A Drosophila systems approach to xenobiotic metabolism.
Insecticide resistance is a major problem for both medicine and agriculture and is frequently associated with overexpression of metabolic enzymes that catalyze the breakdown of pesticides, leading to broad-spectrum resistance. However, the insect tissues within which these metabolic enzymes normally reside remain unclear. Microarray analysis of nine adult tissues from Drosophila melanogaster reveals that cytochrome P-450s and glutathione-S-transferases show highly tissue-specific expression patterns; most were confined to one or more epithelial tissues, and half showed dominant expression in a single tissue. The particular detoxifying enzymes encountered by a xenobiotic thus depend critically on the route of administration. In particular, known insecticide metabolism genes are highly enriched in insect Malpighian (renal) tubules, implicating them in xenobiotic metabolism. The tubules thus display, with the fat body, roles analogous to the vertebrate liver and immune system, as well as its acknowledged renal function. To illustrate this, when levels of a single gene, Cyp6g1, were manipulated in just the Malpighian tubules of adult Drosophila, the survival of the whole insect after 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) challenge was altered, whereas corresponding manipulations in the nervous system or the fat body were without effect. This shows that, although detoxification enzymes are widely distributed, baseline protection against DDT resides primarily in the insect excretory system, corresponding to less than 0.1% of the mass of the organism.
Yang
Jingli
J
Division of Molecular Genetics, University of Glasgow, Glasgow, United Kingdom.
McCart
Caroline
C
Woods
Debra J
DJ
Terhzaz
Selim
S
Greenwood
Karen G
KG
ffrench-Constant
Richard H
RH
Dow
Julian A T
JA
D000818:Animals; D030801:Animals, Genetically Modified; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D003634:DDT / Q000494:pharmacology; D004330:Drosophila / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D008658:Inactivation, Metabolic / Q000235:genetics; D007305:Insecticide Resistance / Q000235:genetics; D053858:Metabolic Networks and Pathways / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity / Q000235:genetics; D014018:Tissue Distribution; D015262:Xenobiotics / Q000378:metabolism*
D029721:Drosophila Proteins; D015262:Xenobiotics; D003577:Cytochrome P-450 Enzyme System; D003634:DDT; C446928:Cyp6g1 protein, Drosophila