Bioénergétique des tumeurs : impact de l'hypoxie et de l'aglycémie sur le métabolisme énergétique du cancer du sein, Non-canonical bioenergetics of the cell
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Thèse soutenue le 28 décembre 2009: Charles University (Prague), Bordeaux 2
Non-canonical bioenergetics concerns with those physiological and pathophysiological situations under which ATP synthesis is suppressed. This thesis brings an outcome of three types of studies within the field of the non-canonical bioenergetics, investigating specific bioenergetic phenotypes of cancer cells, on one hand; and a role of mitochondrial uncoupling proteins as deduced from their transcript distribution in various tissues and organs; plus a role of a novel and likely pro-apoptotic factor CIDEa in mitochondria. Cancer cells generally present abnormal bioenergetic properties including an elevated glucose uptake, a high glycolysis and a poorly efficient oxidative phosphorylation system. However, the determinants of cancer cells metabolic reprogramming remain unknown. The main question in this project was how environmental conditions in vivo can influence functioning of mitochondrial OXPHOS, because details of mitochondrial bioenergetics of cancer cells is poorly documented. We have combined two conditions, namely glucose and oxygen deprivation, to measure their potential interaction. We examined the impact of glucose deprivation and oxygen deprivation on cell survival, overall bioenergetics and OXPHOS protein expression. As a model, we have chosen a human breast carcinoma (HTB-126) and appropriate control (HTB-125) cultured cells, as large fraction of breast malignancies exhibit hypoxic tumor regions with low oxygen concentrations and poor glucose delivery. The results demonstrate that glucose presence or absence largely influence functioning of mitochochondrial oxidative phosphorylation. The level of mitochondrial respiration capacity is regulated by glucose; by Crabtree effect, by energy substrate channeling towards anabolic pathways that support cell growth and by mitochondrial biogenesis pathways. Both oxygen deprivation and glucose deprivation can remodel the OXPHOS system, albeit in opposite directions. As an adaptative response to hypoxia, glucose inhibits mitochondrial oxidative phosphorylation to the larger extent than in normoxia. We concluded that the energy profile of cancer cells can be determined by specific balance between two main environmental stresses, glucose and oxygen deprivation. Thus, variability of intratumoral environment might explain the variability of cancer cells´ bioenergetic profile. Mitochondrial uncoupling proteins are proteins of inner mitochondrial membrane that uncouple respiration from ATP synthesis by their protonophoric activity. Originally determined tissue distribution seems to be invalid, since novel findings show that UCP1 is not restricted exclusively to brown fat and that originally considered brain-specific isoforms UCP4 and UCP5 might have wider tissue distribution. Hence, in second part of this thesis, I discuss consequences of findings of UCPn transcripts in the studied mouse and rat tissues. We have shown that mRNA of UCPn varies up to four orders of magnitude in rat and mouse tissues with highest expression in rat spleen, rat and mouse lung, and rat heart. Levels of the same order of magnitude were found for UCP3 mRNA in rat 100 and mouse skeletal muscle, for UCP4 and UCP5 mRNA in mouse brain, and for UCP2 and UCP5 mRNA in mouse white adipose tissue. Further, we have shown that expression pattern of UCPn varies between animal species, rat versus mouse, such as the dominance of UCP3/UCP5 vs. UCP2 transcript in mouse heart and vice versa in rat heart; or UCP2 (UCP5) dominance in rat brain contrary to 10-fold higher UCP4 and UCP5 dominance in mouse brain. Side pathways of apoptotis were revealed recently, namely those including proteins with homology to nuclease DFF responsible for apoptotic DNA cleavage, CIDE. Migration of CIDEs from mitochondria to nucleus (or to cytosol) has not been reported until 2008, except for cases with staurosporine or etoposide. We have shown for the first time that under conditions of spontaneous apoptosis due to CIDEa overexpression in HeLa cells, adapted for a tetracycline-inducible CIDEa expression, a portion of mitochondria-localized CIDEa molecules migrates to cytosol or nucleus.
-Mitochondries
-Métabolisme énergétique
-Cancer
-Protéines découplantes
-Apoptose
Résumé non disponible
-Mitochondria
-Energy metabolism
-Uncoupling proteins
-Apoptosis
Source: http://www.theses.fr/2009BOR21700/document
UNIVERSITÉ
VICTOR
SEGALEN
BORDEAUX
2
and
CHARLES
UNIVERSITY
IN
PRAGUE
st
1
Faculty
of
Medicine
NON‐CANONICAL
BIOENERGETICS
OF
THE
CELL
DOCTORAL
THESIS
PRAGUE
2009
Katarína
Smolková
This
thesis
was
elaborated
in
cooperation
of
the
Membrane
Transport
Biophysics,
laboratory
of
Institute
of
Physiology,
Academy
of
Sciences
of
the
Czech
Republic
and
the
U688
Physiopathologie
Mitochondriale
of
INSERM,
Bordeaux,
France,
supported
by
postgraduate
fellowship
provided
by
French
government
in
the
program
entitled
“Doctorat
en
co‐tutelle”.
