Apoptosis of skeletal muscles during development and disease

Cells from multicellular organisms self-destroy when no longer needed or wh en damaged. They do this by activating genetically controlled machineries t hat lead to apoptosis. Skeletal muscles in adult animals are fully differen tiated syncytial cells. Apoptosis has been described in developing and. rec ently, in adult skeletal muscle, The cellular and molecular aspects of myob last and myofibre apoptosis and their role in disease are analysed in this review. Alterations in the pathways that regulate myoblasts proliferation/d ifferentiation lead to induction of apoptosis during myogenesis both in viv o and in vitro. In adult muscle myofibres apoptosis seems to start from seg mental areas of myofibres often producing loss of a single myonucleus. The bcl2/bax system is active in muscle when apoptosis occurs. On the other han d conflicting results are reported on the role played by FasL/Fas system. T hese findings are confirmed by in vitro results on myotubes and on their su sceptibility to apoptosis. Though apoptosis has been shown to occur in the skeletal muscle, the role played in diseases and the pattern followed in my ogenic cells are far from being clear. (C) 1999 Elsevier Science Ltd. All r ights reserved.