RbAp48 is essential for viability of vertebrate cells and plays a role in chromosome stability
RbAp46/48, histone chaperone, is a family of evolutionarily conserved WD40 repeat-containing proteins, which are involved in various chromatin-metabolizing processes, but their in vivo functional relevance is yet unclear. In order to examine the biological role of pRbAp48 in chicken DT40 cells, we generated a tetracycline-inducible system for conditional RbAp48-knockout cells. Depletion of RbAp48 led to delayed S phase progression associated with slow DNA synthesis and nascent nucleosome formation, followed by accumulation in G2/M phase, finally leading to cell death. Prior to cell death, these cells exhibited aberrant mitosis such as highly condensed and abnormal chromosome alignment on the metaphase plate, leading to chromosome missegregation. Depletion of RbAp48 also caused dissociation of heterochromatin protein 1 (HP1) from pericentromeric heterochromatin. Furthermore, depletion of RbAp48 from cells led to elevated levels of acetylation and slightly decreased levels of methylation, specifically at Lys-9 residue of histone H3. These results suggest that RbAp48 plays an important role in chromosome stability for proper organization of heterochromatin structure through the regulation of epigenetic mark.
KeywordsHistone chaperone Chromatin assembly Histone modification WD40 protein Heterochromatin
Chromatin assembly factor
Heterochromatin protein 1
This work was supported in part by Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan. We thank Ryoko Masuya and Nahoko Nagamatsu-Yamamoto for their technical assistance and Radha Madhyastha and HarishKumar Madhyastha for useful comments and critical reading of the manuscript.
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Conflict of interest
All the authors declare that they have no conflict of interest of any sort with anyone.
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