Af Rip3, a RIP3-like kinase, is identified as a key modulator of necroptotic death in Aspergillus fumigatus

This is the authors' abstract. We don't add key points for this paper.

Aspergillus fumigatus exhibits autophagic and necroptotic process when its GPI anchor synthesis is suppressed. A putative kinase (AFUA_6G02590) is found to be overexpressed in response to GPI anchor suppression and identified as a RIP3-like protein, namely Af Rip3. To elucidate its function, in this study a Af rip3 -overexpressing strain OE-Af rip3 was constructed. Although OE-Af rip3 strain exhibited an increased cell death, neither apoptotic nor autophagic process was activated. Our evidences demonstrated that overexpression of Af rip3 gene in A. fumigatus only led to necroptosis, while the Af rip3 -knockout mutant was unable to activate necroptotic process. Further analysis revealed that both JNK and SMase pathways were activated in OE-Af rip3 strain, by which an increase of reactive oxygen species (ROS) was induced. We also showed that expression of Af rip3 gene was induced by Ca 2+ . In addition, eEF1Bγ and adenylylsulfate kinase (ASK) were identified as potential candidates to interact with Af Rip3. These results indicate that Af Rip3 is a key modulator that activates necroptotic process in A. fumigatus , which can be induced by Ca 2+ and in turn activate JNK (c-Jun NH 2 -terminal kinase) and SMase (sphingomyelinase) pathway. Our findings suggest that necroptotic pathway in A. fumigatus is distinct from that in mammalian cell and may provide a new strategy for development of anti-fungal drug. Author summary Aspergillus fumigatus is a human fungal pathogen and causes invasive aspergillosis (IA) in immunocompromised patients with high mortality (30-95%). Development of novel therapies is urgently needed. In this study, we confirm Af Rip3 (AFUA_6G02590), a RIP3-like protein, is a key modulator that activates necroptotic process in A. fumigatus . We also find that cytosolic Ca 2+ can induce the expression of Af rip3 and activated Af Rip3 in turn activate JNK (c-Jun NH 2 -terminal kinase) and SMase (sphingomyelinase) pathway. Our findings suggest that necroptotic pathway in A. fumigatus is distinct from that in mammalian cell and may provide a new strategy for development of anti-fungal drug.