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Wojewoda MiP2010

From Bioblast
Wojewoda M, Duszynski J, Szczepanowska J (2010) Selenium affects mitochondrial biogenesis via modulation of nuclear respiratory factors level and activity.

Link: Abstracts Session 2

Wojewoda M, Duszynski J, Szczepanowska J (2010)

Event: MiP2010

Apart from generally recognised role as ATP generators, mitochondria are also main reactive oxygen species (ROS) producers in the cells. Since we found that ROS level was altered in human NARP cells linked to NARP (Neuropathy, Ataxia and Retinitis Pigmentosa) syndrome and Rho0 cells [1], we hypothesised that ROS are implicated in regulation of mitochondrial biogenesis. We also used antioxidant (sodium selenite, 70 nM) that decreased ROS level in these cells [1] to establish to what extent these changes depended on ROS-mediated retrograde communication.

Cell lines: human osteosarcoma cell lines: wild type (WT) cell line, cybrid cells (NARP) with default ATP synthase (mtDNA point mutation in subunit 6 of ATP synthase) and cells lacking mtDNA (Rho0). Laser scanning cytometry: ROS level, mitochondrial mass. Western blotting: the level of transcription factors and respiratory subunits; the level of respiratory subunits corresponds with the level of appropriate respiratory complexes since the chosen subunits are labile when their complexes are not assembled. Confocal imaging: localisation of NRF2 phosphorylated at Ser 40. Respiration: oxygen consumption measured with Clark type oxygen electrode

Nuclear respiratory factors 1 and 2 (NRF1 and NRF2) are major regulators of respiratory gene expression. We found that the level of NRF1 was increased in NARP and Rho0 cells when compared with WT control. Selenium supplementation lead to further increase in NRF1 level. Since an increase in Akt/Protein kinase B phosphorylation at serine 473 (pAkt (Ser473)) was associated with activation of NRF1 transcriptional activity [2], we also assessed the level of pAkt (Ser473) in these cells. Subsequently, we established the activity of NRF2 (measured by its phosphorylation at serine 40 and found it altered in NARP and Rho0 cells. Comparison of pNRF2 (Ser 40) level with total level of NRF2 revealed that its activity was enhanced in cell lines with mtDNA defects. Moreover, we found that selenite further increased NRF2 phosphorylation.

mtDNA defects in NARP and Rho0 cells also triggered adaptive changes at the level of respiratory subunits which were upregulated in NARP but downregulated in Rho0 cells. Selenite lowered the level of some respiratory subunits in WT and NARP cells without affecting their respiratory capacity.

In cells with mtDNA defects the retrograde communication from mitochondria to nucleus modulates adaptive changes in mitochondrial biogenesis at the level of respiratory chain complexes via affecting nuclear respiratory factors. Because selenite supplementation affected both the level/activity of NRFs and the level of some respiratory subunits, we show that ROS play a significant role in the regulation of mitochondrial biogenesis.

1. Wojewoda M, Duszyล„ski J, Szczepanowska J (2010) Antioxidant defence systems and generation of reactive oxygen species in osteosarcoma cells with defective mitochondria; effect of selenium. Biochim. Biophys. Acta [doi:10.1016/j.bbabio.2010.01.035]

2. Piantadosi CA, Suliman HB (2006) Mitochondrial transcription factor A induction by redox activation of nuclear respiratory factor 1. J. Biol. Chem. 281 324-333.


โ€ข O2k-Network Lab: PL Warsaw SzewczykA


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This presentation was a winner of the Young Investigator Poster Award at MiP2010.