The nuclear organization of Polycomb/Trithorax group response elements in larval tissues of Drosophila melanogaster.
We analysed the nuclear organization of the Polycomb/Trithorax group response element (PRE/TRE) Fab-7 and of other PRE/TREs in larval tissues of D. melanogaster. The results show that pairing/clustering of transgenic and endogenous Fab-7 elements and of other endogenous PRE/TREs occurs only to a limited degree in a highly locus-specific and tissue-specific manner. However, transgenic Fab-7 elements as well as the Fab-7-regulated Abd-B gene and other endogenous loci preferentially occupied defined nuclear regions. Preferred association with the nuclear periphery was observed in the inactive state. However, also in the active state, Fab-7 was often found associated with the nuclear periphery as well as with the boundary of heterochromatin in a fly line- and tissue-specific manner. The boundary between heterochromatin and euchromatin revealed a highly complex architecture in the three-dimensional nuclear space with a close juxtaposition of active and repressed domains. The results suggest that such complex architectures create nuclear microenvironments sustaining specific states of activity of defined PRE/TREs. However, the data also show that the positional behaviour of the transgenic Fab-7 element does not apply to PRE/TREs in general. Altogether, this finding and the highly locus-, tissue-, and fly line-specific behaviour with regard to nuclear positioning and pairing/clustering suggest that the relationships between nuclear organization and functional regulation of PRE/TREs are highly complex and that simple models making general predictions might not be appropriate.
Department Biologie II, Ludwig-Maximilians-Universität München, Grosshaderner Str. 2, 82152, Planegg-Martinsried, Germany.
Elena
E
Fedorova
Nicolas
N
Sadoni
Ina K
IK
Dahlsveen
Jeannette
J
Koch
Elisabeth
E
Kremmer
Dirk
D
Eick
Renato
R
Paro
Daniele
D
Zink
D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000235:genetics*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics*; D000078404:Epidermal Cells; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006570:Heterochromatin / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D007814:Larva / Q000235:genetics; D034881:Nuclear Lamina / Q000378:metabolism; D063146:Polycomb-Group Proteins; D012319:RNA Polymerase II / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics*; D020218:Response Elements / Q000235:genetics*; D019076:Transgenes
D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; D006570:Heterochromatin; D006657:Histones; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; C485184:enhanced green fluorescent protein; C512571:trx protein, Drosophila; D049452:Green Fluorescent Proteins; D012319:RNA Polymerase II