Graduate School of Frontier Biosciences, Osaka University

Japanese

Colloquium 197

Speaker Kohei Nishimura (S.A. Assistant Professor, FBS Lab. of Chromosome Biology (Fukagawa Lab.))
Title Genome wide analysis of Centromere region in interphase nuclei
Speaker Mariko Ariyoshi (S.A. Assistant Professor, FBS Lab. of Chromosome Biology (Fukagawa Lab.))
Title Molecular dissection of CENP-A nucleosome recognition by a centromere protein, CENP-C
Date Wed., October 24, 2018, 12:15~13:00
Place 2F Seminar room, BioSystems Building
Host Tetsuya Hori (FBS Lab. of Chromosome Biology, Assoc. Prof.)
Tel :06-6879-4425
E-mail:thori@fbs.osaka-u.ac.jp

Title/Abstract

Genome wide analysis of Centromere region in interphase nuclei

The centromere is a specialized locus associated with centromere factors CENP-A nucleosome and CCAN and it functions in chromosomal segregation via kinetochore formation during mitosis. The centromere is still a special locus in interphase nuclei, but centromere structure and function in interphase are unknown. To understand them, we focused on a genome wide analysis of centromere regions. The mammals human and mouse have highly conserved repetitive sequences at centromere regions, which makes it difficult to apply a genome wide analysis of them. However, chicken cells have centromeres with non-repetitive sequences at chromosomes 5, 27 and Z. In addition, we have many DT40 cell lines that have neocentromere with non-repetitive sequences at various loci on chromosome Z (Shang WH et al., Dev Cell, 2013). This is a great advantage of investigating centromere structure and function in interphase. By applying 4C-seq (Circular Chromosome Conformation Capture) analysis of these cell lines, charismatic features of interphase centromere structure are elucidated.

Molecular dissection of CENP-A nucleosome recognition by a centromere protein, CENP-C

Centromere is an indispensable structural feature of chromatin for accurate cell cycle progression. The primary function of centromere is providing a platform for assembly of the kinetochore super-protein complex driving chromosome segregation. The histone H3 variant, CENP-A is a well-known epigenetic marker for the centromere specification. One of the kinetochore proteins, CENP-C directly interacts with CENP-A nucleosome and secures the kinetochore formation on centromeres. We previously revealed that the middle region of chicken CENP-C is involved in centromere localization during interphase, while the C-terminal region of CENP- C is required for centromere localization during mitosis. These findings imply that kinetochore assembly is partly regulated through conformational changes of CENP-C. To understand how the molecular interaction mode of CENP-C is regulated in a cell cycle dependent manner, we have investigated structural and biochemical properties of chicken CENP-C and its CENP-A nucleosome binding. To gain structural information, we have established in vitro reconstitution and purification system of the CENP-C:CENP-A nucleosome complex suitable for CryoEM analysis. I will present our recent data about CENP-A nucleosome recognition by CENP-C.


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