Barrier-to-autointegration factor is required to segregate and enclose chromosomes within the nuclear envelope and assemble the nuclear lamina.
Barrier-to-autointegration factor (BAF) binds dsDNA, LEM-domain proteins, and lamins. Caenorhabditis elegans BAF requires Ce-lamin and two LEM-domain proteins (Ce-emerin and Ce-MAN1) to localize during nuclear assembly. It was unknown whether Ce-lamin and LEM proteins, in turn, depend on Ce-BAF (mutually dependent structural roles). RNA interference-mediated down-regulation of Ce-BAF caused gross defects in chromosome segregation, chromatin decondensation, and mitotic progression as early as the two-cell stage, and embryos died at the approximately 100-cell stage. Nuclear pores reassembled, whereas Ce-lamin, Ce-emerin, and Ce-MAN1 bound chromatin but remained patchy and disorganized. The nuclear membranes formed but failed to enclose anaphase-bridged chromatin. Time-lapse imaging showed two phenotypes: anaphase-bridged chromatin that eventually resolved, and segregated chromatin that returned to the midzone. Thus, the assembly of BAF, lamins, and LEM-domain proteins is mutually dependent, and is required to capture segregated chromosomes within the nascent nuclear envelope. Embryos that escaped lethality by down-regulation of Ce-BAF grew into sterile adults with misplaced distal tip cells and gonads, further suggesting that mild postembryonic reductions in BAF disrupt tissue-specific functions.
Margalit
Ayelet
A
Department of Genetics, Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel.
Segura-Totten
Miriam
M
Gruenbaum
Yosef
Y
Wilson
Katherine L
KL
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics; D002875:Chromosomes; D019084:Fluorescent Antibody Technique, Indirect; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid
J Biol Chem. 2003 Feb 28;278(9):6969-75
12493765
Genes Dev. 2002 Mar 1;16(5):533-47
11877373
Mol Biol Cell. 1997 Sep;8(9):1751-62
9307971
J Cell Sci. 2001 Dec;114(Pt 24):4575-85
11792822
Trends Genet. 2001 Nov;17(11):633-6
11672863
J Cell Sci. 1999 Aug;112 ( Pt 15):2485-92
10393804
Genetics. 1974 May;77(1):71-94
4366476
EMBO J. 2001 Aug 15;20(16):4399-407
11500367
Dev Biol. 1996 Sep 15;178(2):472-83
8812143
J Cell Biol. 2002 Aug 5;158(3):475-85
12163470
J Cell Sci. 2002 Mar 1;115(Pt 5):923-9
11870211
Proc Natl Acad Sci U S A. 2004 Jul 13;101(28):10428-33
15232008
Cell. 1982 Oct;30(3):687-96
7139712
Proc Natl Acad Sci U S A. 2000 Aug 1;97(16):8997-9002
10908652
Trends Cell Biol. 2004 May;14(5):261-6
15130582
Symp Soc Exp Biol. 2004;(56):329-39
15565891
J Biol Chem. 2002 Nov 8;277(45):43288-300
12215455
Nat Rev Mol Cell Biol. 2005 Jan;6(1):21-31
15688064
Dev Biol. 2003 Apr 1;256(1):173-86
12654300
J Cell Sci. 2003 Sep 15;116(Pt 18):3811-23
12902403
Genetics. 2001 Mar;157(3):1217-26
11238406
Dev Biol. 2001 Dec 1;240(1):77-91
11784048
J Biol Chem. 2001 Sep 28;276(39):36404-10
11473126
Proc Natl Acad Sci U S A. 2003 Apr 15;100(8):4598-603
12684533
Nat Cell Biol. 2004 Jan;6(1):31-7
14688791
Cell Cycle. 2004 Feb;3(2):212-7
14712091
Mol Biol Cell. 2000 Sep;11(9):3089-99
10982402
J Cell Sci. 2004 Dec 1;117(Pt 25):6117-28
15546916
Proc Natl Acad Sci U S A. 2004 May 4;101(18):6987-92
15100407
J Struct Biol. 2004 Jul;147(1):31-41
15109603
Proc Natl Acad Sci U S A. 1998 Feb 17;95(4):1528-33
9465049
J Struct Biol. 2002 Oct-Dec;140(1-3):232-40
12490171
Mol Biol Cell. 2000 Nov;11(11):3937-47
11071918