A functional skeletal system depends upon the coordinated development of cartilages and joints during embryogenesis. However, little is known about the cellular and molecular mechanisms that control cartilage size, shape or connectivity. Progress unraveling the signals that direct mesenchymal cells to condense and align into prechondrogenic stacks is of particular importance in elucidation of the early events that shape the organization and growth of the skeleton. Understanding these processes will allow better diagnostic approaches and treatments for skeletal malformations and birth defects. Moreover, molecules that control cartilage morphogenesis and differentiation may be of considerable clinical importance both for improvements in the treatment of cartilage and joint injuries and in bioengineering efforts to induce cartilage formation from stem cells. Our recent finding that Rere, a close relative of the transcription factor Atrophin which regulates Dachsous (Dchs)-Fat signaling in flies, is required for craniofacial development in zebrafish has implicated the Fat pathway in planar cell polarity (PCP) during skeletogenesis. Dramatic results from our laboratory now demonstrate an even more profound role for a Fat3 in cartilage differentiation, consistent with PCP. Embryos deficient in Rere or Fat3 develop cartilages in which stacking and differentiation are uncoupled in the pharyngeal arches and this leads to joint fusion. Moreover, Rere and Fat3 are critical for coordinating responses of skeletal progenitors to Bmp and Fgf signaling during craniofacial development. We propose to explore the roles of the Fat pathway and PCP in cartilage and joint formation in three sets of experiments.
The first aim will address the hypothesis that the Fat pathway couples cartilage stacking and differentiation. Cartilage and joint phenotypes will be evaluated in Rere and Fat3 mutants using live imaging. We will identify the Dchs ligand(s) for Fat in cartilage and create ectopic sources to study signal propagation and modulation. We will also compare the activities of the Fat pathway and Wnt/PCP and their interdependence in cartilage development.
The second aim will address the hypothesis that the Fat pathway coordinates polarized responses to Bmps and other growth factors, thereby linking early patterning events with later organ formation. For this we have new markers of cytoskeletal polarity and cilia that reveal unexpected boundaries of polarity in skeletal progenitors. Finally, the third aim will focus on joint formation and test the hypothesis that the Fat pathway prevents cartilage stacking and differentiation in the joint interzone with inducible elimination or overexpression of Rere or Fat3. Together these studies will lead to mechanistic insights into the relatively unexplored functions of the vertebrate Fat pathway in cell-cell communication and identify candidate genes for as yet unresolved causes of human congenital skeletal malformations.

Public Health Relevance

The proposed studies will provide some of the first evidence that the Fat pathway influences skeletogenesis. Defining molecules that control cartilage development may be of clinical importance both for improving treatments for cartilage and joint injuries and in efforts to induce cartilage from stem cells. The Fat pathway component Rere is also implicated in dentatorubral-pallido-luysian atrophy and understanding its functions could help improve diagnosis and treatments for this and related neurodegenerative diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE013828-13
Application #
8699030
Study Section
Skeletal Biology Development and Disease Study Section (SBDD)
Program Officer
Scholnick, Steven
Project Start
2001-04-01
Project End
2017-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
13
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of California Irvine
Department
Anatomy/Cell Biology
Type
Schools of Arts and Sciences
DUNS #
City
Irvine
State
CA
Country
United States
Zip Code
92697
Aguillon, Raphaël; Batut, Julie; Subramanian, Arul et al. (2018) Cell-type heterogeneity in the early zebrafish olfactory epithelium is generated from progenitors within preplacodal ectoderm. Elife 7:
Vibert, Laura; Aquino, Gerardo; Gehring, Ines et al. (2017) An ongoing role for Wnt signaling in differentiating melanocytes in vivo. Pigment Cell Melanoma Res 30:219-232
Le Pabic, Pierre; Cooper, W James; Schilling, Thomas F (2016) Developmental basis of phenotypic integration in two Lake Malawi cichlids. Evodevo 7:3
Boer, Elena F; Howell, Elizabeth D; Schilling, Thomas F et al. (2015) Fascin1-dependent Filopodia are required for directional migration of a subset of neural crest cells. PLoS Genet 11:e1004946
Subramanian, Arul; Schilling, Thomas F (2015) Tendon development and musculoskeletal assembly: emerging roles for the extracellular matrix. Development 142:4191-204
Le Pabic, Pierre; Ng, Carrie; Schilling, Thomas F (2014) Fat-Dachsous signaling coordinates cartilage differentiation and polarity during craniofacial development. PLoS Genet 10:e1004726
Subramanian, Arul; Schilling, Thomas F (2014) Thrombospondin-4 controls matrix assembly during development and repair of myotendinous junctions. Elife 3:
Tuttle, Adam M; Hoffman, Trevor L; Schilling, Thomas F (2014) Rabconnectin-3a regulates vesicle endocytosis and canonical Wnt signaling in zebrafish neural crest migration. PLoS Biol 12:e1001852
Alexander, Courtney; Piloto, Sarah; Le Pabic, Pierre et al. (2014) Wnt signaling interacts with bmp and edn1 to regulate dorsal-ventral patterning and growth of the craniofacial skeleton. PLoS Genet 10:e1004479
Wu, Beibei; Piloto, Sarah; Zeng, Weihua et al. (2013) Ring Finger Protein 14 is a new regulator of TCF/ýý-catenin-mediated transcription and colon cancer cell survival. EMBO Rep 14:347-55

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