Hipoksi-Reoksijenasyon ile İndüklenen Kardiyak Mitokondriyal Disfonksiyon
Amaç: Hücrelerin azalan oksijen konsantrasyonuna verdikleri yanıt hipoksinin şiddeti ve süresine göre değişiklik göstermektedir. Bu konuda oldukça fazla çalışma yapılmış olmasına karşın, hipoksi ile indüklenen fonksiyonel yanıtların altında yatan mekanizmalar büyük ölçüde aydınlatılamamıştır.Bu çalışmada, kardiyak kökenli HL-1 hücrelerinin, uzun süreli (48 saat) kesintisiz hipoksiye verdikleri yanıtta mitokondrinin hücresel enerji ve reaktif oksijen türevleri (ROS) dengesindeki rolü araştırılmıştır.Gereç ve Yöntem: Bu çalışmada memeli atriyum kökenli hücre serisi HL-1 hücrelerinde uzun süreli hipokside (48 saat, %1 O2 ) ve normoksik (48 saat, %21 O2 ) şartlarda kültür edilmiştir. Normoksik kontrol ve hipoksik hücrelerden mitokondri membran potansiyeli ve ROS miktarı floresan boyalar ilekonfokal mikroskopta ölçülmüş, GAPDH protein seviyeleri western blot yöntemi ile belirlenmiştir.Bulgular: Sonuçlarımıza göre, kardiyak HL-1 hücrelerinde 48 saat hipoksi bazal mitokondri membran potansiyeli ve oksijenli solunum kapasitesini değiştirmedi. Bununla birlikte hipoksik hücrelerin reoksijenasyon sırasında ortamdan tekrar oksijen uzaklaştırılmasına olan mitokondriyaldepolarizasyon yanıtları normoksik kontrol hücrelere göre yavaştı. Hipoksik hücrelerde bazal ROS miktarında artış gözlenirken, hidrojen peroksite olan yanıtlar normoksik kontrol grubuna göre azaldı. GAPDH protein seviyesinde gruplar arası bir fark saptanmadı.Sonuç: Bu sonuçlar, uzun süreli hipoksi ile indüklenen mitokondriyal oksidatif fosforilasyon kenetindeki kalıcı disfonksiyonun hücresel ROS artışından sorumlu olabileceğini düşündürmektedir.
Hypoxia-Reoxygenation Induced Cardiac Mitochondrial Dysfunction
Objectives: Cellular response to low oxygen tension is altered by severity and duration of hypoxia. Although the subject has been studied extensively, mechanisms leading to hypoxia-reoxygenation demage remain undefined. Here, we investigated the effect of long term continuous hypoxia (48 hours) on cardiac derived HL-1 cells, mainly the role of mitochondria in cellular energy and reactive oxygen species homeostasis. Materials and Methods: In this study, mammalian atrium derived HL-1 cells were cultured either in long term hypoxia (48 hours, 1% O2 ) or in normoxia (48 hours, 21% O2 ) conditions. Mitochondrial membrane potential and reactive oxygen species (ROS) level was measured using florescent dyes in a confocal microscope. GAPDH protein levels were detected by western blotting in normoxic control and hypoxic cells. Results: Present results demonstrate that, 48 hours of hypoxia did not alter baseline mitochondrial membrane potential and its oxidative respiration capacity in cardiac HL-1 cells. The mitochondrial depolarization response to in reoxygenation period of oxygen deprived cells was slower in hypoxic cells. In hypoxic cells, basal ROS levels were higher whereas hydrogen peroxide response was smaller when compared with the normoxic control group. GAPDH protein levels were unaltered between groups. Conclusion: Present results indicate that, persistent mitochondrial oxidation phosphorylation uncoupling may lead to an over production of ROS.
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- Liu B, Tewari AK, Zhang L, et al. Proteomicanalysis of protein tyrosine
nitration afteri schemiareperfusio ninjury:mitochondria as themajortarget.
Biochim Biophys Acta 2009;1794:476-485.
- Solaini G, Harris DA. Biochemicaldysfunction in heart mitochondria exposed
to ischaemia and reperfusion. Biochem J. 2005;390:377-394.
- Semenza GL.Hypoxia-induciblefactor 1: masterregulator of O2 homeostasis.
CurrOpinGenet Dev. 1998;8:588-594.
