The 20-hydroxyecdysone-induced signalling pathway in G2/M arrest of Plodia interpunctella imaginal wing cells.

The mechanisms involved in the control of cellular proliferation by the steroid hormone 20-hydroxyecdysone (20E) in insects are not known. We dissected the 20E signalling pathway responsible for G2/M arrest of imaginal cells from the IAL-PID2 cells of the Indian meal moth Plodia interpunctella. We first used a 5'-3' RACE-based strategy to clone a 4479bp cDNA encoding a putative P.

Identification of steroid hormone signaling pathway in insect cell differentiation.

To dissect the steroid hormone signaling pathway involved in insect cell morphological differentiation, we extended the application of the double-stranded RNA-mediated interference (dsRNAi) method to the epidermal IAL-PID2 cell line from Plodia interpunctella Lepidoptera. We first demonstrated that dsRNA was capable of efficiently blocking the steroid hormone 20-hydroxyecdysone (20E) inducibility of proteins that belong to the nuclear receptor superfamily, including the ecdysone receptor (EcR), its partner Ultraspiracle (USP), the insect homolog of the vertebrate retinoid X receptor and the HR3 transcription factor. We then showed that inhibiting the 20E induction of EcR, USP or HR3 proteins prevented the increased synthesis of beta tubulin and consequently the morphological transformation of cells.

Comparative effects of a non-steroidal ecdysone agonist RH-5992 and 20-hydroxyecdysone in a lepidopteran cell line (IAL-PID2).

The non-steroidal ecdysone agonist, RH-5992, exhibits ecdysteroid activities in vivo as well as in vitro more effectively than 20-hydroxyecdysone (20E). Using the IAL-PID2 cells derived from imaginal wing discs of last larval instar of Plodia interpunctella, we investigated the action of RH-5992 in the control of cell growth. Its effects on the proliferative activity of IAL-PID2 cells, the induction level in G2/M arrest and on the expression rate of Plodia B cyclin (PcycB), ecdysone B1-isoform (PIEcR-B1) and Ultraspiracle-2 isoform (PIUSP-2) were examined.

Cell cycle profiles of EcR, USP, HR3 and B cyclin mRNAs associated to 20E-induced G2 arrest of Plodia interpunctella imaginal wing cells.

Using the IAL-PID2 cell line established from pupally committed imaginal wing discs of Plodia interpunctella, we have investigated the dynamics of cellular and molecular events involved in the G2/M arrest. We have first cloned a cDNA sequence named PIUSP-2 that likely encodes a homologue of the Ultraspiracle-2 isoform of Manduca sexta. When the IAL-PID2 cells were exposed to a 8 h 20E treatment applied at different times of the cell cycle, an optimal period of sensitivity of cells to 20E, in inducing G2 arrest, was determined at the S/G2 transition.

P450 and P450 reductase cDNAs from the moth Mamestra brassicae: cloning and expression patterns in male antennae.

The involvement of cytochrome P450 (CYP) enzymes in olfaction has been demonstrated in vertebrates over the past decade. In insects, these enzymes are well known for their role in biosynthesis of endogenous compounds as well as xenobiotic metabolism, but the presence of olfactory cytochrome P450s was poorly investigated. Using a PCR-based strategy, we have isolated cDNAs of two new microsomal P450s from the antennae of the cabbage armyworm Mamestra brassicae, CYP9A13 and CYP4G20 of two new microsomal P450s, as well as their red-ox partner, the cytochrome P450 reductase (CPR).