Nakao M, Nomiyama H, Shimada K
Department of Biochemistry, Kumamoto University Medical School, Japan.
Mol Cell Biol. 1990 Jul;10(7):3646-58. doi: 10.1128/mcb.10.7.3646-3658.1990.
LD78 is a member of a newly identified superfamily of small inducible proteins involved in inflammatory responses, wound healing, and tumorigenesis. Southern blot analysis of the EcoRI-digested human genomic DNAs, using previously isolated LD78 cDNA as a probe, showed that in each individual there are 4.2- and 4.8-kilobase-pair (kb) fragments and that some have an additional 6.5-kb fragment. The 4.2-kb fragment contained genomic DNA sequences corresponding to the LD78 cDNA and was named the LD78 alpha gene. The 4.8-kb fragment contained similar sequences, showing 94% homology to the LD78 alpha gene, and was named the LD78 beta gene. The LD78 alpha gene was present in a single or a few copies per haploid genome, whereas the copy number of the LD78 beta gene and of the 6.5-kb fragment hybridizable to LD78 cDNA varied among the samples tested. Treatment of human myeloid cell lines HL-60 and U937 with phorbol 12-myristate 13-acetate (PMA) increased within 2 h cellular levels of the RNA hybridizable to LD78 cDNA. The human glioma cell line U105MG and primary culture of human fibroblasts also expressed the hybridizable RNA in response to PMA. Addition of cycloheximide had no apparent effect on this response in U937 cells and inhibited the response in fibroblasts, whereas it stimulated the response in HL-60 and U105MG cells. mRNA phenotyping experiments revealed that the LD78 alpha and LD78 beta genes were both transcribed in PMA-stimulated U937 cells.
LD78是新发现的一个小诱导蛋白超家族的成员，该家族参与炎症反应、伤口愈合和肿瘤发生。用先前分离的LD78 cDNA作为探针，对经EcoRI酶切的人基因组DNA进行Southern印迹分析，结果显示，每个个体中都有4.2千碱基对（kb）和4.8 kb的片段，有些个体还有一个额外的6.5 kb片段。4.2 kb的片段包含与LD78 cDNA对应的基因组DNA序列，被命名为LD78α基因。4.8 kb的片段包含相似序列，与LD78α基因有94%的同源性，被命名为LD78β基因。LD78α基因在每个单倍体基因组中以单拷贝或少数拷贝存在，而LD78β基因以及可与LD78 cDNA杂交的6.5 kb片段的拷贝数在测试样本中各不相同。用佛波酯12 -肉豆蔻酸酯13 -乙酸酯（PMA）处理人髓样细胞系HL - 60和U937，2小时内可杂交至LD78 cDNA的RNA细胞水平增加。人胶质瘤细胞系U105MG和人成纤维细胞原代培养物对PMA也有可杂交RNA的表达。加入放线菌酮对U937细胞的这种反应没有明显影响，对成纤维细胞的反应有抑制作用，而对HL - 60和U105MG细胞的反应有刺激作用。mRNA表型实验表明，在PMA刺激的U937细胞中，LD78α和LD78β基因均被转录。
