Mitochondrial dysfunction in ageing and degenerative disease
Author: Wredenberg, Anna
Date: 2007-10-26
Location: Hörsalen 4V, Alfred Nobels allé 8
Time: 09.00
Department: Institutionen för laboratoriemedicin / Department of Laboratory Medicine
View/ Open:
thesis.pdf (1.836Mb)
Abstract
The cytoplasm of eukaryotic cells contains a dynamic network of
double-membraned organelles, called mitochondria, which perform the
process of oxidative phosphorylation (OXPHOS) that provides cellular
energy in the form of ATP. The respiratory chain creates an
electrochemical gradient across the inner mitochondrial membrane, which
drives ATP synthesis by the ATP synthase. Mitochondria are indispensable
for normal cell function and survival, and dysfunction of the OXPHOS
system can lead to a variety of disease syndromes, collectively termed
mitochondrial encephalomyopathies. Mitochondrial dysfunction has also
been proposed to be involved in age-associated diseases such as diabetes
mellitus, heart disease and neurodegeneration, as well as in the ageing
process itself. Tissues with high metabolism seem to be particularly
vulnerable to mitochondrial dysfunction and myopathy is one of the common
phenotypes in mitochondrial disorders. However, the pathophysiological
mechanisms linking respiratory chain deficiency to the various phenotypic
manifestations are poorly understood. We therefore generated a mouse
model for mitochondrial myopathy by tissue-specific disruption of the
nuclear gene encoding mitochondrial transcription factor A (TFAM). These
myopathy mice develop a progressive respiratory chain dysfunction in
skeletal muscle with typical morphological changes consistent with
mitochondrial myopathy. Surprisingly the overall mitochondrial ATP
production rate was close to normal in the knockout muscles, likely due
to the compensatory increase of mitochondrial mass in the affected
muscles. Thus, other factors besides ATP deficiency are likely of
importance in mitochondrial myopathy. There is a large number of
correlative studies suggesting that mitochondrial dysfunction in skeletal
muscle is causing the peripheral insulin resistance observed in patients
with diabetes mellitus type 2 (DM2). Unexpectedly, the myopathy mice
exhibited normal insulin sensitivity and increased glucose uptake in
skeletal muscle, suggesting that reduced respiratory chain function in
peripheral tissues may be protective against DM2. The mitochondrial
theory of aging proposes that oxidative damage to mitochondrial DNA
(mtDNA) leads to mutations and impaired respiratory chain function, which
in turn, increases reactive oxygen species (ROS) production. ROS have
been suggested to induce oxidative damage to various molecules of the
cell and thereby cause the progressive decline seen in ageing. We
generated mice expressing a proof-reading-deficient version of the mtDNA
polymerase gamma. These mtDNA mutator mice accumulated mtDNA mutations at
an increased rate and developed a progressive respiratory chain
deficiency. They also developed premature ageing phenotypes and exhibited
a reduced lifespan, supporting the suggestion of a causative link between
mitochondrial dysfunction and ageing. However, we found no differences in
ROS production, no increased expression of ROS scavenging enzymes, and no
or minor changes in levels of oxidative damage in cell lines and tissues
from the mtDNA mutator mice. We instead propose that the accumulation of
mtDNA mutations beyond a critical threshold leads to bioenergetic failure
and loss of vital cells. This cell loss caused by respiratory chain
dysfunction may lead to reduced organ function and eventually organ
failure, giving rise to age-associated disease and important ageing
phenotypes.
List of papers:
I. Wredenberg A, Wibom R, Wilhelmsson H, Graff C, Wiener HH, Burden SJ, Oldfors A, Westerblad H, Larsson NG (2002). "Increased mitochondrial mass in mitochondrial myopathy mice." Proc Natl Acad Sci U S A 99(23): 15066-71. Epub 2002 Nov 4
Pubmed
II. Wredenberg A, Freyer C, Sandström ME, Katz A, Wibom R, Westerblad H, Larsson NG (2006). "Respiratory chain dysfunction in skeletal muscle does not cause insulin resistance." Biochem Biophys Res Commun 350(1): 202-7. Epub 2006 Sep 18
Pubmed
III. Trifunovic A, Wredenberg A, Falkenberg M, Spelbrink JN, Rovio AT, Bruder CE, Bohlooly-Y M, Gidlöf S, Oldfors A, Wibom R, Törnell J, Jacobs HT, Larsson NG (2004). "Premature ageing in mice expressing defective mitochondrial DNA polymerase." Nature 429(6990): 417-23
Pubmed
IV. Trifunovic A, Hansson A, Wredenberg A, Rovio AT, Dufour E, Khvorostov I, Spelbrink JN, Wibom R, Jacobs HT, Larsson NG (2005). "Somatic mtDNA mutations cause aging phenotypes without affecting reactive oxygen species production." Proc Natl Acad Sci U S A 102(50): 17993-8. Epub 2005 Dec 6
Pubmed
I. Wredenberg A, Wibom R, Wilhelmsson H, Graff C, Wiener HH, Burden SJ, Oldfors A, Westerblad H, Larsson NG (2002). "Increased mitochondrial mass in mitochondrial myopathy mice." Proc Natl Acad Sci U S A 99(23): 15066-71. Epub 2002 Nov 4
Pubmed
II. Wredenberg A, Freyer C, Sandström ME, Katz A, Wibom R, Westerblad H, Larsson NG (2006). "Respiratory chain dysfunction in skeletal muscle does not cause insulin resistance." Biochem Biophys Res Commun 350(1): 202-7. Epub 2006 Sep 18
Pubmed
III. Trifunovic A, Wredenberg A, Falkenberg M, Spelbrink JN, Rovio AT, Bruder CE, Bohlooly-Y M, Gidlöf S, Oldfors A, Wibom R, Törnell J, Jacobs HT, Larsson NG (2004). "Premature ageing in mice expressing defective mitochondrial DNA polymerase." Nature 429(6990): 417-23
Pubmed
IV. Trifunovic A, Hansson A, Wredenberg A, Rovio AT, Dufour E, Khvorostov I, Spelbrink JN, Wibom R, Jacobs HT, Larsson NG (2005). "Somatic mtDNA mutations cause aging phenotypes without affecting reactive oxygen species production." Proc Natl Acad Sci U S A 102(50): 17993-8. Epub 2005 Dec 6
Pubmed
Issue date: 2007-10-05
Rights:
Publication year: 2007
ISBN: 978-91-7357-311-5
Statistics
Total Visits
Views | |
---|---|
Mitochondrial ...(legacy) | 766 |
Mitochondrial ... | 101 |
Total Visits Per Month
October 2023 | November 2023 | December 2023 | January 2024 | February 2024 | March 2024 | April 2024 | |
---|---|---|---|---|---|---|---|
Mitochondrial ... | 2 | 1 | 0 | 0 | 0 | 2 | 0 |
File Visits
Views | |
---|---|
thesis.pdf(legacy) | 545 |
thesis.pdf | 209 |
thesis.pdf.txt(legacy) | 2 |
Top country views
Views | |
---|---|
United States | 366 |
Sweden | 111 |
Germany | 64 |
China | 56 |
South Korea | 14 |
Finland | 11 |
Russia | 10 |
United Kingdom | 9 |
Ireland | 7 |
Denmark | 6 |
Top cities views
Views | |
---|---|
Stockholm | 58 |
Romeo | 34 |
Sunnyvale | 26 |
Beijing | 21 |
Kiez | 18 |
Seoul | 14 |
Shenzhen | 7 |
Ballerup | 6 |
Dublin | 6 |
Hamburg | 6 |