Foreign
stage
was
further
supported
by
foundation
“Nadání
Josefa,
Marie
a
Zdeňky
Hlávkových”,
foundation
“Dagmar
a
Václava
Havlových
VIZE
97”,
and
Fond
Mobility
UK.
PHD
studies
proceeded
from
October
2005
PHD
in
study
program
Biochemistry
and
Pathobiochemistry.
Author:
Mgr.
Katarína
Smolková
Supervisors:
Rodrigue
Rossignol,
PhD.
RNDr.
Petr
Ježek,
DrSc.
Prague,
June
2009
……………………………………..
Katarína
Smolková
AKNOWLEDGEMENTS
I would like to express my grateful thanks to supervisors Petr Ježek and Rodrigue
Rossignol for giving me the opportunity to work with their groups and introducing me to
the most exciting field of research. I appreciate their kind supervising, patience,
enthusiasm and support.
Thanks belong also to Thierry Letellier, head of the department U688 in Bordeaux for
permitting me to work in his laboratory. I must also thank to authors of the presented
articles, namely Lukáš Alán, Eva Valoušková, Martin Modrianský and Jitka Šantorová.
Special thanks to all people I met in both laboratories for great time I spent with them
and for making my time in lab really enjoyable.
CONTENT
LIST OF FIGURES AND TABLES.............................................................................................................................1
1. INTRODUCTION ........................................................................................................................................3
1.1. Significance of non-canonical bioenergetics..............................................................................3
1.2. Specific aspects of presented studies ........................................................................................5
1.3. Aims ...........................................................................................................................................7
2. BACKGROUND ..........................................................................................................................................8
2.1. Mitochondria – general features ...............................................................................................8
2.1.1. Mitochondria, their structure and composition ...................................................................8
2.1.2. Mitochondrial biogenesis....................................................................................................10
2.1.3. Function of mitochondria....................................................................................................11
2.1.3.1. Oxidative phosphorylation ............................................................................................11
2.1.3.2. Energy metabolism........................................................................................................12
2.1.3.3. Apoptosis.......................................................................................................................13
2.2. Basic facts for CIDE proteins ....................................................................................................14
2.2.1. Expression ...........................................................................................................................14
2.2.2. Bological function................................................................................................................15
2.2.3. Interaction with UCP1 .........................................................................................................16
2.2.4. Possible migration of CIDE proteins into mitochondria and consequences .......................16
2.3. Bioenergetics of cancer cells....................................................................................................18
2.3.1. Energy metabolism of cancer cells......................................................................................18
2.3.1.1. Warburg effect ..............................................................................................................18
2.3.1.2. Variability ......................................................................................................................18
2.3.1.3. Dysfunctional mitochondria and alterations in cancer cells .........................................19
2.3.1.4. Crabtree effect ..............................................................................................................20
2.3.2. Possible origin of cancer metabolic remodeling .................................................................22
2.3.2.1. Hypoxia: Adaptation and survival in low oxygen ..........................................................22
2.3.2.1.1. Tumor oxygenation...............................................................................................22
2.3.2.1.2. Respiration at low oxygen.....................................................................................24
2.3.2.1.3. HIF pathway ..........................................................................................................25
2.3.2.1.4. AMPK pathway NFκB, mTOR participation in hypoxia..........................................32
2.3.2.2. Oncogenes in metabolic reprogramming......................................................................33
2.3.2.3. Proliferation rate ...........................................................................................................36
2.3.2.4. Metabolism of glutamine in cancer cells, glucose deprivation .....................................38
2.3.2.5. Reversal to fetal phenotype ..........................................................................................40
2.4. Mitochondrial uncoupling protein isoforms ............................................................................42
2.4.1. Uncoupling by uncoupling proteins ....................................................................................42
2.4.2. Possible physiological roles of mitochondrial uncoupling proteins UCP2 to 5 ...................45
2.4.2.1. UCP2 and diabetes ........................................................................................................45
2.4.2.2. UCP2 and immunity response .......................................................................................46
2.4.2.3. UCP2 and atherosclerosis......................
