Dosage-sensitive regulation of cohesin chromosome binding and dynamics by Nipped-B, Pds5, and Wapl.
The cohesin protein complex holds sister chromatids together to ensure proper chromosome segregation upon cell division and also regulates gene transcription. Partial loss of the Nipped-B protein that loads cohesin onto chromosomes, or the Pds5 protein required for sister chromatid cohesion, alters gene expression and organism development, without affecting chromosome segregation. Knowing if a reduced Nipped-B or Pds5 dosage changes how much cohesin binds chromosomes, or the stability with which it binds, is critical information for understanding how cohesin regulates transcription. We addressed this question by in vivo fluorescence recovery after photobleaching (FRAP) with Drosophila salivary glands. Cohesin, Nipped-B, and Pds5 all bind chromosomes in both weak and stable modes, with residence half-lives of some 20 seconds and 6 min, respectively. Reducing the Nipped-B dosage decreases the amount of stable cohesin without affecting its chromosomal residence time, and reducing the Pds5 dosage increases the amount of stable cohesin. This argues that Nipped-B and Pds5 regulate transcription by controlling how much cohesin binds DNA in the stable mode, and not binding affinity. We also found that Nipped-B, Pds5, and the Wapl protein that interacts with Pds5 all play unique roles in cohesin chromosome binding.
Gause
Maria
M
Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
Misulovin
Ziva
Z
Bilyeu
Amy
A
Dorsett
Dale
D
D000818:Animals; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D002875:Chromosomes / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D018628:Gene Dosage; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012469:Salivary Glands / Q000378:metabolism; D015533:Transcriptional Activation; D000097722:Cohesins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004247:DNA; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D049452:Green Fluorescent Proteins; D011993:Recombinant Fusion Proteins; D000097722:Cohesins; C541515:Pds5 protein, Drosophila; C506513:cohesin protein complex, Drosophila; C485184:enhanced green fluorescent protein; C119839:nipped-B protein, Drosophila