Regulation of protein phosphatase 2A during embryonic diapause process in the silkworm, Bombyx mori. (November 2017)

• Record Type: Journal Article
• Authors: Gu, Shi-Hong; Hsieh, Hsiao-Yen; Lin, Pei-Ling
• Is Part Of: Journal of insect physiology. Volume 103(2017:Aug.)
• Page Start: 117
• Page End: 124
• Publication Date: 2017-11
• Subjects: Bombyx mori -- PP2A -- Phosphatases -- Diapause -- Gene expression; Insects -- Physiology -- Periodicals; Insectes -- Physiologie -- Périodiques; Insects -- Physiology; Periodicals; 571.157
• DOI: 10.1016/j.jinsphys.2017.09.002
• Languages: English
• ISSNs: 0022-1910

Abstract

Graphical abstract: Highlights: Different PP2A protein levels were detected between diapause and non-diapause eggs. PP2A enzymatic activity remained at low levels in diapause eggs. An increase in PP2A activity was detected in non-diapause eggs. PP2A appears to be related to Bombyx embryonic development . Abstract: Regulation of protein phosphorylation requires coordinated interactions between protein kinases and protein phosphatases. In the present study, we investigated regulation of protein phosphatase 2A (PP2A) during the embryonic diapause process of B. mori . An immunoblotting analysis showed that Bombyx eggs contained a catalytic C subunit, a major regulatory B subunit (B55/PR55 subunit), and a structural A subunit, with the A and B subunits undergoing differential changes between diapause and non-diapause eggs during embryonic process. In non-diapause eggs, eggs whose diapause initiation was prevented by HCl, and eggs in which diapause had been terminated by chilling of diapausing eggs at 5 °C for 70 days and then were transferred to 25 °C, protein levels of the A and B subunits of PP2A gradually increased toward embryonic development. However, protein levels of the A and B subunits in diapause eggs remained at low levels during the first 8 days after oviposition. The direct determination of PP2A enzymatic activity showed that the activity remained at low levels in diapause eggs during the first 8 days after oviposition. However, in non-diapause eggs, eggs whose diapause initiation was prevented by HCl, and eggs in which diapause had been terminated by chilling, PP2A enzymatic activity sharply increased during the first several days, reached a peak during the middle embryonic development, and then greatly decreased 3 or 4 days before hatching. Examination of temporal changes in mRNA expression levels of the catalytic β subunit and regulatory subunit of PP2A showed high levels in eggs whose diapause initiation was prevented by HCl compared to those in diapause eggs. These results demonstrate that the higher PP2A gene expression and PP2A A and B subunit protein levels and increased enzymatic activity are related to embryonic development of B. mori .