The Drosophila MI-2 chromatin-remodeling factor regulates higher-order chromatin structure and cohesin dynamics in vivo.
dMi-2 is a highly conserved ATP-dependent chromatin-remodeling factor that regulates transcription and cell fates by altering the structure or positioning of nucleosomes. Here we report an unanticipated role for dMi-2 in the regulation of higher-order chromatin structure in Drosophila. Loss of dMi-2 function causes salivary gland polytene chromosomes to lose their characteristic banding pattern and appear more condensed than normal. Conversely, increased expression of dMi-2 triggers decondensation of polytene chromosomes accompanied by a significant increase in nuclear volume; this effect is relatively rapid and is dependent on the ATPase activity of dMi-2. Live analysis revealed that dMi-2 disrupts interactions between the aligned chromatids of salivary gland polytene chromosomes. dMi-2 and the cohesin complex are enriched at sites of active transcription; fluorescence-recovery after photobleaching (FRAP) assays showed that dMi-2 decreases stable association of cohesin with polytene chromosomes. These findings demonstrate that dMi-2 is an important regulator of both chromosome condensation and cohesin binding in interphase cells.
Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America.
Barbara
B
Fasulo
Renate
R
Deuring
Magdalena
M
Murawska
Maria
M
Gause
Kristel M
KM
Dorighi
Cheri A
CA
Schaaf
Dale
D
Dorsett
Alexander
A
Brehm
John W
JW
Tamkun
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001324:Autoantigens / Q000235:genetics* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002842:Chromatids; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D007399:Interphase / Q000235:genetics; D009707:Nucleosomes / Q000235:genetics*; D059007:Polytene Chromosomes / Q000235:genetics*; D011485:Protein Binding; D012469:Salivary Glands / Q000166:cytology / Q000378:metabolism; D000097722:Cohesins
D000251:Adenosine Triphosphatases; D001324:Autoantigens; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; D009707:Nucleosomes; D000097722:Cohesins; C116095:Mi-2 protein, Drosophila