Mechanical forces play critical roles in tissue morphogenesis and homeostasis, yet how tissue mechanics are translated into epithelial cell delamination remains poorly understood. Here, we use the Drosophila pupal wing as an in vivo model to examine how release of tissue tension influences cell death and delamination. Surgical severing of the wing hinge or loss of dumpy (dpy) function alters the force distribution, promotes cell crowding, and thereby significantly increases epithelial cell delamination compared to wild-type controls. An RNAi analysis targeting mechanosensitive components identified Vinculin, an adherens junction-associated force adaptor, as a key suppressor of mechanically induced cell delamination. Both tissue tension release and Vinculin depletion reduced junctional Vinculin levels and elevated Notch transcriptional activity, while canonical Notch transcriptional activation remained undetectable within delaminating cells. In contrast, knockdown of the Notch ligand Delta suppressed cell death and delamination. These findings indicate that release of tissue tension causes changes in forces acting on cells and cell crowding, thereby altering Vinculin-dependent regulation of Delta-Notch signaling and promoting cell delamination through a non-canonical Notch pathway.Key words: cell delamination, mechanotransduction, Delta-Notch pathways.
Pancreatic acinar cells (PACs) are specialized for the production and secretion of digestive enzymes. PACs are highly polarized, with rough endoplasmic reticulum (ER) located in the basal and lateral regions, while zymogen granules (ZG) are localized apically. Furthermore, a distinct ER compartment containing inositol 1,4,5-trisphosphate receptors (IP3Rs), which are Ca2+ channels, is positioned underneath the filamentous-actin and tight junctions in the apical region. This structurally polarized architecture underlies the localized elevation of Ca2+ levels in the apical region, which supports the efficient secretion of granules. In this report, we show that Jaw1, a regulatory protein of IP3Rs, is a new component of the distinct ER compartment in PACs, colocalizing with IP3R2 and IP3R3 rather than IP3R1. Importantly, PACs from Jaw1-deficient mice exhibited an accumulation of ZG and cell hypertrophy without disrupting both the arrangement of the distinct ER compartment and the localization of IP3Rs. These findings shed more light on the underlying molecular components of the distinct ER compartment in the apical region of PACs, offering insights into their physiological functions in the homeostatic control of ZG abundance in PACs.Key words: Cell polarity, ER, IP3Rs, Jaw1, Pancreatic acinar cells.
Cell Structure and Function (CSF), the official journal of the Japan Society for Cell Biology (JSCB), celebrates its 50th anniversary in 2025. This essay traces the scientific evolution of CSF from its founding in 1975 to the present, drawing on bibliometric data retrieved from OpenAlex at ten-year intervals. Over five decades, CSF published 1,737 articles, with the Field-Weighted Citation Impact (FWCI) showing a consistent upward trend, even as total output declined following the journal’s shift to electronic publication in 2005. A decade-by-decade analysis of the five most-cited articles reveals a clear evolution in research themes: early issues were dominated by plant cell biology and methodological papers in microscopy and biochemistry, while subsequent decades saw increasing focus on autophagy, the unfolded protein response, and intracellular membrane trafficking—fields in which Japanese researchers have played globally recognized pioneering roles. The turn of the millennium marked a peak in absolute citations, with landmark papers on bafilomycin A1, SNARE proteins, and a review of autophagy co-authored by Nobel Prize laureate Yoshinori Ohsumi. Two major milestones—electronic publication in 2005 and gold open-access adoption in 2016—fundamentally transformed the journal’s publishing model. Looking ahead, the essay considers the role of artificial intelligence in peer review, arguing that while AI can assist in assessing novelty and reproducibility, the judgment of a manuscript’s scientific significance must remain a human responsibility. CSF remains committed to disseminating reliable, foundational cell biology to the international community. Key words: Cell Structure and Function (CSF), bibliometrics, open access, artificial intelligence in peer review
Cancer cells form clusters and invade the surrounding stroma. This phenomenon is associated with metastasis and poor prognosis in patients with cancer. Therefore, prevention of invasion may improve cancer therapy. A previous study suggested that the C-C motif chemokine ligand 5 (CCL5) is more highly expressed in the highly invasive subclone than in the less invasive subclone derived from A431 cell line, a model of human skin squamous cell carcinoma. However, the role of CCL5 and the mechanisms through which it regulates invasion in A431 cell clusters remain unclear. Herein, we investigated the molecular mechanisms underlying CCL5-induced invasion in A431 cell clusters. Knockdown of CCL5 suppressed invasion on A431 cell clusters, whereas treatment with recombinant CCL5 promoted invasion of them. Mechanistically, CCL5 increased the phosphorylation levels of Src and ERK, leading to the invasion of A431 cell clusters. Furthermore, the knockdown of syndecan-1 (SDC1), a transmembrane protein known to interact to CCL5, suppressed CCL5-induced invasion in A431 cell clusters. Consistently, knockdown of SDC1 reduced the level of phosphorylated ERK. These findings demonstrate that the CCL5 promotes the invasion of A431 cells clusters through SDC1-dependent ERK signaling and Src phosphorylation.Key words: invasion, CCL5, syndecan-1, ERK signaling, Src.
