Purchase this article with an account.
M.A. Walter, J. Skarie, F. Mirzayans, B. Link, F.B. Berry; Identification of a FOXC1–FOXO1A Transcriptional Cascade That Implicates Oxidative Stress Responses in Axenfeld–Rieger Pathogenic Mechanisms . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5446.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Mutations in the human Forkhead Box transcription factor gene FOXC1 underlie Axenfeld–Rieger syndrome, a disorder characterized by a spectrum of anterior segment malformations and glaucoma. In order to understand the contribution that FOXC1 makes to normal eye development and how FOXC1 dysregulation causes glaucoma it is crucial to identify targets of FOXC1 transcriptional regulation.
We utilized a caged FOXC1 protein that can be activated in the presence of protein synthesis inhibitors to identify genes directly regulated by the FOXC1 transcription factor. This expression system was coupled with microarray experiments to identify potential FOXC1–target genes.
Microarray analysis of cells expressing the caged FOXC1 molecule identified numerous gene that were differentially regulated by FOXC1 expression. Gene ontogeny profiling revealed key genes involved in a number of biological and molecular processes including cell growth, apoptosis, vesicle mediated transport, protein biosynthesis, transcription, signal transduction, cell structure and vision. One prominent gene that was identified was the FOXO1A transcription factor. FOXO1A contains a FOXC1 binding site that is conserved in the mouse and human promoter regions. We cloned the human FOXO1A promoter and determined that FOXC1 regulates that activity of this promoter by luciferase assays. Furthermore we demonstrate through chromatin immunoprecipitation that FOXC1 binds to the FOXO1A promoter in vivo. Finally we demonstrate that the zebrafish FOXO1A ortholog exhibits a robust expression pattern in the periocular mesenchyme and the retinal ganglion cell layer in the developing eye.
The diverse biological roles of the genes identified in this study indicates that FOXC1 targets are involved in both regulating developmental processes as well as maintenance of the differentiated cell state. As FOXO1A, and its invertebrate orthologs, have prominent roles in regulation of apoptosis and resistance to cellular stress, these findings lends this FOXC1–FOXO1A transcriptional cascade as an exciting mechanism for glaucoma pathogenesis.
This PDF is available to Subscribers Only