Patterns of gene expression in Drosophila InsP₃ receptor mutant larvae reveal a role for InsP₃ signaling in carbohydrate and energy metabolism

Abstract

Background: The Inositol 1,4,5-trisphosphate receptor (InsP₃R) is an InsP₃ gated intracellular Ca²⁺-release channel. Characterization of Drosophila mutants for the InsP₃R has demonstrated that InsP₃-mediated Ca²⁺ release is required in Drosophila larvae for growth and viability. Methodology/Principal Findings: To understand the molecular basis of these growth defects a genome wide microarray analysis has been carried out with larval RNA obtained from a strong InsP₃R mutant combination in which 1504 independent genes were differentially regulated with a log₂ of fold change of 1 or more and P< 0.05. This was followed by similar transcript analyses from InsP₃R mutants where growth defects were either suppressed by introduction of a dominant suppressor or rescued by ectopic expression of an InsP₃R transgene in the Drosophila insulin like peptide-2 (Dilp2) producing cells. Conlusions/Significance: These studies show that expression of transcripts related to carbohydrate and amine metabolism is altered in InsP₃ receptor mutant larvae. Moreover, from a comparative analysis of genes that are regulated in the suppressed and rescued conditions with the mutant condition, it appears that the organism could use different combinations of pathways to restore a 'normal' growth state.