Exclusion of Dlx5/6 expression from the distal-most mandibular arches enables BMP-mediated specification of the distal cap

Significance Within the developing mandible, proper specification and positioning of bone, tongue, and teeth are controlled by secreted morphogens. Among these morphogenetic cues, endothelin 1 (EDN1) and bone morphogenic proteins (BMPs) divide the nascent mandible into subdomains along a proximo-distal axis. The transcriptional mechanisms by which mandibular progenitor cells interpret morphogenetic signals to establish these subdomains are poorly understood. Here, we characterize a Hand1 enhancer that drives gene expression specifically within the distal-most of these subdomains, the distal cap. Our findings show that Bmp-dependent transcription factors provide positive transcriptional inputs that serve to counteract the repressive activity of EDN1-dependent transcription factors within the distal cap, thus integrating the communication between BMP and EDN1 signaling that patterns the mandible. Cranial neural crest cells (crNCCs) migrate from the neural tube to the pharyngeal arches (PAs) of the developing embryo and, subsequently, differentiate into bone and connective tissue to form the mandible. Within the PAs, crNCCs respond to local signaling cues to partition into the proximo-distally oriented subdomains that convey positional information to these developing tissues. Here, we show that the distal-most of these subdomains, the distal cap, is marked by expression of the transcription factor Hand1 (H1) and gives rise to the ectomesenchymal derivatives of the lower incisors. We uncover a H1 enhancer sufficient to drive reporter gene expression within the crNCCs of the distal cap. We show that bone morphogenic protein (BMP) signaling and the transcription factor HAND2 (H2) synergistically regulate H1 distal cap expression. Furthermore, the homeodomain proteins distal-less homeobox 5 (DLX5) and DLX6 reciprocally inhibit BMP/H2-mediated H1 enhancer regulation. These findings provide insights into how multiple signaling pathways direct transcriptional outcomes that pattern the developing jaw.

[1]  Shuichi Tsutsumi,et al.  ChIP-seq reveals cell type-specific binding patterns of BMP-specific Smads and a novel binding motif , 2011, Nucleic acids research.

[2]  G. Levi,et al.  Endothelin-A receptor-dependent and -independent signaling pathways in establishing mandibular identity , 2004, Development.

[3]  Joshua W. Vincentz,et al.  Analysis of the Hand1 cell lineage reveals novel contributions to cardiovascular, neural crest, extra‐embryonic, and lateral mesoderm derivatives , 2010, Developmental dynamics : an official publication of the American Association of Anatomists.

[4]  Joshua W. Vincentz,et al.  Twist1 Controls a Cell-Specification Switch Governing Cell Fate Decisions within the Cardiac Neural Crest , 2013, PLoS genetics.

[5]  Y. Leshem,et al.  Twist1 dimer selection regulates cranial suture patterning and fusion , 2006, Developmental dynamics : an official publication of the American Association of Anatomists.

[6]  Y. Uchijima,et al.  Endothelin regulates neural crest deployment and fate to form great vessels through Dlx5/Dlx6-independent mechanisms , 2013, Mechanisms of Development.

[7]  H. Rohrer,et al.  The transcription factor dHAND is a downstream effector of BMPs in sympathetic neuron specification. , 2000, Development.

[8]  E. Olson,et al.  Hand transcription factors cooperatively regulate development of the distal midline mesenchyme. , 2007, Developmental biology.

[9]  R. Krumlauf,et al.  19 – Neural Crest Cells , 2004 .

[10]  S. Conway,et al.  Mutations within Helix I of Twist1 Result in Distinct Limb Defects and Variation of DNA Binding Affinities* , 2007, Journal of Biological Chemistry.

[11]  Joshua W. Vincentz,et al.  A Phox2- and Hand2-Dependent Hand1 cis-Regulatory Element Reveals a Unique Gene Dosage Requirement for Hand2 during Sympathetic Neurogenesis , 2012, The Journal of Neuroscience.

[12]  R. Behringer,et al.  Requirement for Twist1 in frontonasal and skull vault development in the mouse embryo. , 2009, Developmental biology.

[13]  B. Hogan,et al.  BMP signaling in the development of the mouse esophagus and forestomach , 2010, Development.

[14]  Joshua W. Vincentz,et al.  Hand1 phosphoregulation within the distal arch neural crest is essential for craniofacial morphogenesis , 2014, Development.

