Biology subjects

Sada, A.

Publications and source records attributed to Sada, A..

14 recordsLinked to original sources

bioRxiv2026

In vivo effects of inducible transgene expression of the age-associated glycogenes St6gal1 and Man1a on epidermal homeostasis

Glycosylation of cell-surface proteins plays several essential roles in cell-matrix interactions and receptor signaling, thereby contributing to tissue homeostasis and aging. In aged mouse skin, epidermal stem cells exhibit increased levels of a2,6-sialylated complex-type N-glycans alongside upregulation of glycogenes such as St6gal1 and Man1a; however, the functional importance of these glycosylation changes in vivo remains largely unknown. Here, we generated doxycycline-inducible transgenic mice expressing the age-related glycogenes St6gal1 and Man1a, either individually or in combination, using ubiquitous and epidermis-specific drivers. Lectin-based analyses with SNA and rHeltuba demonstrated corresponding alterations in glycosylation patterns in these mice. Transgenic Man1a induction reduced epidermal proliferation and epidermal thickness. In contrast, St6gal1 induction caused splenomegaly and elevated expression of inflammatory signature genes in the skin but did not measurably alter epidermal proliferation or morphology. Double transgenic mice exhibited a hybrid phenotype combining inflammatory and proliferative impairments, although comparison of ubiquitous and epidermis-specific induction indicated that the observed skin phenotypes depended on the epidermal expression of the transgenes. An SNA lectin-based pull-down assay followed by mass spectrometry identified candidate a2,6-sialylated proteins, including integrin family members, junctional proteins, and surface receptors, following induction of St6gal1 and Man1a. Together, these findings suggest that increased expression of the age-associated glycogenes St6gal1 and Man1a perturbs distinct aspects of epidermal homeostasis in vivo and identify candidate glycoproteins that may mediate these effects.

cell biology↗

bioRxiv2026

The Il1r2-CreERT2 knock-in mouse enables inducible labeling of slow-cycling epidermal basal cells and genetic ablation of the IL-1 decoy receptor

The interfollicular epidermis is maintained by spatially organized basal cell populations with distinct molecular signatures and division kinetics; however, the markers that define these populations remain poorly defined. In this study, we identified Il1r2, which encodes the IL-1 decoy receptor IL-1R2, as a marker of the slow-cycling basal population in the epidermis. Single-cell RNA-seq analysis of epidermal and hair follicle basal populations in the murine tail skin revealed that Il1r2 is preferentially expressed in the slow-cycling epidermal basal population, and immunofluorescence staining confirmed its protein localization in tissues. To enable fate mapping of this population, we generated an Il1r2-CreERT2 knock-in mouse line using a CRISPR-Cas9-based PITCh method. Tamoxifen induction in Il1r2-CreERT2/Rosa-tdTomato mice exhibited selective labeling of basal cells localized to the slow-cycling interscale region of the tail epidermis. Because the CreERT2 cassette was inserted into the Il1r2 coding sequence, homozygous Il1r2-CreERT2 knock-in mice can also serve as an Il1r2 knockout model through targeted gene ablation. Thus, the Il1r2-CreERT2 mouse line provides a dual genetic tool for lineage tracing of the slow-cycling epidermal basal population and for functional modulation of IL-1 signaling in vivo.

developmental biology↗

bioRxiv2026

RUNX1-ETO expression in epidermal keratinocytes induces progressive skin inflammation in vivo

