Analysis of Histones in Xenopus laevis II. MASS SPECTROMETRY REVEALS AN INDEX OF CELL TYPE-SPECIFIC MODIFICATIONS ON H3 AND H4
Analysis of Histones in Xenopus laevis II. MASS SPECTROMETRY REVEALS AN INDEX OF CELL TYPE-SPECIFIC MODIFICATIONS ON H3 AND H4
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DOI：
10.1074/jbc.m807274200
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发表时间：
2009-01-09
影响因子：
4.8
通讯作者：
Hunt, Donald F.
中科院分区：
文献类型：
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作者：
Nicklay, Joshua J.;Shechter, David;Hunt, Donald F.
表观遗传信息被假设为编码在组蛋白变体和翻译后修饰中。这些表观遗传标记的不同细胞和基因座特异性组合可能有助于调节染色质模板化的交易，包括转录，复制，重组和修复。因此，给定细胞类型中组蛋白修饰的相对丰度是细胞命运和特异性的潜在指标。在这里，我们利用质谱技术来表征的相对丰度指数的细胞类型特异性的修改组蛋白H3和H4在不同的细胞类型的青蛙非洲爪蟾，包括精子，存储预沉积组蛋白在鸡蛋中，早期胚胎等效原核，培养的体细胞，和红细胞。我们使用碰撞相关解离来识别各种细胞类型中组蛋白H3上存在的修饰，解析26种不同修饰的H3肽。我们采用电子转移解离碎片化技术，在一个“中间向下”的方法对H4的N-末端尾部，以探讨重叠的翻译后修饰。我们在四种不同的细胞类型中观察到H4 1-23片段的66种离散亚型。从青蛙卵中分离出的储存的、沉积前的组蛋白H4也显示出比先前已知的赖氨酸（5）和赖氨酸（12）上的双乙酰化更多样化的修饰模式。H3和H4上的修饰的发育转变是惊人的变化，这意味着组蛋白密码与细胞类型和命运的强相关性。我们的研究结果与每种细胞类型的组蛋白代码索引一致，并揭示了单个尾部修饰之间的潜在串扰。
Epigenetic information is hypothesized to be encoded in histone variants and post-translational modifications. Varied cell-and locus-specific combinations of these epigenetic marks are likely contributors to regulation of chromatin-templated transactions, including transcription, replication, recombination, and repair. Therefore, the relative abundance of histone modifications in a given cell type is a potential index of cell fate and specificity. Here, we utilize mass spectrometry techniques to characterize the relative abundance index of cell type-specific modifications on histones H3 and H4 in distinct cell types from the frog Xenopus laevis, including the sperm, the stored predeposition histones in the egg, the early embryo equivalent pronuclei, cultured somatic cells, and erythrocytes. We used collisionally associated dissociation to identify the modifications present on histone H3 in a variety of cell types, resolving 26 distinctly modified H3 peptides. We employed the electron transfer dissociation fragmentation technique in a "middle-down" approach on the H4 N-terminal tail to explore the overlap of post-translational modifications. We observed 66 discrete isoforms of the H4 1-23 fragment in four different cell types. Isolation of the stored, predeposition histone H4 from the frog egg also revealed a more varied pattern of modifications than the previously known diacetylation on Lys(5) and Lys(12). The developmental transitions of modifications on H3 and H4 were strikingly varied, implying a strong correlation of the histone code with cell type and fate. Our results are consistent with a histone code index for each cell type and uncover potential cross-talk between modifications on a single tail.