Drosophila melanogaster Methoprene-tolerant (Met) gene homologs from three mosquito species: Members of PAS transcriptional factor family

Abstract

The Methoprene-tolerant (Met) gene in Drosophila melanogaster has been shown to function in juvenile hormone (JH) action. Met homologs were isolated from three mosquito species, Culex pipiens, Aedes aegypti and Anopheles gambiae. Sequence similarity was found to be high in bHLH and PAS conserved domains, and the majority of the 7-9 introns in AaMet and AgMet are located in either identical or similar positions, indicating evolutionary relatedness. Sequence comparison with Met and the similar germ-cell expressed (gce) gene in D. melanogaster showed that the mosquito genes are more similar to gce than to Met. Moreover, the multiple introns in AgMet and AaMet are more similar in number with the 7 introns in Dmgce than to the single intron in DmMet; in fact, six intron positions in AaMet and AgMet are similar to those in Dmgce. Efforts to identify a second homologous gene in mosquitoes were unsuccessful, suggesting a single gene in lower Diptera, consistent with the single gene uncovered in genomic sequencing of Ae. aegypti and An. gambiae. These results suggest that a gene duplication occurred during the evolution of higher Diptera, resulting in Met and gce.

Juvenile hormone resistance gene Methoprene-tolerant controls entry into metamorphosis in the beetle Tribolium castaneum

“…Similar to mosquitoes and the honey bee, the Tribolium genome apparently contains only one counterpart of Dmgce and DmMet. Our phylogenetic analysis confirms a previous notion that Dmgce and DmMet are paralogs that arose by a lineage-specific duplication in higher Diptera (31) and shows that the Tribolium gene is a single ortholog of Drosophila gce and Met (see SI). Because of its functional similarity to Met (see below) and in keeping with the literature, we will refer to the Tribolium gene as TcMet.…”

“…A likely reason for the lack of an expected developmental phenotype is the weak effect of JH on preadult Drosophila. Another explanation might be a potential functional redundancy between Met and a paralogous Drosophila gene germ-cell expressed (gce) (30,31), whose protein product can dimerize with Met in a JH-sensitive manner (26).…”

Interaction of proteins involved in ecdysone and juvenile hormone signal transduction

“…Search of Met homologs in other insects identified single ortholog of D. melanogaster Met and GCE in and three mosquito species, Culex pipiens, Aedes aegypti and Anopheles gambiae (Wang et al, 2007) and in coleopteran, Tribolium castanem (Konopova and Jindra, 2007). RNAi knock-down in the expression of Met in the red flour beetle, T. castaneum rendered beetles resistant to the effects of ectopic JH and caused early-stage beetle larvae to undergo precocious metamorphosis (Konopova and Jindra (2007).…”

The Drosophila FTZ-F1 Nuclear Receptor Mediates Juvenile Hormone Activation of E75A Gene Expression through an Intracellular Pathway

“…However, the fact that Met-knock-out flies are viable indicates that there is more than one receptor for JH. Recently, a paralog protein encoded by the Drosophila gene germ-cell expressed (gce) was identified and proposed to perform as an intracellular receptor for JH that can functionally substitute for MET (35). Indeed, ectopic GCE can rescue some of MET preadult functions (e.g.…”