Muscular atrophy is caused by the fragmentation and elongation of mitochondria, according to researchers from the University of Barcelona.
This fragmentation and elongation lead to an inflammatory process in muscle cells which can cause a diminished resistance to exercise and subsequent muscular atrophy. Mitochondria are essential cellular components that act as power stations within the body.
The fusion of two or more mitochondria, and the fission of a mitochondrion into two units is known as mitochondrial dynamics. Both these processes are essential for the proper functioning of these structures, as well as the cell itself.
The researchers have described a new molecular mechanism related to alterations the mitochondrial dynamics and inflammation that causes muscular atrophy. They found that blocking mitochondria fusion or fission triggered the inflammatory process.
Inflammation can lead to several serious diseases
“Chronic inflammation is one of the processes that affect our health, given that it is linked to a wide range of diseases, such as diabetes, Alzheimer’s, Parkinson’s, and cancer, not to mention ageing. This is why it is important to understand it so that we can tackle it and prevent related disorders”, explained Dr Zorzano, head of the Complex Metabolic Diseases and Mitochondria Laboratory at IRB Barcelona.
This process has been observed in muscle cells in culture, as well as in the muscles of mice. This inflammation is known as ‘sterile inflammation’, as it is not linked to an infectious process.
The researchers believe their findings could help the exploration of alterations in mitochondrial dynamics and improve research into the development of diseases. The findings could be especially relevant to diseases that affect the muscles.
“One of the most remarkable findings of our study is that when we push mitochondrial dynamics towards either of its two extremes (mitochondrial fragmentation or elongation), these inflammatory pathways are activated in different ways. In both cases, the activation of these pathways involves the recognition of mitochondrial DNA by intracellular DNA sensors,” said Dr Andrea Irazoki, first author of the study.
Muscular atrophy affects physical performance
The researchers have also proved that this mechanism has physiological relevance. They found that mice with mitochondrial fragmentation in their muscles display had both inflammation and muscular atrophy, which negatively affected their physical performance.
“In this research, we have discovered an essential role for mitochondrial dynamics in inflammatory processes. Together with the group’s previous results, which revealed alterations in dynamics during ageing, these new findings could explain the increased inflammation associated with ageing” said Dr David Sebastiám, who co-led the project.
The research team analysed molecules that take over dysfunctional mitochondrial proteins, allowing them to guarantee cellular homeostasis. An increasing number of studies have supported the idea that mitochondrial alterations are the reason behind several inflammatory diseases.
The full findings of the study have been published in the journal Nature Communications.
