Immunolocalization of Upstream Binding Factor and Pocket Protein p130 During Final Stages of Bovine Oocyte Growth
The aim of this study was to describe the dynamic changes in the localization of the key nucleolar protein markers, fibrillarin, B23/nucleophosmin, C23/nucleolin, protein Nopp140, during the final stages of bovine oocyte growth. All these proteins were present in the large reticulated nucleoli of oo...
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Published in | Biology of reproduction Vol. 70; no. 4; pp. 877 - 886 |
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Main Authors | , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Madison, WI
Society for the Study of Reproduction
01.04.2004
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Subjects | |
Online Access | Get full text |
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Summary: | The aim of this study was to describe the dynamic changes in the localization of the key nucleolar protein markers, fibrillarin,
B23/nucleophosmin, C23/nucleolin, protein Nopp140, during the final stages of bovine oocyte growth. All these proteins were
present in the large reticulated nucleoli of oocytes from the small-size category follicles (<1 mm). The entire nucleolus
exhibited strong positivity for UBF (upstream binding factor, RNA polymerase I-specific transcription initiation factor),
which displayed a dotted staining pattern. In contrast, protein p130 was diffusely distributed throughout the nucleus and
excluded from nucleoli. In oocytes approaching the late period of growth (2â3-mm follicles), UBF localization shifted to the
nucleolar periphery. Double staining of UBF-p130 revealed a gradual accumulation of p130 at the periphery shell around the
nucleolus. In fully grown oocytes (>3-mm follicles), all studied nucleolar proteins were detected in the small compact nucleoli.
The cap structure, attached to the compact nucleolus surface, was positive for UBF and PAF53 (subunit of RNA polymerase I).
The UBF-positive cap showed a close structural association with p130. It is concluded that, during the process of oocyte nucleolus
compaction, UBF and PAF53, proteins involved in the rDNA transcription, are segregated from fibrillarin and Nopp140, proteins
essential for early steps of pre-rRNA processing. The observed changes may reflect the transition from pre-rRNA synthesis
to pre-rRNA processing as an analysis of the relative abundance of the developmentally important gene transcripts confirmed.
In addition, discovered structural association between UBF and p130 suggests a role for pocket proteins in ribosomal gene
silencing in mammalian oocytes. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0006-3363 1529-7268 |
DOI: | 10.1095/biolreprod.103.018408 |