hcvm member of -herpesvirus family >200 orfs genes are expressed in a regulated cascade some...

HCVM

• Member of -herpesvirus family

• >200 ORFs• Genes are expressed in a

regulated cascade• Some fulfill regulatory

functions• pUL38 expression during

early phase• pUL38 blocks apoptosis

http://www.abbottdiagnostics.co.uk

Tuberous Sclerosis Complex

• Autosomal dominant disorder

• Characterized by benign tumors

Due to inactivating mutations in TSC1 or TSC2

• Conserved signaling pathway that regulates cell growth

• TSC1/TSC2 functions as GAP towards Rheb

How does pUL38 facilitates HCMV replication and what are the

interacting partners?

Construction of mutants and confirmation of normal growth

Fibroblast, 0.01 PFU/cell, 0-10 dpi

Identification of pUL38 interacting proteins

• pUL38 is expressed under proper kinetics and at normal levels

• Isolation by immuno- affinity purification

• Separation by gel electrophoresis

• Identification by sequential MS and MS/MS analysis

~ 50 target proteins

pUL38 interacts with the TSC1/2 protein complex

Fibroblast, 3 PFU/cell, 48 hrs p.i.

pUL38 interacts with the TSC2 but not with the TSC1 protein

293T, Transfection of a vector expressing pUL38, 48 hrs p.t.

TSC1 and TSC2 colocalize in infected fibroblasts

BADinUL99GFP, 0.1 PFU/cell, 24 hrs p.i.

Fibroblasts expressing pUL38 are larger than normal fibroblasts

pUL38 is sufficient to prevent inhibition of the mTORC1 kinase by stress

Phosphorylation of S6 in response to stress is decreased following infection

with a UL38 virus

Summary

• pUL38 interact via TSC2 with the TSC1/2 complex

• Ectopic expression of pUL38 in fibroblasts increased their size

• Interaction of pUL38 with TSC1/2 blocked its ability to regulate mTORC1 in response to stress outside the context of infection

• In the presence of pUL38, AMPK stimulation did not block phosphorylation of rpS6

pUL38 affects cellular pathways that communicate via TSC1/2

Thank you for your attention!

Activation of the TSC1/2 complex

MS & MS/MS

MS/MS: Tandem Mass spectometry