Regulation of feather length: FGF/IGF signaling and NOTCH/YAP modulation of progenitor cell topology.

The regulation of organ size is a fundamental biological question. This study investigates how feather length is regulated in chickens. We found that collar bulge stem cell zones vary in size: main sickle > lesser sickle > contour feathers.

Two waves of adipogenesis in developing avian skin and dermal plasticity.

How the complex architecture of skin is constructed, balancing both similarity and adaptive diversity, is not well understood. We propose that the developmental assembly of skin components, including skin appendages, dermal muscles, dermal adipose tissues, and vasculature, is interdependent and adaptive, enabling different species to adjust to their respective environments. Using the developing chicken skin model, we recently demonstrated that the intradermal muscle network and vasculature are organized with feather buds as reference points during the process of adaptive tissue patterning.

Molecular insights into region-specific sexual dichromatism: Comparative transcriptome analysis of red cheek pigmentation in zebra finches.

Feathers, the primary skin appendage covering the avian body, undergo dynamic phenotypic changes throughout a bird's life. Males and females of the same species can exhibit sexually dichromatic plumage colors which play a critical role in mating choice, survival, and ecological interactions. In this study, we investigate the molecular mechanisms underlying the changes of color that occur during the transition from juvenile to adult feathers, known as the secondary transition.

Wound-Induced Regeneration in Feather Follicles: A Stepwise Strategy to Regenerate Stem Cells.

How to elicit and harness regeneration is a major issue in wound healing. Skin injury in most amniotes leads to repair rather than regeneration, except in hair and feathers. Feather follicles are unique organs that undergo physiological cyclic renewal, supported by a dynamic stem cell niche.

Skin regional specification and higher-order regulation.

The integument plays a critical role in functional adaptation, with macro-regional specification forming structures like beaks, combs, feathers, and scales, while micro-regional specification modifies skin appendage shapes. However, the molecular mechanisms remain largely unknown. Craniofacial integument displays dramatic diversity, exemplified by the Polish chicken (PC) with a homeotic transformation of comb-to-crest feathers, caused by a 195-base pair (bp) duplication in intron.

Conserved regulatory switches for the transition from natal down to juvenile feather in birds.

The transition from natal downs for heat conservation to juvenile feathers for simple flight is a remarkable environmental adaptation process in avian evolution. However, the underlying epigenetic mechanism for this primary feather transition is mostly unknown. Here we conducted time-ordered gene co-expression network construction, epigenetic analysis, and functional perturbations in developing feather follicles to elucidate four downy-juvenile feather transition events.

Gap junctions in Turing-type periodic feather pattern formation.

Periodic patterning requires coordinated cell-cell interactions at the tissue level. Turing showed, using mathematical modeling, how spatial patterns could arise from the reactions of a diffusive activator-inhibitor pair in an initially homogeneous 2D field. Most activators and inhibitors studied in biological systems are proteins, and the roles of cell-cell interaction, ions, bioelectricity, etc.

Epidermal-dermal coupled spheroids are important for tissue pattern regeneration in reconstituted skin explant cultures.

Tissue patterning is critical for the development and regeneration of organs. To advance the use of engineered reconstituted skin organs, we study cardinal features important for tissue patterning and hair regeneration. We find they spontaneously form spheroid configurations, with polarized epidermal cells coupled with dermal cells through a newly formed basement membrane.

Transition from natal downs to juvenile feathers: conserved regulatory switches in Neoaves.

The transition from natal downs for heat conservation to juvenile feathers for simple flight is a remarkable environmental adaptation process in avian evolution. However, the underlying epigenetic mechanism for this primary feather transition is mostly unknown. Here we conducted time-ordered gene co-expression network construction, epigenetic analysis, and functional perturbations in developing feather follicles to elucidate four downy-juvenile feather transition events.

Using Avian Skin Explants to Study Tissue Patterning and Organogenesis.

The developing avian skin during embryogenesis is a unique model that can provide valuable insights into tissue patterning. Here three variations on skin explant cultures to examine different aspects of skin development are described. First, ex vivo organ cultures and manipulations offer researchers opportunities to observe and study the development of feather buds directly.

Gap junctions in Turing-type periodic feather pattern formation.

Periodic patterning requires coordinated cell-cell interactions at the tissue level. Turing showed, using mathematical modeling, how spatial patterns could arise from the reactions of a diffusive activator-inhibitor pair in an initially homogenous two-dimensional field. Most activators and inhibitors studied in biological systems are proteins, and the roles of cell-cell interaction, ions, bioelectricity, etc.

