Actin-dependent intranuclear repositioning of an active gene locus in vivo.
Although bulk chromatin is thought to have limited mobility within the interphase eukaryotic nucleus, directed long-distance chromosome movements are not unknown. Cajal bodies (CBs) are nuclear suborganelles that nonrandomly associate with small nuclear RNA (snRNA) and histone gene loci in human cells during interphase. However, the mechanism responsible for this association is uncertain. In this study, we present an experimental system to probe the dynamic interplay of CBs with a U2 snRNA target gene locus during transcriptional activation in living cells. Simultaneous four-dimensional tracking of CBs and U2 genes reveals that target loci are recruited toward relatively stably positioned CBs by long-range chromosomal motion. In the presence of a dominant-negative mutant of beta-actin, the repositioning of activated U2 genes is markedly inhibited. This supports a model in which nuclear actin is required for these rapid, long-range chromosomal movements.
Dundr
Miroslav
M
Department of Cell Biology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA. mirek.dundr@rosalindfranklin.edu
Ospina
Jason K
JK
Sung
Myong-Hee
MH
John
Sam
S
Upender
Madhvi
M
Ried
Thomas
T
Hager
Gordon L
GL
Matera
A Gregory
AG
D000199:Actins / Q000378:metabolism / Q000502:physiology*; D002875:Chromosomes / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D020541:Coiled Bodies / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000032:analysis; D012342:RNA, Small Nuclear / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000032:analysis; D015533:Transcriptional Activation
D000199:Actins; D008164:Luminescent Proteins; D012342:RNA, Small Nuclear; D011993:Recombinant Fusion Proteins; C405484:U2 small nuclear RNA