title: Suppressor of Fused Is Required for Determining Digit Number and Identity via Gli3/Fgfs/Gremlin.
abstract: The anterior-posterior patterning of the vertebrate limb bud requires closely coordinated signaling interactions, including Sonic Hedgehog (Shh)-mediated counteraction of the Gli3 transcription factor in the distal and posterior mesenchyme of the limb bud. Suppressor of Fused (Sufu), an intracellular negative regulator of Shh signaling via Gli2 and Gli3, is implicated in early development of the mouse limb bud. However, how Sufu is involved in the genetic regulation of limb bud patterning still remains elusive. In this study, we show that the conditional deletion of Sufu in the mesenchyme of the early limb bud results in polydactyly with loss of digit identity and supernumerary bones in the wrist and the ankle. These pattern alterations are associated with anterior expansion of HoxD genes located at the 5' end of the cluster. By focusing on gene expression analysis of Shh/Gremlin1/Fgf signaling critical for the establishment and maintenance of anterior-posterior patterning, we show that early response to loss of Sufu involves anterior prolongation of Fgf4 and Fgf8 expression in the apical ectodermal ridge at E10.5. We also reveal the anterior activation of Shh-dependent posterior markers Ptc1, Gli1 and Gremlin in limb buds lacking Sufu. Furthermore, we find that loss of Sufu leads to attenuated levels of repressor Gli2 and repressor Gli3 in the early limb bud. Moreover, expression of Hand2 is activated in the entire limb bud at the early outgrowth stage in the mutant lacking Sufu. Thus, we provide evidence that Sufu is involved in the genetic network that restricts the posterior expression of Gli2/3/Hand2 and Gremlin/Fgf in limb bud patterning.
authors.affiliation: Zhejiang Key Laboratory for Organogenesis and Regenerative technology, Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Jianying
authors.initials: J
authors.lastname: Li
authors.affiliation: Zhejiang Key Laboratory for Organogenesis and Regenerative technology, Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Qihui
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Zhejiang Key Laboratory for Organogenesis and Regenerative technology, Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Zhejiang Key Laboratory for Organogenesis and Regenerative technology, Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Xueqin
authors.initials: X
authors.lastname: Yang
authors.affiliation: Zhejiang Key Laboratory for Organogenesis and Regenerative technology, Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Zhejiang Key Laboratory for Organogenesis and Regenerative technology, Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Zhejiang Key Laboratory for Organogenesis and Regenerative technology, Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China; Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky 40292, United States of America.
authors.forename: Mengsheng
authors.initials: M
authors.lastname: Qiu
authors.affiliation: Department of Ophthalmology, Tulane University Medical Center, New Orleans, Louisiana 70112, United States of America.
authors.forename: Ze
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Zhejiang Key Laboratory for Organogenesis and Regenerative technology, Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Zunyi
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D019521:Body Patterning / Q000235:genetics; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D053263:Gene Regulatory Networks; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D017689:Polydactyly / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*; D014034:Toes / Q000254:growth & development*; D000074290:Zinc Finger Protein Gli3; D016207:Cytokines
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D005346:Fibroblast Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D051741:Kruppel-Like Transcription Factors; D009419:Nerve Tissue Proteins; D012097:Repressor Proteins; D000074290:Zinc Finger Protein Gli3; C465571:Gli3 protein, mouse; C498766:Hand2 protein, mouse; C490763:Sufu protein, mouse; C113178:Grem1 protein, mouse; D016207:Cytokines