Basal keratinocytes in the skin are essential for epidermal homeostasis and repair; however, how intrinsic alterations in these cells contribute to inflammatory skin pathology remains poorly understood. In this study, we employed a tamoxifen-inducible mouse model to express the human RUNX1-ETO fusion gene, a well-established oncogenic driver of acute myeloid leukemia, in epidermal basal keratinocytes. RUNX1-ETO induction in keratinocytes resulted in progressive skin inflammation in vivo, accompanied by splenomegaly, epidermal hyperplasia, increased cytokine production, and alterations in epidermal stem cell composition. Inflammatory lesions were prominent in the tail, ear, and plantar epidermis, whereas hair-bearing dorsal skin remained largely unaffected. RNA-seq analysis of FACS-isolated RUNX1-ETO+ basal keratinocytes revealed global changes in gene expression, characterized by the suppression of epidermal homeostatic and metabolic programs and the activation of inflammatory signaling pathways. In particular, RUNX1-ETO expression was associated with increased TNF/NF-{kappa}B and IL-6-STAT signaling, as well as interferon-associated inflammatory pathways, together with the induction of neutrophil-attracting chemokines and epithelial inflammatory mediators. Together, these findings indicate that RUNX1-ETO-mediated transcriptional dysregulation in basal keratinocytes promotes a pro-inflammatory cellular state that drives progressive skin inflammation.

cell biology↗

bioRxiv2026

The epidermal stem cell-supporting matricellular protein fibulin 7 modulates skin inflammatory response in a psoriasis model

ECM composition and organization are greatly altered during inflammation but it is still elusive if ECM dynamics may protect tissue stem cells against aberrant inflammation. Fibulin 7 (encoded by Fbln7) is part of the basement membrane ECM where epidermal stem cells (EpSCs) reside. It supports the long-term potential of fast-cycling EpSCs and moderates aging-related inflammatory markers in keratinocytes. Here, we assessed fibulin 7s role during imiquimod (IMQ)-induced inflammation in 1-year-old mouse dorsal skin. We found that loss of Fbln7 aggravates epidermal inflammation, marked by increased epidermal thickness, proliferation, and phosphorylation of JNK (c-Jun N-terminal kinase). Fast-cycling EpSCs labeled with Slc1a3-creER-TdTomato demonstrated that IMQ-induced proliferation in Fbln7 KO mice is contributed by cell divisions in the suprabasal layers, a hallmark of inflammatory epidermal responses. EpSC transcriptomes further reveal IMQ-modulated genes that are more substantially affected in Fbln7 KO mice, including IL-17 pathway-related genes known in psoriasis pathogenesis. Mechanistically, fibulin 7 directly binds to IL-17A and decreases IL-17A-mediated p38 MAPK activation. In public human psoriasis datasets, FBLN7 is reduced in lesional skin compared with non-lesional or normal skin, and it is significantly correlated with common psoriasis-associated genes. Altogether, fibulin 7 is potentially beneficial to protect against skin inflammation.

cell biology↗

bioRxiv2026

Label-free Raman imaging defines distinct cell populations in human skin

Understanding cellular heterogeneity in human skin is crucial for regenerative medicine and tissue engineering. In this study, we applied label-free Raman imaging to visualize molecular features corresponding to the three-dimensional architecture of the epidermis. Spatially resolved Raman spectra, combined with multivariate data analysis, enabled the identification of cell-layer-specific molecular signatures. Based on the region-specific spectra analysis, component C5 was predominantly localized to the basal layer within rete ridges and was characterized by {beta}-sheet-enriched keratin features. This spatially restricted distribution reflects the molecular microenvironment of epidermal stem cell niches, suggesting that C5 may serve as a biomarker for basal stem cell populations associated with skin undulations. These findings provide insight into the molecular basis of epidermal architecture and demonstrate the potential of Raman spectroscopy as a label-free tool for evaluating stem cell localization and differentiation status.

bioengineering↗

bioRxiv2026

Inflammatory IL-1 signaling remodels epidermal stem cell compartments by suppressing Wnt activity

