High-frequency ultrasound (~20 MHz) techniques were investigated using in vitro and ex vivo models to determine whether alterations in chromatin structure are responsible for ultrasound backscatter changes in biological samples. Acute myeloid leukemia (AML) cells and their isolated nuclei were exposed to various chromatin altering treatments. These included 10 different ionic environments, DNA ...

Human cytomegalovirus (hCMV) immediate early 1 (IE1) protein associates with condensed chromatin of the host cell during mitosis. We have determined the structure of the chromatin-tethering domain (CTD) of IE1 bound to the nucleosome core particle, and discovered that IE1-CTD specifically interacts with the H2A-H2B acidic patch and impairs the compaction of higher-order chromatin structure. Our...

Chromatin structure is modulated during deoxyribonucleic acid excision repair, but how this is achieved is unclear. Loss of the yeast Ino80 chromatin-remodeling complex (Ino80-C) moderately sensitizes cells to ultraviolet (UV) light. In this paper, we show that INO80 acts in the same genetic pathway as nucleotide excision repair (NER) and that the Ino80-C contributes to efficient UV photoproduc...

Gene expression studies in mammals and simpler eukaryotes have highlighted the central role that chromatin structure and modifications play in both the activation and repression of transcription. Aberrant chromatin structure can cause human genetic disease. Here we discuss recent progress in understanding the molecular mechanisms that underlie three human genetic diseases linked to perturbation...

Although tremendous progress has been made toward identifying factors that regulate nucleosome structure and positioning, the mechanisms that regulate higher-order chromatin structure remain poorly understood. Recent studies suggest that the ISWI chromatin-remodeling factor plays a key role in this process by promoting the assembly of chromatin containing histone H1. To test this hypothesis, we...

The accessibility of regulatory molecules to specific DNA sequences and chromatin regions in the nucleus is crucial to gene expression. In this study, we examined the chromatin structure in tomato leaf cells and in exponentially growing tomato cell suspension cultures. The structure of ribosomal chromatin was investigated by micrococcal nuclease and psoralen photocrosslinking. We showed that ri...

Background: The maintenance, regulation, and dynamics of heterochromatin in the human malaria parasite, Plasmodium falciparum, has drawn increasing attention due to its regulatory role mutually exclusive virulence gene expression silencing key developmental regulators. The advent genome-wide analyses such as chromatin-immunoprecipitation foll...

The higher order chromatin structure has recently been revealed as a critical new layer of gene transcriptional control. Changes in higher order chromatin structures were shown to correlate with the availability of transcriptional factors and/or MAR (matrix attachment region) binding proteins, which tether genomic DNA to the nuclear matrix. How posttranslational modification to these protein or...

We show that the mechanism by which chromatin displaying higher-order structure is usually isolated from nuclei involves a transition to an extended nucleosomal arrangement. After being released from nuclei, chromatin must refold in order to produce the typical chromatin fibers observed in solution. For starfish sperm chromatin with a long nucleosome repeat (222 bp), isolated fibers are signifi...

The development and progression of lung adenocarcinoma, one of the most common cancers, is driven by the interplay of genetic and epigenetic changes and the role of chromatin structure in malignant transformation remains poorly understood. We used systematic nucleosome distribution and chromatin accessibility microarray mapping platforms to analyze the genome-wide chromatin structure from norma...