Cell cycle behavior of human HP1 subtypes: distinct molecular domains of HP1 are required for their centromeric localization during interphase and metaphase
Cell cycle behavior of human HP1 subtypes: distinct molecular domains of HP1 are required for their centromeric localization during interphase and metaphase
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DOI：
10.1242/jcs.00635
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发表时间：
2003-08-15
影响因子：
4
通讯作者：
Hiraoka, Y
中科院分区：
文献类型：
--
作者：
Hayakawa, T;Haraguchi, T;Hiraoka, Y
异染色质蛋白1（Heterochromatin protein 1，HP 1）在异染色质形成中起重要作用。在人类中已经鉴定出三种HP 1亚型，即HP 1 α、β和γ。在这项研究中，使用黄色荧光蛋白（YFP）融合构建体，我们研究了细胞周期过程中的人HP 1亚型的细胞内定位。在间期，所有三种HP 1亚型均定位于着丝粒异染色质和早幼粒细胞白血病（PML）核小体。然而，不同的偏好，观察亚型之间：在间期HP 1 β本地化最优先的着丝粒异染色质，而HP 1 α和γ更优先本地化PML核小体。在分裂中期，只有HP 1 α，定位于着丝粒。因此，我们确定了哪些分子结构域的HP 1是必要的，他们的细胞内定位。我们的结果表明，HP 1 α的C端片段（氨基酸残基101-180）是定位于中期着丝粒所必需的，HP 1 β的N端片段（氨基酸残基1-76）是定位于间期着丝粒所必需的。有趣的是，在活的HeLa细胞中同时观察HP 1 α的残基101-180和HP 1 β的残基1-76，发现在后期前期，HP 1 β片段从着丝粒区域解离，HP 1 α片段在着丝粒区域积累。这些结果表明，不同的特定区域的人HP 1 α和HP 1 β介导定位到中期和间期着丝粒区域，从而导致关联的不同亚型的HP 1与着丝粒在细胞周期的不同时间。
Heterochromatin protein 1 (HP1) plays an important role in heterochromatin formation. Three subtypes of HP1, namely HP1alpha, beta, and gamma, have been identified in humans. In this study, using yellow fluorescent protein (YFP) fusion constructs, we examined the intracellular localization of human HP1 subtypes during the cell cycle. During interphase, all three HP1 subtypes were localized to centromeric heterochromatin and to promyelocytic leukemia (PML) nuclear bodies. Different preferences, however, were observed among the subtypes: during interphase HP1beta localized most preferentially to centromeric heterochromatin, whereas HP1alpha and gamma were more preferentially localized to PML nuclear bodies. During metaphase, only HP1alpha, was localized to the centromere. We thus determined which molecular domains of HP1 were necessary for their intracellular localization. Our results showed that the C-terminal fragment (amino acid residues 101-180) of HP1alpha was necessary for localization to the metaphase centromere and the N-terminal fragment (amino acid residues 1-76) of HP1beta was necessary for localization to the interphase centromere. Interestingly, simultaneous observations of residues 101-180 of HP1alpha and residues 1-76 of HP1beta in living HeLa cells revealed that during late prophase, the HP1beta fragment dissociated from centromeric regions and the HP1alpha fragment accumulated in centromeric regions. These results indicate that different specific regions of human HP1alpha and HP1beta mediate localization to metaphase and interphase centromeric regions resulting in association of different subtypes of HP1 with the centromere at different times during the cell cycle.