The skin epidermis is maintained by spatially organized stem cell populations with distinct cellular dynamics; however, how inflammation affects this heterogeneity remains largely unknown. Here, we demonstrate that acute skin inflammation alters epidermal stem cell compartments through IL-1-mediated suppression of canonical Wnt signaling. Lineage tracing in inflamed mouse skin revealed that slow-cycling Dlx1+ epidermal stem cell clones persist, whereas fast-cycling Slc1a3+ clones decline through enhanced differentiation and lineage conversion, driving the reorganization of epidermal stem cell compartments. IL-1 signaling is both necessary and sufficient for this change: administration of IL-1/{beta} recapitulates these effects, while transgenic induction of the IL-1 decoy receptor preserves the balance of stem cell populations. IL-1 suppresses canonical Wnt activity in both the mouse epidermis and human keratinocytes, and Wnt ligand administration restores the fast-cycling compartment in vivo. Together, these results identify a reversible IL-1-Wnt axis that governs inflammation-induced stem cell plasticity and spatial tissue remodeling. HighlightO_LIInflammation induces reversible remodeling of epidermal stem cell compartments C_LIO_LIDistinct epidermal stem cell populations exhibit differential responses to inflammation C_LIO_LIIL-1 suppresses canonical Wnt signaling, thereby biasing fast-cycling stem cell behavior C_LIO_LIReactivation of Wnt signaling restores stem cell population balance under inflammatory conditions C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/704488v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@e430e5org.highwire.dtl.DTLVardef@1464550org.highwire.dtl.DTLVardef@70ba1borg.highwire.dtl.DTLVardef@ca502c_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2025

Skin-derived G-CSF activates pathological granulopoiesis upon psoriasis

Psoriasis is an inflammatory skin disease initiated by environmental triggers and driven by disruption of T cell cytokine network in the cutaneous milieu. The fact that complete resolution of disease by targeting key inflammatory cytokines remains challenging indicates a contribution of other immune cells to the pathogenesis. Here, we study the role of neutrophils in psoriasis, the first-line innate immune defender that is short-lived but mobile and infiltrate into various tissues. We found that upon psoriasis induction, skin-resident endothelial cells are activated to produce G-CSF which activates emergency granulopoiesis in bone marrow and induces cutaneous infiltration and accumulation of neutrophil that are functionally overactive. Depletion of neutrophils or blockage of psoriasis-driven granulopoiesis by respective neutralizing antibodies results in reducing cutaneous neutrophil burden and mitigating psoriasis pathogenesis. This mechanism might be conserved in human psoriasis as confirmed by public RNA-seq database. Our findings uncovered and detailed the pathological crosstalk between skin and BM in psoriatic inflammation, proposing a potential therapeutic approach targeting cross-organ communication.

immunology↗

bioRxiv2025

Integrin-binding matricellular protein fibulin-5 maintains epidermal stem cell heterogeneity during skin aging

The extracellular matrix (ECM) is crucial in building the extracellular environment and translating extracellular information into biochemical signals that sustain organ functions. Fibulin-5 (Fbln5) is a multifunctional ECM protein essential for forming elastic fibers and regulating cellular functions by binding to integrins. While fibulin-5 expression decreases with age in human skin, the functional implications of this decrease, particularly in epidermal stem cell regulation, have remained largely unexplored. Here, we find that the knocking out of Fbln5 in mice results in early impairments of epidermal stem cell properties, similar to the chronological aging of the skin. The Fbln5 deficiency suppresses the expression of integrins and other cell junction proteins, leading to the inactivation of YAP signaling in epidermal stem cells. This reduction in YAP signaling results in the downregulation of the fast-cycling epidermal stem cell marker SLC1A3 in human skin and primary keratinocytes. These results suggest that, in addition to its known function in elastic fiber formation, fibulin-5 also plays a critical role in regulating the balance of epidermal stem cell populations during skin aging and coordinating the crosstalk between the extracellular environment and intracellular signaling.

developmental biology↗

bioRxiv2025

Retinoic acid signaling alters the balance of epidermal stem cell populations in the skin

