title: Islet1-expressing cardiac progenitor cells: a comparison across species.
abstract: Adult mammalian cardiac stem cells express the LIM-homeodomain transcription factor Islet1 (Isl1). They are considered remnants of Isl1-positive embryonic cardiac progenitor cells. During amniote heart development, Isl1-positive progenitor cells give rise mainly to the outflow tract, the right ventricle, and parts of the atria. This led to the hypothesis that the development of the right ventricle of the amniote heart depends on the recruitment of additional cells to the primary heart tube. The region from which these additional, Isl1-positive cells originate is called second heart field, as opposed to the first heart field whose cells form the primary heart tube. Here, we review the available data about Isl1 in different species, demonstrating that Isl1 is an important component of the core transcription factor network driving early cardiogenesis in animals of the two clades, deuterostomes, and protostomes. The data support the view of a single cardiac progenitor cell population that includes Isl1-expressing cells and which differentiates into the various cardiac lineages during embryonic development in vertebrates but not in other phyla of the animal kingdom.
authors.affiliation: Institute for Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Pandur
authors.forename: Ioan Ovidiu
authors.initials: IO
authors.lastname: Sirbu
authors.forename: Susanne J
authors.initials: SJ
authors.lastname: Kühl
authors.forename: Melanie
authors.initials: M
authors.lastname: Philipp
authors.forename: Michael
authors.initials: M
authors.lastname: Kühl
mesh_terms: D000818:Animals; D053263:Gene Regulatory Networks; D006321:Heart / Q000196:embryology*; D006801:Humans; D060850:LIM-Homeodomain Proteins / Q000378:metabolism*; D032386:Myoblasts, Cardiac / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D060850:LIM-Homeodomain Proteins; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1