Как правило, активные и неактивные модификации гистонов сегрегированы в разных геномных областях (эухроматин и гетерохроматин)
В эмбриональных стволовых клетках существуют так называемые бивалентные домены, в которых присутствуют одновременно
оба типа модификаций. По ходу дифференцировки эти домены превращаются в активные, либо неактивные
ICM = inner cell mass
ESC = embryonic stem cells
Цветовая кодировка типов хроматина (Filion et. al., Cell Cell 143, 212–224; в основе кодировки – связанные с хроматином негистоновые белки)
зеленый – центромерный гетерохроматин
синий – Polycomb
черный – бедный генами неактивный хроматин (LADs)
желтый, красный – различные типы активного хроматина
красный хроматин: Brahma (BRM), Mediator, GAGA factor, CTCF…
… тканеспецифичные гены
желтый хроматин: H3K36met3 |
гены домашнего хозяйства |
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Kharchenko, Peter V. et al, 2010, Nature 471.7339: 480–485.
кодировка, учитывающая модификации гистонов, присутствие различных негистоновых белков и расположение генов
state 1, red
Active promoter and transcription start site (TSS)-proximal regions H3K4me3/me2 and H3K9ac
state 2, purple
preferentially over exonic regions of transcribed genes H3K36me3
state 3, brown
typically found within intronic regions H3K27ac, H3K4me1, and H3K18ac
state 4, coral
enrichment of H3K36me1, but notably lacking
H3K27ac
state 5, green
high levels of H4K16ac + some enrichment in H3K36me3 and other marks of “elongation” state 2
(typical for dosage compensation)
state 6, black
Polycomb, H3K27me3
state 7, dark blue
Pericentromeric heterochromatin domains high levels of H3K9me2/me3
state 8, light blue
moderate levels of H3K9me2/me3, in chromosome arms
state 9, grey inactive gene-poor
Chromatin colors in human cells
