GABARAPL2 Is Critical for Growth Restriction of Toxoplasma gondii in HeLa Cells Treated with Gamma Interferon.

Gamma interferon (IFN-γ)-induced innate immune responses play important roles in the inhibition of Toxoplasma gondii infection. It has been reported that IFN-γ stimulates non-acidification-dependent growth restriction of T. gondii in HeLa cells, but the mechanism remains unclear. Here, we found that γ-aminobutyric acid (GABA) receptor-associated protein-like 2 (GABARAPL2) plays a critical role in parasite restriction in IFN-γ-treated HeLa cells. GABARAPL2 is recruited to membrane structures surrounding parasitophorous vacuoles (PV). Autophagy adaptors are required for the proper localization and function of GABARAPL2 in the IFN-γ -induced immune response. These findings provide further understanding of a noncanonical autophagy pathway responsible for IFN-γ-dependent inhibition of T. gondii growth in human HeLa cells and demonstrate the critical role of GABARAPL2 in this response.

MeWRKY20 and its interacting and activating autophagy-related protein 8 (MeATG8) regulate plant disease resistance in cassava.

As a highly conserved mechanism, autophagy is responsible for the transport of cytoplasmic constituents in the vacuoles or lysosomes. Moreover, autophagy is essential for plant development and various stress responses. In this study, 34 MeATGs were systematically identified in cassava, and their transcripts were commonly regulated by Xanthomonas axonopodis pv manihotis (Xam). Through transient expression in Nicotiana benthamiana, the subcellular locations of 4 MeATG8s were revealed. Notably, MeWRKY20 was identified as physical interacting protein of MeATG8a/8f/8h and upstream transcriptional activator of MeATG8a. Through virus-induced gene silencing (VIGS) in cassava, we found that MeATG8-silenced and MeWRKY20-silenced plants resulted in disease sensitive, with less callose depositions and lower autophagic activity. This study may facilitate our understanding of the upstream MeWRKY20 and underlying target as well as interacting proteins of MeATG8s in immune response. Taken together, MeWRKY20 and MeATG8a/8f/8h are essential for disease resistance against bacterial blight by forming various transcriptional modules and interacting complex in cassava.

Host autophagy machinery is diverted to the pathogen interface to mediate focal defense responses against the Irish potato famine pathogen.

During plant cell invasion, the oomycete Phytophthora infestans remains enveloped by host-derived membranes whose functional properties are poorly understood. P. infestans secretes a myriad of effector proteins through these interfaces for plant colonization. Recently we showed that the effector protein PexRD54 reprograms host-selective autophagy by antagonising antimicrobial-autophagy receptor Joka2/NBR1 for ATG8CL binding (Dagdas et al., 2016). Here, we show that during infection, ATG8CL/Joka2 labelled defense-related autophagosomes are diverted toward the perimicrobial host membrane to restrict pathogen growth. PexRD54 also localizes to autophagosomes across the perimicrobial membrane, consistent with the view that the pathogen remodels host-microbe interface by co-opting the host autophagy machinery. Furthermore, we show that the host-pathogen interface is a hotspot for autophagosome biogenesis. Notably, overexpression of the early autophagosome biogenesis protein ATG9 enhances plant immunity. Our results implicate selective autophagy in polarized immune responses of plants and point to more complex functions for autophagy than the widely known degradative roles.