Dent A L, Yewdell J, Puvion-Dutilleul F, Koken M H, de The H, Staudt L M
Metabolism Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Blood. 1996 Aug 15;88(4):1423-6.
The PML gene is fused to the retinoic acid receptor alpha (RAR alpha) gene in t(15;17) acute promyelocytic leukemia (APL), creating a PML-RAR alpha fusion oncoprotein. The PML gene product has been localized to subnuclear dot-like structures variously termed PODs, ND10s, Kr bodies, or PML nuclear bodies (PML NBs). The present study describes the cloning of a lymphoid-restricted gene, LYSP100, that is homologous to another protein that localizes to PML NBs, SP100. In addition to SP100 homology regions, one LYSP100 cDNA isoform contains a bromodomain and a PHD/TTC domain, which are present in a variety of transcriptional regulatory proteins. By immunofluorescence, LYSP100 was localized to nuclear dots that were surprisingly largely nonoverlapping with PML NBs. However, a minority of LYSP100 nuclear dots exactly colocalized with PML and SP100. We term the LYSP100 structures "LANDs," for LYSP100-associated nuclear domains. Although LYSP100 is expressed only in lymphoid cells, LANDs could be visualized in HeLa cells by transfection of a LYSP100 cDNA. Immunoelectron microscopy revealed LANDs to be globular, electron-dense structures morphologically distinct from the annular structures characteristic of PML NBs. LANDs were most often found in the nucleoplasm, but were also found at the nuclear membrane and in the cytoplasm, suggesting that these structures may traffic between the cytoplasm and the nucleus. By double-immunogold labeling of PML and LYSP100, some LANDs were shown to contain both PML and LYSP100. Thus, PML is localized to a second subnuclear domain that is morphologically and biochemically distinct from PML NBs.
在t(15;17)急性早幼粒细胞白血病（APL）中，早幼粒细胞白血病（PML）基因与维甲酸受体α（RARα）基因融合，产生PML-RARα融合癌蛋白。PML基因产物定位于亚核点状结构，这些结构有多种名称，如PODs、ND10s、Kr小体或PML核体（PML NBs）。本研究描述了一种淋巴细胞限制性基因LYSP100的克隆，该基因与另一种定位于PML NBs的蛋白SP100同源。除了SP100同源区域外，一种LYSP100 cDNA异构体包含一个溴结构域和一个PHD/TTC结构域，这些结构域存在于多种转录调节蛋白中。通过免疫荧光法，LYSP100定位于核点，令人惊讶的是，这些核点在很大程度上与PML NBs不重叠。然而，少数LYSP100核点与PML和SP100完全共定位。我们将LYSP100结构称为“LANDs”，即LYSP100相关核结构域。尽管LYSP100仅在淋巴细胞中表达，但通过转染LYSP100 cDNA，可在HeLa细胞中观察到LANDs。免疫电子显微镜显示，LANDs是球形的、电子致密的结构，在形态上与PML NBs的环形结构不同。LANDs最常出现在核质中，但也出现在核膜和细胞质中，这表明这些结构可能在细胞质和细胞核之间运输。通过对PML和LYSP100进行双重免疫金标记，发现一些LANDs同时含有PML和LYSP100。因此，PML定位于第二个亚核结构域，该结构域在形态和生化上与PML NBs不同。
