Woc (without children) gene control of ecdysone biosynthesis in Drosophila melanogaster.
The first step in ecdysteroidogenesis, i.e. the 7,8-dehydrogenation of dietary cholesterol (C) to 7-dehydrocholesterol (7dC), is blocked in Drosophila melanogaster homozygous woc (without children) third instar larval ring glands (source of ecdysone). Unlike ring glands from wild-type D. melanogaster larvae, glands from woc mutants cannot convert radiolabelled C or 25-hydroxycholesterol (25C) to 7dC or 7-dehydro-25-hydroxycholesterol (7d25C) in vitro, nor to ecdysone (E). Yet, when these same glands are incubated with synthetic tracer 7d25C, the rate of metabolism of this polar Delta(5,7)-sterol into E is identical to that observed with glands from comparably staged wild-type larvae. The absence of this enzymatic activity in vivo is probably the direct cause of the observed low whole-body ecdysteroid titers in late third instar homozygous mutant larvae, the low ecdysteroid secretory activity in vitro of brain-ring gland complexes from these animals, and the failure of the larvae to pupariate (undergo metamorphosis). Oral administration of 7dC, but not C, results in a dramatic increase in ecdysteroid production both in vivo and in vitro by the woc mutant brain-ring gland complexes and affects a partial rescue to the beginning of pupal-adult development, but no further, despite elevated whole-body ecdysteroid titers. Data previously reported (Wismar et al., 2000) indicate that the woc gene encodes a zinc-finger protein that apparently modulates the activity of the 7,8-dehydrogenase.
Warren
J T
JT
Department of Biology, Campus Box #3280, University of North Carolina at Chapel Hill, 27599-3280, USA.
Wismar
J
J
Subrahmanyam
B
B
Gilbert
L I
LI
D000818:Animals; D001921:Brain / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism*; D004440:Ecdysone / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D026461:Ecdysteroids; D005786:Gene Expression Regulation; D005838:Genotype; D019476:Insect Proteins / Q000235:genetics* / Q000502:physiology; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D013256:Steroids / Q000096:biosynthesis / Q000378:metabolism; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D026461:Ecdysteroids; D019476:Insect Proteins; D013256:Steroids; D014157:Transcription Factors; C414987:WOC protein, Drosophila; D004440:Ecdysone