Understanding the Expression Profile of Hmx in Drosophila melanogaster

Presenter

Sydney Lillian Bailey

Campus

UMass Boston

Sponsor

Jens Rister, Department of Biology, UMass Boston

Schedule

Session 3, 1:30 PM - 2:15 PM [Schedule by Time][Poster Grid for Time/Location]

Location

Poster Board A53, Campus Center Auditorium, Row 3 (A41-A60) [Poster Location Map]

Abstract

The novel Hippo Pathway regulator, H6-like-homeobox (Hmx), is a conserved regulator of ocular development in Drosophila and vertebrates. In humans, mutations in an Hmx orthologue, HMX1, are associated with a severe eye disease known as Oculoauricular syndrome (OAS). We have discovered that in Drosophila, Hmx regulates the Rh5 (blue-sensitive) vs. Rh6 (green-sensitive) photoreceptor (PR) fate decision. We found that RNAi-mediated knockdown of Hmx caused a loss of Rh5 and a gain of Rh6, while overexpression of Hmx caused a gain of Rh5 and loss of Rh6. Thus, Hmx is necessary and sufficient for Rh5 fate. Next, we sought to identify the cis-regulatory logic underlying Hmx expression. To this end, we generated Hmx transcriptional reporters. We found that fusing the 1.5 kb second intron of the Hmx locus to a minimal hsp70 promoter upstream of a GFP coding sequence (Hmx-GFP) led to Hmx-GFP in Rh5 PRs but not Rh6 PRs. This confirmed that Hmx is exclusively expressed in Rh5 PRs and that an enhancer in the second intron regulates its subtype-specific expression. Taken together, our results revealed that Hmx is a subtype-specific determinant of Rh5 fate. These results broaden our understanding of the molecular mechanisms that establish color vision in development.

Keywords

drosophila melanogaster, color vision, tumor supressor pathway

Research Area

Biological Organisms

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