Evidence that POU factor Brn-3b regulates expression of Pax-6 in neuroretina cells

The Pax-6 gene encodes a transcriptional master regulator involved in the d evelopment of the eye. The quail Pax-6 gene is expressed in the neuroretina from two promoters, P0 and P1, and is regulated by an intragenic neuroreti na-specific enhancer (EP enhancer), The activity of this enhancer is restri cted to the P0 promoter, which is activated at the onset of neuronal differ entiation. In this article, we show that the POU domain transcription facto r Brn-3b, which is expressed in various regions of the brain including reti na and sensory neurons, is one of the factors interacting with the EP enhan cer. Brn-3b strongly activates the EP enhancer in neuroretina cells but not in other cell types. Interestingly, this activation appears to be specific for Brn-3b, as the closely related POU factors Brn-3a and Brn-3c do not sh ow activation of the EP enhancer. Our results identify the Pax-6 gene as a new potential downstream effector of the POU transcription factor Brn-3b. ( C) 1999 John Wiley & Sons, Inc.