Macroautophagy is a highly conserved system that degrades various materials inside the cell ranging from proteins to organelles. Atg5 is a protein essential for the formation of autophagosomes, which sequester materials by double membrane and degrade them after fusion with lysosomes. MIN6 cells derived from mouse pancreatic β cells retain the ability to secrete insulin in response to a change in glucose concentration from low to high. We knocked out the Atg5 gene in MIN6 cells and identified an abnormality in the endoplasmic reticulum (ER) under normal culture conditions using electron microscopy. The ER was slightly enlarged and the ER membrane was ruptured at some places adjacent to inclusion body-like structures. Numerous granule-like structures were accumulated in the lumen of the ER, some of which appeared to have leaked into the cytoplasm. These abnormalities caused ER stress, resulting in activation of all three pathways (IRE1, PERK, and ATF6) of the unfolded protein response but no induction of apoptosis. We also observed the activation of alternative autophagy/Golgi membrane-associated degradation in Atg5-KO MIN6 cells, but this was insufficient for the removal of a majority of these granule-like structures from the ER. Thus, macroautophagy but not activation of the unfolded protein response or Golgi membrane-associated degradation is essential for the homeostasis of the ER in MIN6 cells.Key words: autophagy, endoplasmic reticulum, unfolded protein response, proinsulin, Golgi membrane-associated degradation.
Nuclear morphology alters during development and disease. Nuclear size and shape are regulated through several mechanisms. In this study, details of phenotypes of temperature-sensitive mutants, which were isolated from Chinese hamster CHO-K1 cells to identify genes responsible for the maintenance of chromosome integrity, were characterized with particular focus on changes in their nuclear size and shape. DNA replication has been implicated in a mutant exhibiting elongation of the nucleus with an increase in its ellipticity during incubation at the nonpermissive temperature of 39°C. Incubation at this temperature also resulted in nuclear enlargement in other mutants accompanied by increased DNA damage and led to a remarkable increase in cells harboring an abnormal nucleus, particularly multiple nuclei or segmented nuclei. These findings may lead to the discovery of a novel mechanism that regulates nuclear size and shape. Identification of genes responsible for these defects is highly desirable.Key words: 53BP1, γH2AX, mammalian, replication, temperature-sensitive mutant.
Tubular-shaped recycling endosomes, known as tubular endosomes, are present in certain types of cells, including HeLa cells, and they regulate the recycling of clathrin-independent endocytosed (CIE) cargo proteins to the plasma membrane. Several key regulators of tubular endosomes, including Rab small GTPases and related proteins, have been identified thus far, but the entire process of tubular endosome formation is not yet fully understood. We previously showed that expression of a Golgi-related Rab-GTPase-activating protein TBC1D22B in HeLa cells caused their tubular structures to disappear, suggesting a possible link between tubular endosome formation and a certain Golgi function(s). However, nothing is known about the target Rab(s) of TBC1D22B in tubular endosome formation or about the functional relationship between tubular endosomes and the Golgi apparatus. Here, we performed comprehensive Rab-knockdown screening in combination with dominant-negative Rab expression and succeeded in identifying 12 Rabs as regulators of tubular endosome formation. One of them, Rab30, a Golgi-resident Rab, is a novel target of TBC1D22B and involved in both tubular endosome formation and CIE cargo trafficking. We also showed that a Rab30-BICD2-KIF5B axis is likely to be involved in tubular endosome formation. Our findings suggest the importance of Rab30-mediated post-Golgi trafficking in tubular endosome formation.Key words: Golgi, GTPase-activating protein (GAP), Rab30, siRNA screening, tubular endosome.
