The nuclear organization of Polycomb/Trithorax gro

Authors: Elena Fedorova Nicolas Sadoni Ina K Dahlsveen Jeannette Koch Elisabeth Kremmer Dirk Eick Renato Paro Daniele Zink

Publish Date: 2008/06/03

Volume: 16, Issue: 4, Pages: 649-673

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Abstract

We analysed the nuclear organization of the Polycomb/Trithorax group response element PRE/TRE Fab7 and of other PRE/TREs in larval tissues of D melanogaster The results show that pairing/clustering of transgenic and endogenous Fab7 elements and of other endogenous PRE/TREs occurs only to a limited degree in a highly locusspecific and tissuespecific manner However transgenic Fab7 elements as well as the Fab7regulated AbdB 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 Fab7 was often found associated with the nuclear periphery as well as with the boundary of heterochromatin in a fly line and tissuespecific manner The boundary between heterochromatin and euchromatin revealed a highly complex architecture in the threedimensional 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 Fab7 element does not apply to PRE/TREs in general Altogether this finding and the highly locus tissue and fly linespecific 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

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