Function-informed transcriptome analysis of Drosophila renal tubule.
BACKGROUND
Comprehensive, tissue-specific, microarray analysis is a potent tool for the identification of tightly defined expression patterns that might be missed in whole-organism scans. We applied such an analysis to Drosophila melanogaster Malpighian (renal) tubule, a defined differentiated tissue.


RESULTS
The transcriptome of the D. melanogaster Malpighian tubule is highly reproducible and significantly different from that obtained from whole-organism arrays. More than 200 genes are more than 10-fold enriched and over 1,000 are significantly enriched. Of the top 200 genes, only 18 have previously been named, and only 45% have even estimates of function. In addition, 30 transcription factors, not previously implicated in tubule development, are shown to be enriched in adult tubule, and their expression patterns respect precisely the domains and cell types previously identified by enhancer trapping. Of Drosophila genes with close human disease homologs, 50 are enriched threefold or more, and eight enriched 10-fold or more, in tubule. Intriguingly, several of these diseases have human renal phenotypes, implying close conservation of renal function across 400 million years of divergent evolution.


CONCLUSIONS
From those genes that are identifiable, a radically new view of the function of the tubule, emphasizing solute transport rather than fluid secretion, can be obtained. The results illustrate the phenotype gap: historically, the effort expended on a model organism has tended to concentrate on a relatively small set of processes, rather than on the spread of genes in the genome.
Wang
Jing
J
Division of Molecular Genetics, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, UK. j.wang@bio.gla.ac.uk
Kean
Laura
L
Yang
Jingli
J
Allan
Adrian K
AK
Davies
Shireen A
SA
Herzyk
Pawel
P
Dow
Julian A T
JA
D000818:Animals; D020346:Aquaporins / Q000235:genetics / Q000502:physiology; D001693:Biological Transport, Active / Q000235:genetics / Q000502:physiology; D018118:Chloride Channels / Q000235:genetics / Q000502:physiology; D004331:Drosophila melanogaster / Q000235:genetics*; D020869:Gene Expression Profiling / Q000379:methods / Q000592:standards; D017344:Genes, Insect / Q000502:physiology; D008317:Malpighian Tubules / Q000737:chemistry* / Q000378:metabolism*; D046228:Microarray Analysis / Q000379:methods / Q000592:standards; D009928:Organ Specificity / Q000502:physiology; D027701:Organic Cation Transport Proteins / Q000235:genetics / Q000502:physiology; D010641:Phenotype; D015221:Potassium Channels / Q000235:genetics / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics / Q000502:physiology*; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000502:physiology
D020346:Aquaporins; D018118:Chloride Channels; D027701:Organic Cation Transport Proteins; D015221:Potassium Channels; D025262:Vacuolar Proton-Translocating ATPases; D000254:Sodium-Potassium-Exchanging ATPase