RESUMO
The formation of de novo centromeres on artificial chromosomes in humans (HACs) and fission yeast (SpYACs) has provided much insights to the epigenetic and genetic control on regional centromere establishment and maintenance. Similarly, the use of artificial chromosomes in point centromeric budding yeast Saccharomyces cerevisiae (ScYACs) and holocentric Caenorhabditis elegans (WACs) has revealed epigenetic regulation in the originally thought purely genetically-determined point centromeres and some centromeric DNA sequence features in holocentromeres, respectively. These relatively extreme and less characterized centromere organizations, on the endogenous chromosomes and artificial chromosomes, will be discussed and compared to the more well-studied regional centromere systems. This review will highlight some of the common epigenetic and genetic features in different centromere architectures, including the presence of the centromeric histone H3 variant, CENP-A or CenH3, centromeric and pericentric transcription, AT-richness and repetitiveness of centromeric DNA sequences.
Assuntos
Proteína Centromérica A/genética , Centrômero/metabolismo , Cromatina/química , Proteínas Cromossômicas não Histona/genética , Epigênese Genética , Histonas/genética , Animais , Bombyx/genética , Bombyx/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Candida albicans/genética , Candida albicans/metabolismo , Centrômero/ultraestrutura , Proteína Centromérica A/metabolismo , Cromatina/genética , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos Artificiais/química , Cromossomos Artificiais/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Histonas/metabolismo , Humanos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Zea mays/genética , Zea mays/metabolismoRESUMO
The centromere is a specialized region on the chromosome that directs equal chromosome segregation. Centromeres are usually not defined by DNA sequences alone. How centromere formation and function are determined by epigenetics is still not fully understood. Active centromeres are often marked by the presence of centromeric-specific histone H3 variant, centromere protein A (CENP-A). How CENP-A is assembled into the centromeric chromatin during the cell cycle and propagated to the next cell cycle or the next generation to maintain the centromere function has been intensively investigated. In this review, we summarize current understanding of how post-translational modifications of CENP-A and other centromere proteins, centromeric and pericentric histone modifications, non-coding transcription and transcripts contribute to centromere function, and discuss their intricate relationships and potential feedback mechanisms.
