Loss of Pcgf5 Affects Global H2A Monoubiquitination but Not the Function of Hematopoietic Stem and Progenitor Cells

• Published in: PloS one 2016-05, Vol.11 (5), p.e0154561-e0154561
• Main Authors: Si, Sha, Nakajima-Takagi, Yaeko, Aoyama, Kazumasa, Oshima, Motohiko, Saraya, Atsunori, Sugishita, Hiroki, Nakayama, Manabu, Ishikura, Tomoyuki, Koseki, Haruhiko, Iwama, Atsushi
• Format: Article
• Language: English
• Subjects: Animals; Biology and Life Sciences; Bone marrow; Bone marrow transplantation; Cell cycle; Cell Differentiation - genetics; Cell Differentiation - physiology; Cells (biology); Chromatin Immunoprecipitation; Clonal deletion; Drug dosages; Epigenetic inheritance; Epigenetics; Gene expression; Gene silencing; Genotype; Hematopoiesis; Hematopoietic stem cells; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - metabolism; Histone H2A; Histones - metabolism; Immunoglobulins; Impact analysis; Kinases; Laboratories; Lysine; Medicine; Medicine and Health Sciences; Mice; Mice, Inbred C57BL; Mutation; Polycomb group proteins; Polycomb Repressive Complex 1 - genetics; Polycomb Repressive Complex 1 - metabolism; Progenitor cells; Protein Binding - genetics; Protein Binding - physiology; Proteins; Reduction; Research and Analysis Methods; RING finger proteins; Stem cell transplantation; Stem cells; Tamoxifen; Transplantation; Ubiquitin-proteasome system; Ubiquitination; Ubiquitination - genetics; Ubiquitination - physiology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0154561

Polycomb-group RING finger proteins (Pcgf1-Pcgf6) are components of Polycomb repressive complex 1 (PRC1)-related complexes that catalyze monoubiquitination of histone H2A at lysine 119 (H2AK119ub1), an epigenetic mark associated with repression of genes. Pcgf5 has been characterized as a component of PRC1.5, one of the non-canonical PRC1, consisting of Ring1a/b, Rybp/Yaf2 and Auts2. However, the biological functions of Pcgf5 have not yet been identified. Here we analyzed the impact of the deletion of Pcgf5 specifically in hematopoietic stem and progenitor cells (HSPCs). Pcgf5 is expressed preferentially in hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs) compared with committed myeloid progenitors and differentiated cells. We transplanted bone marrow (BM) cells from Rosa::Cre-ERT control and Cre-ERT;Pcgf5fl/fl mice into lethally irradiated recipient mice. At 4 weeks post-transplantation, we deleted Pcgf5 by injecting tamoxifen, however, no obvious changes in hematopoiesis were detected including the number of HSPCs during a long-term observation period following the deletion. Competitive BM repopulating assays revealed normal repopulating capacity of Pcgf5-deficient HSCs. Nevertheless, Pcgf5-deficient HSPCs showed a significant reduction in H2AK119ub1 levels compared with the control. ChIP-sequence analysis confirmed the reduction in H2AK119ub1 levels, but revealed no significant association of changes in H2AK119ub1 levels with gene expression levels. Our findings demonstrate that Pcgf5-containing PRC1 functions as a histone modifier in vivo, but its role in HSPCs is limited and can be compensated by other PRC1-related complexes in HSPCs.