Muscles need to 'remove garbage' to remain strong and healthy
An EU-funded research team has found that muscles need to rid themselves of their waste products regularly if they are to remain strong and healthy. The results of the team's study, published in the December issue of the journal Cell Metabolism, could lead to new treatments for muscle-wasting diseases and conditions. During the process of muscle cleansing, known as 'autophagy', waste products such as spent organelles, toxic clumps of proteins, and pathogens are eliminated from the muscle cells. The research study is part of two EU-funded projects, MYOAGE ('Understanding and combating human age-related muscle weakness') which received EUR 11.2 million of funding under the Health Theme of the Seventh Framework Programme (FP7), and EXGENESIS ('Health benefits of exercise: identification of genes and signalling pathways involved in effects of exercise on insulin resistance, obesity and the metabolic syndrome'), which received EUR 12.7 million under the 'Life sciences, genomics and biotechnology for health' Thematic area of the Sixth Framework Programme (FP6). The research team, led by Dr Marco Sandri from the University of Padua in Italy, carried out tests on mice that were lacking a gene necessary for the process of autophagy to be carried out. The mice showed clear signs of muscle weakness and atrophy that increased with age. 'If there is a failure of the system to remove what is damaged and that persists, the muscle fibre isn't happy,' said Dr Sandri. Damage to the muscle cells includes an accumulation of degraded proteins and free radicals, and damage to the internal cell structures. Eventually, some of the muscle cells die, 'and the muscles become weaker and weaker with age,' explained Dr Sandri. The research team noted that the atrophying process in the muscles of the mice showed some resemblance to certain muscle-wasting diseases in human beings. The results of the study may therefore offer clues as to how muscle weakening occurs in humans, such as that which normally happens with age, a process known as sarcopenia. Although the process of autophagy is vital for muscle health, excessive autophagy can also lead to muscle waste and disease. The study shows the importance of the muscles maintaining a normal level of autophagy. This finding was a surprise to the research team. 'We thought if you reduced autophagy it might protect against atrophy,' said Dr Sandri. 'Instead, it is the opposite. We realised, that, of course, if you don't remove the damage it triggers weakness.' According to Dr Sandri, the findings may have important clinical implications as there is interest in developing therapies to block the degradation of proteins for treating certain muscle-wasting diseases. But in some cases at least 'it may be better to activate autophagy and remove the garbage in the cells,' Dr Sandri said. The research team think that similar treatments might help to slow down the process of age sarcopenia. They also note that another study has shown a similar decline in the efficiency of autophagy as part of the ageing process.
Countries
Italy