title: The transcription factor Hmx1 and growth factor receptor activities control sympathetic neurons diversification.
abstract: The sympathetic nervous system relies on distinct populations of neurons that use noradrenaline or acetylcholine as neurotransmitter. We show that fating of the sympathetic lineage at early stages results in hybrid precursors from which, genetic cell-lineage tracing reveals, all types progressively emerge by principal mechanisms of maintenance, repression and induction of phenotypes. The homeobox transcription factor HMX1 represses Tlx3 and Ret, induces TrkA and maintains tyrosine hydroxylase (Th) expression in precursors, thus driving segregation of the noradrenergic sympathetic fate. Cholinergic sympathetic neurons develop through cross-regulatory interactions between TRKC and RET in precursors, which lead to Hmx1 repression and sustained Tlx3 expression, thereby resulting in failure of TrkA induction and loss of maintenance of Th expression. Our results provide direct evidence for a model in which diversification of noradrenergic and cholinergic sympathetic neurons is based on a principle of cross-repressive functions in which the specific cell fates are directed by an active suppression of the expression of transcription factors and receptors that direct the alternative fate.
authors.affiliation: Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Furlan
authors.forename: Moritz
authors.initials: M
authors.lastname: Lübke
authors.forename: Igor
authors.initials: I
authors.lastname: Adameyko
authors.forename: Francois
authors.initials: F
authors.lastname: Lallemend
authors.forename: Patrik
authors.initials: P
authors.lastname: Ernfors
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000316:Adrenergic alpha-Agonists / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D018679:Cholinergic Agonists / Q000378:metabolism; D059329:Cholinergic Neurons / Q000166:cytology* / Q000502:physiology; D022202:Chromosomes, Artificial, Bacterial; D004622:Embryo, Mammalian; D005260:Female; D018507:Gene Expression Regulation, Developmental; D015723:Gene Library; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009638:Norepinephrine / Q000378:metabolism; D010641:Phenotype; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics / Q000378:metabolism; D020812:Receptor, trkC / Q000235:genetics / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism*; D013564:Sympathetic Nervous System / Q000166:cytology / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics* / Q000378:metabolism
chemical_list: D000316:Adrenergic alpha-Agonists; D018679:Cholinergic Agonists; D018398:Homeodomain Proteins; C529125:NKX5-3 protein, mouse; D017978:Receptors, Growth Factor; C487377:Tlx3 protein, mouse; D014157:Transcription Factors; D014446:Tyrosine 3-Monooxygenase; D051096:Proto-Oncogene Proteins c-ret; D020812:Receptor, trkC; C494999:Ret protein, mouse; D000109:Acetylcholine; D009638:Norepinephrine