Analysis of the role of Aurora B on the chromosomal targeting of condensin I.
During mitosis, chromosome condensation takes place, which entails the conversion of interphase chromatin into compacted mitotic chromosomes. Condensin I is a five-subunit protein complex that plays a central role in this process. Condensin I is targeted to chromosomes in a mitosis-specific manner, which is regulated by phosphorylation by mitotic kinases. Phosphorylation of histone H3 at serine 10 (Ser10) occurs during mitosis and its physiological role is a longstanding question. We examined the function of Aurora B, a kinase that phosphorylates Ser10, in the chromosomal binding of condensin I and mitotic chromosome condensation, using an in vitro system derived from Xenopus egg extract. Aurora B depletion from a mitotic egg extract resulted in the loss of H3 phosphorylation, accompanied with a 50% reduction of chromosomal targeting of condensin I. Alternatively, a portion of condensin I was bound to sperm chromatin, and chromosome-like structures were assembled when okadaic acid (OA) was supplemented in an interphase extract that lacks Cdc2 activity. However, chromosomal targeting of condensin I was abolished when Aurora B was depleted from the OA-treated interphase extract. From these results, it is suggested that Aurora B-dependent and Cdc2-independent pathways of the chromosomal targeting of condensin I are present.
Takemoto
Ai
A
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba Science City, Ibaraki, Japan.
Murayama
Akiko
A
Katano
Miyuki
M
Urano
Takeshi
T
Furukawa
Koichi
K
Yokoyama
Shigeyuki
S
Yanagisawa
Junn
J
Hanaoka
Fumio
F
Kimura
Keiji
K
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D064107:Aurora Kinase B; D002875:Chromosomes / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D007399:Interphase; D008938:Mitosis; D046912:Multiprotein Complexes / Q000378:metabolism*; D019319:Okadaic Acid / Q000494:pharmacology; D010063:Ovum / Q000201:enzymology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D014981:Xenopus; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*
D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D029867:Xenopus Proteins; C108312:condensin complexes; D019319:Okadaic Acid; D064107:Aurora Kinase B; D017346:Protein Serine-Threonine Kinases; D000251:Adenosine Triphosphatases