Signaling to structures: skin appendages, development and diseases--meeting report of the 55th annual Montagna Symposium on the Biology of Skin.

Approximately 120 participants gathered for the 55th Annual Montagna Symposium on the Biology of Skin.* Presentations by 22 invited speakers, seven short talks chosen from submitted abstracts, and 37 posters were heard and discussed. This meeting continues to follow the tradition established in 1950 by Dr. William Montagna. It is a forum where basic cutaneous biologists and clinically trained scientists meet with practicing clinicians to discuss a single major topic in cutaneous bio logy. The topic for the 55th Annual Montagna Symposium was “Signaling to Structures: Skin Appendages, Development and Diseases.” The flow of presentations led the discussion from basic aspects of skin biology to clinical challenges and potential opportunities. This included plenary sessions with vibrant discussions and breakout sessions where we discussed topics necessary to advance this research. The three program chairs, Sarah E. Millar, PhD, George Cotsarelis, MD (both from University of Pennsylvania Medical School, Philadelphia, PA), and Andrzej A. Dlugosz, MD (University of Michigan Comprehensive Cancer Center, Ann Arbor, MI), put together an exciting program, beginning with a keynote talk by Pierre Coulombe (Johns Hopkins University, Baltimore, MD), who discussed the roles of keratin 17 in appendages, including the exciting finding that keratin 17 is upregulated in basal-cell carcinoma and may be a target of Gli2. Hair Follicle/Sebaceous Gland. Ralf Paus (University of Lubeck, Germany) began with an overview of the hair follicle, which included a discussion of the hair follicle’s immune privilege and how this is broken down in autoimmune disease. Raphael Kopan (Washington University, St. Louis, MO) followed with a presentation of how notch-1 and transforming growth factor-β control the G1-to-S cell-cycle phase transition of epidermal and mesenchymal cells in hair follicles. Diane Thiboutot (Pennsylvania State University College of Medicine, Hershey) gave an overview of the sebaceous gland and acne. Her take-home message was that we need better FDA-approved ways to reduce sebaceous production and thereby reduce acne. Vladimir Botchkarev (Boston University School of Medicine, Boston, MA) followed with a discussion of the signaling of bone morphogenic proteins (BMPs) in hair follicles of various sizes. Angela Christiano (Columbia University, New York, NY) presented findings that high expression of P-cadherin directly relates to down-growth of hair follicles during development and to the sparsity of hair in diseases such as juvenile muscular dystrophy. Integument Appendages: Beyond Hair. The topic of this session was nonhair appendages. John Wysolmerski (Yale University School of Medicine, New Haven, CT) began by explaining that expression of parathyroid hormone-related protein (PTHrP) first in the epithelial cells, then in the mesenchymal cells, is required for mammary gland morphogenesis. Marja Mikkola (University of Helsinki, Finland) gave a short talk concerning her findings that mutated Eda-1, found in ectodermal dysplasia, results in the failure of molar cusps to form properly on teeth. Cynthia Loomis (New York University School of Medicine, New York, NY) followed with her studies showing that engrailed (En-1) is required for proper formation of nails, even in adults. Continuing this theme, Vu Nguyen (University of Pennsylvania, Philadelphia) described his studies using the zebrafish model to discover genes required for scales of teeth formation, and Benjamin Yu (University of California, San Francisco) gave a short talk on sprouty and its requirement for hand formation. Stem Cells in Appendages. George Cotsarelis (University of Pennsylvania, Philadelphia) discussed the role of hair follicle bulge stem cells in wound healing. Weimin Zhong (Yale University, New Haven, CT) compared the expression of Numb in brain and hair follicle development. Carol Trempus (National Institute of Environmental Health Sciences, Research Triangle Park, NC) gave a short talk on her findings that CD34positive bulge cells were the targets of chemical carcinogenic inducers. Fiona Watt (Cancer Research UK Cambridge Research Institute, Cambridge) used an inducible mouse model to determine that β-catenin signaled before notch