Johnson J E, Wei Y Q, Prevette D, Oppenheim R W
Department of Neurobiology and Anatomy, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina 27157-1010, USA.
J Neurobiol. 1995 Aug;27(4):573-89. doi: 10.1002/neu.480270411.
Spinal motoneurons that normally die during early development can be rescued by a variety of purified growth or neurotrophic factors and target tissue extracts. There is also indirect evidence that brain or supraspinal afferent input may influence lumbar motoneuron survival during development and that this effect may be mediated by central nervous system-derived trophic agents. This report examines the biological and biochemical properties of motoneuron survival activity obtained from extracts of the embryonic chick brain. Treatment with an ammonium sulfate (25% to 75%) fraction of embryonic day 16 (E16) or E10 brain extracts rescued many spinal motoneurons that otherwise die during the normal period of cell death in vivo (E6 to E10). The same fractions also enhanced lumbar motoneuron survival following deafferentation. There were both similarities and differences between the active fractions derived from brain extracts (BEX) when compared with extracts derived from target muscles (MEX) or with purified neurotrophic factors. Survival activity from E10 BEX was as effective in promoting motoneuron survival as E10 MEX and more effective than astrocyte-conditioned media. Unlike MEX, the active fractions from BEX also rescued placode-derived nodose ganglion cells. In addition, unlike nerve growth factor and brain-derived neurotrophic factor, active BEX fractions did not rescue neural crest-derived dorsal root ganglion cells or sympathetic ganglion neurons. Interestingly, among many cranial motor and other brainstem nuclei examined, only the survival of motoneurons from the abducens nucleus was enhanced by BEX. Active proteins obtained from BEX were further separated by gel filtration chromatography and by preparative isoelectric focusing techniques. Activity was recovered in a basic (pI 8) and an acidic (pI 5) small molecular weight protein fraction (20 kD or less). The specific activity of the basic fraction was increased x66 when compared with the specific activity of crude BEX, and the basic fraction had a slightly higher specific activity than the acidic fraction. The biological and biochemical properties of these fractions are discussed in the context of known neurotrophic factors and their effects on normal and lesion-induced motoneuron death during development.
在早期发育过程中通常会死亡的脊髓运动神经元，可被多种纯化的生长因子或神经营养因子以及靶组织提取物所挽救。也有间接证据表明，大脑或脊髓上的传入输入可能会影响发育过程中腰段运动神经元的存活，并且这种作用可能由中枢神经系统衍生的营养因子介导。本报告研究了从胚胎鸡脑提取物中获得的运动神经元存活活性的生物学和生化特性。用胚胎第16天（E16）或E10脑提取物的硫酸铵（25%至75%）级分进行处理，挽救了许多在体内正常细胞死亡期（E6至E10）会死亡的脊髓运动神经元。相同的级分在去传入神经后也提高了腰段运动神经元的存活率。与来自靶肌肉的提取物（MEX）或纯化的神经营养因子相比，来自脑提取物（BEX）的活性级分既有相似之处，也有不同之处。E10 BEX的存活活性在促进运动神经元存活方面与E10 MEX一样有效，且比星形胶质细胞条件培养基更有效。与MEX不同，BEX的活性级分还挽救了基板衍生的结状神经节细胞。此外，与神经生长因子和脑源性神经营养因子不同，活性BEX级分不能挽救神经嵴衍生的背根神经节细胞或交感神经节神经元。有趣的是，在许多检查的颅运动神经元和其他脑干核中，只有展神经核的运动神经元存活率通过BEX得到了提高。通过凝胶过滤色谱法和制备性等电聚焦技术进一步分离从BEX获得的活性蛋白。活性在一个碱性（pI 8）和一个酸性（pI 5）的小分子量蛋白级分（20 kD或更小）中恢复。与粗制BEX的比活性相比，碱性级分的比活性提高了66倍，且碱性级分的比活性略高于酸性级分。在已知神经营养因子及其对发育过程中正常和损伤诱导的运动神经元死亡的影响的背景下，讨论了这些级分的生物学和生化特性。
