Notch-Rbpj signaling is required for the development of noradrenergic neurons in the mouse locus coeruleus.
The locus coeruleus (LC) is the main source of noradrenaline in the brain and is implicated in a broad spectrum of physiological and behavioral processes. However, genetic pathways controlling the development of noradrenergic neurons in the mammalian brain are largely unknown. We report here that Rbpj, a key nuclear effector in the Notch signaling pathway, plays an essential role in LC neuron development in the mouse. Conditional inactivation of Rbpj in the dorsal rhombomere (r) 1, where LC neurons are born, resulted in a dramatic increase in the number of Phox2a- and Phox2b-expressing early-differentiating LC neurons, and dopamine-β-hydroxylase- and tyrosine-hydroxylase-expressing late-differentiating LC neurons. In contrast, other neuronal populations derived from the dorsal r1 were either reduced or unchanged. In addition, a drastic upregulation of Ascl1, an essential factor for noradrenergic neurogenesis, was observed in dorsal r1 of conditional knockout mice. Through genomic sequence analysis and EMSA and ChIP assays, a conserved Rbpj-binding motif was identified within the Ascl1 promoter. A luciferase reporter assay revealed that Rbpj per se could induce Ascl1 transactivation but this effect was counteracted by its downstream-targeted gene Hes1. Moreover, our in vitro gene transfection and in ovo electroporation assays showed that Rbpj upregulated Ascl1 expression when Hes1 expression was knocked down, although it also exerted a repressive effect on Ascl1 expression in the presence of Hes1. Thus, our results provide the first evidence that Rbpj functions as a key modulator of LC neuron development by regulating Ascl1 expression directly, and indirectly through its target gene Hes1.
Key Laboratory of Arrhythmias, Ministry of Education of China East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China. biomidas@163.com
Ming
M
Shi
Ze-Lan
ZL
Hu
Min-Hua
MH
Zheng
Ning-Ning
NN
Song
Ying
Y
Huang
Gang
G
Zhao
Hua
H
Han
Yu-Qiang
YQ
Ding
D059331:Adrenergic Neurons / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D051836:COUP Transcription Factors / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000378:metabolism / Q000473:pathology; D015536:Down-Regulation / Q000235:genetics; D004622:Embryo, Mammalian / Q000378:metabolism; D017353:Gene Deletion; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006965:Hyperplasia; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000378:metabolism*; D008125:Locus Coeruleus / Q000196:embryology / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D055495:Neurogenesis; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D051880:Receptors, Notch / Q000378:metabolism*; D012097:Repressor Proteins; D059326:Serotonergic Neurons / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism
D051792:Basic Helix-Loop-Helix Proteins; D019485:Bone Morphogenetic Proteins; D051836:COUP Transcription Factors; D018398:Homeodomain Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D051880:Receptors, Notch; D012097:Repressor Proteins; C499317:Ascl1 protein, mouse; C484221:Nr2f6 protein, mouse; C497571:Rbpj protein, mouse