Possible Involvement of 2',3'-Cyclic Nucleotide-3'-Phosphodiesterase in the Protein Phosphorylation-Mediated Regulation of the Permeability Transition Pore.

Yulia Baburina,Tamara Azarashvili,Olga Krestinina,Vladimir Akatov,Irina Odinokova,Linda Sotnikova

doi:10.3390/ijms19113499

Yulia Baburina, Tamara Azarashvili + Show 4 more

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https://doi.org/10.3390/ijms19113499

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Abstract

Calcium as a secondary messenger regulates the phosphorylation of several membrane-bound proteins in brain and liver mitochondria. Regulation of the activity of different protein kinases and phosphatases by Ca2+ occurs through its binding with calmodulin. The protein phosphorylation is strongly dependent on the Ca2+-induced mitochondrial permeability transition pore (mPTP) opening. 2′,3′-Cyclic nucleotide-3′-phosphodiesterase (CNPase) was phosphorylated by protein kinases A and C. CNPase and melatonin (MEL) might interact with calmodulin. The effects of the calmodulin antagonist calmidazolium and the inhibitor of protein kinase A H89 on mPTP opening in rat brain mitochondria of male Wistar rats were investigated. In addition, the role of CNPase, serine/threonine kinases, and MEL in the mPTP opening was examined. The anti-CNPase antibody added to rat brain mitochondria (RBM) reduced the content of CNPase in mitochondria. The threshold [Ca2+] decreased, and mitochondrial swelling was accelerated in the presence of the anti-CNPase antibody. H89 enhanced the effect of anti-CNPase antibody and accelerated the swelling of mitochondria, while CmZ abolished the effect of anti-CNPase antibody under mPTP opening. The levels of phospho-Akt and phospho-GSK3β increased, while the MEL content did not change. It can be assumed that CNPase may be involved in the regulation of these kinases, which in turn plays an important role in mPTP functioning.

Highlights

The protein phosphorylation/dephosphorylation system regulates many cell functions and is involved in signal transduction
Akt has a direct effect in mitochondria, which is mediated by phosphorylation of hexokinase-II, resulting in the protection of mitochondria from oxidants or the opening of the Ca2+-induced mitochondrial permeability transition pore [6]
We measured the parameters of mitochondrial permeability transition pore (mPTP) function such as Ca2+ retention capacity, oxygen consumption, and rat brain mitochondria (RBM) swelling and compared them in different experimental conditions (in the presence of CmZ (30 μM), H89 (5 μM), the anti-Cyclic nucleotide-3 -phosphodiesterase (CNPase) antibody (0.18 μg/mL) and their combination)

Summary

Introduction

The protein phosphorylation/dephosphorylation system regulates many cell functions and is involved in signal transduction. It can significantly influence the structural and morphological features of protein [1]. Several studies showed that mitochondrial Akt catalyzes a phosphorylation and inactivates the pro-apoptotic protein BAD, and the recruitment of Raf-1 to the mitochondria promotes cell survival [3,4]. The mPTP opening results in the inhibition of respiration, mitochondrial swelling, the inner membrane depolarization, and the release of pro-apoptotic factors [7]. Another serine/threonine kinase, GSK3β, is present in mitochondria of the rat cerebellum [8]. CaM is found in great amounts in the nervous system where it interacts most intensively with the myelin basic protein, which has been confirmed by structural studies [19,20,21,22]

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