Characterization of calcium signaling proteins from the fat body of the Colorado Potato Beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae): Implications for diapause and lipid metabolism

• Published in: Insect biochemistry and molecular biology Vol. 133; p. 103549
• Main Authors: Doğan, Cansu, Hänniger, Sabine, Heckel, David G., Coutu, Cathy, Hegedus, Dwayne D., Crubaugh, Linda, Groves, Russell L., Mutlu, Damla Amutkan, Suludere, Zekiye, Bayram, Şerife, Toprak, Umut
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2021
• Subjects: Calcineurin; Calmodulin; Diapause; Fat body; Lipid metabolism; Regucalcin; Regucalcin; Fat body; Lipid metabolism; Calcineurin; Diapause; Calmodulin
• ISSN: 0965-1748; 1879-0240
• DOI: 10.1016/j.ibmb.2021.103549

Calcium (Ca2+) regulates many cellular and physiological processes from development to reproduction. Ca2+ is also an important factor in the metabolism of lipids, the primary energy source used during insect starvation and diapause. Ca2+ signaling proteins bind to Ca2+ and maintain intracellular Ca2+ levels. However, knowledge about Ca2+ signaling proteins is mostly restricted to the model Drosophila melanogaster and the response of Ca2+ signaling genes to starvation or diapause is not known. In this study, we identified three Ca2+ signaling proteins; the primary Ca2+ binding protein Calmodulin (LdCaM), phosphatase Calcineurin B (LdCaNB), and the senescence marker protein Regucalcin (LdRgN), from the fat body of the Colorado Potato Beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae). This insect is a major pest of potato worldwide and overwinters under hibernation diapause as adults while utilizing lipids as the primary energy source. Putative EF-hand domains involved in Ca2+ binding were present in LdCaM, LdCaNB, but absent in LdRgN. LdCaM and LdCaNB were expressed in multiple tissues, while LdRgN was primarily expressed in the fat body. LdCaM was constitutively-expressed throughout larval development and at the adult stage. LdCaNB was primarily expressed in feeding larvae, and LdRgN in both feeding larvae and adults at comparable levels; however, both genes were down-regulated by molting. A response to starvation was observed only for LdRgN. Transcript abundance analysis in the entire body in relation to diapause revealed differential regulation with a general suppression during diapause, and higher mRNA levels in favor of females at post-diapause for LdCaM, and in favor of males at non-diapause for LdCaNB. Fat body-specific transcript abundance was not different between non-diapause and post-diapause for LdCaNB, but both LdCaM and LdRgN were down-regulated in males and both sexes, respectively by post-diapause. Silencing LdCaNB or LdRgN in larvae led to decreased fat content, indicating their involvement in lipid accumulation, while RNAi of LdCaM led to lethality. [Display omitted] •Calmodulin (LdCaM), Calcineurin B (LdCaNB) and Regucalcin (LdRgN) were identified.•Starvation-response was detected only for LdRgN.•Each gene revealed a differential expression pattern in response to diapause.•RNAi knockdown of LdCaNB and LdRgN decreased lipid accumulation.•RNAi knockdown of LdCaM was lethal.