[15]  Karl K. Murphy,et al.  Functional characterization of tissue-specific enhancers in the DLX5/6 locus. , 2012, Human molecular genetics.

[16]  M. Morasso,et al.  Transcriptional activation by the homeodomain protein distal-less 3. , 1999, Nucleic acids research.

[17]  J. D. Engel,et al.  Temporal and spatial control of murine GATA-3 transcription by promoter-proximal regulatory elements. , 1997, Developmental biology.

[18]  J. Rubenstein,et al.  Dlx genes pattern mammalian jaw primordium by regulating both lower jaw-specific and upper jaw-specific genetic programs , 2008, Development.

[19]  A. Visel,et al.  HAND2 targets define a network of transcriptional regulators that compartmentalize the early limb bud mesenchyme. , 2014, Developmental cell.

[20]  Yanding Zhang,et al.  Directed Bmp4 expression in neural crest cells generates a genetic model for the rare human bony syngnathia birth defect. , 2014, Developmental biology.

[21]  C. Wolberger.  Homeodomain interactions. , 1996, Current opinion in structural biology.

[22]  D. Srivastava,et al.  Heart and extra-embryonic mesodermal defects in mouse embryos lacking the bHLH transcription factor Hand1 , 1998, Nature Genetics.

[23]  R. Schwartz,et al.  Threshold-specific requirements for Bmp4 in mandibular development. , 2005, Developmental biology.

[24]  Joshua W. Vincentz,et al.  Hand2 Loss-of-Function in Hand1-Expressing Cells Reveals Distinct Roles in Epicardial and Coronary Vessel Development , 2011, Circulation research.

[25]  Joshua W. Vincentz,et al.  An absence of Twist1 results in aberrant cardiac neural crest morphogenesis. , 2008, Developmental biology.

[26]  E. Olson,et al.  Targeted deletion of a branchial arch-specific enhancer reveals a role of dHAND in craniofacial development , 2003, Development.

[27]  Y. Kaneda,et al.  Comparative roles of Twist-1 and Id1 in transcriptional regulation by BMP signaling , 2007, Journal of Cell Science.

[28]  Jun Wang,et al.  Bmp signaling regulates a dose-dependent transcriptional program to control facial skeletal development , 2012, Development.

[29]  K. Kinzler,et al.  Human Smad3 and Smad4 are sequence-specific transcription activators. , 1998, Molecular cell.

[30]  E. Jabs,et al.  A twisted hand: bHLH protein phosphorylation and dimerization regulate limb development. , 2005, BioEssays : news and reviews in molecular, cellular and developmental biology.

[31]  K. Lyons,et al.  A phylogenetically conserved cis-regulatory module in the Msx2 promoter is sufficient for BMP-dependent transcription in murine and Drosophila embryos , 2004, Development.

[32]  Y. Chai,et al.  Recent advances in craniofacial morphogenesis , 2006, Developmental dynamics : an official publication of the American Association of Anatomists.

[33]  H. Luder,et al.  Deletion of BMP7 affects the development of bones, teeth, and other ectodermal appendages of the orofacial complex. , 2009, Journal of experimental zoology. Part B, Molecular and developmental evolution.

[34]  M. Depew,et al.  21st Century neontology and the comparative development of the vertebrate skull , 2006, Developmental dynamics : an official publication of the American Association of Anatomists.

[35]  Joshua W. Vincentz,et al.  Cooperative interaction of Nkx2.5 and Mef2c transcription factors during heart development , 2008, Developmental dynamics : an official publication of the American Association of Anatomists.

[36]  Daniel Meulemans Medeiros,et al.  New perspectives on pharyngeal dorsoventral patterning in development and evolution of the vertebrate jaw. , 2012, Developmental biology.

[37]  Francie Barron,et al.  Downregulation of Dlx5 and Dlx6 expression by Hand2 is essential for initiation of tongue morphogenesis , 2011, Development.

[38]  D. Stainier,et al.  A conserved role for H15-related T-box transcription factors in zebrafish and Drosophila heart formation. , 2000, Developmental biology.

[39]  James Douglas Engel,et al.  Targeted disruption of the GATA3 gene causes severe abnormalities in the nervous system and in fetal liver haematopoiesis , 1995, Nature Genetics.

[40]  T. Schilling,et al.  Neural Crest Cells in Craniofacial Skeletal Development , 2014 .