title: Mechanisms for maintaining muscle.
abstract: OBJECTIVE
  The balance between the rates of protein synthesis and protein degradation governs the maintenance of muscle mass in the body. The main purpose of this review is to highlight the latest understanding of the various pathways that maintain this balance between muscle atrophy and hypertrophy.
  
  
  RESULTS
  The maintenance of muscle mass is an interplay between anabolic and catabolic pathways that are interconnected at several junctures. The insulin-like growth factor 1/IRS1/PI3K/Akt pathway along with the ubiquitin-proteasome pathway, lysosomal/autophagy pathway and myostatin pathway maintain this homeostasis with the aid of various transcriptional and genetic factors, many of which continue to be discovered and studied in an ongoing fashion.
  
  
  CONCLUSIONS
  We tried to present, in this short review, a holistic view of the various players, old and new, responsible for the maintenance of this delicate equilibrium between muscle gain and loss. The development of novel therapeutics aimed at the activation or suppression of these described mediators may help the field of medicine in the management of a myriad of clinical conditions, thereby improving mobility and quality of life of affected patients.
authors.affiliation: Department of Surgery, St. John Hospital and Medical Center, Detroit, Michigan, USA.
authors.forename: Ambar
authors.initials: A
authors.lastname: Banerjee
authors.forename: Denis C
authors.initials: DC
authors.lastname: Guttridge
mesh_terms: D001343:Autophagy; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005786:Gene Expression Regulation; D006706:Homeostasis; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009133:Muscular Atrophy / Q000378:metabolism; D055435:Myostatin / Q000378:metabolism; D015398:Signal Transduction; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D051858:Forkhead Transcription Factors; D009124:Muscle Proteins; D055435:Myostatin; D007334:Insulin-Like Growth Factor I; D044767:Ubiquitin-Protein Ligases