DNA moves sequentially towards the nuclear matrix during DNA replication in vivo.
BACKGROUND
In the interphase nucleus of metazoan cells DNA is organized in supercoiled loops anchored to a nuclear matrix (NM). There is varied evidence indicating that DNA replication occurs in replication factories organized upon the NM and that DNA loops may correspond to the actual replicons in vivo. In normal rat liver the hepatocytes are arrested in G0 but they synchronously re-enter the cell cycle after partial-hepatectomy leading to liver regeneration in vivo. We have previously determined in quiescent rat hepatocytes that a 162 kbp genomic region containing members of the albumin gene family is organized into five structural DNA loops.


RESULTS
In the present work we tracked down the movement relative to the NM of DNA sequences located at different points within such five structural DNA loops during the S phase and after the return to cellular quiescence during liver regeneration. Our results indicate that looped DNA moves sequentially towards the NM during replication and then returns to its original position in newly quiescent cells, once the liver regeneration has been achieved.


CONCLUSIONS
Looped DNA moves in a sequential fashion, as if reeled in, towards the NM during DNA replication in vivo thus supporting the notion that the DNA template is pulled progressively towards the replication factories on the NM so as to be replicated. These results provide further evidence that the structural DNA loops correspond to the actual replicons in vivo.
Laboratorio de Biología Molecular, Facultad de Medicina, Universidad Autónoma del Estado de México, Apartado Postal 428, CP 50000 Toluca, Edo Méx, México.
Juan Carlos
JC
Rivera-Mulia
Rolando
R
Hernández-Muñoz
Federico
F
Martínez
Armando
A
Aranda-Anzaldo
D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D004261:DNA Replication; D003850:Deoxyribonuclease I / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D007700:Kinetics; D008115:Liver Regeneration; D008297:Male; D015530:Nuclear Matrix / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D016196:S Phase
D004247:DNA; D003850:Deoxyribonuclease I
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