Formation and inheritance of heterochromatin by nucleosome assembly factors

DNA replication-coupled nucleosome assembly pathway is involved in inheritance and formation of yeast heterochromatin.

Epigenetic silencing, the heritable repression of gene expression without alterations in DNA sequences, is achieved through formation of a specialized chromatin structure called heterochromatin. In higher eukaryotic cells, heterochromatin is marked by DNA methylation, special modifications on histones such as methylation on H3 lysine 9 and proteins residing at heterochromatin such as HP-1 proteins. We use the yeast S. cerevisiae as a model organism to study heterochromatin formation and maintenance. We are interested in how nucleosome assembly factors, most of which are conserved from yeast to human cells, function in epigenetic silencing. The nucleosome assembly factors that we are interested in are chromatin assembly factor 1 (CAF-1), Asf1 and Rtt106. Our working hypothesis is that these nucleosome assembly factors are involved in both formation and maintenance of silent chromatin, and these roles are likely to be conserved from yeast to mammalian cells.