A screen for proteins that interact with PAX6: C-terminal mutations disrupt interaction with HOMER3, DNCL1 and TRIM11.
BACKGROUND
The PAX6 protein is a transcriptional regulator with a key role in ocular and neurological development. Individuals with heterozygous loss-of-function mutations in the PAX6 gene have malformations of the eye and brain. Little is known about the interactions of PAX6 with other proteins, so we carried out a systematic screen for proteins that interact with PAX6.


RESULTS
We used bioinformatics techniques to characterise a highly conserved peptide at the C-terminus of the PAX6 protein. Yeast two-hybrid library screens were then carried out to identify brain-expressed proteins that interact with the C-terminal peptide and with the entire PAX6 proline-serine-threonine-rich domain. Three novel PAX6-interacting proteins were identified: the post-synaptic density (PSD) protein HOMER3, the dynein subunit DNCL1, and the tripartite motif protein TRIM11. Three C-terminal PAX6 mutations, previously identified in patients with eye malformations, all reduced or abolished the interactions.


CONCLUSIONS
Our preliminary data suggest that PAX6 interacts with HOMER3, DNCL1 and TRIM11. We propose that the interaction of PAX6 with HOMER3 and DNCL1 is a mechanism by which synaptic activation could lead to changes in neuronal transcriptional activity, and that some of the neural anomalies in patients with PAX6 mutations could be explained by impaired protein-protein interactions.
Cooper
Simon T
ST
University of Edinburgh, School of Molecular and Clinical Medicine, Medical Sciences (Medical Genetics), Molecular Medicine Centre, Western General Hospital, Edinburgh EH4 2XU. simon.t.cooper@ed.ac.uk
Hanson
Isabel M
IM
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism; D017124:Conserved Sequence; D056445:Cytoplasmic Dyneins; D004398:Dyneins / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D000072233:Homer Scaffolding Proteins; D006801:Humans; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D000070584:Tripartite Motif Proteins; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases
D002352:Carrier Proteins; D005136:Eye Proteins; C000606616:HOMER3 protein, human; D018398:Homeodomain Proteins; D000072233:Homer Scaffolding Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors; D000070584:Tripartite Motif Proteins; C510874:TRIM11 protein, human; D044767:Ubiquitin-Protein Ligases; C427758:DYNLL1 protein, human; D056445:Cytoplasmic Dyneins; D004398:Dyneins