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Developmentally regulated chromatin acetylation and histone H1(0) accumulation.
Seigneurin D
,
Grunwald D
,
Lawrence JJ
,
Khochbin S
.
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There exists a close relationship between core histone acetylation and the induced expression of the histone H1(0) gene. We took advantage of this fact to evaluate the influence of chromatin hyperacetylation on the developmentally regulated expression of this specific gene. In this study, the in situ immunodetection approach has been used to analyze both the acetylated histone H4 isoforms and histone H1(0) accumulation during early Xenopus laevis development. We have chosen two stages of development, gastrula stage, when H1(0) is not expressed and not inducible by butyrate treatment, and stage 27 when H1(0) is not expressed but is inducible by butyrate. At stage 27 of development, the early induced accumulation of histone H1(0) under butyrate treatment, occurs mainly in tissues that express the protein normally during later development. These experiments suggest that histone acetylation may be part of a pathway which, in a specific set of cells, keeps H1(0) and probably a series of specific genes, competent for transcription, but cell-specific factors are involved in the induced expression of these genes.
Fig. 1. Influence of sodium butyrate
on embryonic development and
specific gene expression. (AI
Fertilized eggs were either maintained
in a normal medium (control) or in the
presence of 10 mM sodium butyrate.
Photographs were taken at the indicated
developmental stage of the control
embryos. (B) RNA was prepared from
either control or butyrate treated
embryos shown in (A!. A Northern blot
was obtained and hybridized with
probes for HI°, Hl, cardiac actin and
MyoD
Fig. 2. Pattern of histone H4 acetylation and H10 accumulation in normal and butyrate treated gastrula. Successive cryosecrions were
obtained from control (AI and treated IB) embryos. taken at the gastrula stage of control embryos. These sections were used to immunodetecr acetylated
histone H4 by an antibody recogmzing a/l acetyfared Isoforms of H4 (H4.) and an antibody recognizing preferentially hyper8ceryfated Isoforms
of histOne H4 (R17) and finally Hl° was detected by specific anti HID antibody (right panel!_ After immunodetection sections were counter-stained
wirh Hoechsr fluorochrome to visualize nuclei (left panel). Arrows are used to underlme the variation of immunofluorescence intensity m the mdicated
regions (compare Hoechst fluorescence. with immunofluorescence).
Fig. 3. Early accumulation of H1° during normal development. Cryosections obtained from embryo at stage 36 of normal development were used
for HID immunodetecrion. Sections were counter-stained wirh the DNA-specific fluorochrome Hoechst, which allows for the detection of all nuclei.
S, somires; N, neural tube; B, brain.
Fig. 4. Pattern of histone H4 acetylation and H1° accumulation in butyrate treated embryos taken at stage 27. Successive cryosecrions were
obrained from treated embryos taken at stage 27 of development and immunodetection of these sections was carried our as in Fig. 2. Here again
H4- indicates aeery/aced H4, R17shows nuclei containing hyperacetyfated H4, and H1° indicates the presence of histone H 1°.As In Fig. 2. nuclei in
each section are visualized by Hoechsr fluorescence and shown in the left side of rhe immunofluorescence (FITC) panel. Arrows are used to show
underacetylatedregions.InHIDpanel.N refers to the nervoussystem andS to the som/ces.
