Small Molecules Targeting Hepatitis C Virus-Encoded NS5A Cause Subcellular Redistribution of their Target: Insights into Compound Mode of Action

[Guest guest]

J Virol. 2011 Apr 20. [Epub ahead of print]

Small Molecules Targeting Hepatitis C Virus-Encoded NS5A Cause Subcellular

Redistribution of their Target: Insights into Compound Mode of Action.

Targett- P, Graham EJ, Middleton J, Palmer A, Shaw SM, Lavender H, Brain P,

Tran TD, LH, Wakenhut F, Stammen B, Pryde D, Pickford C, Westby M.

Source

Pfizer Global Research & Development, Sandwich, Kent, CT13 9NJ, UK.

Abstract

The current standard of care for hepatitis C virus (HCV)-infected patients

consists of lengthy interferon and ribavirin treatment. To increase the

effectiveness of HCV therapy, future regimens will incorporate multiple

direct-acting antiviral (DAA) drugs. Recently, the HCV-encoded NS5A protein has

emerged as a promising DAA target. Compounds targeting NS5A exhibit remarkable

potency in vitro and demonstrate early clinical promise, suggesting NS5A

inhibitors could feature in future DAA combination therapies. Since the

mechanisms through which these molecules operate are unknown, we have used NS5A

inhibitors as tools to investigate their mode of action. Analysis of

replicon-containing cells revealed dramatic phenotypic alterations in NS5A

localization following treatment with NS5A inhibitors; NS5A was redistributed

from the endoplasmic reticulum to lipid droplets. NS5A relocalization did not

occur in cells treated with other classes of HCV inhibitors and NS5A-targeting

molecules did not cause similar alterations in the localization of other

HCV-encoded proteins. Time-course analysis of NS5A redistribution revealed

transfer of protein to lipid droplets was concomitant with the onset of

inhibition as judged by the kinetic profile for these compounds. Furthermore,

analysis of the kinetic profile of inhibition for a panel of test molecules

permitted separation of compounds to different kinetic classes based on their

mode of action. Results from this approach suggested NS5A inhibitors perturbed

function of new replication complexes, rather than acting on pre-formed

complexes. Taken together, our data reveal novel biological consequences of NS5A

inhibition, which may help enable development of future assay platforms for

identification of new/different NS5A inhibitors.

PMID: 21507963 [PubMed - as supplied by publisher]

[Guest guest]

J Virol. 2011 Apr 20. [Epub ahead of print]

Small Molecules Targeting Hepatitis C Virus-Encoded NS5A Cause Subcellular

Redistribution of their Target: Insights into Compound Mode of Action.

Targett- P, Graham EJ, Middleton J, Palmer A, Shaw SM, Lavender H, Brain P,

Tran TD, LH, Wakenhut F, Stammen B, Pryde D, Pickford C, Westby M.

Source

Pfizer Global Research & Development, Sandwich, Kent, CT13 9NJ, UK.

Abstract

The current standard of care for hepatitis C virus (HCV)-infected patients

consists of lengthy interferon and ribavirin treatment. To increase the

effectiveness of HCV therapy, future regimens will incorporate multiple

direct-acting antiviral (DAA) drugs. Recently, the HCV-encoded NS5A protein has

emerged as a promising DAA target. Compounds targeting NS5A exhibit remarkable

potency in vitro and demonstrate early clinical promise, suggesting NS5A

inhibitors could feature in future DAA combination therapies. Since the

mechanisms through which these molecules operate are unknown, we have used NS5A

inhibitors as tools to investigate their mode of action. Analysis of

replicon-containing cells revealed dramatic phenotypic alterations in NS5A

localization following treatment with NS5A inhibitors; NS5A was redistributed

from the endoplasmic reticulum to lipid droplets. NS5A relocalization did not

occur in cells treated with other classes of HCV inhibitors and NS5A-targeting

molecules did not cause similar alterations in the localization of other

HCV-encoded proteins. Time-course analysis of NS5A redistribution revealed

transfer of protein to lipid droplets was concomitant with the onset of

inhibition as judged by the kinetic profile for these compounds. Furthermore,

analysis of the kinetic profile of inhibition for a panel of test molecules

permitted separation of compounds to different kinetic classes based on their

mode of action. Results from this approach suggested NS5A inhibitors perturbed

function of new replication complexes, rather than acting on pre-formed

complexes. Taken together, our data reveal novel biological consequences of NS5A

inhibition, which may help enable development of future assay platforms for

identification of new/different NS5A inhibitors.

PMID: 21507963 [PubMed - as supplied by publisher]