Functional genomics of the insect epitheliome

Insects are (in terms of species) the most diverse group of organisms on earth, and show astonishing variability, both in size and lifestyle. Insects can range in size from well under a milligram, right up to 80g; they can survive on land, freshwater and saline lakes, and from the equator to the Antarctic. Remarkably, all of this diversity is accommodated by the same body plan. Critical to their success is their ability to tightly regulate their internal milieu in the face of dietary and environmental challenges. Most of this control is through their epithelia; sheets of specialized cells that line their alimentary canal. In recent work, we identified a core fingerprint of genes (the 'epitheliome') that is common to the four critical insect epithelia; the salivary glands, midgut, Malpighian (renal) tubules and the hindgut. Although they perform different roles (secretion of saliva, digestion and absorption, excretion and selective reabsorption, respectively), all show a reliance on a common set of molecular pumps, channels and transporters.
The aim of this project is to test the validity of this gene expression model, using a combination of genetic and transgenic tools uniquely available in the fruit fly Drosophila melanogaster, to selectively disrupt the function of individual genes in individual epithelia within an otherwise normal insect. The impact of these knockdowns or overexpression protocols will be assessed with a battery of physiological assays, many developed by our group. Gene groups to be targeted include key transporters, cell signaling genes that are thought to regulate transport and so produce optimal function, and the key transcription factors that control gene expression and give each epithelium its unique properties.
This project will pioneer a new discipline of comparative epitheliomics, and will produce valuable insights and lasting resources that can be employed in the future to address the whole of insect diversity , including key beneficials (such as bees), and agricultural, veterinary and medical pests.

Critical to the extraordinary success of insects is the ability of their epithelia to regulate their internal milieu in the face of external challenges. In recent work, we identified a core set of genes (the 'epitheliome') that is enriched in four critical insect epithelia; the salivary glands, midgut, Malpighian (renal) tubules and the hindgut. Despite their very different roles, all show enriched expression of a common set of molecular pumps, channels and transporters.
We will test the functional validity of this model, using the genetic and transgenic tools uniquely available in the fruit fly Drosophila melanogaster, to selectively disrupt the function of individual genes in individual epithelia within an otherwise normal insect. The impact of these knockdowns will be assessed with physiological assays.
1. Experimental testing of the epitheliome model: To test that the computational Drosophila epitheliome reflects physiological function with knockdown analysis and physiological assays.
2. Extending the core model: To identify informatically genes that show enriched expression in the major transporting epithelia in Drosophila, but not in other epithelia or other tissues.
3. Functionally testing our expanded model: To perform a directed screen using genes and drivers identified in objective 2, and to phenotype knockdowns using physiological, structural and functional assays
4. Multi-species epitheliome: To extend the computational analysis to other insect species, and so establish the generality of the insect epitheliome model.
This project will pioneer a new discipline of comparative epitheliomics, and will produce valuable insights and lasting resources that can be employed in the future for key beneficials (such as bees), and agricultural, veterinary and medical pests. Critically, by seeking emergent patterns across multiple epithelia, we will be able to identify key epithelial genes that would be missed by studying each epithelium individually.