Tumor endothelial cells (TECs) play a key role in tumor growth and metastasis. They exhibit distinct phenotypic and functional features compared with normal endothelial cells (NECs). Although microRNAs (miRNAs) play diverse roles in tumor progression, the differences in the miRNA expression profiles between TECs and NECs and their role in the TEC phenotype remain unclear.In this study, we isolated NECs and TECs from non-tumor and tumor regions of human renal cancer tissues and conducted an miRNA array analysis. Of the 13 differentially expressed miRNAs, miR-199a-3p was expressed the highest in TECs. Overexpression of miR-199a-3p in NECs significantly enhanced their proliferation, migration, and invasion.Target gene analysis using four databases identified CD151 as a potential target of miR-199a-3p. CD151 expression was downregulated in TECs compared with NECs, and miR-199a-3p transfection decreased CD151 expression in NECs. CD151 knockdown by siRNA promotes cell proliferation, migration, and invasion, and reduces cell adhesion to the extracellular matrix. Moreover, miR-199a-3p overexpression and CD151 silencing upregulated MMP2 expression in TECs. Taken together, these results suggest that miR-199a-3p contributes to the proangiogenic phenotype in TECs by suppressing CD151 expression.Key words: miR-199a-3p, tumor endothelial cells, CD151, angiogenesis, cell migration and invasion.
Mei-P26, a member of the TRIM-NHL family, plays a pivotal role in Drosophila germline development, including female meiosis. However, its role in male meiosis remains unclear. We observed abnormal spermatid cysts comprising 16 cells in mei-P26 mutant testes, which resulted from spermatid differentiation in the absence of meiosis. The same phenotype was observed in the cysts derived from spermatocytes subjected to mei-P26 knockdown. No cysts undergoing meiosis were observed, and cyclin-dependent kinase 1 (Cdk1) was not activated in the knockdown spermatocytes. However, these phenotypes are unlikely to result from altered phosphorylation of Cdk1, which is necessary for its activation. Instead, aberrant subcellular localization of Cyclin B (CycB) was observed. In wild-type, CycB first migrates into the nucleus of spermatocytes at earlier stages, is then exported from the nucleus, and re-enters the nucleus just before meiosis. By contrast, in mei-P26mfs1 spermatocytes and mei-P26 knockdown cells, CycB remained accumulated in the nucleus before meiosis. Another M-phase Cyclin, Cyclin A also showed nuclear accumulation in mei-P26 knockdown spermatocytes. Interactions between CycB and the nuclear export factors Emb and Nup62 remained unchanged. Although mammalian PLK1 modifies nuclear export signal of CycB in mitosis, a Drosophila orthologue, Polo, is unlikely to be involved in this meiotic phenotype. The loss of mei-P26 resulted in continuous activation of the meiotic checkpoint, which retains M-phase cyclins within the nucleus until multiple conditions necessary for meiosis are satisfied, thereby preventing Cdk1 from full activation. Our findings will be useful for understanding the role of Mei-P26 in other developmental processes.Key words: meiosis, spermatogenesis, Drosophila, mei-P26, checkpoint, cyclins, Cdk1.
