Fanti Laura, Berloco Maria, Piacentini Lucia, Pimpinelli Sergio
Dipartimento di Genetica e Biologia Molecolare, Istituto Pasteur, Fondazione Cenci Bolognetti, Università La Sapienza, 00185 Roma, Italy.
Genetica. 2003 Mar;117(2-3):135-47. doi: 10.1023/a:1022971407290.
The Heterochromatin Protein 1 (HP1) is a conserved protein which is best known for its strong association with the heterochromatin of Drosophila melanogaster. We previously demonstrated that another important property of HP1 is its localization to the telomeres of Drosophila, a feature that reflects its critical function as a telomere capping protein. Here we report our analysis of the euchromatic sites to which HP1 localizes. Using an anti-HP1 antibody, we compared immunostaining patterns on polytene chromosomes of the Ore-R wild type laboratory strain and four different natural populations. HP1 was found to accumulate at specific euchromatic sites, with a subset of the sites conserved among strains. These sites do not appear to be defined by an enrichment of known repetitive DNAs. Comparisons of HP1 patterns among several Drosophila species revealed that association with specific euchromatic regions, heterochromatin and telomeres is a conserved characteristic of HP1. Based on these results, we argue that HP1 serves a broader function than typically postulated. In addition to its role in heterochromatin assembly and telomere stability, we propose that HP1 plays an important role in regulating the expression of many different euchromatic regions.
异染色质蛋白1（HP1）是一种保守蛋白，因其与黑腹果蝇的异染色质紧密相关而最为人所知。我们之前证明了HP1的另一个重要特性是它定位于果蝇的端粒，这一特征反映了它作为端粒封端蛋白的关键功能。在此，我们报告对HP1所定位的常染色质位点的分析。使用抗HP1抗体，我们比较了俄勒冈-R野生型实验室品系以及四个不同自然种群的多线染色体上的免疫染色模式。发现HP1在特定的常染色质位点积累，其中一部分位点在不同品系中是保守的。这些位点似乎并非由已知重复DNA的富集所界定。对几种果蝇物种中HP1模式的比较显示，与特定常染色质区域、异染色质和端粒的关联是HP1的一个保守特征。基于这些结果，我们认为HP1发挥的功能比通常假定的更为广泛。除了在异染色质组装和端粒稳定性方面的作用外，我们提出HP1在调控许多不同常染色质区域的表达中发挥重要作用。
