Cell Cycle. 2017 Jan 23:0. doi: 10.1080/15384101.2017.1281484. [Epub ahead of print]
Chu JQ1,2,
Jing KP1,
Gao X1,
Li P1,
Huang R1,
Niu YR2,
Yan SQ1,
Kong JC2,
Yu CY3,
Shi G4,
Fan YM4,
Lee YH5,
Zhou Y3,
Quan JH3.
Autophagy and apoptosis are critical for controlling Toxoplasma gondii (T. gondii) infection. T. gondii infection during pregnancy can damage the fetus and cause birth defects; however, the molecular mechanisms of this process are poorly understood. This study aims to determine the activities of autophagy and apoptosis as well as their regulatory mechanisms during T. gondii infection by using human umbilical cord mesenchymal stem cells (hUC-MSCs) as a model of congenital diseases. LC3B, a hallmark protein of autophagy was incrementally up-regulated with the infection duration, whereas p62 was down-regulated in T. gondii-infected hUC-MSCs. Concurrent to this result, the invasion of T. gondii into hUC-MSCs increased in a time-dependent manner. The expression levels of Bcl-2 family proteins including Bcl-2, Bcl-xL, Bim, Bax, Bid and Bak were not altered; however, Mcl-1 levels in hUC-MSCs were dramatically decreased upon T. gondii infection. In addition, at 24 h post-infection, cleaved PARP and cleaved caspase-3 protein levels were elevated in hUC-MSCs. Importantly, Mcl-1 overexpression reduced the levels of autophagy- and apoptosis-related proteins in T. gondii-infected hUC-MSCs. Mcl-1 proteins were primarily expressed in the fraction containing mitochondria and strongly interacted with Beclin-1 under normal conditions; however, these interactions were remarkably attenuated by T. gondii infection. These results suggest that mitochondrial Mcl-1 is an essential signaling mediator regulating the activation of autophagy and apoptosis during T. gondii infection.
KEYWORDS:
Beclin-1; Mcl-1; Toxoplasma gondii; apoptosis; autophagy; cell death; umbilical cord mesenchymal stem cell
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