Regulation of the Pax6 : Pax6(5a) mRNA ratio in the developing mammalian brain.
BACKGROUND
Early in mammalian brain development cell proliferation generates a population of progenitor cells whose subsequent divisions produce increasing numbers of postmitotic neurons. Pax6 affects both processes and it has been suggested that this changing role is due at least in part to changes in the relative concentrations of its two main isoforms, (i) Pax6 and (ii) Pax6(5a), created by insertion of a 42 bp exon (exon 5a) into one of the two DNA-binding domains. Crucially, however, no previous study has determined whether the ratio between Pax6 and Pax6(5a) transcripts alters during mammalian neurogenesis in vivo.


RESULTS
Using RNase protection assays, we show that Pax6 transcripts are 6-10 times more prevalent than Pax6(5a) transcripts early in neurogenesis in the murine telencephalon, diencephalon and hindbrain and that the ratio later falls significantly to about 3:1 in these regions.


CONCLUSIONS
These changes in vivo are similar in magnitude to those shown previously to alter target gene activity in vitro and might, therefore, allow the single mammalian Pax6 gene to carry out different functions at different times in mammalian brain development.
Pinson
Jeni
J
Biomedical Sciences, Hugh Robson Building, University of Edinburgh, George Square, Edinburgh, EH8 9XD, UK. J.Pinson@ed.ac.uk
Mason
John O
JO
Simpson
T Ian
TI
Price
David J
DJ
D000818:Animals; D001921:Brain / Q000254:growth & development*; D004027:Diencephalon / Q000254:growth & development / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics*; D051379:Mice; D008815:Mice, Inbred Strains; D009474:Neurons / Q000166:cytology; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis*; D012097:Repressor Proteins / Q000235:genetics*; D012249:Rhombencephalon / Q000254:growth & development / Q000378:metabolism; D013687:Telencephalon / Q000254:growth & development / Q000378:metabolism
D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D020033:Protein Isoforms; D012333:RNA, Messenger; D012097:Repressor Proteins