Perry Chava, Sklan Ella H, Birikh Klara, Shapira Michael, Trejo Leonor, Eldor Amiram, Soreq Hermona
Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Israel 91904.
Oncogene. 2002 Dec 5;21(55):8428-41. doi: 10.1038/sj.onc.1205945.
To study the regulation of acetylcholinesterase (AChE) gene expression in human brain tumors, 3' splice variants of AChE mRNA and potentially relevant transcription factor mRNAs were labeled in primary astrocytomas and melanomas. AChE-S and AChE-R mRNA, as well as Runx1/AML1 mRNA accumulated in astrocytomas in correlation with tumor aggressiveness, but neither HNF3beta nor c-fos mRNA was observed in melanoma and astrocytomas. Immunohistochemistry demonstrated nuclear Runx1/AML1 and cellular AChE-S and AChE-R in melanomas, however, only AChE-S, and not the secreted AChE-R variant, was retained in astrocyte tumor cells. Runx1/AML1 revealed weak linkage with ACHE promoter sequences, yet enhanced ACHE gene expression in co-transfected COS1 cells. The p300 co-activator and the ACHE promoter's distal enhancer facilitated this effect, which was independent of much of the Runx1/AML1 trans-activation domain. Surprisingly, GASP, a fusion product of green fluorescence protein (GFP) and ASP(67), a peptide composed of the 67 C-terminal amino acid residues of AChE-S, localized to COS1 cell nuclei. However, GARP, the corresponding fusion product of GFP with a peptide having the 51 C-terminal residues of AChE-E or GFP alone, remained cytoplasmic. Runx1/AML1 exhibited improved nuclear retention in GASP-expressing COS1 cells, suggesting modulated nuclear localization processes. Together, these findings reveal brain tumor-specific regulation of both expression and cellular retention of variant ACHE gene products.
为研究人脑肿瘤中乙酰胆碱酯酶（AChE）基因表达的调控情况，在原发性星形细胞瘤和黑色素瘤中对AChE mRNA的3'剪接变体以及潜在相关转录因子mRNA进行了标记。AChE - S和AChE - R mRNA以及Runx1/AML1 mRNA在星形细胞瘤中的积累与肿瘤侵袭性相关，但在黑色素瘤和星形细胞瘤中均未观察到HNF3β和c - fos mRNA。免疫组织化学显示黑色素瘤中有核Runx1/AML1以及细胞AChE - S和AChE - R，然而，星形细胞瘤肿瘤细胞中仅保留了AChE - S，而非分泌型AChE - R变体。Runx1/AML1与ACHE启动子序列显示出弱连接，但在共转染的COS1细胞中增强了ACHE基因表达。p300共激活因子和ACHE启动子的远端增强子促进了这种效应，该效应独立于Runx1/AML1的大部分反式激活结构域。令人惊讶的是，绿色荧光蛋白（GFP）与AChE - S的67个C末端氨基酸残基组成的肽ASP(67)的融合产物GASP定位于COS1细胞核。然而，GFP与具有AChE - E的51个C末端残基的肽或单独的GFP的相应融合产物GARP仍保留在细胞质中。Runx1/AML1在表达GASP的COS1细胞中核保留有所改善，表明核定位过程受到调节。总之，这些发现揭示了脑肿瘤对ACHE基因产物表达和细胞保留的特异性调控。
