PGC-1a, a transcriptional coactivator, controls inflammation and mitochondrial gene expression in insulin-sensitive tissues
following exercise intervention. However, attributing such effects to PGC-1a is counfounded by exercise-induced
fluctuations in blood glucose, insulin or bodyweight in diabetic patients. The goal of this study was to investigate the role of
PGC-1a on inflammation and mitochondrial protein expressions in aging db/db mice hearts, independent of changes in
glycemic parameters. In 8-month-old db/db mice hearts with diabetes lasting over 22 weeks, short-term, moderate-intensity
exercise upregulated PGC-1a without altering body weight or glycemic parameters. Nonetheless, such a regimen lowered
both cardiac (macrophage infiltration, iNOS and TNFa) and systemic (circulating chemokines and cytokines) inflammation.
Curiously, such an anti-inflammatory effect was also linked to attenuated expression of downstream transcription factors of
PGC-1a such as NRF-1 and several respiratory genes. Such mismatch between PGC-1a and its downstream targets was
associated with elevated mitochondrial membrane proteins like Tom70 but a concurrent reduction in oxidative
phosphorylation protein expressions in exercised db/db hearts. As mitochondrial oxidative stress was predominant in these
hearts, in support of our in vivo data, increasing concentrations of H2O2 dose-dependently increased PGC-1a expression
while inhibiting expression of inflammatory genes and downstream transcription factors in H9c2 cardiomyocytes in vitro.
We conclude that short-term exercise-induced oxidative stress may be key in attenuating cardiac inflammatory genes and
impairing PGC-1a mediated gene transcription of downstream transcription factors in type 2 diabetic hearts at an advanced
age.
PGC-1a, a transcriptional coactivator, controls inflammation and mitochondrial gene expression in insulin-sensitive tissues
following exercise intervention. However, attributing such effects to PGC-1a is counfounded by exercise-induced
fluctuations in blood glucose, insulin or bodyweight in diabetic patients. The goal of this study was to investigate the role of
PGC-1a on inflammation and mitochondrial protein expressions in aging db/db mice hearts, independent of changes in
glycemic parameters. In 8-month-old db/db mice hearts with diabetes lasting over 22 weeks, short-term, moderate-intensity
exercise upregulated PGC-1a without altering body weight or glycemic parameters. Nonetheless, such a regimen lowered
both cardiac (macrophage infiltration, iNOS and TNFa) and systemic (circulating chemokines and cytokines) inflammation.
Curiously, such an anti-inflammatory effect was also linked to attenuated expression of downstream transcription factors of
PGC-1a such as NRF-1 and several respiratory genes. Such mismatch between PGC-1a and its downstream targets was
associated with elevated mitochondrial membrane proteins like Tom70 but a concurrent reduction in oxidative
phosphorylation protein expressions in exercised db/db hearts. As mitochondrial oxidative stress was predominant in these
hearts, in support of our in vivo data, increasing concentrations of H2O2 dose-dependently increased PGC-1a expression
while inhibiting expression of inflammatory genes and downstream transcription factors in H9c2 cardiomyocytes in vitro.
We conclude that short-term exercise-induced oxidative stress may be key in attenuating cardiac inflammatory genes and
impairing PGC-1a mediated gene transcription of downstream transcription factors in type 2 diabetic hearts at an advanced
age.
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