Developmental delay in DCP2l(3)tb of Drosophila melanogaster is due to disruption in the regulation of ecdysone signaling.

Abstract

The balance between mRNA synthesis and degradation plays an important role in gene regulation, their perturbation can lead to deleterious consequences to the cell. In eukaryotes, mRNA is degraded by a decapping protein-2 (DCP2). A hypomorph mutant allele of DCP2, DCP2^l(3)tb, identified in our lab, shows delayed moulting, pupariation and absolute lethality in pupal stages. In Drosophila, moulting and pupariation are primarily regulated by ecdysone which is modulated by a few regulators synthesized by the larval brain, some are stimulatory such as Prothoracicotropic hormone (PTTH) and Drosophila insulin-like peptides (Dilps); whereas some are inhibitory, such as Lgr3-expressing neurons. We aimed to investigate the cause of the delay in moulting and pupariation in DCP2^l(3)tb homozygous mutants. Through our RNA Seq data, we found downregulated expression of brain-derived neuropeptides such as PTTH and Dilps which were further confirmed and validated through qRT-PCR and semiquantitative PCR. Furthermore, we assessed the mRNA level of Lgr3 which was found to be upregulated in the larval CNS of DCP2^l(3)tb homozygotes suggesting insufficient production of stimulatory modulators. Further, providing 20H-ecdysone exogenously through diet, curtailed the extended larval life. We propose that the larval CNS of DCP2^l(3)tb homozygotes produces insufficient brain-derived neuropeptides to stimulate the prothoracic gland to synthesize the ecdysone required for moulting and metamorphosis.