Galea E, Dupouey P, Feinstein D L
Division of Neurobiology, Cornell University Medical School, New York, New York 10021, USA.
J Neurosci Res. 1995 Jul 1;41(4):452-61. doi: 10.1002/jnr.490410404.
Glial fibrillary acidic protein (GFAP) and its mRNA, primarily expressed in astrocytes, are also expressed in peripheral nervous system Schwann cells as well as in certain non-neural tissues. Schwann cells express a GFAP mRNA (GFAP-beta) which differs from the CNS-type mRNA (GFAP-alpha) by the presence of an extended 5' untranslated region. We have developed a polymerase chain reaction assay which allows distinction of these two GFAP mRNAs, as well as quantitative analysis of their levels. In the cultured rat Schwannoma cell line RT4-D6, GFAP-beta was the major GFAP mRNA species, accounting for at least 75% of total GFAP (alpha + beta) mRNA. GFAP-beta was also detected in primary rat astrocyte cultures, where it constituted approximately 5% of the total GFAP mRNA, as well as in RNA samples prepared from normal rat cerebral cortex, and from hamster and human brain. In rat cortex, the temporal expression of GFAP-beta mRNA paralleled that of total GFAP mRNA, with plateau levels reached between postnatal days 15 and 20. In astrocyte cultures, the relative levels of GFAP-alpha and -beta mRNAs were differentially regulated by exposure to interferon-gamma (10 to 25 units/ml), which caused an increase in GFAP-beta levels while at the same time no change or a small decrease in total GFAP levels. In rat brain cortical slices, 4 hr exposure to 25 units/ml interferon-gamma decreased total GFAP mRNA levels over tenfold, while GFAP-beta levels were unaffected. These data indicate that a second form of the GFAP mRNA is expressed in astrocytes both in vivo and in vitro and provide evidence for independent regulation of these two GFAP mRNA species.
胶质纤维酸性蛋白（GFAP）及其mRNA主要在星形胶质细胞中表达，在外周神经系统的施万细胞以及某些非神经组织中也有表达。施万细胞表达一种GFAP mRNA（GFAP-β），它与中枢神经系统型mRNA（GFAP-α）的区别在于其5'非翻译区延长。我们开发了一种聚合酶链反应检测方法，可区分这两种GFAP mRNA，并对其水平进行定量分析。在培养的大鼠神经鞘瘤细胞系RT4-D6中，GFAP-β是主要的GFAP mRNA种类，占总GFAP（α + β）mRNA的至少75%。在原代大鼠星形胶质细胞培养物中也检测到了GFAP-β，它约占总GFAP mRNA的5%，在从正常大鼠大脑皮层、仓鼠和人类大脑制备的RNA样本中也有发现。在大鼠皮层中，GFAP-β mRNA的时间表达与总GFAP mRNA平行，在出生后第15至20天达到平台期水平。在星形胶质细胞培养物中，GFAP-α和-β mRNA的相对水平受到干扰素-γ（10至25单位/毫升）的不同调节，这导致GFAP-β水平增加，而总GFAP水平同时没有变化或略有下降。在大鼠脑皮质切片中，暴露于25单位/毫升干扰素-γ 4小时可使总GFAP mRNA水平降低超过10倍，而GFAP-β水平不受影响。这些数据表明，GFAP mRNA的第二种形式在体内和体外的星形胶质细胞中均有表达，并为这两种GFAP mRNA种类的独立调节提供了证据。
