Related Experiment Videos
Differential modulation of cellular signaling pathways by mild and severe hypovirus strains
Todd B Parsley1, Baoshan Chen, Lynn M Geletka
1Center for Agricultural Biotechnology, University of Maryland Biotechnology Institute, College Park, Maryland 20742-4450, USA.
Abstract:
Hypoviruses persistently alter multiple phenotypic traits, stably modify gene expression, and attenuate virulence (hypovirulence) of their pathogenic fungal host, the chestnut blight fungus Cryphonectria parasitica. The pleiotropic nature of these changes is consistent with hypovirus-mediated perturbation of one or more cellular signal transduction pathways. We now report that two hypoviruses that differ in the severity of symptom expression differentially perturb specific cellular signaling pathways. The C. parasitica 13-1 gene, originally identified as a hypovirus-inducible and cyclic AMP (cAMP)-regulated gene, was used to design a promoter-GFP reporter construct with which to monitor perturbation of cAMP-mediated signaling. Virus-mediated modulation of calcium/calmodulin/inositol trisphosphate-dependent signaling was monitored by measuring transcript accumulation from the C. parasitica laccase gene, lac-1. Infection by the severe hypovirus strain CHV1-EP713 caused a substantial induction of 13-1 promoter activity and a reduction of total extracellular laccase enzymatic activity (LAC-1 and LAC-3). In contrast, 13-1 promoter activity and total laccase activity were only marginally altered upon infection with the mild hypovirus strain CHV1-Euro7. However, examination of lac-1-specific transcript accumulation under previously defined culture conditions revealed that both CHV1-EP713 and CHV1-Euro7 perturbed calcium/calmodulin/inositol trisphosphate-dependent signaling. CHV1-EP713/CHV1-Euro7 chimeric viruses were used to map viral determinants responsible for modulation of cAMP-dependent signaling to domains within the central portion of the second open reading frame.
Insights
Severe hypovirus strains significantly alter fungal signaling pathways, impacting cyclic AMP (cAMP) and calcium pathways. Mild strains also affect calcium signaling, revealing distinct viral impacts on host gene expression and virulence in chestnut blight fungus.
Area of Science:
- Mycology
- Virology
- Molecular Biology
Background:
- Hypoviruses are known to alter fungal phenotypes, gene expression, and virulence.
- These alterations suggest hypoviruses perturb cellular signal transduction pathways.
- Understanding these pathways is crucial for comprehending hypovirus-host interactions.
Purpose of the Study:
- To investigate how different hypovirus strains differentially affect cellular signaling pathways in *Cryphonectria parasitica*.
- To identify viral determinants responsible for modulating specific signaling pathways.
Main Methods:
- Utilized a promoter-GFP reporter construct for the *C. parasitica* 13-1 gene to monitor cyclic AMP (cAMP)-mediated signaling.
- Measured transcript accumulation of the *C. parasitica* laccase gene (lac-1) to assess calcium/calmodulin/inositol trisphosphate-dependent signaling.
- Employed chimeric hypoviruses (CHV1-EP713/CHV1-Euro7) to map viral determinants.
Main Results:
- The severe hypovirus strain CHV1-EP713 significantly induced 13-1 promoter activity and reduced total laccase activity.
- The mild hypovirus strain CHV1-Euro7 only marginally altered 13-1 promoter activity and total laccase activity.
- Both hypovirus strains perturbed calcium/calmodulin/inositol trisphosphate-dependent signaling, as indicated by lac-1 transcript levels.
- Viral determinants for modulating cAMP-dependent signaling were mapped to the central portion of the second open reading frame.
Conclusions:
- Hypovirus strains differentially perturb specific cellular signaling pathways, correlating with symptom severity.
- Both severe and mild hypoviruses impact calcium signaling, though to varying degrees.
- Specific viral elements within the hypovirus genome dictate the modulation of host cAMP signaling.