Identification and isolation of newly incorporated myonuclei
Skeletal muscle accounts for 40% of total body mass and is responsible for movement and body posture. It also significantly contributes to energy metabolism. Given its diverse functions, loss of muscle mass is closely related to various adverse health outcomes. Muscle loss occurs in numerous of contexts including muscular dystrophy, cancer, obesity, diabetes, and chronic pulmonary disease, and also ageing. Loss of muscle mass is associated with delayed recovery from illness, slowed wound healing, reduced resting metabolic rate, physical disability, poorer quality of life, and higher health care costs.
When skeletal muscle mass increase each myofiber grow in size by increasing protein synthesis and incorporating new myonuclei to the cell. Nuclear positioning within cells is important for an array of cellular activities during development, immune response, tissue homeostasis and regeneration. In muscle nuclear positioning defects result in muscle disorders such as muscular dystrophy and ataxia, and it is shown that nuclear positioning within myofibers is required for proper muscle function.
We recently showed that the myonuclear number increase in muscle cells during hypertrophy. However, we have not until recently had any method to distinguish newly inserted myonuclei from already existing myonuclei in the hypertrophying fibers. Thus, we could not investigate how nuclear positioning occur for newly inserted nuclei. In this study we aim to investigate the positioning of newly inserted myonuclei from already existing myonuclei. We will investigate how these newly inserted myonuclei differs from already existing myonuclei by localization and epigenetic markers.
The proposed research is important to further highlight the benefits of exercise for maintaining muscle mass and function. This contribution will be significant because whereas numerous studies have identified that the number of myonuclei increase during hypertrophy, no one have yet shown how this happen and no one have had the ability to distinguish between different populations of myonuclei.
Our proposed research therefore will be an important step in understanding how the myonuclear number in muscle cells are regulated. Indeed, the mechanisms identified in this study will also serve to widen the knowledge concerning treatment (e.g. exercise strategies) and enhancement of muscle function by activity and also point to therapeutic strategies for maintaining muscle repair ability in diseases.
In these experiments we will use 100 mice. There will be used anesthesia, analgesia and sedatives. We have experienced that animals recover fast after this protocol and do not expected animals to be stressed out or to be sick.
Muscle cells do not normally differentiate in culture so for this experiments cell culture cannot be used. The hypertrophy model used in this experiment is the only established hypertrophy model for mice, and to investigate positioning of newly inserted nuclei we need a model that leads to myonuclear addition. For injury model we aim to use BaCl2 injection. There are other models to consider: mechanical injury, freeze injury and injection of toxic chemicals. The BaCl2 injection leads to faster regeneration and is less invasive than the other injury models described, thus we mean this is the most human injury model.
When skeletal muscle mass increase each myofiber grow in size by increasing protein synthesis and incorporating new myonuclei to the cell. Nuclear positioning within cells is important for an array of cellular activities during development, immune response, tissue homeostasis and regeneration. In muscle nuclear positioning defects result in muscle disorders such as muscular dystrophy and ataxia, and it is shown that nuclear positioning within myofibers is required for proper muscle function.
We recently showed that the myonuclear number increase in muscle cells during hypertrophy. However, we have not until recently had any method to distinguish newly inserted myonuclei from already existing myonuclei in the hypertrophying fibers. Thus, we could not investigate how nuclear positioning occur for newly inserted nuclei. In this study we aim to investigate the positioning of newly inserted myonuclei from already existing myonuclei. We will investigate how these newly inserted myonuclei differs from already existing myonuclei by localization and epigenetic markers.
The proposed research is important to further highlight the benefits of exercise for maintaining muscle mass and function. This contribution will be significant because whereas numerous studies have identified that the number of myonuclei increase during hypertrophy, no one have yet shown how this happen and no one have had the ability to distinguish between different populations of myonuclei.
Our proposed research therefore will be an important step in understanding how the myonuclear number in muscle cells are regulated. Indeed, the mechanisms identified in this study will also serve to widen the knowledge concerning treatment (e.g. exercise strategies) and enhancement of muscle function by activity and also point to therapeutic strategies for maintaining muscle repair ability in diseases.
In these experiments we will use 100 mice. There will be used anesthesia, analgesia and sedatives. We have experienced that animals recover fast after this protocol and do not expected animals to be stressed out or to be sick.
Muscle cells do not normally differentiate in culture so for this experiments cell culture cannot be used. The hypertrophy model used in this experiment is the only established hypertrophy model for mice, and to investigate positioning of newly inserted nuclei we need a model that leads to myonuclear addition. For injury model we aim to use BaCl2 injection. There are other models to consider: mechanical injury, freeze injury and injection of toxic chemicals. The BaCl2 injection leads to faster regeneration and is less invasive than the other injury models described, thus we mean this is the most human injury model.