The role of heterochromatin in species formation and centromere function

• Applicant: Professor Dr. Axel Imhof
• Subject Area: Developmental Biology
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 232395386

Heterochromatin is the gene poor, late replication and DNA dense domain in the nucleus. Traditionally, it was solely cytologically defined as nuclear regions strongly staining with basophilic dyes. Since then, it has been connected to a variety of cellular processes like transcriptional repression, suppression of recombination and the protection of telomers. These features are in part conferred by structural heterochromatin proteins of the HP1 family. In Drosophila, HP1a is also required for telomere integrity and transcription of eu- and heterochromatic genes. To gain insight into the mechanisms of HP1a 's multifunctionality, we purified its interaction partners. Two major copurifying proteins were the speciation gene products Hmr and Lhr that genetically interact to cause lethality of hybrids from crosses of Drosophila melanogaster with animals of the D. simulans clade. We find that HP1a, Hmr and Lhr form a complex in Drosophila Schneider cells that localizes to centromeric chromatin. Elucidating the molecular functions of this complex will further our understanding of centromere regulation and provide molecular insights into the process of speciation.

• DFG Programme: Research Grants