Biology subjects

Kono, K.

Publications and source records attributed to Kono, K..

7 recordsLinked to original sources

bioRxiv2026

Constitutive macropinocytosis sustains the inflammatory phenotype of senescent cells

SummarySenescent cells upregulate constitutive macropinocytosis that is required for inflammatory SASP production through PAK1 and TGF{beta} signaling, revealing a novel role for macropinocytosis in the senescence associated secretory phenotype. Cellular senescence is a stable cell cycle arrest characterized by extensive metabolic remodeling and a proinflammatory secretome known as senescence-associated secretory phenotype (SASP). While transient SASP supports tissue repair and wound healing, its persistent activation drives chronic inflammation and age-related pathology. Despite the complex regulation of SASP, the contribution of vesicle trafficking and endocytic pathways to its control remains poorly defined. Here, we identify macropinocytosis as a constitutively active endocytic pathway in multiple cell lines and senescence subtypes. Using pharmacological and genetic perturbations, we demonstrate that PAK1 is a key regulator of macropinocytosis in senescent cells. Moreover, PAK1-dependent macropinocytosis regulates production of inflammatory SASP factors, such as IL6 and CCL2, through TGF{beta} signaling. Our findings define senescence-associated macropinocytosis as a mechanistic link between endocytosis and the proinflammatory phenotype of senescent cells, establishing PAK1 and macropinocytosis as potential therapeutic targets for alleviating the deleterious effects of senescence in aging and cancer.

cell biology↗

bioRxiv2024

Comprehensive identification of plasma membrane repair proteins revealed spatiotemporal cellular responses to plasma membrane damage

Damage to the plasma membrane (PM) is common in all types of cells. PM repair processes, including exocytosis and endocytosis, are not mutually exclusive; rather, they collaborate to repair the wound. However, the temporal coordination between the repair processes remains poorly understood. Here, by large-scale identification and live-cell imaging of PM repair proteins, we analyzed the spatiotemporal PM damage responses in Saccharomyces cerevisiae. Of the 80 repair proteins identified, 72 proteins were previously unreported repair protein candidates. Among the observed repair processes, the polarized exocytosis and clathrin-mediated endocytosis (CME) are coupled at the damage site, with exocytosis predominating in the early stage of PM repair and CME predominating in the late stage of PM repair. Furthermore, we showed that CME at the growing bud site directs PM repair proteins with transmembrane domains to the damage site. We propose a model in which CME delivers repair proteins with transmembrane domains between the growing bud site and the damage site. This study provides a functional catalog of PM repair proteins and insights into spatiotemporal cellular responses to PM damage.

cell biology↗

bioRxiv2023

Time-deterministic cryo-optical microscopy

We developed a technique to rapidly freeze biological systems during observation under an optical microscope, which allows for detailed optical observation at a precise time in the biological dynamics at high spatial resolution and quantifiability under low-temperature conditions. Our study further found that ion distributions and molecular conformations can be fixed in space and time, demonstrated by visualization of calcium waves rapid-frozen at an instant using fluorescent ion indicators. These results show that time-deterministic cryo-optical microscopy can suspend cellular dynamics while maintaining molecular and ionic states, allowing us to view cellular dynamics in a way that has not been possible before. One-Sentence SummaryRapid freezing of dynamic biological systems during optical observation presents time information to the fixed samples

biophysics↗

bioRxiv2022

Time-resolved transcriptomic profiling of senescence-associated secretory phenotype (SASP) in multiple senescent cell subtypes

Cellular senescence, irreversible cell cycle arrest, is induced by various triggers including telomere shortening, oncogene activation, and DNA damage. Senescent cells exhibit the senescence-associated secretory phenotype (SASP), a pathological feature that contributes to organismal aging. We previously showed that transient plasma membrane damage (PMD) induces a novel subtype of cellular senescence (PMDS) accompanied by SASP, but the overall expression profiles of SASP during PMDS induction was unknown. Here, using mRNA-seq, qPCR, and bioinformatics, we revealed the time-resolved SASP transcriptomic profile in PMDS in comparison with calcium influx-induced senescence, DNA damage response-induced senescence, and replicative senescence. Although the expression of SASP factors was postulated to increase steadily during senescence, we counterintuitively found that the variety of SASP peaks in early PMDS. The pathway comparison analyses and Ingenuity Pathway Analysis suggest that, in early PMDS, wound-healing SASP factors, namely Il-6, Mmp1, and Mmp3, inhibit the GPVI collagen signaling pathway, which in turn further upregulates the same SASP factors, forming a feedback loop. At late senescence, common SASP factors including Il-6 and Ccl2 are upregulated in all senescent cell subtypes. Thus, SASP is diverse at early senescence and becomes relatively uniform at late senescence. Diverse SASP may contribute to senescent cell subtype-specific paracrine/autocrine functions in vivo.

