Jarosław Walczak, Ph.D.

Department of Biosystems and Soft Matter (ZBiMM)
Division of Modelling in Biology and Medicine (PMBM)
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 468
room: 309
e-mail: jwalczak

Doctoral thesis
2016-09-30Zmiany funkcjonowania mitochondriów i organizacji sieci mitochondrialnej w fibroblastach pacjentów ze stwardnieniem bocznym zanikowym (ALS) 
supervisor -- Joanna Szczepanowska, Ph.D., Dr. Habil., IBD PAN
1406 
Recent publications
1.Malińska D., Szymański J., Patalas-Krawczyk P., Michalska B., Wojtala A., Prill M., Partyka M., Drabik K., Walczak J., Sewer A., Johne S., Luettich K., Peitsch M.C., Hoeng J., Duszyński J., Szczepanowska J., van der Toorn M., Więckowski M.R., Assessment of mitochondrial function following short- and long-term exposure of human bronchial epithelial cells to total particulate matter from a candidate modified-risk tobacco product and reference cigarettes, Food and Chemical Toxicology, ISSN: 0278-6915, DOI: 10.1016/j.fct.2018.02.013, Vol.115, pp.1-12, 2018
Abstract:

Mitochondrial dysfunction caused by cigarette smoke is involved in the oxidative stress-induced pathology of airway diseases. Reducing the levels of harmful and potentially harmful constituents by heating rather than combusting tobacco may reduce mitochondrial changes that contribute to oxidative stress and cell damage. We evaluated mitochondrial function and oxidative stress in human bronchial epithelial cells (BEAS 2B) following 1- and 12-week exposures to total particulate matter (TPM) from the aerosol of a candidate modified-risk tobacco product, the Tobacco Heating System 2.2 (THS2.2), in comparison with TPM from the 3R4F reference cigarette. After 1-week exposure, 3R4F TPM had a strong inhibitory effect on mitochondrial basal and maximal oxygen consumption rates compared to TPM from THS2.2. Alterations in oxidative phosphorylation were accompanied by increased mitochondrial superoxide levels and increased levels of oxidatively damaged proteins in cells exposed to 7.5 μg/mL of 3R4F TPM or 150 μg/mL of THS2.2 TPM, while cytosolic levels of reactive oxygen species were not affected. In contrast, the 12-week exposure indicated adaptation of BEAS-2B cells to long-term stress. Together, the findings indicate that 3R4F TPM had a stronger effect on oxidative phosphorylation, gene expression and proteins involved in oxidative stress than TPM from the candidate modified-risk tobacco product THS2.2.

Keywords:

Mitochondria, Mitochondrial respiratory chain, Oxidative stress, BEAS-2B cells, Cigarette, Tobacco heating system

Affiliations:
Malińska D.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Szymański J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Johne S.-Philip Morris Products S.A. (CH)
Luettich K.-Philip Morris Products S.A. (CH)
Peitsch M.C.-Philip Morris Products S.A. (CH)
Hoeng J.-Philip Morris Products S.A. (CH)
Duszyński J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Szczepanowska J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
van der Toorn M.-Philip Morris Products S.A. (CH)
Więckowski M.R.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Patalas-Krawczyk P.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Michalska B.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Wojtala A.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Prill M.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Partyka M.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Drabik K.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Walczak J.-other affiliation
Sewer A.-Philip Morris Products S.A. (CH)
2.Walczak J., Partyka M., Duszyński J., Szczepanowska J., Implications of mitochondrial network organization in mitochondrial stress signalling in NARP cybrid and Rho0 cells, Scientific Reports, ISSN: 2045-2322, DOI: 10.1038/s41598-017-14964-y, Vol.7, No.14864, pp.1-14, 2017
Abstract:

Mitochondrial dysfunctions lead to the generation of signalling mediators that influence the fate of that organelle. Mitochondrial dynamics and their positioning within the cell are important elements of mitochondria-nucleus communication. The aim of this project was to examine whether mitochondrial shape, distribution and fusion/fission proteins are involved in the mitochondrial stress response in a cellular model subjected to specifically designed chronic mitochondrial stress: WT human osteosarcoma cells as controls, NARP cybrid cells as mild chronic stress and Rho0 as severe chronic stress. We characterized mitochondrial distribution in these cells using confocal microscopy and evaluated the level of proteins directly involved in the mitochondrial dynamics and their regulation. We found that the organization of mitochondria within the cell is correlated with changes in the levels of proteins involved in mitochondrial dynamics and proteins responsible for regulation of this process. Induction of the autophagy/mitophagy process, which is crucial for cellular homeostasis under stress conditions was also shown. It seems that mitochondrial shape and organization within the cell are implicated in retrograde signalling in chronic mitochondrial stress.

