Instytut Biologii Doświadczalnej im. Marcelego Nenckiego PAN ; Universität Bonn
Szewczyk, Adam (1960- ) : Supervisor ; Kunz, Wolfram S. : Supervisor ; Kulawiak, Bogusz : Assistant supervisor
Nencki Institute of Experimental Biology PAS
165 pages : illustrations ; 30 cm ; Bibliography ; Summmary in Polish
Instytut Biologii Doświadczalnej im. Marcelego Nenckiego PAN
The defining property of mitochondria – generation of mitochondrial membrane potential –interlinks the metabolic and signaling functions of this organelle. Mitochondrial large- conductance calcium-activated potassium channels (mitoBK) execute its fine regulation by allowing the controlled influx of potassium ions into the mitochondrial matrix. This functionendows them with unique properties, resulting in a cytoprotective phenomenon of mitoBKactivation in ischemia-reperfusion injury. The functional and structural interaction of mitoBKchannels with the electron transfer chain, and in particular, its terminal enzyme cytochrome c oxidase (COX), can be one of its molecular mechanisms.To investigate the interaction between the COX and mitoBK channels, different COX-deficientcellular models were employed. Specifically, human astrocytoma cells were depleted ofmitochondrial DNA (mtDNA) by the treatment with 2’,3’-dideoxycytidine. The comparison ofthe protein complexes formed by the mitoBK and COX in the mtDNA-depleted and WTastrocytoma cells identified the interaction of the pore-forming mitoBK subunit with the COX-containing complexes and respirasomes. Furthermore, downregulation of mitoBK-α subunits on both protein and mRNA levels occurred upon mtDNA-induced COX deficiency. Theanalysis of the retrograde signaling pathways induced by the mtDNA depletion in the mtDNA-depleted astrocytoma cells showed activation of the integrated stress response signaling.Human dermal fibroblasts with a mutation in the structural COX subunit – COX8A – were usedas another cellular model with a deficiency in COX. The organization of the electron transportchain was characterized in the COX8A-deficient fibroblasts and HEK293T cells with CRISPR/Cas9 induced mutations in COX8A and ensuing COX deficiency, identifying that theresidual COX was stabilized in the respirasomes. The decrease in the protein amount of mitoBKpore-forming subunit, as well as its protein complexes, was observed.To follow the systemic implications of this coupling, the effect of a gaseous transmitter carbonmonoxide (CO), putatively targeting both COX and mitoBK, was assessed in the patch-clampstudies. While direct application of CO-saturated solution has not exerted significantmodulation of the mitoBK channel activity, patch perfusion with CO-releasing moleculesinduced pleiotropic effects. Perfusion with heme and hemin inhibited mitoBK channels. Thesubsequent application of CO-saturated solution released this inhibition, activating mitoBKchannels in the presence of heme
Nencki Institute of Experimental Biology of the Polish Academy of Sciences
Library of the Nencki Institute of Experimental Biology PAS
Dec 22, 2023
Oct 20, 2022
75
https://rcin.org.pl/publication/272928
Sęk, Aleksandra
Krajewska, Milena.
Konopacki, M. [Mieczysław]
Piecyk, Karolina
Prill, Monika
Simões, Inês
Strosznajder, Joanna