Defective Chromosome Segregation, Microtubule Bundling and Nuclear Bridging in Inner Centromere Protein Gene (Incenp)-Disrupted Mice

• Published in: Human molecular genetics Vol. 8; no. 7; pp. 1145 - 1155
• Main Authors: Cutts, Suzanne M., Fowler, Kerry J., Kile, Benjamin T., Hii, Linda L. P., O'Dowd, Rachael A., Hudson, Damien F., Saffery, Richard, Kalitsis, Paul, Earle, Elizabeth, Choo, K. H. A.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.07.1999; Oxford Publishing Limited (England)
• Subjects: Animals; Biological and medical sciences; Cell cycle, cell proliferation; Cell Nucleus; Cell physiology; Chickens; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - physiology; Chromosome Segregation; Chromosomes; Embryonic and Fetal Development - genetics; Embryonic and Fetal Development - physiology; Fundamental and applied biological sciences. Psychology; Gene Targeting; Immunohistochemistry; Mice; Mice, Knockout; Microtubules - physiology; Molecular and cellular biology; Mutation; Phenotype; Tubulin - analysis; Embryonic development; Cell function; Mitosis; Rodentia; Chromosome; Vertebrata; Disjunction; Phenotype; Mammalia; Centromere; Mouse; Cell cycle; Cytoskeleton; Microtubule; Mutation; Nuclear protein
• ISSN: 0964-6906; 1460-2083; 1460-2083
• DOI: 10.1093/hmg/8.7.1145

INCENP is a chromosomal passenger protein which relocates from the centromere to thel spindle midzone during the metaphase-anaphase transition, ultimately being discarded in the cell midbody at the completion of cytokinesis. Using homologous recombination, we have generated Incenp gene-targeted heterozygous mice that are phenotypically indistinguishable from their wild-type littermates. Intercrossing the heterozygotes results in no live-born homozygous Incenp-disrupted progeny, indicating an early lethality. Day 3.5 affected pre-implantation embryos contain large, morphologically abnormal cells that fail to fully develop a blastocoel cavity or thrive in utero and in culture. Chromatin and tubulin immunocytochemical stainings of these and day 2.5 affected embryos reveal a high mitotic index, no discernible metaphase or anaphase stages, complete absence of midbodies, micronuclei formation, morphologically irregular macronuclei with large chromosome complements, multipolar mitotic configurations, binucleated cells, internuclear bridges and abnormal spindle bundling. The phenotype is consistent with a defect in the modulation of microtubule dynamics, severely affecting chromosome segregation and resulting in poorly resolved chromatin masses, aberrant karyokinesis and internuclear bridge formation. These latter occurrences could pose a physical barrier blocking cytokinesis.