Metastasis of cancer cells to the brain leads to a poor prognosis in patients with cancer. The brain environment is characterized by cell types, extracellular matrices (ECMs), and mechanical properties that differ from those of the primary tumors. A previous study using human melanoma cells (WM266.4 cells) and its highly brain-metastatic subline cells (WM266.4-BrM3 cells) revealed that WM266.4-BrM3 cells showed enhanced proliferation in brain tissues after cardiac injection in mice compared with WM266.4 cells. However, the effects of mechanical properties such as ECM stiffness on growth and gene expression in WM266.4-BrM3 cells remain to be clarified. In this study, we cultured these cells on ECMs of different stiffnesses. On a soft ECM, WM266.4-BrM3 cells showed significantly higher proliferation and lower expression of early growth response 1 (EGR1) and TP53 than WM266.4 cells. In contrast, on a stiff ECM, the proliferation and EGR1 expression of WM266.4 and WM266.4-BrM3 cells were not significantly different. Additionally, EGR1 knockdown by siRNA transfection in WM266.4 cells results in promoted cell proliferation and downregulated TP53 on a soft ECM. These results suggest that brain metastatic WM266.4 cells decrease EGR1 expression, thereby promoting cell proliferation via TP53 downregulation on a soft ECM.Key words: EGR1, ECM stiffness, metastasis, cancer, growth.
Hypocalcemia and hypomagnesemia frequently occur under pathological conditions such as Crohn’s disease or during diuretic treatment. However, how the combined deficiency of Ca2+ and Mg2+ affects cellular physiology has remained unclear. In this study, we focused on this issue and found that Ca2+/Mg2+ deprivation is a potent driver of stress granule (SG) formation. When SG formation was inhibited by G3BP1/2 knockdown, Ca2+/Mg2+ deprivation caused a further decrease in intracellular Mg2+ levels and an increase in cell death, indicating that SGs function to mitigate Mg2+ loss and protect cells from death under cation-deficient conditions. Furthermore, we found that the expression of the Mg2+ transporter MAGT1 is upregulated in an SG-dependent manner, and that MAGT1 knockdown further decreases intracellular Mg2+ levels and increases cell death. Collectively, our results demonstrate that SG formation acts as an adaptive mechanism to maintain Mg2+ homeostasis during Ca2+/Mg2+ deficiency. Key words: stress granule, MAGT1, magnesium, calcium
Adherens junctions (AJs) mediate cell-cell adhesion and mechanical coupling in epithelial tissues. During AJ formation, punctate AJs (punctum adherens; PA) initially appear and subsequently transition into linear AJs or zonula adherens (ZAs). The mechanosensitive interaction of α-catenin with its binding partners-actin filaments and vinculin-is thought to act as a key switch that stabilizes AJs under tension. However, the physiological role of α-catenin's force sensitivity during the early stages of AJ formation remains unclear. Here, we analyzed α-catenin mutants with altered force sensitivity: Insensitive mutant L344P lacking vinculin binding, and Hypersensitive mutant L378P binding vinculin constitutively. Using calcium-switch assays combined with fluorescence and electron microscopy, we found that cells expressing insensitive α-catenin exhibited persistent, elongated PA-like structures corresponding to lateral associations of cellular protrusions from opposing cells, accompanied by delayed ZA formation. In contrast, cells expressing the hypersensitive mutant rapidly formed ZAs, possibly bypassing the PA stage. Similar phenotypes were observed in vinculin-knockout cells, indicating that the defects in Insensitive mutants result from the lack of vinculin recruitment to α-catenin. Based on these findings, we propose a model in which clusters of the cadherin-catenin complex (CCC) along actin filaments on opposing protrusions serve as initial adhesion sites. As protrusions shorten through actomyosin contraction, CCC clusters move toward the protrusion tips along actin filaments, where stretched α-catenin recruits vinculin to reinforce the adhesion, leading to PA formation. Thus, α-catenin's force sensitivity is crucial for smooth and timely AJ assembly, ensuring proper epithelial morphogenesis by coupling intercellular adhesion with cytoskeletal tension.Key words: α-catenin, vinculin, adherens junction, actin filament, force sensitivity.
