Millán-Ariño Lluís, Izquierdo-Bouldstridge Andrea, Jordan Albert
Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona E-08028, Spain.
Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona E-08028, Spain.
Biochim Biophys Acta. 2016 Mar;1859(3):510-9. doi: 10.1016/j.bbagrm.2015.10.013. Epub 2015 Oct 21.
Histone H1 is a structural component of chromatin that may have a role in the regulation of chromatin dynamics. Unlike core histones, the linker histone H1 family is evolutionarily diverse and many organisms have multiple H1 variants or subtypes, distinguishable between germ-line and somatic cells. In mammals, the H1 family includes seven somatic H1 variants with a prevalence that varies between cell types and over the course of differentiation, H1.1 to H1.5 being expressed in a replication-dependent manner, whereas H1.0 and H1X are replication-independent. Until recently, it has not been known whether the different variants had specific roles in the regulation of nuclear processes or were differentially distributed across the genome. To address this, an increasing effort has been made to investigate divergent features among H1 variants, regarding their structure, expression patterns, chromatin dynamics, post-translational modifications and genome-wide distribution. Although H1 subtypes seem to have redundant functions, several reports point to the idea that they are also differently involved in specific cellular processes. Initial studies investigating the genomic distribution of H1 variants have started to suggest that despite a wide overlap, different variants may be enriched or preferentially located at different chromatin types, but this may depend on the cell type, the relative abundance of the variants, the differentiation state of the cell, or whether cells are derived from a neoplastic process. Understanding the heterogeneity of the histone H1 family is crucial to elucidate their role in chromatin organization, gene expression regulation and other cellular processes.
组蛋白H1是染色质的一种结构成分，可能在染色质动力学调控中发挥作用。与核心组蛋白不同，连接组蛋白H1家族在进化上具有多样性，许多生物体有多种H1变体或亚型，可在生殖细胞和体细胞之间区分。在哺乳动物中，H1家族包括七种体细胞H1变体，其在不同细胞类型和分化过程中的丰度各不相同，H1.1至H1.5以复制依赖的方式表达，而H1.0和H1X则不依赖复制。直到最近，人们还不清楚不同变体在核过程调控中是否具有特定作用，或者在基因组中的分布是否存在差异。为了解决这个问题，人们越来越努力地研究H1变体之间的不同特征，包括它们的结构、表达模式、染色质动力学、翻译后修饰和全基因组分布。尽管H1亚型似乎具有冗余功能，但一些报告指出，它们在特定细胞过程中的参与方式也有所不同。最初研究H1变体基因组分布的研究开始表明，尽管存在广泛重叠，但不同变体可能在不同染色质类型中富集或优先定位，但这可能取决于细胞类型、变体的相对丰度、细胞的分化状态，或者细胞是否源自肿瘤过程。了解组蛋白H1家族的异质性对于阐明它们在染色质组织、基因表达调控和其他细胞过程中的作用至关重要。
