Nuclear distribution of Oct-4 transcription factor in transcriptionally active and inactive mouse oocytes and its relation to RNA polymerase II and splicing factors.
The intranuclear distribution of the transcription factor Oct-4, which is specifically expressed in totipotent mice stem and germ line cells, was studied in mouse oocytes using immunogold labeling/electron microscopy and immunofluorescence/confocal laser scanning microcopy. The localization of Oct-4 was studied in transcriptionally active (uni/bilaminar follicles) and inactive (antral follicles) oocytes. Additionally, the Oct-4 distribution was examined relative to that of the unphosphorylated form of RNA polymerase II (Pol II) and splicing factor (SC 35) in the intranuclear entities such as perichromatin fibrils (PFs), perichromatin granules (PGs), interchromatin granule clusters (IGCs), Cajal bodies (CBs), and nucleolus-like bodies (NLBs). It was shown that: (i) Oct-4 is localized in PFs, IGCs, and in the dense fibrillar component (DFC) of the nucleolus at the transcriptionally active stage of the oocyte nucleus; (ii) Oct-4 present in PFs and IGCs colocalizes with Pol II and SC 35 at the transcriptionally active stage; (iii) Oct-4 accumulates in NLBs, CBs, and PGs at the inert stage of the oocyte. The results confirm the previous suggestion that PFs represent the major nucleoplasmic structural domain involved in active pre-mRNA transcription/processing. The colocalization of Oct-4 with Pol II in both IGCs and PFs in active oocytes (uni/bilaminar follicles) suggests that Oct-4 is intimately associated with the Pol II holoenzyme before and during transcription. The colocalization of Oct-4, Pol II, and SC 35 with coilin-containing structures such as NLBs and CBs at the inert stage (antral follicles) suggests that the latter may represent storage sites for the transcription/splicing machinery during the decline of transcription.
Parfenov
Vladimir N
VN
Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia 194064.
Pochukalina
Galina N
GN
Davis
Donna S
DS
Reinbold
Rolland
R
Schöler
Hans R
HR
Murti
Kuruganti G
KG
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D004257:DNA Polymerase II / Q000378:metabolism / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron / Q000379:methods; D009687:Nuclear Proteins / Q000378:metabolism*; D050814:Octamer Transcription Factor-3; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism*; D012326:RNA Splicing; D012261:Ribonucleoproteins; D000068103:Serine-Arginine Splicing Factors; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; D012261:Ribonucleoproteins; C499372:SRSF2 protein, mouse; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D000068103:Serine-Arginine Splicing Factors; D012319:RNA Polymerase II; D004257:DNA Polymerase II