Differential Phosphatidylinositol-3-Kinase-Akt-mTOR Activation by Semliki Forest and Chikungunya Viruses Is Dependent on nsP3 and Connected to Replication Complex Internalization

Autor: Benjamin Götte, Andres Merits, Roberta Biasiotto, Gerald M. McInerney, Kai Eng, Margit Mutso, Finny S. Varghese, Tero Ahola, Giuseppe Balistreri, Maarit Neuvonen, Lara Rheinemann, Bastian Thaa, Age Utt
Jazyk: angličtina
Rok vydání: 2015
Předmět:
media_common.quotation_subject
viruses
Immunology
Alphavirus
Viral Nonstructural Proteins
Virus Replication
Semliki Forest virus
Microbiology
Mice
Cell Line
Tumor
Cricetinae
Virology
Animals
Humans
Naphthyridines
Phosphorylation
Internalization
Protein kinase B
PI3K/AKT/mTOR pathway
Phosphoinositide-3 Kinase Inhibitors
media_common
Sirolimus
biology
Alphavirus Infections
TOR Serine-Threonine Kinases
RNA-Binding Proteins
virus diseases
Virus Internalization
biochemical phenomena
metabolism
and nutrition
biology.organism_classification
Semliki forest virus
Protein Structure
Tertiary
Author Corrections
3. Good health
Virus-Cell Interactions
Androstadienes
Enzyme Activation
Viral replication
Cell culture
Insect Science
Phosphatidylinositol 3-Kinase
Signal transduction
Wortmannin
Chikungunya virus
Proto-Oncogene Proteins c-akt
Signal Transduction
Popis: Many viruses affect or exploit the phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) pathway, a crucial prosurvival signaling cascade. We report that this pathway was strongly activated in cells upon infection with the Old World alphavirus Semliki Forest virus (SFV), even under conditions of complete nutrient starvation. We mapped this activation to the hyperphosphorylated/acidic domain in the C-terminal tail of SFV nonstructural protein nsP3. Viruses with a deletion of this domain (SFV-Δ50) but not of other regions in nsP3 displayed a clearly delayed and reduced capacity of Akt stimulation. Ectopic expression of the nsP3 of SFV wild type (nsP3-wt), but not nsP3-Δ50, equipped with a membrane anchor was sufficient to activate Akt. We linked PI3K-Akt-mTOR stimulation to the intracellular dynamics of viral replication complexes, which are formed at the plasma membrane and subsequently internalized in a process blocked by the PI3K inhibitor wortmannin. Replication complex internalization was observed upon infection of cells with SFV-wt and SFV mutants with deletions in nsP3 but not with SFV-Δ50, where replication complexes were typically accumulated at the cell periphery. In cells infected with the closely related chikungunya virus (CHIKV), the PI3K-Akt-mTOR pathway was only moderately activated. Replication complexes of CHIKV were predominantly located at the cell periphery. Exchanging the hypervariable C-terminal tail of nsP3 between SFV and CHIKV induced the phenotype of strong PI3K-Akt-mTOR activation and replication complex internalization in CHIKV. In conclusion, infection with SFV but not CHIKV boosts PI3K-Akt-mTOR through the hyperphosphorylated/acidic domain of nsP3 to drive replication complex internalization. IMPORTANCE SFV and CHIKV are very similar in terms of molecular and cell biology, e.g., regarding replication and molecular interactions, but are strikingly different regarding pathology: CHIKV is a relevant human pathogen, causing high fever and joint pain, while SFV is a low-pathogenic model virus, albeit neuropathogenic in mice. We show that both SFV and CHIKV activate the prosurvival PI3K-Akt-mTOR pathway in cells but greatly differ in their capacities to do so: Akt is strongly and persistently activated by SFV infection but only moderately activated by CHIKV. We mapped this activation capacity to a region in nonstructural protein 3 (nsP3) of SFV and could functionally transfer this region to CHIKV. Akt activation is linked to the subcellular dynamics of replication complexes, which are efficiently internalized from the cell periphery for SFV but not CHIKV. This difference in signal pathway stimulation and replication complex localization may have implications for pathology.
Databáze: OpenAIRE
Externí odkaz: