Graves Hillary K, Wang Pingping, Lagarde Matthew, Chen Zhihong, Tyler Jessica K
Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX 77030 USA.
Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX 77030 USA ; Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY 10065 USA.
Epigenetics Chromatin. 2016 Feb 29;9:9. doi: 10.1186/s13072-016-0059-3. eCollection 2016.
Understanding the function of histone post-translational modifications is the key to deciphering how genomic activities are regulated. Among the least well-understood histone modifications in vivo are those that occur on the surface of the globular domain of histones, despite their causing the most profound structural alterations of the nucleosome in vitro. We utilized a Drosophila system to replace the canonical histone genes with mutated histone transgenes.
Mutations predicted to mimic or prevent acetylation on histone H3 lysine (K) 56, K115, K122, and both K115/K122, or to prevent or mimic phosphorylation on H3 threonine (T) 118 and T80, all caused lethality, with the exception of K122R mutants. T118 mutations caused profound growth defects within wing discs, while K115R, K115Q, K56Q, and the K115/K122 mutations caused more subtle growth defects. The H3 K56R and H3 K122R mutations caused no defects in growth, differentiation, or transcription within imaginal discs, indicating that H3 K56 acetylation and K122 acetylation are dispensable for these functions. In agreement, we found the antibody to H3 K122Ac, which was previously used to imply a role for H3 K122Ac in transcription in metazoans, to be non-specific in vivo.
Our data suggest that chromatin structural perturbations caused by acetylation of K56, K115, or K122 and phosphorylation of T80 or T118 are important for key developmental processes.
了解组蛋白翻译后修饰的功能是破译基因组活动如何被调控的关键。在体内最不为人所了解的组蛋白修饰中，有一些发生在组蛋白球状结构域的表面，尽管它们在体外会导致核小体最深刻的结构改变。我们利用果蝇系统用突变的组蛋白转基因取代了经典的组蛋白基因。
预测模拟或阻止组蛋白H3赖氨酸（K）56、K115、K122以及K115/K122双位点的乙酰化，或阻止或模拟H3苏氨酸（T）118和T80磷酸化的突变，除K122R突变体外，均导致致死性。T118突变导致翅芽内出现严重的生长缺陷，而K115R、K115Q、K56Q以及K115/K122双位点突变导致更细微的生长缺陷。H3 K56R和H3 K122R突变在成虫盘内未引起生长、分化或转录缺陷，表明H3 K56乙酰化和K122乙酰化对于这些功能是可有可无的。与此一致，我们发现先前用于暗示H3 K122Ac在多细胞动物转录中起作用的H3 K122Ac抗体在体内是非特异性的。
我们的数据表明，由K56、K115或K122乙酰化以及T80或T118磷酸化引起的染色质结构扰动对于关键的发育过程很重要。
