Histones visualized via Histone H2B type 1-J

Movie. Z-stack of live hiPS cell colony expressing mEGFP-tagged Histone H2B type 1-J protein. Cells were imaged in 3D on a spinning-disk confocal microscope. Movie starts at the bottom of the cells and ends at the top. Scale bar, 5µm.

Movie. Time-lapse movie of live hiPS cell colony expressing mEGFP-tagged Histone H2B type 1-J protein. Cells were imaged in 3D on a spinning-disk confocal microscope every 3 min. A single mid-level z-section is shown. Movie plays at 1260x real time. Scale bar, 5 µm.

Movie. ​Z-stack of live hiPS cell colony expressing mEGFP-tagged Histone H2B type 1-J protein. Cell Mask Deep Red Plasma Membrane dye was applied to mark cell boundaries (magenta). NucBlue Live Ready Probe Reagent was used to compare mEGFP-tagged H2B localization (left panel) to a NucBlue Live (Hoechst) DNA stain (left panel). Cells were imaged in 3D on a spinning-disk confocal microscope. Movie starts at the bottom of the cells and ends at the top. Scale bar, 5µm.

Observations

• Histone H2B type 1-J is a protein that participates in organizing DNA. It and other histone proteins form a core around which DNA wraps. These structures, called nucleosomes, are the fundamental repeating units within chromatin (DNA and histones). The packing of these structures impacts DNA accessibility, affecting functions like transcription, replication, and repair of DNA.
• In hiPS cells imaged with spinning-disk light microscopy, mEGFP-tagged Histone H2B type 1-J appears within the nucleus as puncta of varying size and intensity, likely reflecting more densely packed regions of nucleosomes, and in a “haze”, where nucleosomes cannot be resolved.
• The localization of mEGFP-tagged Histone H2B type 1-J is similar to the pattern of the DNA-binding dye Hoechst. Hoechst binds the minor grove of DNA (with preference for A-T rich regions), while mEGFP-tagged Histone H2B type 1-J localizes to the nucleosomal cores around which the DNA wraps.
• Histone H2B type 1-J pattern of localization and intensity changes through the cell cycle. During interphase, Histone H2B type 1-J localizes throughout the nucleus, with some regions of greater intensity (reflecting a greater density of protein) near the nuclear periphery and the nucleolus. During cell division, Histone H2B type 1-J localizes to chromosomes.