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Identification of MyoD Interactome Using Tandem Affinity Purification Coupled to Mass Spectrometry
Published on: May 17, 2016
Control of mitochondrial biogenesis during myogenesis
C S Kraft1, C M R LeMoine, C N Lyons
1Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada.
American Journal of Physiology. Cell Physiology
|March 15, 2006
Summary
This study reveals distinct regulatory pathways for mitochondrial gene expression during muscle development. Nuclear respiratory factors (NRF-1 and NRF-2) and Sp1 influence mitochondrial biogenesis, with specific inhibitors highlighting unique roles in regulating key enzymes like citrate synthase.
Area of Science:
- Molecular Biology
- Cellular Biology
- Biochemistry
Background:
- Mitochondrial gene expression is crucial for cellular energy production and is tightly regulated during muscle differentiation (myogenesis).
- Nuclear respiratory factors (NRF-1, NRF-2) and peroxisome proliferator-activated receptors (PPARs) are known regulators of mitochondrial biogenesis.
- The precise transcriptional control mechanisms governing mitochondrial gene expression during myogenesis are not fully elucidated.
Purpose of the Study:
- To investigate the roles of specific transcription factors and signaling pathways in regulating mitochondrial gene expression during myogenesis.
- To delineate the mechanisms controlling the expression of citrate synthase (CS), a key mitochondrial enzyme, during muscle cell differentiation.
- To explore the potential involvement of post-transcriptional regulation in mitochondrial biogenesis.
Main Methods:
- Utilized expression and reporter gene analyses in cultured murine myoblasts (C2C12 and Sol8).
- Performed promoter analysis of the citrate synthase (CS) gene, including deletion mutants and site-directed mutagenesis.
- Employed inhibitor studies using LY-294002 (phosphatidylinositol 3-kinase inhibitor) and SB-203580 (p38-MAPK inhibitor) to assess pathway-specific effects.
Main Results:
- NRF-1 and NRF-2 mRNA and reporter gene activity increased significantly during myogenesis.
- PPARalpha mRNA levels rose, but PPAR reporter activity remained unchanged; PGC1alpha was undetectable, while PGC1beta mRNA increased.
- CS gene promoter analysis suggested a role for Sp1 regulation, independent of PPAR, NRF-1, or NRF-2 binding sites.
- SB-203580 inhibited myogenic increases in cytochrome oxidase activity, while LY-294002 specifically blocked increases in CS activity, indicating distinct regulatory pathways.
Conclusions:
- Myogenesis involves complex regulation of mitochondrial gene expression, with distinct roles for NRF-1, NRF-2, and Sp1.
- The regulation of citrate synthase during myogenesis appears to involve a pathway distinct from those controlled by PPARs and NRFs.
- These findings highlight the importance of both transcriptional and post-transcriptional regulatory mechanisms in mitochondrial biogenesis during muscle development.
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