真菌次级代谢产物11’-deoxyverticillin A（C42）通过降低自噬基因的表达抑制肝炎病毒（HBV）复制

C42属于epipolythiodioxopiperazines（ETPs）二酮呱嗪类化合物,具有多种生物学活性,包括抑制病毒复制;不过其对hepatitis B virus（HBV）复制的影响及机理鲜有报道。自噬是广泛存在于真核细胞、通过溶酶体降解长半衰期蛋白的现象,参与多种生理、病理过程。有研究发现自噬对HBV的复制至关重要。C42是否通过改变自噬来影响此病毒的复制目前还未见报道。在该研究中,我们发现表达HBV基因组的HepG2.215细胞较原始的HepG2细胞,自噬体明显增加并伴随着Akt磷酸化的增高。C42可以降低自噬基因LC3-II和p62的水平,同时会影响Akt信号通路。氯喹是一种自噬抑制剂,它的存在可以抑制C42导致的LC3-II降低,表明C42可以引起该细胞的自噬。敲降自噬基因和抑制Akt磷酸化均可以减少HBV-X蛋白表达。而利用氯喹抑制自噬体与溶酶体的融合却提高了HBV-X蛋白水平。由于HBV-X对该病毒的复制至关重要,因此,我们认为,C42通过自噬和Akt信号通路来抑制HBV的复制。

Fungal secondary metabolite 11’-deoxyverticillin A (C42) decreases HBV-X replication by down-regulating autophagy related gene expression

The metabolite 11’-deoxyverticillin A (C42), which belongs to epipolythiodioxopiperazines (ETPs), has various bioactivities including viral replication inhibition. Autophagy, a phenomenon that participates in the degrading long-half-life proteins, exists extensively in eukaryotic cells. Autophagy regulates many physiological and pathological processes, and has been demonstrated to play a critical role in the replication of hepatitis B virus (HBV). However, it remains almost unknown whether C42 has a regulatory role in HBV replication via altering autophagy. In this study, we found that, in contrast to primary HepG2 cells, HepG2.215 cells have an increase in the formation of autophagosomes concurring with upregulation of Akt signaling. C42 down-regulated the levels of LC3-II and p62, both of them are autophagic genes, accompanying with a decrease in Akt signaling. The presentation of chloroquine (CQ), a compound often used in autophagic flux detection, was found to block C42-induced LC3-II degradation, suggesting that C42 activates autophagy in the cells. The inhibition of Akt activity or depletion of LC3 and p62 reduced the expression of HBV-X, which is believed to be essential for HBV replication. Notably, CQ, which inhibits the fusion between autophagosome and lysosome, was demonstrated to increase the expression of HBV-X protein. Thus, we consider that C42 inhibits viral replication by decreasing the expression of autophagic genes and altering Akt signal pathway.