Plagiochin E, an antifungal active macrocyclic bis(bibenzyl), induced apoptosis in Candida albicans through a metacaspase-dependent apoptotic pathway.
BACKGROUND
Plagiochin E (PLE) is an antifungal active macrocyclic bis(bibenzyl) isolated from liverwort Marchantia polymorpha L. To elucidate the mechanism of action, previous studies revealed that the antifungal effect of PLE was associated with the accumulation of ROS, an important regulator of apoptosis in Candida albicans. The present study was designed to find whether PLE caused apoptosis in C. albicans.


METHODS
We assayed the cell cycle by flow cytometry using PI staining, observed the ultrastructure by transmission electron microscopy, studied the nuclear fragmentation by DAPI staining, and investigated the exposure of phosphatidylserine at the outer layer of the cytoplasmic membrane by the FITC-annexin V staining. The effect of PLE on expression of CDC28, CLB2, and CLB4 was determined by RT-PCR. Besides, the activity of metacaspase was detected by FITC-VAD-FMK staining, and the release of cytochrome c from mitochondria was also determined. Furthermore, the effect of antioxidant L-cysteine on PLE-induced apoptosis in C. albicans was also investigated.


RESULTS
Cells treated with PLE showed typical markers of apoptosis: G(2)/M cell cycle arrest, chromatin condensation, nuclear fragmentation, and phosphatidylserine exposure. The expression of CDC28, CLB2, and CLB4 was down-regulated by PLE, which may contribute to PLE-induced G(2)/M cell cycle arrest. Besides, PLE promoted the cytochrome c release and activated the metacaspase, which resulted in the yeast apoptosis. The addition of L-cysteine prevented PLE-induced nuclear fragmentation, phosphatidylserine exposure, and metacaspase activation, indicating the ROS was an important mediator of PLE-induced apoptosis.


CONCLUSIONS
PLE induced apoptosis in C. albicans through a metacaspase-dependent apoptotic pathway.


CONCLUSIONS
In this study, we reported for the first time that PLE induced apoptosis in C. albicans through activating the metacaspase. These results would conduce to elucidate its underlying antifungal mechanism.
Wu
Xiu-Zhen
XZ
Department of Natural Products Chemistry, School of Pharmaceutical Sciences, Shandong University, No. 44 West Wenhua Road, Jinan 250012, PR China.
Chang
Wen-Qiang
WQ
Cheng
Ai-Xia
AX
Sun
Ling-Mei
LM
Lou
Hong-Xiang
HX
D017304:Annexin A5 / Q000187:drug effects / Q000378:metabolism; D000935:Antifungal Agents / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001952:Bridged-Ring Compounds / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002176:Candida albicans / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D061945:Caspase Inhibitors; D002453:Cell Cycle / Q000187:drug effects; D017931:DNA Primers; D005434:Flow Cytometry; D047028:Macrocyclic Compounds / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D047008:Marchantia / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D011480:Protease Inhibitors / Q000494:pharmacology; D012331:RNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013267:Stilbenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*
D017304:Annexin A5; D000935:Antifungal Agents; D001952:Bridged-Ring Compounds; D061945:Caspase Inhibitors; D017931:DNA Primers; D047028:Macrocyclic Compounds; D011480:Protease Inhibitors; D012331:RNA, Fungal; D013267:Stilbenes; C529889:plagiochin E