骨形成蛋白於神經肌肉系統功能之研究

Abstract

The naturally occurring cell death of developing motor neurons is considered to be guided by the influence of their peripheries (Hamburger, 1934, 1958). Skeletal muscle cells have been implicated as a key source of peripheral-derived survival factors, as the absence of them causes a near total loss of developing motor neurons (Grieshammer et al., 1998). Many neuronal cell types are controlled by a small number of survival factors, with the genetic deletion of a single factor leading to a profound loss of neurons (Lindsay, 1996). Motor neurons, in contrast, appear to be controlled by numerous survival factors. The null mutation of a single, or even multiple, factors only leads to partial loss of motor neurons (Liu and Jaenisch, 2000; Oppenheim et al., 2000; Oppenheim et al., 2001). This may indicate that there are distinct subpopulations of motor neurons (Oppenheim et al., 2000). Equally, it implies that muscle fibers produce more than one regulator of motor neurons, as the consequence of the genetic deletion of them type is more profound than the deletion of any growth factor.