Undifferentiated cells in the developing Drosophila eye influence facet assembly and require the Fat facets ubiquitin-specific protease

Abstract

The Drosophila compound eye develops by a complex series of cell interactions where multiple positive and inhibitory cues guide cells in each facet into their positions and fates. The results of many genetic and molecular experiments have led to the view that facet assembly is directed by cells within developing ommatidial preclusters. Here fat facets mutants and the cloned fat facets gene were used to show that, in order to limit the number of photoreceptors in a facet to eight, undifferentiated cells surrounding assembling facets send an inhibitory signal to extraneous cells within the facet preclusters. Generation of the inhibitory signal requires the ubiquitin-specific protease encoded by the fat facets gene and is thus regulated by ubiquitin-dependent proteolysis.

Substrate Specificity of Deubiquitinating Enzymes: Ubiquitin C-Terminal Hydrolases

“…These enzymes hydrolyze ubiquitin fusion proteins and also can cotranslationally process the ubiquitin proproteins; however, quantitative rates for these processes are not available. Many additional homologous sequences have been identified from yeast to man, including those involved in tumorigenesis (24), in development and embryogenesis (25), in transcriptional silencing (26,27), and in growth control and cytokine response (28,29).…”