Translocation of histone H1 subtypes between chromatin and cytoplasm during mitosis in normal human fibroblasts

Abstract

Histone H1 is an important constituent of chromatin, which undergoes major structural rearrangements during mitosis. However, the role of H1, multiple H1 subtypes, and H1 phosphorylation is still unclear. In normal human fibroblasts, phosphorylated H1 was found located in nuclei during prophase and in both cytoplasm and condensed chromosomes during metaphase, anaphase, and telophase as detected by immunocytochemistry. Moreover, we detected remarkable differences in the distribution of the histone H1 subtypes H1.2, H1.3, and H1.5 during mitosis. H1.2 was found in chromatin during prophase and almost solely in the cytoplasm of metaphase and early anaphase cells. In late anaphase, it appeared in both chromatin and cytoplasm and again in chromatin during telophase. H1.5 distribution pattern resembled that of H1.2, but H1.5 was partitioned between chromatin and cytoplasm during metaphase and early anaphase. H1.3 was detected in chromatin in all cell cycle phases. We propose therefore, that H1 subtype translocation during mitosis is controlled by phosphorylation, in combination with H1 subtype inherent affinity. We conclude that H1 subtypes, or their phosphorylated forms, may leave chromatin in a regulated way to give access for chromatin condensing factors or transcriptional regulators during mitosis. ' 2010International Society for Advancement of Cytometry Key terms histone H1; chromatin; cell cycle; mitosis IN the cell cycle, DNA and protein content are duplicated, and the cell divides in two in a strict sequential order of events. During prophase, the replicated chromosomes condense, and the nuclear membrane breaks down in prometaphase. At metaphase, the chromosomes are aligned at the equator of the mitotic spindle, and the sister chromatids are segregated to the two poles of the spindle during anaphase. Finally, the separation is completed during telophase by cytoplasmic division. Impaired cell cycle control or cell cycle progression may result in cell death or malignant transformation.

Evidence for a Transketolase-Mediated Metabolic Checkpoint Governing Biotrophic Growth in Rice Cells by the Blast Fungus Magnaporthe oryzae

“…In fibroblasts, different histone H1 subtypes have different cellular localizations during cell division. For example, Histone H1.2 is associated with chromatin during prophase but cytoplasmically localized during metaphase and early anaphase [46]. Histone H1.5 is partitioned between chromatin and cytoplasm during metaphase and early anaphase [46].…”

“…For example, Histone H1.2 is associated with chromatin during prophase but cytoplasmically localized during metaphase and early anaphase [46]. Histone H1.5 is partitioned between chromatin and cytoplasm during metaphase and early anaphase [46]. In addition, histone H1 diffusion dynamics in HeLa cells are affected by ATP depletion [47].…”

Isolation and analysis of linker histones across cellular compartments

“…In addition to the function of histone H1 on chromatin structure, the histone H1.2 isoform has been shown to have extra-chromatin function [28-30]. Confocal imaging of mitotic fibroblasts have shown histone H1.2 localized to the cytosol demonstrating compartmental mobility in vitro [30].…”

A shift in erythrocyte histone H1 complement following selection in quail (Coturnix japonica)

“…The specific functions of histone H1 subtypes has been inferred from their selective distribution in chromatin (Trollope et al 2010) and differential condensing capabilities (Clausell et al 2009) which may determine formation of active and inactive chromatin regions. Acting as peculiar modifiers of chromatin organization, the histone H1 subtypes may control expression of individual genes that influence many important cellular processes, such as chromosome alignment and segregation (Takata et al 2007), mitotic progression (Green et al 2010), and DNA damage response (Kratzmeier et al 1999;Hashimoto et al 2007). Since histone H1 condensing function is mediated by a specific C-terminal domain amino acid composition (Hansen et al 2006;Lu et al 2009), the alterations in the C-terminal domain amino acid sequence (Kosterin et al 1994;Palyga et al 2000;Gornicka-Michalska et al 2006;Kowalski et al 2011a, b) seem to support functional diversity of these chromatin proteins.…”