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Familial dysautonomia (FD; also known as "Riley-Day syndrome"), an Ashkenazi Jewish disorder, is the best known and most frequent of a group of congenital sensory neuropathies and is characterized by widespread sensory and variable autonomic dysfunction. Previously, we had mapped the FD gene, DYS, to a 0.5-cM region on chromosome 9q31 and had shown that the(More)
Heterochromatin is defined classically by condensation throughout the cell cycle, replication in late S phase and gene inactivity. Facultative heterochromatin is of particular interest, because its formation is developmentally regulated as a result of cellular differentiation. The most extensive example of facultative heterochromatin is the mammalian(More)
Chromatin on the mammalian inactive X chromosome differs in a number of ways from that on the active X. One protein, macroH2A, whose amino terminus is closely related to histone H2A, is enriched on the heterochromatic inactive X chromosome in female cells. Here, we report the identification and localization of a novel and more distant histone variant,(More)
Histone modifications are thought to serve as epigenetic markers that mediate dynamic changes in chromatin structure and regulation of gene expression. As a model system for understanding epigenetic silencing, X chromosome inactivation has been previously linked to a number of histone modifications including methylation and hypoacetylation. In this study,(More)
MacroH2A1 is an unusual variant of the core histone H2A which is enriched in chromatin on the inactive X chromosome of female mammals. The N-terminal third of the protein shares 65% amino acid identity with core histone H2A, while the remaining two-thirds of the protein are novel, with a small stretch of basic amino acids and a putative leucine zipper(More)
Macrosatellite DNA is composed of large repeat units, arranged in tandem over hundreds of kilobases. The macrosatellite repeat DXZ4, localized at Xq23-24, consists of 50-100 copies of a CpG-rich 3-kb monomer. Here I report that on the active X chromosome (Xa), DXZ4 is organized into constitutive heterochromatin characterized by a highly organized pattern of(More)
The heterochromatin of the inactive X chromosome (Xi) is organized into nonoverlapping bands of trimethylated lysine-9 of histone H3 (H3K9me3) and trimethylated lysine-27 of histone H3 (H3K27me3). H3K27me3 chromatin of the Xi is further characterized by ubiquitylated H2A and H4 monomethylated at lysine-20. A detailed examination of the metaphase H3K9me3(More)
Knockdown of the insulator factor CCCTC binding factor (CTCF), which binds XL9, an intergenic element located between HLA-DRB1 and HLA-DQA1, was found to diminish expression of these genes. The mechanism involved interactions between CTCF and class II transactivator (CIITA), the master regulator of major histocompatibility complex class II (MHC-II) gene(More)
X chromosome inactivation refers to the developmentally regulated process of silencing gene expression from all but one X chromosome per cell in female mammals in order to equalize the levels of X chromosome derived gene expression between the sexes. While much attention has focused on the genetic and epigenetic events early in development that initiate the(More)
The human lymphoid cell activation antigen CD39 is a known E-type apyrase that hydrolyzes extracellular ATP and ADP, a function important in homotypic adhesion, platelet aggregation, and removal by activated lymphocytes of the lytic effect of ATP. The recently identified putative rat homologue of CD39L1 has been shown to have E-type ecto-ATPase activity, by(More)