title: A novel TaulacZ allele reveals a requirement for Pitx2 in formation of the mammillothalamic tract.
abstract: The hypothalamic mammillary region is critical for spatial memory and vestibular processing. Pitx2 encodes a paired-like transcription factor that is highly expressed in the developing mammillary region and is required for subthalamic nucleus formation. Here we analyzed a loss of function Pitx2-TaulacZ knock-in allele to study the effects of Pitx2 deficiency on neuronal projections in the embryonic mammillary region. Pitx2-expressing neurons contribute axons to principal mammillary, mammillotegmental and mammillotectal tracts. Embryos with Pitx2 deficiency exhibit axonal fibers in the principal mammillary tract that are improperly bundled and disorganized, yet project caudally toward the tectum and tegmentum. Embryos with Nestin-Cre mediated conditional Pitx2 deficiency exhibit truncated mammillothalamic tracts (mtt) that fail to elongate, and reduced Pax6-positive cells at the branching point of the principal mammillary and mtt. These data suggest that Pitx2 mediates cell-autonomous and nonautonomous guidance cues necessary for mammillary collaterals destined to project to the anterior thalamus.
authors: Department of Pediatrics, The University of Michigan, Ann Arbor, Michigan 48109-5652, USA.
authors: Jennifer M
authors: JM
authors: Skidmore
authors: Mindy R
authors: MR
authors: Waite
authors: Gonzalo
authors: G
authors: Alvarez-Bolado
authors: Luis
authors: L
authors: Puelles
authors: Donna M
authors: DM
authors: Martin
mesh_terms: D000483:Alleles; D000818:Animals; D001369:Axons / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods; D005838:Genotype; D007031:Hypothalamus / Q000378:metabolism; D019426:Integrases / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008326:Mammillary Bodies / Q000196:embryology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence / Q000379:methods; D009417:Nerve Tissue / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D064231:Nestin; D009474:Neurons / Q000378:metabolism; D013681:Tegmentum Mesencephali / Q000196:embryology / Q000378:metabolism; D013788:Thalamus / Q000196:embryology / Q000378:metabolism
chemical_list: D007381:Intermediate Filament Proteins; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; C045073:Cre recombinase; D019426:Integrases