title: The LIM homeodomain factor Lhx2 is required for hypothalamic tanycyte specification and differentiation.
abstract: Hypothalamic tanycytes, a radial glial-like ependymal cell population that expresses numerous genes selectively enriched in embryonic hypothalamic progenitors and adult neural stem cells, have recently been observed to serve as a source of adult-born neurons in the mammalian brain. The genetic mechanisms that regulate the specification and maintenance of tanycyte identity are unknown, but are critical for understanding how these cells can act as adult neural progenitor cells. We observe that LIM (Lin-11, Isl-1, Mec-3)-homeodomain gene Lhx2 is selectively expressed in hypothalamic progenitor cells and tanycytes. To test the function of Lhx2 in tanycyte development, we used an intersectional genetic strategy to conditionally delete Lhx2 in posteroventral hypothalamic neuroepithelium, both embryonically and postnatally. We observed that tanycyte development was severely disrupted when Lhx2 function was ablated during embryonic development. Lhx2-deficient tanycytes lost expression of tanycyte-specific genes, such as Rax, while also displaying ectopic expression of genes specific to cuboid ependymal cells, such as Rarres2. Ultrastructural analysis revealed that mutant tanycytes exhibited a hybrid identity, retaining radial morphology while becoming multiciliated. In contrast, postnatal loss of function of Lhx2 resulted only in loss of expression of tanycyte-specific genes. Using chromatin immunoprecipitation, we further showed that Lhx2 directly regulated expression of Rax, an essential homeodomain factor for tanycyte development. This study identifies Lhx2 as a key intrinsic regulator of tanycyte differentiation, sustaining Rax-dependent activation of tanycyte-specific genes while also inhibiting expression of ependymal cell-specific genes. These findings provide key insights into the transcriptional regulatory network specifying this still poorly characterized cell type.
authors.affiliation: Department of Neuroscience.
authors.forename: Juan
authors.initials: J
authors.lastname: Salvatierra
authors.affiliation: Department of Neuroscience, Department of Biology and Bioengineering, California Institute of Technology, Pasadena, California 91125.
authors.forename: Daniel A
authors.identifier: http://orcid.org/0000-0001-7411-2740
authors.initials: DA
authors.lastname: Lee
authors.affiliation: Department of Neuroscience.
authors.forename: Cristina
authors.initials: C
authors.lastname: Zibetti
authors.affiliation: Neuroregeneration and Multiple Sclerosis Research Unit, University of Valencia/Hospital La Fe, Valencia 46009, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Duran-Moreno
authors.affiliation: Department of Neuroscience.
authors.forename: Sooyeon
authors.identifier: http://orcid.org/0000-0003-4718-900X
authors.initials: S
authors.lastname: Yoo
authors.affiliation: Department of Neuroscience.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Newman
authors.affiliation: Department of Neuroscience.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Neuroscience.
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Bedont
authors.affiliation: Department of Neuroscience.
authors.forename: Jimmy
authors.initials: J
authors.lastname: de Melo
authors.affiliation: Department of Neuroscience, Institute of Medical Research, Universidad de Antioquia, Medellín, Colombia 050001.
authors.forename: Ana L
authors.identifier: http://orcid.org/0000-0002-1511-3644
authors.initials: AL
authors.lastname: Miranda-Angulo
authors.affiliation: Neuroregeneration and Multiple Sclerosis Research Unit, University of Valencia/Hospital La Fe, Valencia 46009, Spain, Comparative Neurobiology Laboratory, Instituto Cavanilles, Centro Investigación Biomédica en Red Enfermedes Neurodegenerativas, University of Valencia, Valencia 46980, Spain, and.
authors.forename: Sara
authors.initials: S
authors.lastname: Gil-Perotin
authors.affiliation: Neuroregeneration and Multiple Sclerosis Research Unit, University of Valencia/Hospital La Fe, Valencia 46009, Spain.
authors.forename: Jose Manuel
authors.initials: JM
authors.lastname: Garcia-Verdugo
authors.affiliation: Department of Neuroscience, Department of Ophthalmology, Department of Neurology, Center for High-Throughput Biology, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, sblack@jhmi.edu.
authors.forename: Seth
authors.initials: S
authors.lastname: Blackshaw
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D063928:Ependymoglial Cells / Q000502:physiology*; D005260:Female; D007031:Hypothalamus / Q000166:cytology* / Q000502:physiology*; D060850:LIM-Homeodomain Proteins / Q000502:physiology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D055495:Neurogenesis / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D060850:LIM-Homeodomain Proteins; C489784:Lhx2 protein, mouse; D014157:Transcription Factors
keywords: ependymal cells; hypothalamus; metabolism; radial glia; tanycytes; transcription factor;