-acting mutation affecting transcription is underlying the within-feather pigmentation pattern in chickens.

() is a mutation in chickens that extends black (eumelanin) pigmentation in normally brown or red (pheomelanin) areas, thus affecting multiple within-feather patterns [J. W. Moore, J.

Cyclic growth of dermal papilla and regeneration of follicular mesenchymal components during feather cycling.

How dermis maintains tissue homeostasis in cyclic growth and wounding is a fundamental unsolved question. Here, we study how dermal components of feather follicles undergo physiological (molting) and plucking injury-induced regeneration in chickens. Proliferation analyses reveal quiescent, transient-amplifying (TA) and long-term label-retaining dermal cell (LRDC) states.

Regional specific differentiation of integumentary organs: SATB2 is involved in α- and β-keratin gene cluster switching in the chicken.

Background: Animals develop skin regional specificities to best adapt to their environments. Birds are excellent models in which to study the epigenetic mechanisms that facilitate these adaptions. Patients suffering from SATB2 mutations exhibit multiple defects including ectodermal dysplasia-like changes.

Global feather orientations changed by electric current.

During chicken skin development, each feather bud exhibits its own polarity, but a population of buds organizes with a collective global orientation. We used embryonic dorsal skin, with buds aligned parallel to the rostral-caudal body axis, to explore whether exogenous electric fields affect feather polarity. Interestingly, brief exogenous current exposure prior to visible bud formation later altered bud orientations.

Symmetry breaking of tissue mechanics in wound induced hair follicle regeneration of laboratory and spiny mice.

Tissue regeneration is a process that recapitulates and restores organ structure and function. Although previous studies have demonstrated wound-induced hair neogenesis (WIHN) in laboratory mice (Mus), the regeneration is limited to the center of the wound unlike those observed in African spiny (Acomys) mice. Tissue mechanics have been implicated as an integral part of tissue morphogenesis.

Human Fetal Scalp Dermal Papilla Enriched Genes and the Role of R-Spondin-1 in the Restoration of Hair Neogenesis in Adult Mouse Cells.

Much remains unknown about the regulatory networks which govern the dermal papilla's (DP) ability to induce hair follicle neogenesis, a capacity which decreases greatly with age. To further define the core genes which characterize the DP cell and to identify pathways prominent in DP cells with greater hair inductive capacity, comparative transcriptome analyses of human fetal and adult dermal follicular cells were performed. 121 genes were significantly upregulated in fetal DP cells in comparison to both fetal dermal sheath cup (DSC) cells and interfollicular dermal (IFD) populations.

The Making of a Flight Feather: Bio-architectural Principles and Adaptation.

The evolution of flight in feathered dinosaurs and early birds over millions of years required flight feathers whose architecture features hierarchical branches. While barb-based feather forms were investigated, feather shafts and vanes are understudied. Here, we take a multi-disciplinary approach to study their molecular control and bio-architectural organizations.

Instructive role of melanocytes during pigment pattern formation of the avian skin.

Animal skin pigment patterns are excellent models to study the mechanism of biological self-organization. Theoretical approaches developed mathematical models of pigment patterning and molecular genetics have brought progress; however, the responsible cellular mechanism is not fully understood. One long unsolved controversy is whether the patterning information is autonomously determined by melanocytes or nonautonomously determined from the environment.

Comparative regenerative biology of spiny (Acomys cahirinus) and laboratory (Mus musculus) mouse skin.

Wound-induced hair follicle neogenesis (WIHN) has been demonstrated in laboratory mice (Mus musculus) after large (>1.5 × 1.5 cm ) full-thickness wounds.

Morpho-regulation in diverse chicken feather formation: Integrating branching modules and sex hormone-dependent morpho-regulatory modules.

Many animals can change the size, shape, texture and color of their regenerated coats in response to different ages, sexes, or seasonal environmental changes. Here, we propose that the feather core branching morphogenesis module can be regulated by sex hormones or other environmental factors to change feather forms, textures or colors, thus generating a large spectrum of complexity for adaptation. We use sexual dimorphisms of the chicken to explore the role of hormones.

Transcriptome analyses of reprogrammed feather / scale chimeric explants revealed co-expressed epithelial gene networks during organ specification.

Background: The molecular mechanism controlling regional specific skin appendage phenotypes is a fundamental question that remains unresolved. We recently identified feather and scale primordium associated genes and with functional studies, proposed five major modules are involved in scale-to-feather conversion and their integration is essential to form today's feathers. Yet, how the molecular networks are wired and integrated at the genomic level is still unknown.