Scaling Pattern to Variations in Size during Development of the Vertebrate Neural Tube.
Anatomical proportions are robustly maintained in individuals that vary enormously in size, both within a species and between members of related taxa. However, the mechanisms underlying scaling are still poorly understood. We have examined this phenomenon in the context of the patterning of the ventral neural tube in response to a gradient of the morphogen Sonic hedgehog (SHH) in the chick and zebra finch, two species that differ in size during the time of neural tube patterning. We find that scaling is achieved, at least in part, by altering the sensitivity of the target cells to SHH and appears to be achieved by modulating the ratio of the repressive and activating transcriptional regulators, GLI2 and GLI3. This mechanism contrasts with previous experimental and theoretical analyses of morphogenic scaling that have focused on compensatory changes in the morphogen gradient itself.
Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
Aysu
A
Uygur
Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
John
J
Young
Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
Tyler R
TR
Huycke
Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
Mervenaz
M
Koska
Mill Hill Laboratory, The Francis Crick Institute, London NW7 1AA, UK.
James
J
Briscoe
Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA. Electronic address: tabin@genetics.med.harvard.edu.
Clifford J
CJ
Tabin
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D002645:Chickens; D047108:Embryonic Development / Q000502:physiology; D004627:Embryonic Induction / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D053823:Hedgehog Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D054259:Neural Tube / Q000254:growth & development*; D009474:Neurons / Q000378:metabolism*; D013116:Spinal Cord / Q000254:growth & development; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014714:Vertebrates / Q000254:growth & development
D053823:Hedgehog Proteins; D009419:Nerve Tissue Proteins; D015534:Trans-Activators; D014157:Transcription Factors