Kitamura Hiroshi, Matsumori Haruka, Kalendova Alzbeta, Hozak Pavel, Goldberg Ilya G, Nakao Mitsuyoshi, Saitoh Noriko, Harata Masahiko
Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoka-ku, Sendai 981-8555, Japan.
Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811, Japan.
Biochem Biophys Res Commun. 2015 Aug 21;464(2):554-60. doi: 10.1016/j.bbrc.2015.07.005. Epub 2015 Jul 9.
The actin family members, consisting of actin and actin-related proteins (ARPs), are essential components of chromatin remodeling complexes. ARP6, one of the nuclear ARPs, is part of the Snf-2-related CREB-binding protein activator protein (SRCAP) chromatin remodeling complex, which promotes the deposition of the histone variant H2A.Z into the chromatin. In this study, we showed that ARP6 influences the structure and the function of the nucleolus. ARP6 is localized in the central region of the nucleolus, and its knockdown induced a morphological change in the nucleolus. We also found that in the presence of high concentrations of glucose ARP6 contributed to the maintenance of active ribosomal DNA (rDNA) transcription by placing H2A.Z into the chromatin. In contrast, under starvation, ARP6 was required for cell survival through the repression of rDNA transcription independently of H2A.Z. These findings reveal novel pleiotropic roles for the actin family in nuclear organization and metabolic homeostasis.
肌动蛋白家族成员由肌动蛋白和肌动蛋白相关蛋白（ARPs）组成，是染色质重塑复合物的重要组成部分。ARP6是一种核内ARPs，是与Snf-2相关的CREB结合蛋白激活蛋白（SRCAP）染色质重塑复合物的一部分，该复合物促进组蛋白变体H2A.Z沉积到染色质中。在本研究中，我们表明ARP6影响核仁的结构和功能。ARP6定位于核仁的中央区域，其敲低诱导了核仁的形态变化。我们还发现，在高浓度葡萄糖存在的情况下，ARP6通过将H2A.Z置于染色质中有助于维持活性核糖体DNA（rDNA）转录。相反，在饥饿条件下，ARP6通过独立于H2A.Z抑制rDNA转录来维持细胞存活。这些发现揭示了肌动蛋白家族在核组织和代谢稳态中的新的多效性作用。
