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Xin Sun

Assistant Professor of Medical Genetics

Lab Home Page:

Sun Lab

Address:

5264 Genetics/Biotech

Telephone:

265-5405

Email:

xsun@wisc.edu

Research Fields:

Human and Mammalian

Developmental Genetics

Mouse Genetics

Research Interests

Molecular Genetics of Vertebrate Organogenesis; Animal Pattern Formation and Evolution

Research Description

Vertebrate organogenesis follows stereotypic cellular programs, indicating precise genetic control. Deviations from these programs result in birth defects. We study the molecular mechanisms of organogenesis using a combination of mouse genetic, genomic and organ culture approaches, along with chick embryonic manipulation. The two organ systems we concentrate on are the limb and the lung. Regarding limb, our study of the Fibroblast Growth Factor (FGF) family of molecules led to data that challenge a prominent model in developmental biology (the Progress Zone model). Our current investigation focuses on testing new models, as well as identifying molecules that mediate FGF function in limb. Our second organ system of interest, the lung, is vital starting the first day of life. The mammalian lung initiates as a simple lung bud, then undergoes elaborate branching morphogenesis and cell differentiation to form a respiratory tree with vast surface area and specialized cell types to facilitate gas exchange. Despite its importance, the molecular mechanisms underlying many aspects of lung formation are poorly understood and are the subjects of our study. Based on emerging similarities between cellular events in adult organ homeostasis and embryonic organ formation, findings in organogenesis have prompted parallel investigations in lung stem cell maintenance and activation. We anticipate that our research on lung will contribute to the understanding of lung diseases such as cancer and asthma. An additional fascinating feature of the lung is the vast array of distinct lung morphologies among vertebrates, a result of adaptation to diverse habitats and metabolic requirements. We are beginning to investigate the embryological and molecular basis of lung evolution.

Representative Publications

• Verheyden, J.M, and Sun, X. 2008. An Fgf/Gremlin inhibitory feedback loop triggers termination of limb bud outgrowth. Nature. 454:638-41.
• Verheyden, J.M., Lewandoski, M., Deng, C., Harfe, B.D. and Sun, X. 2005. Conditional inactivation of Fgfr1 in mouse defines its role in limb bud establishment, outgrowth and digit patterning. Development. 132:4235-4245..
• Sun, X., Mariani, F. and Martin, G.R. 2002. Functions of FGF signaling from the apical ectodermal ridge in limb development. Nature. 418:501-508.
• Lewandoski, M., Sun, X. and Martin, G.R. 2000. FGF8-signaling from the AER is essential for normal limb development. Nature Genet. 26:460-463.
• Sun, X., Lewandoski, M., Meyers, E.N., Liu, Y.-H., Maxson, R.E.,Jr. and Martin, G.R. 2000. Conditional inactivation of Fgf4 reveals complexity of signaling during limb bud development. Nature Genet. 25:83-86.