Scientists have identified distinct functions for regions of a super-enhancer that controls gene expression during retina formation, calling it a ‘modular’ super-enhancer.

Gene expression is important during development as cells establish their identity and become various cell types with distinct functions. The transcription factor Vsx2 is essential to proper eye development. It is expressed in retinal progenitor cells and found in established bipolar neurons and Mu?ller glia.

For decades, researchers studied Vsx2 to understand how it affects development. Gene function is typically studied by knocking out (removing) the gene and observing what changes. However, when Vsx2 is knocked out, the eye does not form. Researchers cannot study something that does not form, so they needed the ability to fine-tune Vsx2 expression, at different times during retina formation.

«In brain development, important transcription factors, like Vsx2, and many others, are often expressed in different parts of the developing brain at different times but in a precisely orchestrated way,» said corresponding author Michael Dyer, Ph.D., St. Jude Department of Developmental Neurobiology chair and Howard Hughes Medical Institute Investigator. «We wanted to better understand how this complicated dance of expression is controlled where the gene is turned on at one moment in one cell type, then turned off in another and later activated in a different region completely.»

Testing the first modular super-enhancer

A super-enhancer of Vsx2 controls the complex and dynamic pattern of expression involved in retinal development.

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Materials provided by St. Jude Children’s Research Hospital. Note: Content may be edited for style and length.