Manipulation of RNA polymerase III by Herpes Simplex Virus-1

Area of Science:

• Molecular Biology
• Virology
• Gene Expression

Background:

• RNA polymerase III (Pol III) transcribes essential noncoding RNAs like transfer RNA (tRNA).
• Pol III is frequently targeted in cancer and viral infections.
• Herpes Simplex Virus-1 (HSV-1) is a common human pathogen.

Purpose of the Study:

• To investigate how HSV-1 affects host tRNA synthesis.
• To elucidate the mechanisms of viral-induced alterations in host transcription.
• To explore the interaction between viral components and host transcriptional machinery.

Main Methods:

• Analysis of tRNA expression levels in HSV-1 infected cells.
• Investigation of the role of nuclear viral entry and viral transcript synthesis.
• Chromatin immunoprecipitation to assess Pol II and Pol III binding at host and viral loci.
• Examination of transcriptional crosstalk between Pol II and Pol III.

Main Results:

• HSV-1 infection leads to a 10-fold increase in host tRNA expression.
• Increased tRNA transcription originates from actively transcribed euchromatic regions.
• Viral infection causes Pol II to bind more frequently to tRNA loci, despite depleting it from mRNA promoters.
• Pol III and associated factors were found to bind the HSV-1 viral genome.

Conclusions:

• HSV-1 actively manipulates host tRNA synthesis through intricate crosstalk between Pol II and Pol III.
• The virus hijacks host transcriptional machinery, including Pol III binding to its own genome, to favor viral gene expression.
• These findings reveal a novel mechanism of viral pathogenesis involving host nuclear environment reprogramming.