PU.1, a novel caspase-3 substrate, partially contributes to chemotherapeutic agents-induced apoptosis in leukemic cells.
PU.1 is one of key regulators of hematopoietic cell development, a tightly-regulated lineage-specific process. Here we provide the first evidence that PU.1 protein is cleaved into two fragments of 24 kDa and 16 kDa during apoptosis progression in leukemic cell lines and primary leukemic cells. Further experiments with specific capase-3 inhibitor Z-DEVD-fmk and the in vitro proteolytic system confirmed that PU.1 is a direct target of caspase-3. Using site-directed mutagenesis analyses, the aspartic acid residues at positions 97 and 151 of PU.1 protein were identified as capsase-3 target sites. More intriguingly, the suppression of PU.1 expression by small interfering RNAs (siRNAs) significantly inhibits DNA-damaging agents NSC606985 and etoposide-induced apoptosis in leukemic cells, together with the up-regulated expression of anti-apoptotic bcl-2 gene. These results would provide new insights for understanding the mechanism of PU.1 protein in hematopoiesis and leukemogenesis.
Zhao
Meng
M
Institute of Health Sciences, Shanghai Institutes for Biological Sciences of Chinese Academy of Sciences & Shanghai Jiao-Tong University School of Medicine, Luwan, Shanghai 200025, China.
Duan
Xu-Fang
XF
Wen
Dong-Hua
DH
Chen
Guo-Qiang
GQ
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D002166:Camptothecin / Q000031:analogs & derivatives / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism*; D061945:Caspase Inhibitors; D045744:Cell Line, Tumor; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D006801:Humans; D007938:Leukemia / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D016297:Mutagenesis, Site-Directed; D009842:Oligopeptides / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D000099232:Proto-Oncogene Protein Spi-1
D000970:Antineoplastic Agents; D001224:Aspartic Acid; D002166:Camptothecin; D053148:Caspase 3; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D005047:Etoposide; D009842:Oligopeptides; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C514334:NSC606985; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone