p48 subunit of mouse PTF1 binds to RBP-Jkappa/CBF-1, the intracellular mediator of Notch signalling, and is expressed in the neural tube of early stage embryos.
BACKGROUND
Development of the pancreas and the nervous tissues is regulated by common transcription factors. A basic helix-loop-helix protein, p48 of pancreas transcription factor 1 (PTF1), is essential for differentiation of the exocrine acinar cells.


RESULTS
We isolated PTF1 p48 from 9.5-day mouse embryos as a binding protein of RBP-Jkappa, a mediator of Notch signalling. p48 bound to RBP-Jkappa more strongly than and in a distinct way from Notch1. In 9.5-12.5 day embryos, p48 was expressed in the dorsal part of the neural tube as well as in the pancreatic buds. Two lines of evidence suggested functions of p48 in neurogenesis: (i) expression of p48 was induced in P19 cells when they committed to neural fate upon retinoic acid treatment, and (ii) p48 over-expressed in Xenopus embryos repressed the development of neuronal precursors. p48 inhibited the MASH1-activated transcription from the E-box, while p48 stimulated transcription from the PTF1 motif synergistically with E47. The p48/E47-activated transcription from the PTF1 motif was stimulated further by RBP-Jkappa and RBP-Jkappa derivatives that mimicked the active RBP-Jkappa/Notch complex.


CONCLUSIONS
In developing embryos, p48 is expressed in both the nervous system and the pancreas. p48 inhibits neuronal differentiation. We propose possible mechanisms for this inhibition.
Obata
J
J
Division of Gene Function in Animals, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
Yano
M
M
Mimura
H
H
Goto
T
T
Nakayama
R
R
Mibu
Y
Y
Oka
C
C
Kawaichi
M
M
D016475:3T3 Cells; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D017353:Gene Deletion; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D017403:In Situ Hybridization; D008156:Luciferases / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D009420:Nervous System / Q000196:embryology*; D009687:Nuclear Proteins; D010179:Pancreas / Q000254:growth & development; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D004268:DNA-Binding Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008565:Membrane Proteins; C497762:Notch1 protein, mouse; D009687:Nuclear Proteins; D012333:RNA, Messenger; C497571:Rbpj protein, mouse; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D015534:Trans-Activators; D014157:Transcription Factors; C062602:transcription factor PTF1; D008156:Luciferases