Multiplex live imaging enables simultaneous visualization of multiple signaling pathways in living cells, offering real-time insights into complex cellular networks. This methodology is essential in research fields such as cancer biology, where signaling activities exhibit heterogeneity, feedback regulation, crosstalk, and dynamic changes during pathological progression and the acquisition of therapeutic resistance. While conventional biochemical assays advanced our understanding of signaling signatures through static or population-level analyses, they lack the temporal resolution required to capture dynamic events at single-cell resolution. Recent methodological innovations have expanded multiplex live imaging through several strategies. Spectral multiplexing exploits broadened fluorescent protein palettes and optimized biosensor combinations, sometimes coupled with intracellular multiplexing methods that distinguish signals by targeting fluorescence to subcellular compartments. Intercellular multiplexing distributes reporters across cell populations, and temporal multiplexing leverages optical switching to separate signals over time. Additional modalities such as fluorescence anisotropy, fluorescence lifetime, and Raman imaging provide orthogonal readouts. Furthermore, computational approaches reinforce multiplex strategies by improved spectral unmixing, often complemented by deep learning-based algorithms. Collectively, these advances enable simultaneous tracking of multiple signaling pathways within single cells, revealing how diverse inputs are integrated into cellular responses. Here we review current strategies for multiplex live imaging, especially highlighting its applications to cancer signaling networks. Progress in fluorescent biosensor development, imaging technologies, and computational analysis will further promote the exploration of dynamic cellular regulations in basic research and translational medicine.Key words: multiplex live imaging, fluorescent biosensors, signal dynamics, image analysis, cancer heterogeneity.
Glioblastoma multiform (GBM) exhibit heterogeneity. Persistence of glioma stem cells (GSCs) are the root cause of tumor recurrence and drug resistance. So, targeting GSCs can be a better therapeutic strategy to tackle GBM. To mimic the tumor microenvironment, we have developed tumor spheroids by hanging drop method. Compared to monolayer cells spheroids had higher expression of stemness markers like CD133, CD44, PAX6 and reduced expression of differentiation marker. Cancer cells modulate the metabolic pathways to sustain high proliferation. Among the metabolic pathways, cholesterol biosynthetic pathways are mostly dysregulated in cancers, including GBM. The spheroids showed high expression of cholesterol biosynthetic genes (HMGCR, DHCR24), and Caveolin1 (CAV1). Targeting cholesterol metabolism by lovastatin resulted in depletion of cellular cholesterol levels, including in plasma membrane. Lowering of cholesterol affected membrane fluidity and hampered Hh signaling by lowering Gli1; consequently, causing downregulation of HMGCR, DHCR24, CAV1, and IDH3A, along with the loss of the stemness factors. However, there is enhanced expression of epigenetic chromatin modification enzymes, including DNMT1 and KDM5A. Tracking into the root cause of silencing of CAV1 gene, we found that CAV1 gene promoter is methylated by DNMT1, and H3K4me3 level was depleted due to enhanced KDM5A mediated demethylation. CAV1 gene silencing by siRNA validated its role in maintenance of stem-like phenotype and metabolic alterations of GBM spheroids. Collectively, this study demonstrated the regulatory role of Caveolin1 and cholesterol in maintaining stem-like characteristics of GBM spheroids and the importance of tumor models in better understanding of the molecular mechanism of GBM.Key words: Glioblastoma, cholesterol biosynthesis, stemness, Caveolin1, DNMT1, KDM5A, Gli1.