- Semenza GL, Roth PH, Fang HM, et al. Transcriptional regulation of
genesencoding glycolytic enzymes by hypoxia-induciblefactor 1. J BiolChem
1994;269:23757-23763.
- Semenza GL, Jiang BH, Leung SW, et al. Hypoxia response elements
in thealdolase A, enolase 1, andlactatedehydrogenase A gene
promoterscontain essential binding sitesfor hypoxia-inducible factor 1.J
BiolChem 1996;271:32529-32537.
- Ebert BL, Firth JD, Ratcliffe PJ. Hypoxia and mitochondrial inhibitorsregulate
expression of glucose transporter-1 viadistinctCis-actingsequences. J Biol
Chem 1995;270:29083-29089.
- Turrens JF. Mitochondrial formation of reactive oxygen species. J Physiol
2003;552:335-344.
- Papandreou I, Cairns RA, Fontana L, et al. HIF-1 mediates adaptation to
hypoxia by actively downregulating mitochondrial oxygen consumption.
Cell Metab. 2006;3:187-197.
- Chandel NS, McClintock DS, Feliciano CE, et al. Reactive oxygen species
generated at mitochondrial Complex III stabilize hypoxia-inducible
factor-1alpha during hypoxia: a mechanism of O2 sensing. J Biol Chem.
2000;275:25130-25138.
- Chandel NS, Maltepe E, Goldwasser E, et al. Mitochondrial reactive
oxygen species trigger hypoxia-induced transcription. Proc Natl Acad Sci.
1998;95:11715-11720.
- Baracca A, Chiaradonna F, Sgarbi G, et al. Mitochondrial Complex I decrease
is responsible for bioenergetic dysfunction in K-ras transformed cells.
Biochim Biophys Acta 2010;1797:314-323.
- Şimşek G, Vaughan-Jones RD, Swietach P, et al. Recovery from hypoxiainducedinternalization
of cardiacNa+/H+ exchanger 1 requires an adequate
intracellular store of anti-oxidants. J Cell Physiol 2018.
- Claycomb WC, Lanson NA, Stallworth BS, et al. HL‐1 cells: Acardiac muscle
cell line that contracts and retains phenotypic characteristics of the adult
cardiomyocyte. Proc Natl Acad Sci U S A. 1998;95:2979-2984.
- Jezek P, Plecitá-Hlavatá L. Mitochondrial reticulum network dynamics in
relation to oxidative stress, redox regulation, and hypoxia. Int J Biochem
Cell Biol. 2009;41:1790-1804.
- Skarka L, Ostadal B. Mitochondrial membra nepotential in cardiacmyocytes.
Physiol Res 2002;51:425-434.
- Halestrap AP, Pasdois P. The role of the mitochondrial permeabilitytransition
pore in heartdisease. Biochim Biophys Acta. 2009;1787:1402-1415.
- Sridharan V, Guichard J, Li CY, et al. O(2)-sensing signal cascade: clamping
of O(2) respiration, reduced ATP utilization, and inducible fumarate
respiration. Am J Physiol Cell Physiol. 2008;295:C29-37.
- Ganitkevich V, Reil S, Schwethelm B, et al. Dynamic Responses of Single
Cardiomyocytesto GradedIschemia Studiedby Oxygen Clamp in On-Chip
Picochambers. Circ Res. 2006;99:165-171.
- Chen Q, Moghaddas S, Hoppel CL, et al. Reversibleblockade of electron
transport during ischemia protects mitochondria and decreases myocardial
in jury followingreperfusion. J Pharmacol Exp Ther. 2006;319:1405-1412.
- Chen CH, Budas GR, Churchill EN, et al. Activation of aldehyde
dehydrogenase-2 reduces ischemic damag eto the hear. Science.
2008;321:1493-1495.
- Lesnefsky EJ, Gudz TI, Migita CT, et al. Ischemic injury to mitochondrial
electron transport in the aging heart: damage to the iron-sulfur protein
subunit of electron transport complex III. Arch Biochem Biophys
2001;385:117-128.
- Lesnefsky EJ, Slabe TJ, Stoll MS, et al. Myocardial ischemia selectively
depletes cardiolipin in rabbit heart subsarcolemmal mitochondria. Am J
Physiol Heart Circ Physiol. 2001;280:H2770-2778.
- Görlach A, Dimova EY, Petry A, et al. Reactive oxygen species, nutrition,
hypoxia and diseases: Problems solved? Redox Biology. 2015;6:372-385.