REVERSIBLE DISASSEMBLY OF TRANSCRIPTION DOMAINS IN LYMPHOCYTE NUCLEI DURING INHIBITION OF RNA-SYNTHESIS BY DRB

Citation
L. Davis et al., REVERSIBLE DISASSEMBLY OF TRANSCRIPTION DOMAINS IN LYMPHOCYTE NUCLEI DURING INHIBITION OF RNA-SYNTHESIS BY DRB, Biology of the cell, 78(3), 1993, pp. 163-180
Citations number
84
Categorie Soggetti
Cytology & Histology
Journal title
ISSN journal
02484900
Volume
78
Issue
3
Year of publication
1993
Pages
163 - 180
Database
ISI
SICI code
0248-4900(1993)78:3<163:RDOTDI>2.0.ZU;2-#
Abstract
We are investigating the roles of RNA synthesis, chromatin structure a nd nuclear matrix organization in establishing and maintaining transcr iption domains, using mitogen stimulated lymphocytes as a model system . In a continuing study, the effects of the RNA polymerase inhibitor D RB and of its removal on nuclear organization have been examined by EM cytochemistry and by immunofluorescence labelling of the nuclear matr ix PI1, Sm and nucleolar fibrillarin antigens. Chromatin, interchromat in granules and nucleoli were extensively restructured after DRB, as w ere matrix antigens. According to cytochemical staining properties, th e conformation of DRB-induced condensed chromatin resembled that in pa rtially stimulated lymphocytes. The nucleoplasmic fibrogranular RNP ne twork appeared little altered, but the fibrillar proteinaceous interch romatinic regions, interpreted as representing the nuclear matrix in s itu, were more affected. After removal of DRB, nuclei recovered the or ganization and transcriptional activity of controls within 8 h. These results suggest that the matrix subtending transcription domains remai ns stable when transcription is arrested, even though the chromatin an d individual RNP components of the domains are disorganized. The data further indicate that absence of transcription is not solely accountab le for the highly aggregated state of the chromatin in resting lymphoc ytes.