Chromatin binding of SRp20 and ASF/SF2 and dissociation from mitotic chromosomes is modulated by histone H3 serine 10 phosphorylation.
Histone H3 serine 10 phosphorylation is a hallmark of mitotic chromosomes, but its full function remains to be elucidated. We report here that two SR protein splicing factors, SRp20 and ASF/SF2, associate with interphase chromatin, are released from hyperphosphorylated mitotic chromosomes, but reassociate with chromatin late in M-phase. Inhibition of Aurora B kinase diminished histone H3 serine 10 phosphorylation and increased SRp20 and ASF/SF2 retention on mitotic chromosomes. Unexpectedly, we also found that HP1 proteins interact with ASF/SF2 in mitotic cells. Strikingly, siRNA-mediated knockdown of ASF/SF2 caused retention of HP1 proteins on mitotic chromatin. Finally, ASF/SF2-depleted cells released from a mitotic block displayed delayed G0/G1 entry, suggesting a functional consequence of these interactions. These findings underscore the evolving role of histone H3 phosphorylation and demonstrate a direct, functional, and histone-modification-regulated association of SRp20 and ASF/SF2 with chromatin.
Loomis
Rebecca J
RJ
Division of Reproductive Biology Research, Department of Obstetrics and Gynecology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
Naoe
Yoshinori
Y
Parker
J Brandon
JB
Savic
Velibor
V
Bozovsky
Matthew R
MR
Macfarlan
Todd
T
Manley
James L
JL
Chakravarti
Debabrata
D
D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D002645:Chickens; D002843:Chromatin / Q000378:metabolism*; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008938:Mitosis; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism; D010766:Phosphorylation; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000378:metabolism*; D000068103:Serine-Arginine Splicing Factors
D002843:Chromatin; D006657:Histones; D009687:Nuclear Proteins; D009707:Nucleosomes; D016601:RNA-Binding Proteins; C491388:SRSF3 protein, human; D000068103:Serine-Arginine Splicing Factors; D012694:Serine