Association of DNAse sensitive chromatin domains with the nuclear periphery in 3T3 cells in vitro

Abstract

DNAse sensitive chromatin, putative transcriptionally competent sequences, exists either as pan-nuclear speckles in cells with nuclei which exhibit a flat geometry, or as a shell apposed to the nuclear envelope in cells with spheroidal nuclei. To test the hypothesis that DNAse sensitive chromatin is similarly associated with the nuclear periphery in cell types with a very flat geometry such as 3T3 fibroblasts, cells were subjected to hypotonic expansion to change their nuclei from a flat ellipsoid to a spheriod. This was based on the assumption that such a spatial association is not resolvable due to the interdigitation at the nuclear midplane of DNAse sensitive chromatin associated with the upper and lower nuclear surfaces. In situ nick translation was used to visualize the distribution of DNAse sensitive chromatin as a function of nuclear geometry. Both unexpanded and expanded cells exhibit DNAse sensitive chromatin as a dome at the apical side of the nucleus, i.e., that aspect of the cell facing the culture medium. The results argue for a polarized association of DNAse sensitive chromatin with the nuclear envelope and indicate that the nuclear periphery may function as a compartment for the spatial coupling of transcription and nucleo-cytoplasmic transport.

Influenza A replication and host nuclear compartments: Many changes and many questions

“…While some experiments showed that neosynthesized vRNPs interact with some components of chromatin, 57,64-66 one study reported a polar-peripheral location of DNAse sensitive chromatin similar to the polarized distribution of NP. 4 However, these putative functional implications of specific chromatin territories in the intranuclear traffic of viral genome remains to be evaluated.…”

“…An emerging hypothesis suggests that nuclear environments are decisive in regulating viral replication cycle. [4][5][6] However, despite extensive investigations, the nuclear localization of viral replication and transcription remains unknown.…”