Rabbit Anti-Human Histone H2A.Z (Acetyl-Lys7) monoclonal antibody, clone SN333

Background: Ras-PI3K pathway aberrant activation plays an important role in the occurrence and development of osteosarcoma. This study investigated the functions of Ras-PI3K pathway specific activation on histone H2A phosphorylation at threonine 120 (H2A(T120ph)) in osteosarcoma cells, along with the possible internal molecular mechanisms. Methods: Cell transfection was done to alter Ras(G12V/Y40C), H2A(T120ph) and vaccinia-related kinase 1 (VRK1) expression. Then, cell viability, proliferation, migration and cell cycle distribution were assessed, respectively. qRT-PCR was utilized to measure the VRK1 and Ras-PI3K pathway downstream genes (CYR61, IGFBP3, WNT16B, NT5E, GDF15 and CARD16) expression. Chromatin immunoprecipitation (ChIP) was conducted to evaluate the input levels of H2A(T120ph) and VRK1 in the promoter regions of Ras-PI3K pathway downstream genes. Results: Ras-PI3K specific activation promoted histone H2A(T120ph). H2A(T120ph) participated in the oncogenic functions of Ras-PI3K pathway on osteosarcoma by modulating the transcription of Ras-PI3K-targeted genes. Moreover, VRK1 contributed to the Ras-PI3K specific activation-induced up-regulation of H2A(T120ph) and osteosarcoma progression. Ras-PI3K pathway-specific activation-induced up-regulation of H2A(T120ph) was achieved by up-regulation of VRK1. Conclusions: Ras-PI3K pathway activation promoted osteosarcoma progression might be via up-regulating VRK1-mediated H2A(T120ph). We proposed that VRK1 and H2A(T120ph) could be the potential targets for osteosarcoma diagnosis and treatment.

Centromeres are defined epigenetically by nucleosomes containing the histone H3 variant CENP-A, upon which the constitutive centromere-associated network of proteins (CCAN) is built. CENP-C is considered to be a central organizer of the CCAN. We provide new molecular insights into the structure of human CENP-A nucleosomes, in isolation and in complex with the CENP-C central region (CENP-C-CR), the main CENP-A binding module of human CENP-C. We establish that the short alpha N helix of CENP-A promotes DNA flexibility at the nucleosome ends, independently of the sequence it wraps. Furthermore, we show that, in vitro, two regions of human CENP-C (CENP-C-CR and CENP-C-motif) both bind exclusively to the CENP-A nucleosome. We find CENP-C-CR to bind with high affinity due to an extended hydrophobic area made up of CENP-A(V532) and CENP-A(V533). Importantly, we identify two key conformational changes within the CENP-A nucleosome upon CENP-C binding. First, the loose DNA wrapping of CENP-A nucleosomes is further exacerbated, through destabilization of the H2A C-terminal tail. Second, CENP-C-CR rigidifies the N-terminal tail of H4 in the conformation favoring H4(K20) monomethylation, essential for a functional centromere.