High impact information on His2Av

• The role of histone H2Av variant replacement and histone H4 acetylation in the establishment of Drosophila heterochromatin [1].
• The results suggest an ordered cascade of events leading to the establishment of heterochromatin and requiring the recruitment of the histone H2Av variant followed by H4 Lys 12 acetylation as necessary steps before H3 Lys 9 methylation and HP1 recruitment can take place [1].
• We recently showed that H2A.Z is required for proper chromosome segregation [2].
• Here we demonstrate that depletion of H2A.Z by RNA interference perturbs Xenopus laevis development at gastrulation leading to embryos with malformed, shortened trunks [2].
• H2A.Z modifies the surface of a canonical nucleosome by creating an extended acidic patch and a metal ion-binding site stabilized by two histidine residues [2].

Biological context of His2Av

• H2AvD, a Drosophila melanogaster histone variant of the H2A.Z class, is encoded by a single copy gene in the 97CD region of the polytene chromosomes [3].
• P-element mediated transformation using a 4.1-kilobase fragment containing the H2AvD gene rescues the lethal phenotype [3].
• Using an antibody against the phosphorylated form of His2Av (gamma-His2Av), we have described the time course for the series of events leading from the formation of a double-strand break (DSB) to a crossover in Drosophila female meiotic prophase [4].
• H2Av was widely distributed in the genome and not limited to sites of active transcription [5].
• H2Av, the H2A.F/Z variant of Drosophila melanogaster, was localized in polytene chromosomes by indirect immunofluorescence and in diploid chromosomes by chromatin immunoprecipitation [5].

Anatomical context of His2Av

• The Tetrahymena histone H2A variant designated hv1 is localized exclusively in the transcriptionally active macronucleus and is absent from the quiescent micronucleus (1) [6].
• Consistent with this result, whole embryo in situ hybridization indicates that endogenous expression of H2A.Z is highly enriched in the notochord [2].

Other interactions of His2Av

• H2AvD is therefore both essential and continuously present, suggesting a requirement for its utilization, either to provide an alternative capability for nucleosome assembly or to generate an alternative nucleosome structure [3].
• We have generated Drosophila melanogaster lines carrying a modified genomic fragment which encodes the D. melanogaster variant H2A.F/Z class histone, His2AvD, fused to the green fluorescent protein (GFP) of the jellyfish Aequorea victoria [7].
• Here we show that Caenorhabditis elegans HTZ-1/H2A.Z and the remodeling complex MYS-1/ESA1-SSL-1/SWR1 synergize with the FoxA transcription factor PHA-4 to coordinate temporal gene expression during foregut development [8].

Analytical, diagnostic and therapeutic context of His2Av

• The complex banding pattern of H2Av in polytene chromosomes did not parallel the concentration of DNA, as did the pattern of immunofluorescence using H2A antibodies, and the density of H2Av measured by immunoprecipitation varied between different sequences [5].
• A cross-hybridizing clone was recovered and shown by sequence analysis to code for a protein homologous to hv1 as well as to the chicken H2A variant, H2A.F (3), the sea urchin H2A variant, H2A.F/Z (4) and the mammalian H2A variant H2A.Z (5) [6].

References