title: Hand2 determines the noradrenergic phenotype in the mouse sympathetic nervous system.
abstract: The basic helix-loop-helix (bHLH) transcription factor Hand2 has been shown to play a role in the development of the mammalian sympathetic nervous system (SNS); however, its precise role could not be uncovered because Hand2 is required for early embryonic survival. We therefore generated a conditional Hand2 knockout mouse line by excising Hand2 in Wnt1-Cre-expressing neural crest-derived cells. These mice die at 12.5 dpc with embryos showing severe cardiovascular and facial defects. Crest-derived cells, however, populate sites of SNS development and proliferate normally. Sympathetic precursors differentiate into neurons and express the pan-neuronal markers, beta3-tubulin (Tuj1) and Hu showing that Hand2 is not essential for SNS neuronal differentiation. To determine whether Hand2 regulates noradrenergic differentiation, the levels of the norepinephrine biosynthetic enzymes, tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) was examined. Both enzymes were dramatically reduced in mutant embryos suggesting that the primary role of Hand2 in the SNS is determination of neuronal phenotype. Loss of Hand2 did not affect the expression of other members of the transcriptional circuit regulating SNS development, including Phox2a/b, Mash1 and Gata2/3; however, Hand2 was required for Hand1 expression. Our data suggest that the major role of Hand2 during SNS development is to permit sympathetic neurons to acquire a catecholaminergic phenotype.
authors.affiliation: Department of Cell and Molecular Biology, Tulane University, 2000 Percival Stern Hall, New Orleans, LA 70118, USA.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Morikawa
authors.forename: Fabien
authors.initials: F
authors.lastname: D'Autréaux
authors.forename: Michael D
authors.initials: MD
authors.lastname: Gershon
authors.forename: Peter
authors.initials: P
authors.lastname: Cserjesi
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D002395:Catecholamines; D002454:Cell Differentiation; D049109:Cell Proliferation; D004622:Embryo, Mammalian; D051379:Mice; D018345:Mice, Knockout; D009432:Neural Crest / Q000166:cytology; D009474:Neurons / Q000166:cytology; D009638:Norepinephrine; D010641:Phenotype; D013564:Sympathetic Nervous System / Q000254:growth & development; D014157:Transcription Factors
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002395:Catecholamines; D009638:Norepinephrine; D014157:Transcription Factors; C095572:Hand1 protein, mouse; C498766:Hand2 protein, mouse