Apoptosis 2006; 11: 183–196l

Overexpression of peptidylarginine deiminase IV features in apoptosis of haematopoietic cells

 G.-Y. Liu, Y.-F. Liao, W.-H. Chang, C.-C. Liu, M.-C. Hsieh, P.-C. Hsu, G. J. Tsay and H.-C. Hung
Institute of Immunology, Chung Shan Medical University, Taichung, Taiwan ROC ( G.-Y. Liu, C.-C. Liu, M.-C. Hsieh); Department of Life Sciences, National Chung-Hsing University, Taichung, Taiwan ROC (Y.-F. Liao, H.-C. Hung ); School of Applied Chemistry, Chung Shan Medical University, Taichung, Taiwan ROC (W.-H. Chang); Department of Medicine, Da-Chien General Hospital, Miao-Li, Taiwan ROC (P.-C. Hsu); Department of Internal Medicine, Chung Shan Medical University Hospital and Institute of Immunology, Chung Shan Medical University (G. J. Tsay), Taichung, Taiwan ROC (G. J. Tsay)

摘要

Peptidylarginine deiminases (PADIs) convert peptidylarginine into citrulline via posttranslational modi?cation. One member of the family, PADI4, plays an important role in immune cell differentiation and cell death. To elucidate the participation of PADI4 in haematopoietic cell death, we examine whether inducible overexpression of PADI4 enhances the apoptotic cell death. PADI4 reduced the viability in a dose- and time-dependent manner of human leukemia HL-60 cells and human acute T leukemia Jurkat cells. The apoptosis-inducing activities were determined by nuclear condensation, DNA fragmentation, sub-G1 appearance, loss of mitochondrial membrane potential ( ψm ), release of mitochondrial cytochrome c into cytoplasm and proteolytic activation of caspase 9 and 3. Following PADI4 overexpression, cells arrest in G1 phase signi?cantly before their entrance into apoptotic cell death. PADI4 increases tumor suppressor p53 and its downstream p21 to control cell cycle. In the detections of protein expression and kinase activity, all protein levels of cyclin-dependent kinases (CDKs) and cyclins are not reduced except cyclin D, however, CDK2 (G1 entry S phase) and CDK1 (G2 entry M phase) enzyme activities are inhibited by conditionally inducible PADI4. p53 also expands its other downstream Bax to induce cytochrome c release from mitochondria. According to these data, we suggest that PADI4 induces apoptosis mainly through cell cycle arrest and mitochondria-mediated pathway. Furthermore, p53 features in PADI4-induced apoptosis by increasing intracellular p21 to control cell cycle and by Bax accumulation to decline Bcl-2 function, destroy ψ m , release cytochrome c to cytoplasm and activate the caspase cascade.

关键字：apoptosis; Bax; Bcl-2; p21; p53; PADIs; PADI4. Abbreviations: PADIs, peptidylarginine deiminases; ψ m , mitochondrial membrane potential; CDKs, cyclin-dependent kinases

文中提及的产品

T-PCR RNA was isolated from cells by Trizol (MDBio) according to the manufacturer’s instructions. Synthesis of cDNA was performed using mRNA templates, reverse transcriptase (RT) and 500 ng of random primers. The reaction mixture was incubated for 90 min at 42? C. For PCR assay, cDNA was added to 40 ?l mixture buffer containing 75 mM TrisHCl, pH 8.8, 20 mM (NH4 )2 SO4 , 0.01% Tween-20 (v/v), 2 mM MgCl2 , 0.2 mM dNTPs, 0.5 ?M forward and reverse primers, and 1 U Taq DNA polymerase (MDBio).