Our long term objective is to study how ectodermal organ size is determined. In the last funding period, we studied the regulation of organ size and shape in feather, hair, beak, tooth, etc. We developed the topobiological concept of localized growth zone (LoGZ), suggesting the number, size, position and activity of clustered transient amplifying (TA) cells can determine an organ's size and shape. In this renewal, we ask what unique characteristics in hairs and feathers enable them to increase in size and regenerate continuously throughout adult life. We hypothesize it is made possible by forming a sustaining growth unit, composed of epidermal stem / TA / differentiated cells and a dermal signaling center, topologically arranged in a follicle design that allows the continuous flow of growth and regeneration without structural constraints. Using the feather model, we postulate that FGF / MARK is the major driving force of cell proliferation for size increases throughout bud and follicle stages. Organized growth is essential in organ building and tissue engineering. In the upward feather bud outgrowth, the Notch pathway may specify a growth - maturation gradient to the feather filament growth zone, conferring orientation to the elongating feather buds (Aim 1). In the downward follicle wall invagination, the dermal papilla may work as a signaling center to direct the epithelial tongue extension via FGF 10 (Aim 2). In the growing follicle, FGF activity is modulated by sprouty and antagonized by BMP to generate different structures along the feather axis (Aim 3). Preliminary microarray data are consistent with these candidate pathways. Efforts are made to alter dermal papilla properties so we can convert small feathers into large ones via modulation of the stem cell microenvironment, rather than stem cells themselves (Aim 4). RCAS retroviral vectors, siRNAs, electroporation, protein coated beads, chicken/quail chimeric explant, follicle dermal papilla transplantations, Oil tracing, time lapse movies, microarrays, bioinformatics analyses, etc. are the techniques we will apply to these studies. Using this excellent animal model, we will identify gene pathways critical for follicle morphogenesis and essential topobiological principles for this process. We should learn the developmental origin of appendage stem cells and dermal papilla. The knowledge acquired can be directed to make short hairs grow longer, and to engineer ectodermal stem cells into follicles with sustaining growth ability.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
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Special Emphasis Panel (ZRG1-MOSS-H (06))
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Baker, Carl
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University of Southern California
Schools of Medicine
Los Angeles
United States
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Wu, Ping; Yan, Jie; Lai, Yung-Chih et al. (2018) Multiple Regulatory Modules Are Required for Scale-to-Feather Conversion. Mol Biol Evol 35:417-430
Lai, Yung-Chih; Liang, Ya-Chen; Jiang, Ting-Xin et al. (2018) Transcriptome analyses of reprogrammed feather / scale chimeric explants revealed co-expressed epithelial gene networks during organ specification. BMC Genomics 19:780
Qiu, Weiming; Chuong, Cheng-Ming; Lei, Mingxing (2018) Regulation of melanocyte stem cells in the pigmentation of skin and its appendages: Biological patterning and therapeutic potentials. Exp Dermatol :
Widelitz, Randall B; Lin, Gee-Way; Lai, Yung-Chih et al. (2018) Morpho-regulation in diverse chicken feather formation: Integrating branching modules and sex hormone-dependent morpho-regulatory modules. Dev Growth Differ :
Wu, Ping; Lai, Yung-Chih; Widelitz, Randall et al. (2018) Comprehensive molecular and cellular studies suggest avian scutate scales are secondarily derived from feathers, and more distant from reptilian scales. Sci Rep 8:16766
Wang, Shuo; Stiegler, Josef; Wu, Ping et al. (2017) Heterochronic truncation of odontogenesis in theropod dinosaurs provides insight into the macroevolution of avian beaks. Proc Natl Acad Sci U S A 114:10930-10935
Cooke, Thomas F; Fischer, Curt R; Wu, Ping et al. (2017) Genetic Mapping and Biochemical Basis of Yellow Feather Pigmentation in Budgerigars. Cell 171:427-439.e21
Li, Ang; Figueroa, Seth; Jiang, Ting-Xin et al. (2017) Diverse feather shape evolution enabled by coupling anisotropic signalling modules with self-organizing branching programme. Nat Commun 8:ncomms14139
Cho, Jung-Hwa; Swanson, Carter J; Chen, Jeannie et al. (2017) The GCaMP-R Family of Genetically Encoded Ratiometric Calcium Indicators. ACS Chem Biol 12:1066-1074
Lai, Yung Chih; Chuong, Cheng-Ming (2016) The ""tao"" of integuments. Science 354:1533-1534

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