Long-range directional movement of an interphase chromosome site.
Increasing evidence suggests functional compartmentalization of interphase nuclei. This includes preferential interior localization of gene-rich and early replicating chromosome regions versus peripheral localization of gene-poor and late replicating chromosome regions , association of some active genes with nuclear speckles or transcription "factories", and association of transcriptionally repressed genes with heterochromatic regions. Dynamic changes in chromosome compartmentalization imply mechanisms for long-range interphase chromatin movements. However, live cell imaging in mammalian cells has revealed limited chromatin mobility, described as "constrained diffusion". None of these studies, though, have examined a chromosome locus undergoing an inducible repositioning between two different nuclear compartments. Here we demonstrate migration of an interphase chromosome site from the nuclear periphery to the interior 1-2 hr after targeting a transcriptional activator to this site. Spot redistribution is perturbed by specific actin or nuclear myosin I mutants. Extended periods of chromosome immobility are interspersed with several minute periods in which chromosomes move unidirectionally along curvilinear paths oriented roughly perpendicular to the nuclear envelope at velocities of 0.1-0.9 microm/min over distances of 1-5 microm. Our results suggest an active mechanism for fast and directed long-range interphase chromosome movements dependent directly or indirectly on actin/myosin.
Chuang
Chien-Hui
CH
Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, 61801, USA.
Carpenter
Anne E
AE
Fuchsova
Beata
B
Johnson
Terezina
T
de Lanerolle
Primal
P
Belmont
Andrew S
AS
D000199:Actins / Q000502:physiology; D000818:Animals; D016466:CHO Cells / Q000166:cytology; D045584:Chromosome Positioning / Q000502:physiology*; D002875:Chromosomes / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D007399:Interphase / Q000502:physiology*; D009068:Movement / Q000502:physiology; D009218:Myosins / Q000502:physiology; D013997:Time Factors
D000199:Actins; D009218:Myosins