Journal Article

A specific type of insulin-like peptide regulates the conditional growth of a beetle weapon

Fujioka, Haruna, Okamoto, Naoki, Okada, Yasukazu, Katsuki, Masako, Okada, Kensuke

2019

Overview

Evolutionarily conserved insulin/insulin-like growth factor (IGF) signaling (IIS) has been identified as a major physiological mechanism underlying the nutrient-dependent regulation of sexually selected weapon growth in animals. However, the molecular mechanisms that couple nutritional state with weapon growth remain largely unknown. Here, we show that one specific subtype of insulin-like peptide (ILP) responds to nutrient status and thereby regulates weapon size in the broad-horned flour beetle Gnatocerus cornutus. By using transcriptome information, we identified five G. cornutus ILP (GcorILP1-5) and two G. cornutus insulin-like receptor (GcorInR1, -2) genes in the G. cornutus genome. RNA interference (RNAi)-mediated gene silencing revealed that a certain subtype of ILP, GcorILP2, specifically regulated weapon size. Importantly, GcorILP2 was highly and specifically expressed in the fat body in a condition-dependent manner. We further found that GcorInR1 and GcorInR2 are functionally redundant but that the latter is partially specialized for regulating weapon growth. These results strongly suggest that GcorILP2 is an important component of the developmental mechanism that couples nutritional state to weapon growth in G. cornutus. We propose that the duplication and subsequent diversification of IIS genes played a pivotal role in the evolution of the complex growth regulation of secondary sexual traits.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Amino acids / Animal growth / Animals / Beetles / Biological evolution / Biology and Life Sciences / Coleoptera - genetics / Coleoptera - growth & development / Coleoptera - metabolism / Engineering and Technology / Entomology / Evolution & development / Evolutionary genetics / Fat body / Flour / Gene expression / Gene silencing / Genes / Genetic engineering / Genomes / Genomics / Growth / Growth factors / Insects / Insulin / Insulin - metabolism / Insulin-like growth factors / Larva - metabolism / Ligands / Males / Medicine and Health Sciences / Metabolism / Molecular modelling / Mosquitoes / Nutrient status / Nutrients / Peptides / Physiological aspects / Physiological effects / Receptor, Insulin - genetics / Receptors, Somatomedin - genetics / Receptors, Somatomedin - metabolism / RNA Interference / RNA-mediated interference / Sex Characteristics / Signal Transduction / Somatomedins - metabolism / Somatomedins - physiology / Weapons / Whole Exome Sequencing