Lysine-specific demethylase 2A enhances binding of various nuclear factors to CpG-rich genomic DNAs by action of its CXXC-PHD domain

RNAmetasome network for macromolecule biogenesis in human cells

RNA plays a central role in macromolecule biogenesis for various pathways, such as gene expression, ribosome biogenesis, and chromatin remodeling. However, RNA must be converted from its nascent to functional forms for that role. Here, we describe a large RNA metabolic network (RNAmetasome network) for macromolecule biogenesis in human cells. In HEK293T, the network consists of proteins responsible for gene expression, splicing, ribosome biogenesis, chromatin remodeling, and cell cycle. Reciprocal immunoprecipitations show that MKI67, GNL2, MDN1, and ELMSAN1 are core proteins of the network, and knockdown of either MKI67 or GNL2 affects the state of the other protein, MDN1, and some other network members. Furthermore, GNL2 knockdown retards cell proliferation. Several proteins of the RNAmetasome network are diminished in Hela.cl1, and this diminishment is associated with low expression of MDN1 and elevated MKI67 degradation. These results together suggest that the RNAmetasome network is present in human cells and associated with proliferation, and that MKI67, GNL2, and MDN1 play an important role in organizing the RNAmetasome network.

Iuchi and Paulo identify a large metabolic complex for macromolecule biogenesis composed of numerous RNA processing proteins in HEK293T cells, which the authors term the RNAmetasome. The authors identify the complex by mass-spec using ELMSAN1 as bait and utilize reciprocal immunoprecipitation and immunocytochemistry for validation, and find that MKI67, GNL2, and MDN1 have important roles organizing the RNAmetasome network.

Histone demethylase KDM2A: Biological functions and clinical values (Review)

Histone lysine demethylation modification is a critical epigenetic modification. Lysine demethylase 2A (KDM2A), a Jumonji C domain-containing demethylase, demethylates the dimethylated H3 lysine 36 (H3K36) residue and exerts little or no activity on monomethylated and trimethylated H3K36 residues. KDM2A expression is regulated by several factors, such as microRNAs, and the phosphorylation of KDM2A also plays a vital role in its function. KDM2A mainly recognizes the unmethylated region of CpG islands and subsequently demethylates histone H3K36 residues. In addition, KDM2A recognizes and binds to phosphorylated proteins, and promotes their ubiquitination and degradation. KDM2A plays an important role in chromosome remodeling and gene transcription, and is involved in cell proliferation and differentiation, cell metabolism, heterochromosomal homeostasis and gene stability. Notably, KDM2A is crucial for tumorigenesis and progression. In the present review, the documented biological functions of KDM2A in physiological and pathological processes are comprehensively summarized.

C1188D mutation abolishes specific recognition between MLL1-CXXC domain and CpG site by inducing conformational switch of flexible N-terminal

Mixed lineage leukemia protein (MLL1 protein) recognizes the CpG site via its CXXC domain and is frequently associated with leukemia. The specific recognition is abolished by C1188D mutation, which also prevents MLL-related leukemia. In this paper, multiple molecular dynamic (MD) simulations were performed to investigate the mechanism of recognition and influences of C1188D mutation. Started from fully dissociated DNA and MLL1-CXXC domain, remarkably, the center of mass (COM) of MLL1-CXXC domain quickly concentrates on the vicinity of the CpG site in all 53 short MD simulations. Extended simulations of the wild type showed that the native complex formed in 500 ns among 4 of 53 simulations. In contrast, the C1188D mutant COM distributed broadly around the DNA and the native complex was not observed in any of the extended simulations. Simulations on the apo MLL1-CXXC domain further suggest that the wild type protein remained predominantly in an open form that closely resembles its structure in the native complex whereas C1188D mutant formed predominantly compact structures in which the N- terminal bends to D1188. This conformational switch hinders the formation of encounter complex, thus abolishes the recognition. Our study also provides clues to the study mechanism of recognition, by the CXXC domain from proteins like DNA methyltransferase and ten-eleven translocation enzymes.