Histone H1 is essential for mitotic chromosome architecture and segregation in Xenopus laevis egg extracts.
During cell division, condensation and resolution of chromosome arms and the assembly of a functional kinetochore at the centromere of each sister chromatid are essential steps for accurate segregation of the genome by the mitotic spindle, yet the contribution of individual chromatin proteins to these processes is poorly understood. We have investigated the role of embryonic linker histone H1 during mitosis in Xenopus laevis egg extracts. Immunodepletion of histone H1 caused the assembly of aberrant elongated chromosomes that extended off the metaphase plate and outside the perimeter of the spindle. Although functional kinetochores assembled, aligned, and exhibited poleward movement, long and tangled chromosome arms could not be segregated in anaphase. Histone H1 depletion did not significantly affect the recruitment of known structural or functional chromosomal components such as condensins or chromokinesins, suggesting that the loss of H1 affects chromosome architecture directly. Thus, our results indicate that linker histone H1 plays an important role in the structure and function of vertebrate chromosomes in mitosis.
Maresca
Thomas J
TJ
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
Freedman
Benjamin S
BS
Heald
Rebecca
R
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000705:Anaphase / Q000235:genetics; D000818:Animals; D002457:Cell Extracts / Q000737:chemistry; D002503:Centromere / Q000473:pathology / Q000502:physiology / Q000648:ultrastructure; D020090:Chromosome Segregation / Q000235:genetics*; D002875:Chromosomes / Q000235:genetics* / Q000648:ultrastructure; D004261:DNA Replication / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D006657:Histones / Q000235:genetics*; D016547:Kinesins / Q000378:metabolism; D018386:Kinetochores / Q000473:pathology / Q000502:physiology / Q000648:ultrastructure; D008938:Mitosis / Q000235:genetics*; D008954:Models, Biological; D046912:Multiprotein Complexes; D009687:Nuclear Proteins / Q000378:metabolism; D009865:Oocytes / Q000737:chemistry / Q000378:metabolism*; D008941:Spindle Apparatus / Q000235:genetics / Q000473:pathology / Q000648:ultrastructure; D014982:Xenopus laevis
D002457:Cell Extracts; D004268:DNA-Binding Proteins; D006657:Histones; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; C092349:chromokinesin; C108312:condensin complexes; D000251:Adenosine Triphosphatases; D016547:Kinesins