Biology subjects

Harn, H. I.-C.

Publications and source records attributed to Harn, H. I.-C..

4 recordsLinked to original sources

bioRxiv2026

A regenerative fibroblast competence field supports multiple cell fates in adult skin regeneration

Adult mammalian wounds typically restore tissue integrity through fibrotic repair rather than regeneration of the original architecture. Here, we compared small non-regenerative and large regenerative skin wounds to investigate how fibroblasts acquire regenerative competence and enter alternative cell-fate programs. Integrated single-cell RNA sequencing identified a transient signaling and extracellular-matrix-remodeling niche enriched in large wounds, together with NCAM1-associated competent fibroblast states. Time-resolved analysis positioned these states within a root-like fibroblast manifold connected to hair dermal-condensate, endothelial, pericyte and glial-associated fate-entry programs. Inferred cell-cell communication networks revealed shared matrix and adhesion signals, superimposed with branch-associated inputs, including VEGF signaling toward NCAM1-positive endothelial-transition cells. Lineage tracing showed that PDGFRA- and NCAM1-expressing lineages contributed to vascular- and nerve/glial-associated regenerative compartments. Functionally, partial NCAM1 perturbation reduced vascular organization while increasing hair follicle neogenesis, whereas stronger inhibition impaired both outcomes. These findings identify NCAM1 as a regulator of regenerative competence and fate specification within a regenerative competence field rather than a marker of a single terminal lineage. We propose that regenerative wounds activate an NCAM1-associated fibroblast competence field whose quantitative modulation biases competent fibroblasts toward alternative outcomes.

cell biology↗

bioRxiv2025

Epigenetic Coalitions Couple Tissue Growth to Generate Periodic Colour Patterns in Birds

Periodic patterning is fundamental to biological organization. In birds, colour stripes and spots on growing embryonic surface and elongating feather filaments provide a unique system to study continuous periodic patterning in expanding domains. Agouti-signaling protein (ASIP) directly reports epigenomic activity during colour patterning. Using a neural-network-like architecture, we show that ASIPs cis-regulatory landscape functions as hidden layers, integrating morphogen feedback, chromatin topology, and tissue geometry to generate discrete colour outputs. Single-nucleus multiome and Micro-C uncover stage- and context-specific enhancer-silencer coalitions. Epidermal Wnt ligands activate ASIP while inducing Wnt inhibitors in fibroblasts, forming a negative-feedback loop coupling periodic patterning to domain expansion. Comparative cross-tissue and cross-species analyses define cis-regulatory modules comprising an epigenetic grammar; functional assays highlight retrotransposon co-option expanding ASIPs cis-regulatory repertoire, potentially contributing to colour pattern evolution. Together, these findings motivate a Turing-principle-based communication model: ASIP reflects epigenetic coalitions shifting to drive diverse, environmentally tunable colour motifs for adaptation.

developmental biology↗

bioRxiv2025

Novel Tissue Mechanics-Guided Cellular Flows Enable the Evolution of Feather Follicles

Complex tissue architecture is achieved through multiple rounds of morphological transitions. Here, we analyzed cellular flows and tissue mechanics during avian skin development. We showed how novel cellular flows initiate chemo-mechanical circuits that guide epithelial protrusion, folding, invagination, and spatial cell fate specification. In the initial feather bud formation, stiff dermal condensates protrude vertically out of the locally softened epithelial sheet. As the bud elongates, it stretches the epithelial cells at the base, which mechanically activates YAP and causes the epithelial sheet to fold downward and form a stiff cylindrical wall that invaginates into the skin. This stiff epithelial tongue is essential to the compaction and formation of the tightly packed dermal papillae. These topological transformational events are mechanically interconnected, and the completion of the previous circuit initializes the next one. On the contrary, during scale development, its rigid epithelial sheet restricts dermal cell flows, preventing other further topological transformation. We generated a topological transformation model to show how the process enables the novel evolution of feather follicles.

developmental biology↗

bioRxiv2022

Signaling modality within gp130 receptor enhances tissue regeneration

Adult mammals are incapable of multi-tissue regeneration and augmentation of this potential may drastically shift current therapeutic paradigms. Here, we found that a common co-receptor of IL-6 cytokines, glycoprotein 130 (gp130), serves as a major nexus integrating various context-specific signaling inputs to either promote regenerative outcomes or aggravate disease progression. Via genetic and pharmacological experiments in vitro and in vivo, we demonstrated that a signaling tyrosine 814 (Y814) within gp130 serves as a major cellular stress sensor. Mice with constitutively inactivated Y814 (F814) exhibit regenerative, not reparative, responses after wounding in skin and anti-degenerative responses in the synovial joint. In addition, pharmacological inhibition of gp130 Y814 results in regeneration of multiple tissues in several species as well as disease modification in animal models of osteoarthritis. Our study characterizes a novel molecular mechanism that, if selectively manipulated, enhances the intrinsic regenerative capacity while preventing pathological outcomes in injury and disease. SummaryGp130 Y814 signaling module serves as a cellular stress sensor responsible for hindering tissue regeneration while triggering pathological outcomes after injury.

molecular biology↗