Accumulation and dynamics of proteins of the MCM family during mouse oogenesis and the first embryonic cell cycle.
We describe the localization of three proteins of the minichromosome maintenance (MCM) family, Mcm2, -6 and -7 in mouse ovarian oocytes. We showed that Mcm proteins are stored in two forms: soluble and insoluble. Soluble Mcm2, -6 and -7 were uniformly distributed in the nuclei of ovarian oocytes. Insoluble Mcm2 and Mcm7 (but not Mcm6) were detected in the nuclei of resting, growing and fully-grown transcribing oocytes. In transcriptionally inactive fully-grown oocytes, Mcm2 underwent redistribution and Mcm7 disappeared. A similar effect was observed when transcription in growing oocytes was inhibited with alpha-amanitin. We postulate that in mouse oogenesis, the insoluble Mcm proteins are engaged in processes related to regulation of transcription and/or chromatin organization. In oocytes preparing for meiotic maturation, aggregates of the insoluble form of Mcm2 fragmented, dispersed and ultimately disappeared from the nuclei. Numerous Mcm2-positive deposits were observed in the cytoplasm of maturing oocytes. In the one-cell embryo, insoluble Mcm2 appeared in the G1 nucleus, persisted in the S phase and was undetectable in the G2 nucleus. Such behavior of Mcm2 supports its involvement in chromatin licensing in the first embryonic cell cycle.
Swiech
Lukasz
L
Department of Embryology, Institute of Zoology, Warsaw University, Warsaw, Poland.
Kisiel
Katarzyna
K
Czolowska
Renata
R
Zientarski
Maciej
M
Borsuk
Ewa
E
D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D003433:Crosses, Genetic; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004622:Embryo, Mammalian; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D064111:Minichromosome Maintenance Complex Component 2; D064151:Minichromosome Maintenance Complex Component 6; D064168:Minichromosome Maintenance Complex Component 7; D009687:Nuclear Proteins / Q000096:biosynthesis*; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D009866:Oogenesis; D012995:Solubility; D014158:Transcription, Genetic / Q000187:drug effects
D000546:Amanitins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C491205:Mcm6 protein, mouse; C491086:Mcm7 protein, mouse; D064111:Minichromosome Maintenance Complex Component 2; D064151:Minichromosome Maintenance Complex Component 6; D064168:Minichromosome Maintenance Complex Component 7