title: A distant downstream enhancer directs essential expression of Tbx18 in urogenital tissues.
abstract: The vertebrate T-box transcription factor gene Tbx18 performs a vital role in development of multiple organ systems. Tbx18 insufficiency manifests as recessive phenotypes in the upper urinary system, cardiac venous pole, inner ear, and axial skeleton; homozygous null mutant animals die perinatally. Here, we report a new regulatory mutation of Tbx18, a reciprocal translocation breaking 78kbp downstream of the gene. 12Gso homozygotes present urinary and vertebral defects very similar to those associated with Tbx18-null mutations, but 12Gso is clearly not a global null allele since homozygotes survive into adulthood. We show that 12Gso down-regulates Tbx18 expression in a manner that is both spatially- and temporally-specific; combined with other data, the mutation points particularly to the presence of an essential urogenital enhancer located near the translocation breakpoint site. In support of this hypothesis, we identify a distal enhancer element, ECR1, which is active in developing urogenital and other tissues; we propose that disruption of this element leads to premature loss of Tbx18 function in 12Gso mutant mice. These data reveal a long-range regulatory architecture extending far downstream of Tbx18, identify a novel and likely essential urogenital enhancer, and introduce a new tool for dissecting postnatal phenotypes associated with dysregulation of Tbx18.
authors.affiliation: Department of Cell & Developmental Biology, University of Illinois, Urbana, IL, USA; Institute for Genomic Biology, University of Illinois, Urbana, IL, USA.
authors.forename: C Chase
authors.initials: CC
authors.lastname: Bolt
authors.affiliation: St. Vincent׳s Institute, Melbourne, Australia.
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Elso
authors.affiliation: Institute for Genomic Biology, University of Illinois, Urbana, IL, USA.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Lu
authors.affiliation: Roy J. Carver Biotechnology Center, University of Illinois, Urbana, IL, USA.
authors.forename: Fuming
authors.initials: F
authors.lastname: Pan
authors.affiliation: Institut für Molekularbiologie, OE5250, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kispert
authors.affiliation: Department of Cell & Developmental Biology, University of Illinois, Urbana, IL, USA; Institute for Genomic Biology, University of Illinois, Urbana, IL, USA. Electronic address: ljstubbs@illinois.edu.
authors.forename: Lisa
authors.initials: L
authors.lastname: Stubbs
mesh_terms: D000423:Alcian Blue; D000818:Animals; D000880:Anthraquinones; D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers / Q000235:genetics; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics*; D006652:Histological Techniques; D007150:Immunohistochemistry; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism*; D014178:Translocation, Genetic / Q000235:genetics; D014566:Urogenital System / Q000196:embryology* / Q000378:metabolism
chemical_list: D000880:Anthraquinones; D017931:DNA Primers; D020825:T-Box Domain Proteins; C420983:Tbx18 protein, mouse; C010078:alizarin; D000423:Alcian Blue
keywords: Chromosome translocation; Regulatory mutation; T-box transcription factor; Urogenital development