PDE2A2 regulates mitochondria morphology and apoptotic cell death via local modulation of cAMP/PKA signalling.

Stefania Monterisi,Michael Weinberger,Nshunge Musheshe,George Baillie,Alessandra Stangherlin,Nicoletta C Surdo,Massimo Micaroni,Manuela Zaccolo,Craig Livie,Rory Maizels,Miguel J Lobo,Mario Bortolozzi,John C Castle,Eyal Gottlieb

doi:10.7554/elife.21374

Abstract

cAMP/PKA signalling is compartmentalised with tight spatial and temporal control of signal propagation underpinning specificity of response. The cAMP-degrading enzymes, phosphodiesterases (PDEs), localise to specific subcellular domains within which they control local cAMP levels and are key regulators of signal compartmentalisation. Several components of the cAMP/PKA cascade are located to different mitochondrial sub-compartments, suggesting the presence of multiple cAMP/PKA signalling domains within the organelle. The function and regulation of these domains remain largely unknown. Here, we describe a novel cAMP/PKA signalling domain localised at mitochondrial membranes and regulated by PDE2A2. Using pharmacological and genetic approaches combined with real-time FRET imaging and high resolution microscopy, we demonstrate that in rat cardiac myocytes and other cell types mitochondrial PDE2A2 regulates local cAMP levels and PKA-dependent phosphorylation of Drp1. We further demonstrate that inhibition of PDE2A, by enhancing the hormone-dependent cAMP response locally, affects mitochondria dynamics and protects from apoptotic cell death.

Highlights

Mitochondria produce the majority of ATP required for a cell to function and perform vital functions in the maintenance of cellular metabolism and ion homeostasis
When we expressed PDE2A2-GFP in primary neonatal rat ventricular myocytes (NRVM), we found that it is distinctly located at the mitochondria, unlike PDE2A1-GFP, which is cytosolic, and PDE2A3GFP, which localises predominantly to the plasmalemma (Figure 1A)
Western blotting analysis of lysates from NRVM treated with Bay 60–7550 showed significant increase in dynamin-related protein 1 (Drp1) phosphorylation at the protein kinase A (PKA) site ser637 (Figure 1F,G) compared to DMSO-treated controls, whereas no increased phosphorylation was detected at ser616, a site phosphorylated by the kinase CDK1 (Taguchi et al, 2007) (Figure 1—figure supplement 2)

Summary

Introduction

Mitochondria produce the majority of ATP required for a cell to function and perform vital functions in the maintenance of cellular metabolism and ion homeostasis. Mitochondria play an important role in apoptosis and are implicated in the pathogenesis of many diseases (Nunnari and Suomalainen, 2012). Mitochondria exist in a dynamic network and are continuously remodelled by fusion and fission reactions. Alteration of the fusion/fission balance contributes to the pathogenesis of many complex conditions, including common neurodegenerative diseases, cancers and cardiovascular disorders (Archer, 2013), including the adaptive response to ischaemia–reperfusion injury

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