A case of selfish nucleolar segregation.
Mitotic segregation of nucleolus in fission and budding yeast proceeds without disassembling its complex structure, creating challenging problems for transmission of nucleolus-organizing regions during nuclear division. The SMC complex called condensin, which plays a leading role in organizing mitotic structure of chromosomes in all eukaryotes, is essential for nucleolar segregation in budding yeast, where rDNA chromatin is the main target of mitotic condensin activity. Mitosis-specific condensin targeting to the nucleolus presents an attractive model to study mechanisms controlling condensin binding to specific chromatin domains. Recent reports suggest that the early-anaphase release of Cdc14 from the nucleolus (FEAR pathway) controls the proficiency of nucleolar segregation by promoting the mitotic condensin function in rDNA. This finding uncovers an essential function for the FEAR pathway and postulates the unique nucleolar self-regulatory mechanism, which evolved to recruit two essential enzymatic activities, Cdc14 phosphatase and condensin ATP-dependent supercoiling, for the specific task of segregating nucleoli without their disassembly.
Strunnikov
Alexander V
AV
NIH, NICHD, Laboratory of Gene Regulation and Development, 18T Library Drive, Room 106, Bethesda, Maryland 20892, USA. strunnik@mail.nih.gov
D000251:Adenosine Triphosphatases / Q000502:physiology; D000705:Anaphase / Q000502:physiology; D018797:Cell Cycle Proteins / Q000502:physiology; D002455:Cell Division / Q000502:physiology*; D002466:Cell Nucleolus / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone; D020090:Chromosome Segregation / Q000235:genetics / Q000502:physiology*; D004275:DNA, Ribosomal / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000502:physiology; D008938:Mitosis / Q000235:genetics / Q000502:physiology; D046912:Multiprotein Complexes / Q000502:physiology; D009687:Nuclear Proteins / Q000502:physiology; D017027:Protein Tyrosine Phosphatases / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology; D004718:Saccharomycetales / Q000166:cytology / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic; D000097722:Cohesins
D000251:Adenosine Triphosphatases; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D017027:Protein Tyrosine Phosphatases; D029701:Saccharomyces cerevisiae Proteins; D000097722:Cohesins; C074860:CDC14 protein, S cerevisiae; C108312:condensin complexes