|Title||Early chordate origins of the vertebrate second heart field.|
|Publication Type||Journal Article|
|Year of Publication||2010|
|Authors||Stolfi, A, T Gainous, B, Young, JJ, Mori, A, Levine, M, Christiaen, L|
|Date Published||2010 Jul 30|
|Keywords||Animals, Biological Evolution, Cell Movement, Ciona intestinalis, Embryo, Nonmammalian, Embryonic Development, Heart, Jaw, Mesoderm, Metamorphosis, Biological, Muscle, Skeletal, Muscles, Myocytes, Cardiac, Pharyngeal Muscles, Stem Cells, Transcription Factors, Vertebrates, Xenopus|
The vertebrate heart is formed from diverse embryonic territories, including the first and second heart fields. The second heart field (SHF) gives rise to the right ventricle and outflow tract, yet its evolutionary origins are unclear. We found that heart progenitor cells of the simple chordate Ciona intestinalis also generate precursors of the atrial siphon muscles (ASMs). These precursors express Islet and Tbx1/10, evocative of the splanchnic mesoderm that produces the lower jaw muscles and SHF of vertebrates. Evidence is presented that the transcription factor COE is a critical determinant of ASM fate. We propose that the last common ancestor of tunicates and vertebrates possessed multipotent cardiopharyngeal muscle precursors, and that their reallocation might have contributed to the emergence of the SHF.