title: The bHLH transcription factor Hand2 is essential for the maintenance of noradrenergic properties in differentiated sympathetic neurons.
abstract: The basic helix-loop-helix transcription factor Hand2 is essential for the proliferation and noradrenergic differentiation of sympathetic neuron precursors during development. Here we address the function of Hand2 in postmitotic, differentiated sympathetic neurons. Knockdown of endogenous Hand2 in cultured E12 chick sympathetic neurons by siRNA results in a significant (about 60%) decrease in the expression of the noradrenergic marker genes dopamine-beta-hydroxylase (DBH) and tyrosine hydroxylase (TH). In contrast, expression of the pan-neuronal genes TuJ1, HuC and SCG10 was not affected. To analyze the in vivo role of Hand2 in differentiated sympathetic neurons we used mice harboring a conditional Hand2-null allele and excised the gene by expression of Cre recombinase under control of the DBH promotor. Mouse embryos homozygous for Hand2 gene deletion showed decreased sympathetic neuron number and TH expression was strongly reduced in the residual neuron population. The in vitro Hand2 knockdown also enhances the CNTF-induced expression of the cholinergic marker genes vesicular acetylcholine transporter (VAChT) and choline acetyltransferase (ChAT). Taken together, these findings demonstrate that the Hand2 transcription factor plays a key role in maintaining noradrenergic properties in differentiated neurons.
authors.affiliation: RG Developmental Neurobiology, Department of Neurochemistry, MPI for Brain Research, Deutschordenstr. 46, 60528 Frankfurt/M, Germany.
authors.forename: Mirko
authors.initials: M
authors.lastname: Schmidt
authors.forename: Shengyin
authors.initials: S
authors.lastname: Lin
authors.forename: Manuela
authors.initials: M
authors.lastname: Pape
authors.forename: Uwe
authors.initials: U
authors.lastname: Ernsberger
authors.forename: Matthias
authors.initials: M
authors.lastname: Stanke
authors.forename: Kazuto
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Marthe J
authors.initials: MJ
authors.lastname: Howard
authors.forename: Hermann
authors.initials: H
authors.lastname: Rohrer
mesh_terms: D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation; D017931:DNA Primers; D004299:Dopamine beta-Hydroxylase / Q000235:genetics; D004843:Epistasis, Genetic; D005260:Female; D055785:Gene Knockdown Techniques; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009638:Norepinephrine / Q000378:metabolism*; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013564:Sympathetic Nervous System / Q000166:cytology*; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D017931:DNA Primers; D004299:Dopamine beta-Hydroxylase; D009638:Norepinephrine; D034741:RNA, Small Interfering; D014446:Tyrosine 3-Monooxygenase; C498766:Hand2 protein, mouse