Functional implications of caspase-mediated RhoGDI2 processing during apoptosis of HL60 and K562 leukemia cells.
RhoGDI2, a cytosolic regulator of Rho GTPase, is cleaved during apoptosis in a caspase-3 dependent fashion. By using 2D-gel electrophoresis, mass spectrometry and Western blotting we investigate in this paper the functional consequences of RhoGDI2 processing. We can show that loss of the N-terminal 19 amino acids results in a shift of the isoelectric point of the truncated RhoGDI2 (NDelta19) to a more basic value due to the removal of 9 acidic amino acids from the N-terminus, which may be responsible for enhanced retention of the N-terminally truncated protein within the nuclear compartment. Fusion of the p53 nuclear export signaling sequence MFRELNEALELK to NDelta19 (NDelta19NES) abolished its apoptosis promoting properties, while overexpression of NDelta19 significantly increased the susceptibility to apoptosis induction by the proteasome inhibitor PSI and by staurosporine. These results suggest that cleavage of RhoGDI2 by caspase-3 is not a functionally irrelevant bystander effect of caspase activation during apoptosis, but rather expedites progression of the apoptotic process.
Choi
Mi-Ran
MR
Max-Planck-Institute for Heart and Lung Research, Parkstr.1, Bad Nauheim 61231, Germany.
Groot
Marcel
M
Drexler
Hannes C A
HC
D000595:Amino Acid Sequence; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D020169:Caspases / Q000502:physiology*; D015180:Electrophoresis, Gel, Two-Dimensional; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000235:genetics / Q000378:metabolism*; D018922:HL-60 Cells; D006801:Humans; D020014:K562 Cells; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism* / Q000473:pathology; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism* / Q000473:pathology; D008969:Molecular Sequence Data; D012323:RNA Processing, Post-Transcriptional; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D020298:U937 Cells; D062949:rho Guanine Nucleotide Dissociation Inhibitor beta; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
C569658:ARHGDIB protein, human; D020730:Guanine Nucleotide Dissociation Inhibitors; D025521:Tumor Suppressor Proteins; D062949:rho Guanine Nucleotide Dissociation Inhibitor beta; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020169:Caspases