Multiple lineage-specific roles of Smad4 during neural crest development.
During vertebrate development, neural crest cells are exposed to multiple extracellular cues that drive their differentiation into neural and non-neural cell lineages. Insights into the signals potentially involved in neural crest cell fate decisions in vivo have been gained by cell culture experiments that have allowed the identification of instructive growth factors promoting either proliferation of multipotent neural crest cells or acquisition of specific fates. For instance, members of the TGFbeta factor family induce neurogenesis and smooth muscle cell formation at the expense of other fates in culture. In vivo, conditional ablation of various TGFbeta signaling components resulted in malformations of non-neural derivatives of the neural crest, but it is unclear whether these phenotypes involved aberrant fate decisions. Moreover, it remains to be shown whether neuronal determination indeed requires TGFbeta factor activity in vivo. To address these issues, we conditionally deleted Smad4 in the neural crest, thus inactivating all canonical TGFbeta factor signaling. Surprisingly, neural crest cell fates were not affected in these mutants, with the exception of sensory neurogenesis in trigeminal ganglia. Rather, Smad4 regulates survival of smooth muscle and proliferation of autonomic and ENS neuronal progenitor cells. Thus, Smad signaling plays multiple, lineage-specific roles in vivo, many of which are elicited only after neural crest cell fate decision.
Division of Cell and Developmental Biology, Institute of Anatomy, University of Zurich, CH-8057 Zurich, Switzerland.
Stine
S
Büchmann-Møller
Iris
I
Miescher
Nessy
N
John
Jaya
J
Krishnan
Chu-Xia
CX
Deng
Lukas
L
Sommer
D000818:Animals; D001483:Base Sequence; D049109:Cell Proliferation; D002478:Cells, Cultured; D017931:DNA Primers; D051379:Mice; D018345:Mice, Knockout; D009130:Muscle, Smooth / Q000166:cytology / Q000196:embryology; D009432:Neural Crest / Q000166:cytology / Q000196:embryology*; D055495:Neurogenesis; D015398:Signal Transduction; D051901:Smad4 Protein / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000378:metabolism
D017931:DNA Primers; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D016212:Transforming Growth Factor beta