Drosophila for Breast Cancer Research – Especially on H2AvD, H2A.Z and H2A.X

Despite having no mammary glands, Drosophila is a very useful model for conducting research on molecular mechanisms as well as the regulation of transcription including epigenetic changes associated with breast cancer development. Drosophila has been used as one of the model systems since it was first introduced by Thomas Morgan, a pioneer in genetics for the study of heredity, in the early 20th century [1]. The complete mapping of all Drosophila chromosomes was completed by Dr. Morgan and his colleagues. Drosophila has extremely large polytene chromosomes in the salivary glands. These polytene chromosomes have enabled us to directly observe chromosomal structures and band-patterns including euchromatin and heterochromatin since the early 1960s [2,3]. Most notably, the loci involved in gene activation can be visualized as chromosome puffing [3,4]. When chromosomes including puffs are immuno-stained using antibodies against factors associated with transcription and chromatin structures such as RNA polymerase II and histones, we can evaluate the state of transcription as well as modification of histone tails which are epigenetic markers on genes of interest [4,5]. In Drosophila, Position-effect variegation (PEV) which is observed when a gene normally in euchromatin is juxtaposed with heterochromatin, is also a very useful phenotype for analyzing factors which can convert chromatin structures from euchromatin to heterochromatin or vice versa [6]. We can analyze the functions of chromatin modifiers in the degree of eye pigmentation, i.e., the proportions of white and red pigmentation in Drosophila eyes, by crossing mutant lines of interest with an original PEV line [6].