title: Expression and function of the LIM-homeodomain transcription factor Islet-1 in the developing and mature vertebrate retina.
abstract: The LIM-homeodomain transcription factor Islet-1 (Isl1) has been widely used as a marker of different subtypes of neurons in the developing and mature retina of vertebrates. During retinal neurogenesis, early Isl1 expression is detected in the nuclei of neuroblasts that give rise to ganglion, amacrine, bipolar, and horizontal cells. In the mature retina, Isl1 expression is restricted to the nuclei of ganglion cells, cholinergic amacrine cells, ON-bipolar cells, and subpopulations of horizontal cells. Recent studies have explored the functional mechanisms of Isl1 during specification and differentiation of these retinal cell types. Thus, conditional inactivation of Isl1 in the developing mouse retina disrupts retinal function, and also results in optic nerve hypoplasia, marked reductions in mature ganglion, amacrine, and bipolar cells, and a substantial increase in horizontal cells. Furthermore, conditional knockout shows delayed ganglion cell axon growth, ganglion cell axon guidance error, and ganglion cell nerve fiber defasciculation. These data together suggest a possible role for Isl1 in the early differentiation and maintenance of different vertebrate retinal cell types. This review examines whether the expression pattern of Isl1 during vertebrate retinal development is conserved across vertebrate species, and discusses current understanding of the developmental functions of Isl1 in retinogenesis.
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain.
authors.forename: Ruth
authors.initials: R
authors.lastname: Bejarano-Escobar
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Álvarez-Hernán
authors.affiliation: Departamento de Biología Celular, Facultad de Biología, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Ruth
authors.initials: R
authors.lastname: Morona
authors.affiliation: Departamento de Biología Celular, Facultad de Biología, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Agustín
authors.initials: A
authors.lastname: González
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain.
authors.forename: Gervasio
authors.initials: G
authors.lastname: Martín-Partido
authors.affiliation: Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain. Electronic address: morcillo@unex.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Francisco-Morcillo
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D005123:Eye / Q000196:embryology; D006801:Humans; D060850:LIM-Homeodomain Proteins / Q000378:metabolism*; D055495:Neurogenesis / Q000502:physiology*; D012160:Retina / Q000196:embryology* / Q000502:physiology; D055351:Retinal Neurons / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D060850:LIM-Homeodomain Proteins; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1
keywords: Eye development; Islet-1; LIM-homeobox; Neural retina; Retinogenesis; Transcription factor