Role of autophagy in bone and muscle biology

Autophagy is a major catabolic process in eukaryotic cells in which damaged macromolecules and organelles are degraded and recycled. Several studies have demonstrated its crucial role in bone and muscle cell homeostasis. Deficiency or dysfunction in autophagy can result in pathological conditions such as osteoporosis and sarcopenia, which are associated with ageing. It is important to understand the role of the macromolecules involved in autophagy to devise how to counteract its decline and to hinder irreversible cell damage. Abstract Autophagy in eukaryotic cells represents a constitutive process and functions as homeostatic mechanism; it is upregulated in response to specific stimuli, such as starvation, hypoxia as well as oxidative stress. Besides playing a crucial role in adaptive response to different stimuli, autophagy is also required for intracellular quality control. This second aspect is important in order to prevent pathological processes. Autophagy plays a central role in cellular development and differentiation since it is involved in the regulation of energetic balance. This last aspect is important in order to prevent pathological processes and for maintaining the correct function of bone and muscle. Therefore, the knowledge of new molecular targets involved in autophagyc process is important to assure a good quality life.