Establishment and mitotic stability of an extra-chromosomal mammalian replicon.
BACKGROUND
Basic functions of the eukaryotic nucleus, like transcription and replication, are regulated in a hierarchic fashion. It is assumed that epigenetic factors influence the efficiency and precision of these processes. In order to uncouple local and long-range epigenetic features we used an extra-chromosomal replicon to study the requirements for replication and segregation and compared its behavior to that of its integrated counterpart.


RESULTS
The autonomous replicon replicates in all eukaryotic cells and is stably maintained in the absence of selection but, as other extra-chromosomal replicons, its establishment is very inefficient. We now show that following establishment the vector is stably associated with nuclear compartments involved in gene expression and chromosomal domains that replicate at the onset of S-phase. While the vector stays autonomous, its association with these compartments ensures the efficiency of replication and mitotic segregation in proliferating cells.


CONCLUSIONS
Using this novel minimal model system we demonstrate that relevant functions of the eukaryotic nucleus are strongly influenced by higher nuclear architecture. Furthermore our findings have relevance for the rational design of episomal vectors to be used for genetic modification of cells: in order to improve such constructs with respect to efficiency elements have to be identified which ensure that such constructs reach regions of the nucleus favorable for replication and transcription.
Institute of Cell Biology, University Witten/Herdecke, Witten, Germany. stehle@uni-wh.de <stehle@uni-wh.de>
Isa M
IM
Stehle
Jan
J
Postberg
Sina
S
Rupprecht
Thomas
T
Cremer
Dean A
DA
Jackson
Hans J
HJ
Lipps
D000818:Animals; D016466:CHO Cells; D002467:Cell Nucleus / Q000235:genetics; D047369:Chromatin Immunoprecipitation; D033481:Chromosomes, Mammalian / Q000235:genetics; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D008938:Mitosis; D010957:Plasmids / Q000235:genetics; D012093:Replicon / Q000235:genetics*
D004247:DNA