Pax6 localizes to chromatin-rich territories and displays a slow nuclear mobility altered by disease mutations.
The transcription factor Pax6 is crucial for the embryogenesis of multiple organs, including the eyes, parts of the brain and the pancreas. Mutations in one allele of PAX6 lead to eye diseases including Peter's anomaly and aniridia. Here, we use fluorescence recovery after photobleaching to show that Pax6 and also other Pax family proteins display a strikingly low nuclear mobility compared to other transcriptional regulators. For Pax6, the slow mobility is largely due to the presence of two DNA-binding domains, but protein-protein interactions also contribute. Consistently, the subnuclear localization of Pax6 suggests that it interacts preferentially with chromatin-rich territories. Some aniridia-causing missense mutations in Pax6 have impaired DNA-binding affinity. Interestingly, when these mutants were analyzed by FRAP, they displayed a pronounced increased mobility compared to wild-type Pax6. Hence, our results support the conclusion that disease mutations result in proteins with impaired function because of altered DNA- and protein-interaction capabilities.
Elvenes
Julianne
J
Molecular Cancer Research Group, Institute of Medical Biology, University of Tromsø, 9037 Tromso, Norway.
Sjøttem
Eva
E
Holm
Turid
T
Bjørkøy
Geir
G
Johansen
Terje
T
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D005124:Eye Abnormalities / Q000235:genetics; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D017930:Genes, Reporter; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D020125:Mutation, Missense; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
D002843:Chromatin; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins