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Projekt Druckansicht

Activation and function of the phosphatidylinositol-3-kinase signalling pathway in influenza virus infected cells

Fachliche Zuordnung Virologie
Förderung Förderung von 2008 bis 2016
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 61949045
 
Erstellungsjahr 2016

Zusammenfassung der Projektergebnisse

Influenza A viruses (IAV), the causative agents for severe respiratory diseases strongly depend on the host cell machinery. However, the knowledge of virus host interactions is still incomplete. Several studies indicated seemingly antiviral acting signaling pathways to be manipulated by the virus to ensure efficient replication. In project-related work we introduced the phosphatidyl-inositol-3 kinase (PI3K) as a perfect example of this phenomenon that we characterized further. Major findings of our studies point to a complete novel concept in signaling-induced virus entry as well as a paradigm change of viral non-structural protein 1 (A/NS1) regulatory functions. We identified receptor tyrosine kinases (RTKs), activated by IAV binding, as mediators of virus internalization, transmitting signals across the cellular plasma membrane, resulting in the activation of factors, such as PI3K. Addressing further aspects of the PI3K signaling network, the initially introduced signaling blocker A/NS1 was identified as signaling activator. Several A/NS1 interaction partners, such as the regulatory subunit of PI3K (p85), the non-receptor tyrosine kinase c-Abl as well as the adapter proteins CRK and CRKL were characterized in detail within our studies. Investigation of interaction motives within A/NS1, responsible for interference with cellular factors, revealed strain-specific variations that are responsible for differences in regulatory functions. Disruption of the p85-A/NS1 interaction results in restricted virus spread in mouse lung and strongly reduced virulence. Binding capacity of A/NS1 to CRK/CRKL has evolved in virus strains that over-induce the antiviral acting JNK-ATF2 signaling module and helps to suppress the detrimental apoptosis promoting action of this pathway. And also A/NS1-mediated c-Abl regulation occurs in a subtype-specific manner, regulating cell fate and pathogenicity. Interestingly, besides A/NS1 we identified other viral factors counteracting host defense mechanisms in a strain-specific manner. The polymerase complex proteins PB1 and PA of IAV that harbor a specific amino-acid motive (ESIE) alter type I IFN response. In that line we recently were surprised to recognize a novel bacterial-mediated mechanism also promoting viral replication. Actually, metabolically active intracellular Staphylococcus aureus inhibits type I IFN-mediated STAT1 phosphorylation and STAT1-STAT2 dimerization. As a result, in the presence of S. aureus the first line of defence against IAV is interrupted, resulting in a boost of viral replication. In summary, these exciting findings represent perfect examples of the complex interplay of IAV with their hosts, but also with co-infecting pathogens.

Projektbezogene Publikationen (Auswahl)

 
 

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