Characterization of the Drosophila Methoprene -tolerant gene product. Juvenile hormone binding and ligand-dependent gene regulation.
Juvenile hormones (JHs) of insects are sesquiterpenoids that regulate a great diversity of processes in development and reproduction. As yet the molecular modes of action of JH are poorly understood. The Methoprene-tolerant (Met) gene of Drosophila melanogaster has been found to be responsible for resistance to a JH analogue (JHA) insecticide, methoprene. Previous studies on Met have implicated its involvement in JH signaling, although direct evidence is lacking. We have now examined the product of Met (MET) in terms of its binding to JH and ligand-dependent gene regulation. In vitro synthesized MET directly bound to JH III with high affinity (Kd = 5.3 +/- 1.5 nm, mean +/- SD), consistent with the physiological JH concentration. In transient transfection assays using Drosophila S2 cells the yeast GAL4-DNA binding domain fused to MET exerted JH- or JHA-dependent activation of a reporter gene. Activation of the reporter gene was highly JH- or JHA-specific with the order of effectiveness: JH III >> JH II > JH I > methoprene; compounds which are only structurally related to JH or JHA did not induce any activation. Localization of MET in the S2 cells was nuclear irrespective of the presence or absence of JH. These results suggest that MET may function as a JH-dependent transcription factor.
Miura
Ken
K
Department of Medical Zoology, School of Medicine, Mie University, Tsu City, Japan. k-miura@doc.medic.mie-u.ac.jp
Oda
Masahito
M
Makita
Sumiko
S
Chinzei
Yasuo
Y
D000818:Animals; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000378:metabolism; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004331:Drosophila melanogaster / Q000187:drug effects / Q000502:physiology*; D007305:Insecticide Resistance / Q000235:genetics*; D008024:Ligands; D008726:Methoprene / Q000378:metabolism* / Q000633:toxicity; D011485:Protein Binding; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C052130:GAL4 protein, S cerevisiae; D008024:Ligands; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D008726:Methoprene; D004247:DNA