cells. We compare their cell-autonomous oscillatory and arrest dynamics to those we observe in the embryo at cellular resolution, finding similarity in the relative slowing of oscillations and arrest in concert with differentiation. This shows that cell-extrinsic signals are not required by the cells to instruct the developmental program underlying the wave pattern. We show that a cell-autonomous timing activity initiates during cell exit from the tailbud, then runs down in the anterior-ward cell flow in the PSM, thereby using elapsed time to provide positional information to the clock. Exogenous FGF lengthens the duration of the cell-intrinsic timer, indicating extrinsic factors in the embryo may regulate the segmentation clock via the timer. In sum, our work suggests that a noisy cell-autonomous, intrinsic timer drives the slowing and arrest of oscillations underlying the wave pattern, while extrinsic factors in the embryo tune this timer’s duration and precision. This is a new insight into the balance of cell-intrinsic and -extrinsic mechanisms driving tissue patterning in development.

### Competing Interest Statement

Competing Interests: PS is a co-founder of Viventis Microscopy.

Cell-autonomous timing drives the vertebrate segmentation clock’s wave pattern

単一細胞における脊椎動物分節時計の波パターンの自律的な生成


CAR T細胞の初期増殖と長期持続性は治療効果を予測するが、エフェクター細胞とメモリー細胞への分化メカニズムは不明であった。本研究では、標的抗原との相互作用によって引き起こされる非対称細胞分裂が、CAR T細胞の運命決定に重要な役割を果たすことを明らかにした。


We show that target-induced proximity labelling enables isolation of first-division CD8 chimeric antigen receptor T cells that asymmetrically distribute their surface proteome and transcriptome, resulting in distinct phenotypic, metabolic&nbsp;and functional profiles&nbsp;in proximal and distal&nbsp;daughter cells.

Fate induction in CD8 CAR T cells through asymmetric cell division - Nature

cd8-car-t細胞の運命決定における非対称細胞分裂の役割


CD8 CAR T細胞の運命決定における非対称細胞分裂の役割



PP2A-B56リン酸化酵素は、Mid1タンパク質のレベルを調整することで、分裂酵母の適切な細胞分裂を促進する。


Protein phosphorylation regulates many steps in the cell division process including cytokinesis. In the fission yeast S. pombe , the anillin-like protein Mid1 sets the cell division plane and is regulated by phosphorylation. Multiple protein kinases act on Mid1, but no protein phosphatases have been shown to regulate Mid1. Here, we discovered that the conserved protein phosphatase PP2A-B56 is required for proper cytokinesis by promoting Mid1 protein levels. We find that par1 Δ cells lacking the primary B56 subunit divide asymmetrically due to the assembly of misplaced cytokinetic rings that slide toward cell tips. These par1 Δ mutants have reduced whole-cell levels of Mid1 protein, leading to reduced Mid1 at the cytokinetic ring. Restoring proper Mid1 expression suppresses par1 Δ cytokinesis defects. This work identifies a new PP2A-B56 pathway regulating cytokinesis through Mid1, with implications for control of cytokinesis in other organisms.

### Competing Interest Statement

The authors have declared no competing interest.

PP2A-B56 regulates Mid1 protein levels for proper cytokinesis in fission yeast

pp2a-b56リン酸化酵素がmid1タンパク質レベルを調整することで-分裂酵母の適切な細胞分裂を制御する


PP2A-B56リン酸化酵素がMid1タンパク質レベルを調整することで、分裂酵母の適切な細胞分裂を制御する



IL-6シグナリングは、腱の修復性線維芽細胞の活性化と損傷部位への移動を促進し、腱疾患の特徴を悪化させる。


Tendinopathies are debilitating diseases currently increasing in prevalence and associated costs. There is a need to deepen our understanding of the underlying cell signaling pathways to unlock effective treatments. In this work, we screen cell signaling pathways in human tendinopathies and find positively enriched IL-6/JAK/STAT signaling alongside signatures of cell populations typically activated by IL-6 in other tissues. In human tendinopathic tendons, we also confirm the strong presence and co-localization of IL-6, IL6R, and CD90, an established marker of reparative fibroblasts. To dissect the underlying causalities, we combine IL-6 knock-out mice with an explant-based assembloid model of tendon damage to successfully connect IL-6 signaling to reparative fibroblast activation and recruitment. Vice versa, we show that these reparative fibroblasts promote the development of tendinopathy hallmarks in the damaged explant upon IL-6 activation. We conclude that IL-6 activates tendon fibroblast populations which then initiate and deteriorate tendinopathy hallmarks.

### Competing Interest Statement

The authors have declared no competing interest.

IL-6 SIGNALING EXACERBATES HALLMARKS OF CHRONIC TENDON DISEASE BY STIMULATING REPARATIVE FIBROBLASTS

慢性腱疾患の特徴を悪化させるil-6シグナリング-前駆細胞の増殖と損傷部位への移動を刺激する


慢性腱疾患の特徴を悪化させるIL-6シグナリング:前駆細胞の増殖と損傷部位への移動を刺激する



カンジダ・アルビカンス感染によりIRE1αが非典型的に活性化され、マクロファージの殺菌活性を促進する。


While the canonical function of IRE1α is to detect misfolded proteins and activate the unfolded protein response (UPR) to maintain cellular homeostasis, microbial pathogens can also activate IRE1α, which modulates innate immunity and infection outcomes. However, how infection activates IRE1α and its associated inflammatory functions have not been fully elucidated. Recognition of microbe-associated molecular patterns can activate IRE1α, but it is unclear whether this depends on protein misfolding. Here, we report that a common and deadly fungal pathogen, Candida albicans , activates macrophage IRE1α through C-type lectin receptor signaling, reinforcing a role for IRE1α as a central regulator of host responses to infection by a broad range of pathogens. This activation did not depend on protein misfolding in response to C. albicans infection. Moreover, lipopolysaccharide treatment was also able to activate IRE1α prior to protein misfolding, suggesting that pathogen-mediated activation of IRE1α occurs through non-canonical mechanisms. During C. albicans infection, we observed that IRE1α activity promotes phagolysosomal fusion that supports the fungicidal activity of macrophages. Consequently, macrophages lacking IRE1α activity displayed inefficient phagosome maturation, enabling C. albicans to lyse the phagosome, evade fungal killing, and drive aberrant inflammatory cytokine production. Mechanistically, we show that IRE1α activity supports phagosomal calcium flux after phagocytosis of C. albicans , which is crucial for phagosome maturation. Importantly, deletion of IRE1α activity decreased the fungicidal activity of phagocytes in vivo during systemic C. albicans infection. Together, these data provide mechanistic insight for the non-canonical activation of IRE1α during infection, and reveal central roles for IRE1α in macrophage antifungal responses.

### Competing Interest Statement

The authors have declared no competing interest.

Non-canonical activation of IRE1α during Candida albicans infection enhances macrophage fungicidal activity

カンジダ-アルビカンス感染時のire1αの非典型的な活性化が-マクロファージの殺菌活性を高める


カンジダ・アルビカンス感染時のIRE1αの非典型的な活性化が、マクロファージの殺菌活性を高める
