Epigenetic engineering shows H3K4me2 is required for HJURP targeting and CENP-A assembly on a synthetic human kinetochore

Kinetochores assemble on distinct 'centrochromatin' containing the histone H3 variant CENP-A and interspersed nucleosomes dimethylated on H3K4 (H3K4me2). Little is known about how the chromatin environment at active centromeres governs centromeric structure and function. Here, we report that centrochromatin resembles K4-K36 domains found in the body of some actively transcribed housekeeping genes. By tethering the lysine-specific demethylase 1 (LSD1), we specifically depleted H3K4me2, a modification thought to have a role in transcriptional memory, from the kinetochore of a synthetic human artificial chromosome (HAC). H3K4me2 depletion caused kinetochores to suffer a rapid loss of transcription of the underlying α-satellite DNA and to no longer efficiently recruit HJURP, the CENP-A chaperone. Kinetochores depleted of H3K4me2 remained functional in the short term, but were defective in incorporation of CENP-A, and were gradually inactivated. Our data provide a functional link between the centromeric chromatin, α-satellite transcription, maintenance of CENP-A levels and kinetochore stability.

Drosophila melanogaster as a model for basal body research

The fruit fly, Drosophila melanogaster, is one of the most extensively studied organisms in biological research and has centrioles/basal bodies and cilia that can be modelled to investigate their functions in animals generally. Centrioles are nine-fold symmetrical microtubule-based cylindrical structures required to form centrosomes and also to nucleate the formation of cilia and flagella. When they function to template cilia, centrioles transition into basal bodies. The fruit fly has various types of basal bodies and cilia, which are needed for sensory neuron and sperm function. Genetics, cell biology and behaviour studies in the fruit fly have unveiled new basal body components and revealed different modes of assembly and functions of basal bodies that are conserved in many other organisms, including human, green algae and plasmodium. Here we describe the various basal bodies of Drosophila, what is known about their composition, structure and function.