S100A11 is a small calcium-binding protein that has been studied in the context of growth regulation and membrane repair. However, it has recently been linked to the disassembly of focal adhesions. This new role of S100A11 has been linked to calcium influx through the stretch-activated channel Piezo1. In this review, we look at what’s currently known about S100A11’s structural features, interactome, and functional roles. We focus on how it responds to mechanical stress and becomes recruited to focal adhesions. We also look into its role in the disassembly of these adhesions and consider potential mechanisms. To place its activity in context, we compare S100A11 with other members of the S100 family members and discuss its contribution to calcium-dependent cytoskeletal regulation and extracellular signaling. We examine the effects of S100A11 activity in cancer metastasis, wound healing, and fibrosis. Finally, we evaluate potential ways to modulate S100A11 function for prospective therapeutic intervention. Collectively, this review projects S100A11 as a mechanosensitive calcium effector at the intersection of adhesion biology and mechanotransduction. Key words: S100A11, focal adhesions, mechanosensing, Piezo1, cytoskeleton, cell migration, cancer
Podocytes are terminally differentiated renal epithelial cells that play a crucial role in kidney filtration. Given this essential function, podocyte dysfunction results in kidney diseases known as podocytopathies. Previous studies have demonstrated that maintaining the activation-deactivation balance of mechanistic target of rapamycin complex 1 (mTORC1) is vital for podocyte function. Podocyte-specific knockout (KO) mouse models revealed that abnormal mTORC1 activation leads to severe podocytopathy. Therefore, elucidating the mechanism underlying mTORC1 activation in podocytes may contribute to the development of treatments for certain podocytopathies. In our previous study, we showed that macropinocytosis-large-scale endocytosis-is involved in the molecular mechanism of mTORC1 activation in podocytes. Growth factor (GF) stimulation induces circular dorsal ruffles (CDRs), which are large membrane protrusions on the dorsal surface of podocytes. CDRs serve as precursors to macropinocytosis, generating vesicles called macropinosomes, which transport extracellular nutrients to lysosomes, thereby activating mTORC1. These findings suggest that CDRs-derived macropinosomes modulate the mTORC1 pathway. In the present study, we investigated the molecular mechanism underlying macropinosome formation in podocytes, focusing on flotillin-1 (Flot1), a protein enriched in lipid microdomains. Imaging analysis revealed the localization of Flot1 at CDRs, and Flot1 depletion reduced macropinosome formation. Biochemical analysis further demonstrated impaired GF-stimulated mTORC1 activation in Flot1-KO cells, which exhibited slower growth than control cells. Notably, immuno-staining analysis showed that Flot1 is expressed specifically in podocytes but not in other renal cells. These findings indicate that Flot1 participates in the formation of CDRs-derived macropinosomes and contributes to macropinosome-dependent mTORC1 activation in podocytes.Key words: Flot1, circular dorsal ruffles, macropinocytosis, mTORC1, podocytes.
In higher eukaryotic cells, genomic DNA is packaged into dynamic chromatin domains whose physical behavior is coupled to DNA transactions such as transcription and DNA repair. Although chromatin organization is altered in cancer, how oncogenic signals modulate chromatin dynamics over time remains unclear. To address this issue, we established a doxycycline-inducible carcinogenesis model in hTERT-immortalized human RPE-1 cells expressing HPV16 E6/E7, MYC(T58A), and KRAS(G12V) (EMR cells) and investigated chromatin behavior during oncogene-driven transformation. Upon induction, EMR cells displayed accelerated proliferation, loss of contact inhibition, anchorage-independent growth in soft agar, and tumor formation in nude mice. Using time-resolved single-nucleosome imaging to track local chromatin dynamics over days to weeks of oncogene induction, we found that local nucleosome motion was unchanged at 1-3 days, significantly increased at 5-7 days, and returned to parental levels by 4 weeks, despite sustained oncogene expression and stable malignant growth. To explore the basis of this transient increase, we quantified DNA damage, histone marks, and transcription. γH2AX foci were elevated in EMR cells, but ATM/ATR inhibition had only minor effects on local chromatin motion, indicating that the DNA damage response is not the principal driver. By contrast, H3/H4 acetylation and nascent RNA synthesis were upregulated specifically during the early window of enhanced dynamics, whereas the heterochromatin mark H3K9me3 decreased, consistent with transient chromatin loosening associated with increased transcription. These findings reveal a biphasic change in local chromatin dynamics during human oncogene-driven transformation and provide a physical and temporal framework for understanding how oncogenic pathways reorganize chromatin.Key words: cancer, oncogenesis, single-nucleosome imaging, chromatin dynamics.