Affiliations:
Walczak J.-other affiliation
Partyka M.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Duszyński J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Szczepanowska J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
3.Oparka M., Walczak J., Malińska D., van Oppen L.M.P.E., Szczepanowska J., Koopman W.J.H., Więckowski M.R., Quantifying ROS levels using CM-H2DCFDA and HyPer, Methods, ISSN: 1046-2023, DOI: 10.1016/j.ymeth.2016.06.008, Vol.109, pp.3-11, 2016
Abstract:

At low levels, reactive oxygen species (ROS) can act as signaling molecules within cells. When ROS production greatly exceeds the capacity of endogenous antioxidant systems, or antioxidant levels are reduced, ROS levels increase further. The latter is associated with induction of oxidative stress and associated signal transduction and characterized by ROS-induced changes in cellular redox homeostasis and/or damaging effects on biomolecules (e.g. DNA, proteins and lipids). Given the complex mechanisms involved in ROS production and removal, in combination with the lack of reporter molecules that are truly specific for a particular type of ROS, quantification of (sub)cellular ROS levels is a challenging task. In this chapter we describe two strategies to measure ROS: one approach to assess general oxidant levels using the chemical reporter CM-H2DCFDA (5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate), and a second approach allowing more specific analysis of cytosolic hydrogen peroxide (H2O2) levels using protein-based sensors (HyPer and SypHer).

Keywords:

Reactive oxygen species, Hydrogen peroxide, CM-H2DCFDA, HyPer, SypHer

Affiliations:
Oparka M.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Walczak J.-other affiliation
Malińska D.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
van Oppen L.M.P.E.-RIMLS, RCMM, Radboudumc, Nijmegen (NL)
Szczepanowska J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Koopman W.J.H.-RIMLS, RCMM, Radboudumc, Nijmegen (NL)
Więckowski M.R.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
4.Wojewoda M., Walczak J., Duszyński J., Szczepanowska J., Selenite activates the ATM kinase-dependent DNA repair pathway in human osteosarcoma cells with mitochondrial dysfunction, Biochemical Pharmacology, ISSN: 0006-2952, DOI: 10.1016/j.bcp.2015.03.016, Vol.95, No.3, pp.170-176, 2015
Abstract:

Mitochondrial dysfunction and reactive oxygen species (ROS) induced oxidative damage are implicated in the pathogenesis of several human diseases. Based on our previous findings that ROS level was higher in human osteosarcoma cybrids—Neuropathy, Ataxia and Retinitis Pigmentosa (NARP) and was reduced by selenite treatment, this study was designed to elucidate the effects of selenite administration on oxidative and nitrosative damage to lipids, proteins and DNA.

Oxidative and nitrosative damage to lipids and proteins was not increased in NARP cybrids or mitochondrial DNA-lacking Rho0 cells (displaying mitochondrial dysfunction) when compared with control WT cells. However, we found the enhanced formation of DNA double-strand breaks based on the level of histone γH2AX (phosphorylated at Ser 139), which is known to be phosphorylated by ATM (Ataxia Telangiectasia Mutated) kinase in response to DNA damage. Selenite increased the activity of ATM kinase in NARP cybrids and Rho0 cells without concomitant increase in levels of histone γH2AX.

Activation of the ATM kinase-dependent DNA repair pathway triggered by selenite could not be associated with enhanced DNA damage but might rather result from selenite-induced activation of ATM-dependent DNA repair mechanisms which could account for protective effects of this agent.

Keywords:

Mitochondrial dysfunction, Selenite, DNA repair, ATM kinase, Oxidative damage

Affiliations:
Wojewoda M.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Walczak J.-other affiliation
Duszyński J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
Szczepanowska J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)
5.Walczak J., Szczepanowska J., Zaburzenia dynamiki i dystrybucji mitochondriów w komórkach w stwardnieniu zanikowym bocznym (ALS), Postępy Biochemii, ISSN: 0032-5422, Vol.61, No.2, pp.183-190, 2015
Abstract:

Stwardnienie zanikowe boczne (ALS) jest chorobą o złożonej etiologii, prowadzącą do degradacji neuronów ruchowych. Jednym z pierwszych objawów w rozwoju wielu chorób neurodegeneracyjnych, m. in. w ALS, są zaburzenia funkcjonowania mitochondriów. Już kilka dekad temu obserwowano zmiany morfologii mitochondriów w tkankach pacjentów cierpiących na to schorzenie. Mitochondria są organellami dynamicznymi, ulegają ciągłym procesom fuzji i fragmentacji oraz przemieszczania się w komórce. Prawidłowy przebieg procesów związanych z dynamiką i dystrybucją mitochondriów jest kluczowy dla funkcjonowania komórek, a w szczególności komórek nerwowych o silnie wydłużonych aksonach. Praca ta stanowi podsumowanie istniejącej wiedzy na temat roli dynamiki i dystrybucji mitochondriów w patofizjologii ALS, formy rodzinnej i sporadycznej.

Keywords:

ALS, dynamika mitochondriów, transport mitochondriów, neurodegeneracja

Affiliations:
Walczak J.-other affiliation
Szczepanowska J.-Nencki Institute of Experimental Biology, Polish Academy of Sciences (PL)