Distinct cis-essential modules direct the time-space pattern of the Pax6 gene activity

Pax6 is a regulatory gene with restricted expression and essential function s in the developing eye and pancreas and distinct domains of the CNS. In th is study we report the identification of three conserved transcription star t sites (P0, P1, alpha) in the murine Pax6 locus. Furthermore, using transg enic mouse technology we localized independent cis-regulatory elements cont rolling the tissue-specific expression of Pax6. Specifically, a 107-bp enha ncer and a 1.1-kb sequence within the 4.6-kb untranslated region upstream o f exon 0 are required to mediate Pax6 expression in the lens, cornea, lacri mal gland, conjunctiva, or pancreas, respectively. Another 530-bp enhancer fragment located downstream of the Pax6 translational start site is require d for expression in the neural retina, the pigment layer of the retina, and the iris. Finally, a 5-kb fragment located between the promoters P0 and P1 can mediate expression into the dorsal telencephalon, the hindbrain, and t he spinal cord. The identified Pax6/cis-essential elements are highly conse rved in pufferfish, mouse, and human DNA and contain binding sites for seve ral transcription factors indicative of the cascade of control events. Corr esponding regulatory elements from pufferfish are able to mimic the reporte r expression in transgenic mice. Thus, the results indicate a structural an d functional conservation of the Pax6 regulatory elements in the vertebrate genome. (C) 1999 Academic Press.