Mocchetti I, Rabin S J, Colangelo A M, Whittemore S R, Wrathall J R
Department of Cell Biology, Georgetown University School of Medicine, Washington, DC 20007, USA.
Exp Neurol. 1996 Sep;141(1):154-64. doi: 10.1006/exnr.1996.0149.
Neurotrophic factors appear to be crucial for the survival and potential regeneration of injured neurons. We have previously demonstrated that contusive spinal cord injury (SCI) increases the levels of mRNA for basic fibroblast growth factor (FGF2). To determine whether FGF2 protein levels also increase, Western blot analysis was performed on extracts of spinal cord tissue after a standardized SCI and compared to laminectomy controls. In spinal cord extracts, a monoclonal antibody to FGF2 recognized various molecular forms of FGF2 (18-24 kDa) and some characteristic proteolytic fragments. Extracts of spinal cords 1 day after SCI showed a slight increase in the levels of these polypeptides. By 4 days, a significant increase (two-fold) was detected in the levels of the 18-kDa and higher molecular weight forms as well as the proteolytic fragments. Immunohistochemical analyses on spinal cord tissue sections confirmed an increased cellular (glial) FGF2 as well as interstitial immunoreactivity surrounding neurons and along blood vessels. Heparinpurified spinal cord extracts from tissue 4 days after SCI showed increased biological activity as indicated by their ability to (i) increase [3H]thymidine incorporation in cultures of Balb/c 3T3 cells and (ii) induce phosphorylation of suc-associated neurotrophic factor-induced tyrosine-phosphorylated target, a FGF2 target protein. These data suggest that SCI induces increased FGF2 expression and support the hypothesis that FGF2 may play a role in the partial recovery of function seen following SCI.
神经营养因子对于受损神经元的存活和潜在再生似乎至关重要。我们之前已经证明，脊髓挫伤性损伤（SCI）会增加碱性成纤维细胞生长因子（FGF2）的mRNA水平。为了确定FGF2蛋白水平是否也会升高，我们对标准化SCI后的脊髓组织提取物进行了蛋白质印迹分析，并与椎板切除术对照组进行了比较。在脊髓提取物中，一种针对FGF2的单克隆抗体识别出FGF2的各种分子形式（18 - 24 kDa）以及一些特征性的蛋白水解片段。SCI后1天的脊髓提取物显示这些多肽水平略有升高。到第4天，检测到18 kDa及更高分子量形式以及蛋白水解片段的水平显著增加（两倍）。对脊髓组织切片的免疫组织化学分析证实，细胞（神经胶质）FGF2增加，以及神经元周围和血管沿线的间质免疫反应性增强。SCI后4天从组织中提取的经肝素纯化的脊髓提取物显示出生物活性增加，这表现为它们能够（i）增加Balb/c 3T3细胞培养物中[3H]胸腺嘧啶核苷的掺入，以及（ii）诱导suc相关神经营养因子诱导的酪氨酸磷酸化靶标（一种FGF2靶蛋白）的磷酸化。这些数据表明，SCI诱导FGF2表达增加，并支持FGF2可能在SCI后所见的部分功能恢复中起作用的假说。