bioinformatics↗

bioRxiv2021

Nuclear activation in dual-durotaxing cells on a matrix with cell-scale stiffness-heterogeneity

Living organisms are typically composed of various tissues with microscopic cell-scale stiffness-heterogeneity, in which some cells receive dynamically fluctuating mechanical stimuli from the heterogeneous extracellular milieu during long-term movement. Although intracellular stress dynamics (ISD), which are closely related to the regulation of cell functions such as proliferation and differentiation, can be characteristically modulated in cells migrating on a matrix with stiffness-heterogeneity, it has been unclear how the mode of fluctuation of ISD affects cell functions. In the present study, we demonstrate that mesenchymal stem cells (MSCs) dual-durotaxing (i.e., both forward and reverse durotaxis) on microelastically-patterned gels with stiff triangular domains markedly amplify the fluctuation of ISD, nuclear shape, and the spatial distribution of chromatins, which makes the cells remain far from tensional equilibrium. We provide evidence that amplified chromatin fluctuation in the dual-durotaxing MSCs can cause activation of cellular vigor and maintenance of the stemness.

biophysics↗

bioRxiv2021

Plasma membrane damage limits replicative lifespan in yeast and human fibroblasts

Plasma membrane damage (PMD) occurs in all cell types due to environmental perturbation and cell-autonomous activities. However, cellular outcomes of PMD remain largely unknown except for recovery or death. Here, using budding yeast and normal human fibroblasts, we show that cellular senescence, irreversible cell cycle arrest contributing to organismal aging, is the long-term outcome of PMD. To identify the genes essential for PMD response, we developed a simple PMD-damaging assay using a detergent and performed a systematic yeast genome-wide screen. The screen identified 48 genes. The top hits in the screen are the endosomal sorting complexes required for transport (ESCRT) genes, encoding the well-described plasma membrane repair proteins in eukaryotes. Unexpectedly, the replicative lifespan regulator genes are enriched in our 48 hits. This finding suggests a close genetic association between the PMD response and the replicative lifespan regulations. Indeed, we show that PMD limits the replicative lifespan in budding yeast; the ESCRT activator AAA-ATPase VPS4-overexpression extends it. These results suggest that PMD limits replicative lifespan in budding yeast. Moreover, in normal human fibroblasts, we find that PMD induces premature senescence via the Ca2+-p53 axis but not the major senescence pathway, ATM/ATR pathway. Consistent with the results in yeast, transient overexpression of ESCRT-III, CHMP4B, suppressed the PMD-dependent senescence in normal human fibroblasts. Our study proposes that PMD limits cellular lifespan in two different eukaryotic cell types and highlights an underappreciated but ubiquitous senescent cell subtype, namely PMD-dependent senescent cells.

cell biology↗

bioRxiv2019

Reconstruction of Par polarity in apolar cells reveals a dynamic process of cortical polarization

Cellular polarization is fundamental for various biological processes. The Par network system is conserved for cellular polarization. Its core complex consists of Par3, Par6, and aPKC. However, the dynamic processes that occur during polarization are not well understood. Here, we artificially reconstructed Par-dependent polarity using non-polarized Drosophila S2 cells expressing all three components endogenously in the cytoplasm. The results indicated that elevated Par3 expression induces cortical localization of the Par-complex at the interphase. Its asymmetric distribution goes through three steps: emergence of cortical dots, development of island-like structures with dynamic amorphous shapes, repeating fusion and fission, and polarized clustering of the islands. Our findings also showed that these islands contain a meshwork of unit-like segments. Par-complex patches resembling Par-islands exist in Drosophila mitotic neuroblasts. Thus, this reconstruction system provides an experimental paradigm to study features of the assembly process and structure of Par-dependent cell-autonomous polarity.

cell biology↗