Barrier-to-autointegration factor plays crucial roles in cell cycle progression and nuclear organization in Drosophila.
Barrier-to-autointegration factor (BAF) is potentially a DNA-bridging protein, which directly associates with inner nuclear membrane proteins carrying LEM domains. These features point to a key role in regulation of nuclear function and organization, dependent on interactions between the nuclear envelope and chromatin. To understand the functions of BAF in vivo, Drosophila baf null mutants generated by P-element-mediated imprecise excision were analyzed. Homozygous null mutants showed a typical mitotic mutant phenotype: lethality at the larval-pupal transition with small brains and missing imaginal discs. Mitotic figures were decreased but a defined anaphase defect as reported for C. elegans RNAi experiments was not observed in these small brains, suggesting a different phase or phases of cell cycle arrest. Specific abnormalities in interphase nuclear structure were frequently found upon electron microscopic examination of baf null mutants, with partial clumping of chromatin and convolution of nuclear shape. At the light microscopic level, grossly aberrant nuclear lamina structure and B-type lamin distribution correlated well with the loss of detectable amounts of BAF protein from nuclei. Together, these data represent evidence of BAF's anticipated function in mediating interactions between the nuclear envelope and interphase chromosomes. We thus conclude that BAF plays essential roles in nuclear organization and that these BAF functions are required in both M phase and interphase of the cell cycle.
Furukawa
Kazuhiro
K
Department of Chemistry, Faculty of Science, Niigata University, Niigata 950-2181, Japan. furukawa@chem.sc.niigata-u.ac.jp
Sugiyama
Shin
S
Osouda
Shinichi
S
Goto
Hidemasa
H
Inagaki
Masaki
M
Horigome
Tsuneyoshi
T
Omata
Saburo
S
McConnell
Maeve
M
Fisher
Paul A
PA
Nishida
Yasuyoshi
Y
D000818:Animals; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000378:metabolism; D007150:Immunohistochemistry; D007399:Interphase / Q000502:physiology*; D034921:Lamin Type B / Q000378:metabolism*; D008854:Microscopy, Electron; D008938:Mitosis / Q000502:physiology*; D009154:Mutation; D009685:Nuclear Envelope / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D017434:Protein Structure, Tertiary
C501957:BAF protein, Drosophila; D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D034921:Lamin Type B; D009687:Nuclear Proteins