Geminin cleavage during apoptosis by caspase-3 alters its binding ability to the SWI/SNF subunit Brahma.
Geminin has been proposed to coordinate cell cycle and differentiation events through balanced interactions with the cell cycle regulator Cdt1 and with homeobox transcription factors and chromatin remodeling activities implicated in cell fate decisions. Here we show that Geminin is cleaved in primary cells and cancer cell lines induced to undergo apoptosis by a variety of stimuli. Geminin targeting is mediated by caspase-3 both in vivo and in vitro. Two sites at the carboxyl terminus of Geminin (named C1 and C2) are cleaved by the caspase, producing truncated forms of Geminin. We provide evidence that Geminin cleavage is regulated by phosphorylation. Casein kinase II alters Geminin cleavage at site C1 in vitro, whereas mutating phosphorylation competent Ser/Thr residues proximal to site C1 affects Geminin cleavage in vivo. We show that truncated Geminin produced by cleavage at C1 can promote apoptosis. In contrast, Geminin cleaved at site C2 has lost the ability to interact with Brahma (Brm), a catalytic subunit of the SWI/SNF chromatin remodeling complex, while binding efficiently to Cdt1, indicating that targeting of Geminin during apoptosis differentially affects interactions with its binding partners.
Roukos
Vassilis
V
Laboratory of General Biology, School of Medicine, University of Patras, 26500 Rio, Patras, Greece.
Iliou
Maria S
MS
Laboratory of General Biology, School of Medicine, University of Patras, 26500 Rio, Patras, Greece.
Nishitani
Hideo
H
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan.
Gentzel
Marc
M
Gene Expression Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
Wilm
Matthias
M
Gene Expression Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
Taraviras
Stavros
S
Laboratory of Pharmacology, Medical School, University of Patras, 26500 Rio, Patras, Greece.
Lygerou
Zoi
Z
Laboratory of General Biology, School of Medicine, University of Patras, 26500 Rio, Patras, Greece. Electronic address: lygerou@med.upatras.gr.
D000595:Amino Acid Sequence; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3 / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D064248:Geminin; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000502:physiology; D021122:Protein Subunits / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C577995:GMNN protein, human; D064248:Geminin; D021122:Protein Subunits; C499336:SMARCA1 protein, human; D014157:Transcription Factors; D053148:Caspase 3