@article{7d3e4294ff3e48c1b48920094297a1a4,
title = "CDON contributes to Hedgehog-dependent patterning and growth of the developing limb",
abstract = "Hedgehog (HH) signaling is a major driver of tissue patterning during embryonic development through the regulation of a multitude of cell behaviors including cell fate specification, proliferation, migration, and survival. HH ligands signal through the canonical receptor PTCH1 and three co-receptors, GAS1, CDON and BOC. While previous studies demonstrated an overlapping and collective requirement for these co-receptors in early HH-dependent processes, the early embryonic lethality of Gas1;Cdon;Boc mutants precluded an assessment of their collective contribution to later HH-dependent signaling events. Specifically, a collective role for these co-receptors during limb development has yet to be explored. Here, we investigate the combined contribution of these co-receptors to digit specification, limb patterning and long bone growth through limb-specific conditional deletion of Cdon in a Gas1;Boc null background. Combined deletion of Gas1, Cdon and Boc in the limb results in digit loss as well as defects in limb outgrowth and long bone patterning. Taken together, these data demonstrate that GAS1, CDON and BOC are collectively required for HH-dependent patterning and growth of the developing limb.",
keywords = "BOC, CDON, Digit specification, GAS1, HH co-receptors, Hedgehog, Limb development",
author = "Echevarr{\'i}a-Andino, {Martha L.} and Franks, {Nicole E.} and Schrader, {Hannah E.} and Mingi Hong and Krauss, {Robert S.} and Allen, {Benjamin L.}",
note = "Funding Information: During limb patterning, one of the three mammalian HH ligands, Sonic Hedgehog (SHH) is secreted from the zone of polarizing activity (ZPA) to regulate anterior-posterior patterning (Echelard et al., 1993; Riddle et al., 1993; Saunders and Gasseling, 1968). Specifically, SHH regulates the outgrowth of the limb, and dictates the specification of digits 2 to 5 (index to pinky) (Ahn and Joyner, 2004; Chiang et al., 1996; Harfe et al., 2004; Scherz et al., 2007). Genetic removal of Shh results in severe patterning defects in the distal skeletal elements of both forelimbs and hindlimbs and complete absence of digits 2–5 (Chiang et al., 1996). Digit 1 (thumb) is retained in Shh mutants, suggesting its patterning is SHH-independent (Chiang et al., 1996). SHH-dependent digit specification is regulated by the SHH morphogen gradient through autocrine (digits 5, 4, and part of 3) and paracrine (part of digit 3 and digit 2) signaling (Harfe et al., 2004; Scherz et al., 2007). Despite detailed genetic and pharmacologic studies supporting this model, it is still unclear how SHH mediates digit specification during limb patterning (Harfe et al., 2004; Scherz et al., 2007). While different models for SHH-dependent digit specification have been proposed, HH co-receptor function has not been integrated into these models (Ahn and Joyner, 2004; Drossopoulou et al., 2000; Sanz-Ezquerro and Tickle, 2000; Towers et al., 2008; Zhu et al., 2008, 2022). Additionally, during limb development a second mammalian ligand, Indian Hedgehog (IHH), is required for proper development of the long bones of the skeleton. Specifically, Ihh mutants display severe limb defects characterized by shortened bones with abnormal morphology and delayed mineralization (Amano et al., 2015; St-Jacques et al., 1999). It remains unclear whether IHH signals through the HH co-receptors to mediate long bone development.This work was supported by the National Science Foundation Graduate Research Fellowship Program [DGE1256260], Bradley M. Patten Fellowship [Department of Cell and Developmental Biology, Medical School University of Michigan], Rackham Merit Fellowship [Horace H. Rackham School of Graduate Studies, University of Michigan], and the Center for Cell Plasticity and Organ Design [T32 HD007505], awarded to M.L.E.-A. This work was also supported by the National Institutes of Health [R01 DC014428, R01 CA198074, R01 GM118751, to B.L.A. and R01 DE24748 and R01 AR070231 to R.S.K.]. The research in this publication was also supported by the University of Michigan Comprehensive Cancer Center Support Grant [P30 CA046592] by the use of the following Cancer Center Shared Resource: Cell and Tissue Imaging.We thank members of the Allen lab for discussions and experimental suggestions. We also thank Dr. Ernestina Schipani (University of Pennsylvania) for providing the Prx1-Cre allele. We also gratefully acknowledge the Department of Cell and Developmental Biology for providing access to research equipment. Finally, we acknowledge the Biomedical Research Core Facilities Microscopy Core for providing access to confocal microscopy equipment, which is supported by the Rogel Cancer Center. Funding Information: We thank members of the Allen lab for discussions and experimental suggestions. We also thank Dr. Ernestina Schipani (University of Pennsylvania) for providing the Prx1-Cre allele. We also gratefully acknowledge the Department of Cell and Developmental Biology for providing access to research equipment. Finally, we acknowledge the Biomedical Research Core Facilities Microscopy Core for providing access to confocal microscopy equipment, which is supported by the Rogel Cancer Center . Funding Information: This work was supported by the National Science Foundation Graduate Research Fellowship Program [ DGE1256260 ], Bradley M. Patten Fellowship [Department of Cell and Developmental Biology, Medical School University of Michigan], Rackham Merit Fellowship [Horace H. Rackham School of Graduate Studies, University of Michigan], and the Center for Cell Plasticity and Organ Design [ T32 HD007505 ], awarded to M.L.E.-A. This work was also supported by the National Institutes of Health [ R01 DC014428 , R01 CA198074 , R01 GM118751 , to B.L.A. and R01 DE24748 and R01 AR070231 to R.S.K.]. The research in this publication was also supported by the University of Michigan Comprehensive Cancer Center Support Grant [ P30 CA046592 ] by the use of the following Cancer Center Shared Resource: Cell and Tissue Imaging. Publisher Copyright: {\textcopyright} 2022",
year = "2023",
month = jan,
doi = "10.1016/j.ydbio.2022.09.011",
language = "English",
volume = "493",
pages = "1--11",
journal = "Developmental Biology",
issn = "0012-1606",
publisher = "Elsevier Inc.",
}