Mouse myeloid leukemic cells (M1) could be induced to differentiate into macrophage-like and granulocyte-like cells by a lysine-rich, histone H1 fraction (10 to 100 microgram/ml). The differentiated M1 cells expressed phagocytic and lysozyme activity and were macrophage-like and granulocyte-like cells. The differentiation-inducing activity of histone H1 was found in histone H1 fractions isolate...

Chromatin structure and activity can be modified through ATP-dependent repositioning of nucleosomes and posttranslational modifications of core histone tails within nucleosome core particles and by deposition of linker histones into the oligonucleosome fiber. The linker histone H1 is essential in metazoans. It has a profound effect on organization of chromatin into higher-order structures and o...

The vertebrate kinetochore complex assembles at the centromere on alpha-satellite DNA. In humans, alpha-satellite DNA has a repeat length of 171 bp slightly longer than the DNA in the chromatosome containing the linker histone H1. The centromere-binding protein CENP-B binds specifically to alpha-satellite DNA with properties of a centromeric-linker histone. Here, we analysed if linker histone H...

Mouse myeloid leukemic cells (M1) could be induced to differentiate into macrophage-like and granulocyte-like cells by a lysine-rich, histone H1 fraction (10 to 100 jug/ml). The differentiated M1 cells expressed phagocytic and lysozyme activity and were macrophage-like and granulocyte-like cells. The differentiation-inducing activity of histone H1 was found in histone H1 fractions isolated from...

The MLL gene breakpoint-cluster region (BCR) is a known hot-spot for chromosomal translocations in human leukemias. We mapped core histone modifications and histone H1 along the MLL gene in Jurkat cells and human CD34(+) progenitor blood cells by chromatin immunoprecipitation. Within the BCR, we found specific histone patterns that were different from other genomic regions and a histone H1-free...

To investigate the potentials of DNA methylation and H1 histone in regulating the action of DNA binding proteins, well ordered complexes were formed by slow salt gradient dialysis of mixtures of H1 histone with either methylated or nonmethylated DNA. The sites methylated in the plasmids were CCGG. Methylation of cytosine in this site protects the DNA against HpaII endonuclease but not against M...

Cellular senescence is a tumor-suppressing mechanism that is accompanied by characteristic chromatin condensation called senescence-associated heterochromatic foci (SAHFs). We found that individual SAHFs originate from individual chromosomes. SAHFs do not show alterations of posttranslational modifications of core histones that mark condensed chromatin in mitotic chromosomes, apoptotic chromati...

In Tetrahymena cells, phosphorylation of linker histone H1 regulates transcription of specific genes. Phosphorylation acts by creating a localized negative charge patch and phenocopies the loss of H1 from chromatin, suggesting that it affects transcription by regulating the dissociation of H1 from chromatin. To test this hypothesis, we used FRAP of GFP-tagged H1 to analyze the effects of mutati...

Despite the key role of the linker histone H1 in chromatin structure and dynamics, its location and interactions with nucleosomal DNA have not been elucidated. In this work we have used a combination of electron cryomicroscopy, hydroxyl radical footprinting, and nanoscale modeling to analyze the structure of precisely positioned mono-, di-, and trinucleosomes containing physiologically assemble...

Promoter- and enhancer-binding factors appear to function by facilitating the transcription reaction as well as by counteracting chromatin-mediated repression (antirepression). We have examined the mechanism by which a hybrid activator, GAL4-VP16, is able to counteract histone H1-mediated repression by using both H1-DNA complexes and reconstituted H1-containing chromatin templates. The GAL4 DNA...