Pitx2 promotes development of splanchnic mesoderm-derived branchiomeric muscle.
Recent experiments, showing that both cranial paraxial and splanchnic mesoderm contribute to branchiomeric muscle and cardiac outflow tract (OFT) myocardium, revealed unexpected complexity in development of these muscle groups. The Pitx2 homeobox gene functions in both cranial paraxial mesoderm, to regulate eye muscle, and in splanchnic mesoderm to regulate OFT development. Here, we investigated Pitx2 in branchiomeric muscle. Pitx2 was expressed in branchial arch core mesoderm and both Pitx2 null and Pitx2 hypomorphic embryos had defective branchiomeric muscle. Lineage tracing with a Pitx2cre allele indicated that Pitx2 mutant descendents moved into the first branchial arch. However, markers of both undifferentiated core mesoderm and specified branchiomeric muscle were absent. Moreover, lineage tracing with a Myf5cre allele indicated that branchiomeric muscle specification and differentiation were defective in Pitx2 mutants. Conditional inactivation in mice and manipulation of Pitx2 expression in chick mandible cultures revealed an autonomous function in expansion and survival of branchial arch mesoderm.
Dong
Feiyan
F
Institute of Biosciences and Technology, Texas A&M System Health Science Center, Houston, TX 77030, USA.
Sun
Xiaoxia
X
Liu
Wei
W
Ai
Di
D
Klysik
Elizabetha
E
Lu
Mei-Fang
MF
Hadley
Julia
J
Antoni
Laurent
L
Chen
Li
L
Baldini
Antonio
A
Francis-West
Pip
P
Martin
James F
JF
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D005075:Biological Evolution; D001934:Branchial Region / Q000196:embryology* / Q000502:physiology; D002642:Chick Embryo; D005152:Facial Muscles / Q000196:embryology* / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D008648:Mesoderm / Q000502:physiology*; D051379:Mice; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000196:embryology* / Q000502:physiology; D009154:Mutation; D032446:Myoblasts / Q000502:physiology; D009334:Neck Muscles / Q000196:embryology* / Q000502:physiology; D020825:T-Box Domain Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D000097577:Homeobox Protein PITX2
D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D020825:T-Box Domain Proteins; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2; C117673:Msc protein, mouse; C491573:Tbx1 protein, mouse