Downregulation of ANP32B, a novel substrate of caspase-3, enhances caspase-3 activation and apoptosis induction in myeloid leukemic cells.
The acidic leucine-rich nuclear phosphoprotein 32 (ANP32)B has been reported to regulate gene expression by acting as a histone chaperone or modulate messenger RNA trafficking by serving as a HuR ligand. However, its exact cellular functions are poorly understood. By utilizing a proteomics-based approach, in this work, we identify that the human ANP32B protein is cleaved during apoptosis induction by NSC606985, a novel camptothecin analog. Further investigation shows that various apoptosis inducers cause a decrease of full-length ANP32B in multiple cell lines with a concomitant increase of an approximately 17 kDa fragment. The proteolytic cleavage of ANP32B is inhibited by a specific caspase-3 inhibitor Z-DEVD-fmk, and it cannot be seen in NSC606985-induced death of caspase-3-deficient MCF-7 cells. In vitro caspase cleavage assay and mutagenesis experiment reveal that ANP32B is a direct substrate of caspase-3 and it is primarily cleaved at the sequence of Ala-Glu-Val-Asp, after Asp-163. Additionally, the reduced expression of endogenous ANP32B by specific small interfering RNA enhances caspase-3 activation and apoptosis induction by NSC606985 and etoposide. These results suggest that ANP32B is a novel substrate for caspase-3 and acts as a negative regulator for apoptosis, the mechanism of which remains to be explored.
Shen
Shao-Ming
SM
Institute of Health Science, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences-Shanghai Jiao-Tong University School of Medicine, No. 280, Chong-Qing South Road, Shanghai 200025, China.
Yu
Yun
Y
Wu
Ying-Li
YL
Cheng
Jin-Ke
JK
Wang
Li-Shun
LS
Chen
Guo-Qiang
GQ
D000098:Acetophenones / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001578:Benzopyrans / Q000494:pharmacology; D002166:Camptothecin / Q000031:analogs & derivatives / Q000494:pharmacology; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology*; D053148:Caspase 3 / Q000378:metabolism*; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D015536:Down-Regulation; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D007951:Leukemia, Myeloid / Q000378:metabolism / Q000473:pathology*; D008297:Male; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity
C490341:ANP32B protein, human; D000098:Acetophenones; D000970:Antineoplastic Agents; D001578:Benzopyrans; D015853:Cysteine Proteinase Inhibitors; C514334:NSC606985; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; C085746:rottlerin; C505407:CASP3 protein, human; D053148:Caspase 3; D002166:Camptothecin