All-trans retinoic acid (ATRA), the active form of retinoids, is a potent anti-aging and anti-inflammatory agent with pleiotropic effects on various skin conditions. In the interfollicular epidermis, tissue turnover is maintained by heterogeneous epidermal stem cell populations located at the basal layer. Mouse tail skin contains slow- and fast-cycling epidermal stem cell populations. The reduction of fast-cycling epidermal regions after ATRA application was first documented in 1987; however, stem cell-level changes remained largely unexplored. This study demonstrates that ATRA treatment leads to reversible changes which decrease the fast-cycling epidermal compartment while expanding the slow-cycling one. ATRA biases both slow- and fast-cycling epidermal stem cell populations toward differentiation, with the remaining Slc1a3-CreER+ fast-cycling clones in the basal layers biasing to the slow-cycling lineage. Similar changes in slow- and fast-cycling epidermal stem cell populations are also evident in human primary cultures in vitro. These findings shed light on the role of retinoic acid signaling in regulating the balance of epidermal stem cell heterogeneity and lineages.

developmental biology↗

bioRxiv2025

Defining epithelial stem cell heterogeneity through undulating structures of the skin and oral mucosa

Epithelial stem cells exhibit heterogeneity, with distinct stem cell populations occupying specific tissue regions. The human skin displays a characteristic undulating structure at the epidermal-dermal junction, which supports mechanical strength and influences the spatial organization of epithelial stem cells. Unlike human skin, mouse skin lacks these undulations, complicating studies into the effects of tissue architecture on stem cell distribution. Here, we leverage the mouse oral mucosa, which possesses an undulating structure similar to human skin, to characterize stem cell division dynamics and long-term fate in vivo. Using a combination of H2B-GFP pulse-chase analysis and lineage tracing with Dlx1-CreER and Slc1a3-CreER models, we demonstrate that slow-and fast-cycling stem cells localize to distinct anatomical regions relative to the undulating structure and maintain their respective compartments during tissue homeostasis. A three-dimensional culture model using micropatterned collagen scaffolds that recapitulate the undulating structures in vitro reveals that the mechanical environment generated by the undulating structures partially induces proliferative heterogeneity in epithelial stem cells. This study proposes tissue undulating surface structure as a common principle as a niche component that defines the localization of compartmentalized stem cell populations across different epithelial tissues. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=123 SRC="FIGDIR/small/634195v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@b3046aorg.highwire.dtl.DTLVardef@e6cd8forg.highwire.dtl.DTLVardef@c169ccorg.highwire.dtl.DTLVardef@8f772_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2024

Epithelium Stratifies via Nucleation and Growth Induced by Foam-Geometric Instability

The epithelium undergoes stratification, transitioning from a monolayer to a multilayer structure, across broad phenomena. Recent studies have identified several cell behaviors as triggers, including junctional tension, cell density and geometry, and topological defects. However, how these factors drive stratification throughout the entire epithelium remains poorly understood. Here, we report a mechanism underlying epithelial stratification that mirrors the physics of phase transition. Combining cell culture with three-dimensional vertex modeling, we demonstrate that epithelial stratification is analogous to a structural phase transition driven by the nucleation-growth process, i.e., multilayer origins dispersedly appear and expand across the epithelium via unordered intermediate states. This transition is induced by a mechanical instability inherent in the foam-like geometry of the epithelium. Moreover, the nucleation-growth concept applies to embryonic skin development and intestinal cancer transformation. These findings conceptualize epithelial stratification as a form of a phase transition governed by foam mechanics, offering a physical perspective on various epithelial developments.

biophysics↗

bioRxiv2022

Metabolic intervention that reduces glucose-insulin signaling suppresses the onset and progression of neuroendocrine tumors

Insulin signaling often plays a role in the regulation of cancer including tumor initiation, progression, and response to treatment. In addition, the insulin-regulated PI3K-Akt-mTOR pathway plays an important role in the regulation of islet cell proliferation and this pathway is hyperactivated in human non-functional pancreatic neuroendocrine tumors (PanNETs). We therefore investigated the effect of a very low carbohydrate diet (ketogenic diet) on a mouse model that develops non-functional PanNETs to ask how reduced PI3K-Akt-mTOR signaling might affect the development and progression of non-functional PanNET. We found that this dietary intervention resulted in lower PI3K-Akt-mTOR signaling in islet cells and a significant reduction in PanNET formation and progression. We also found that this treatment had a significant effect on the suppression of pituitary NET development. Furthermore, we found that non-functional PanNET patients with lower blood glucose levels tend to have a better prognosis than patients with higher blood glucose levels. This preclinical study shows that a dietary intervention that results in lower serum insulin levels leads to lower insulin signal within the neuroendocrine cells and has a striking suppressive effect on the development and progression of both pancreatic and pituitary NETs.

cancer biology↗

bioRxiv2022

The extracellular matrix fibulin 7 maintains epidermal stem cell heterogeneity during skin aging

Tissue stem cells divide infrequently as a protective mechanism against internal and external stresses associated with aging. Here, we demonstrate that slow- and fast-cycling interfollicular epidermal stem cells in mouse skin undergo distinct aging processes. Two years of lineage tracing reveals that Dlx1+ slow-cycling clones expanded into the fast-cycling stem cell territory, while the number of Slc1a3+ fast-cycling clones gradually declined. Transcriptome analysis further indicated that the molecular properties of each stem cell population are altered with age. Mice lacking fibulin 7, an extracellular matrix (ECM), show early impairments resembling epidermal stem cell aging, such as the loss of fast-cycling clones, delayed wound healing, and increased expression of inflammation- and differentiation-related genes. Fibulin 7 interacts with structural ECM and matricellular proteins, and the overexpression of fibulin 7 in primary keratinocytes results in slower proliferation in the absence or presence of inflammatory cytokine IL-6. Thus, these results suggest that fibulin 7 plays a crucial role in maintaining tissue resilience and epidermal stem cell heterogeneity during skin aging.

developmental biology↗

bioRxiv2020

Defining compartmentalized stem and progenitor populations with distinct cell division frequency in the ocular surface epithelium

SummaryAdult tissues contain label-retaining cell (LRC)s, which are relatively slow-cycling and considered to represent a unique property of tissue stem cell (SC)s. In the ocular surface epithelium, LRCs are detected in the limbus, a boundary between cornea and conjunctiva, and the fornix of the conjunctiva; however, the character of LRCs and identity of SCs remain unclear due to lack of appropriate molecular markers. Here we show that the ocular surface epithelium accommodates spatially distinct stem/progenitor populations with different cell division frequency. By combining EdU pulse-chase analysis and lineage tracing with three CreER transgenic mouse lines: Slc1a3CreER, Dlx1CreER and K14CreER, we detect distinct dynamics of epithelial SCs in the cornea and conjunctiva. In the limbus, long-lived SCs are labeled with Slc1a3CreER and they either migrate centripetally toward the central cornea or laterally expand their clones within the limbal region. In the central cornea, cells are mostly non-LRCs, labeled by Dlx1CreER and K14CreER, and the number of clones declines after a short period of time with rare long-lasting clones, suggesting their properties as short-lived progenitor cells. In the conjunctival epithelium, which consists of bulbar, fornix and palpebral conjunctiva, each territory is regenerated by compartmentalized, distinct SC populations without migrating one region to another. The severe damage of the cornea leads to the cancellation of SC compartments, causing conjunctivalization of the eye, whereas milder limbal injury induces a rapid increase of laterally-expanding clones in the limbus. Taken together, our work provides lineage tracing tools of the eye and defines compartmentalized, multiple SC/progenitor populations in homeostasis and their behavioral changes in response to injury.Competing Interest StatementThe authors have declared no competing interest.View Full Text

developmental biology↗