Interleukin-1 receptor type 2 (IL-1R2) functions as a decoy receptor that suppresses IL-1-induced inflammatory signaling. Both membrane-bound IL-1R2 (WT IL-1R2) and its soluble form (sIL-1R2) bind interleukin-1α (IL-1α) at the cell surface or in the extracellular space, thereby inhibiting downstream signaling. However, the anti-inflammatory role of IL-1R2 varies depending on the cellular context and receptor structure. In this study, we generated two IL-1R2 deletion mutants-ΔTM, lacking the transmembrane domain, and ΔTMCP, lacking both the transmembrane and cytoplasmic domains-and compared their functions with those of WT IL-1R2 in HeLa cells. Western blotting, immunoprecipitation, and enzyme-linked immunosorbent assay were used to assess receptor expression, IL-1α binding, and IL-1β-induced interleukin-8 (IL-8) production, respectively. Both ΔTM and ΔTMCP were secreted more efficiently than WT IL-1R2. WT IL-1R2 exhibited weak intracellular interaction with IL-1α, whereas the deletion mutants showed minimal binding. WT IL-1R2 most effectively suppressed IL-1α extracellular release; however, ΔTM and ΔTMCP also reduced secretion. Notably, both deletion mutants suppressed IL-1β-induced IL-8 production more effectively than WT IL-1R2, indicating enhanced extracellular decoy activity. These findings demonstrate that structural modifications of IL-1R2 influence its function as a decoy receptor, and the enhanced inhibitory effects of the deletion mutants on IL-1 signaling provide new insight into the anti-inflammatory potential of soluble IL-1R2 in non-immune cells.Key words: Interleukin-1, Interleukin-1 receptor type 2, decoy receptor, transmembrane, soluble interleukin-1 receptor type 2.
A primary cilium is a hair-like organelle that protrudes from the cell surface in many cell types. Growing evidence indicates that extracellular vesicles are released from primary cilia, and research is increasingly focused on defining the functions of these cilia-derived extracellular vesicles (EVs). EVs are known to modulate the behavior of various cancer cells, and structural and functional abnormalities in primary cilia have been reported in multiple cancer types. We previously demonstrated that PANC-1 cells, a human pancreatic ductal adenocarcinoma cell line, acquire enhanced primary cilia formation after surviving solitary culture conditions, and that their cilia contribute to tumor-like cell mass formation. Here, we explored part of the underlying mechanism of this phenotype by investigating the contribution of EVs released from the primary cilia of PANC-1 cells. PANC-1 clones generated by limiting dilution exhibited enhanced ciliogenesis and distinct ciliary morphologies compared with parental cells. These clones also released higher levels of cilia-derived EVs, including an expanded population of freely floating EVs within the culture environment. Biochemical analyses further showed that this increase was selective for primary cilia-derived EVs rather than reflecting a global rise in total EV production. Functionally, EV fractions enriched in cilia-derived EVs suppressed parental PANC-1 cell migration, altered cell morphology, and promoted cell aggregation, mimicking key behavioral traits of solitary condition-surviving PANC-1 clones. Together, these findings identify enhanced release of primary cilia-derived EVs as a distinct feature of PANC-1 cells adapted to solitary growth and suggest their potential involvement in the malignant and metastatic behaviors of pancreatic cancer.Key words: primary cilia, PDAC, extracellular vesicles, cell migration, cell aggregation.
The Golgi stress response is a homeostatic mechanism that augments Golgi function when Golgi function becomes insufficient (Golgi stress). Glycosylation of the core proteins of proteoglycans is one of the important functions of the Golgi. If the production of core proteins is increased and the amount of glycosylation enzymes for proteoglycans becomes insufficient (PG-type Golgi stress), the proteoglycan pathway of the Golgi stress response is activated, resulting in the transcriptional induction of glycosylation enzymes, including NDST2, HS6ST1 and GLCE. The transcriptional induction of these glycosylation enzymes is regulated by the enhancer element, PGSE-A; however, transcription factors that induce transcription from PGSE-A have not yet been identified. We herein identified KLF2 and KLF4 as transcription factors that directly bind to PGSE-A, and found that overexpression of KLF2 and KLF4 augments transcriptional induction from PGSE-A during PG-type Golgi stress, whereas their dominant negative mutants suppress the transcriptional induction. Moreover, expression of KLF2 and KLF4 was up-regulated in response to PG-type Golgi stress. Transcriptional induction of human KLF4 gene is regulated by PGSE-A, while that of human KLF2 gene is mainly controlled by a novel enhancer called PGSE-C. These results suggest that KLF2 and KLF4 are important regulators of the proteoglycan pathway of the mammalian Golgi stress response.Key words: Golgi stress, proteoglycan, ER stress, organelle zone, organelle autoregulation, KLF2, KLF4, xyloside.
