Immediate-early gene product ICP22 inhibits the trans-transcription activating function of P53-mdm-2

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HongXiong Guo1, Wei Cun, LongDing Liu

  • 1Department of Viral Immunology, Institute of Medical Biology, CAMS and PUMC, Kunming 650118, China.

Science in China. Series C, Life Sciences
|July 27, 2007
PubMed

Insights

Herpes Simplex Virus type 1 (HSV-1) ICP22 protein drives infected cells into S phase by binding the mdm-1 promoter. This interaction indirectly increases P53 levels, promoting cell cycle progression.

Area of Science:

  • Molecular Biology
  • Virology
  • Cell Biology

Background:

  • Herpes Simplex Virus type 1 (HSV-1) immediate-early gene products play crucial roles in viral replication and host cell manipulation.
  • ICP22 is an HSV-1 immediate-early protein known to interact with cellular factors.
  • Understanding ICP22's function is key to deciphering viral pathogenesis and host-pathogen interactions.

Purpose of the Study:

  • To elucidate the mechanism by which ICP22 influences host cell cycle progression.
  • To investigate the interaction between ICP22, P53, and MDM-2.
  • To determine how ICP22 binding to the mdm-1 promoter affects cellular transcription.

Main Methods:

  • Expression of ICP22 in transfected cells.
  • Analysis of cell cycle progression (S phase entry).
  • Investigation of protein-DNA interactions (mdm-1 promoter binding).
  • Assessment of P53 and MDM-2 protein levels and interactions.

Main Results:

  • ICP22 expression induced host cell entry into S phase.
  • ICP22 was found to bind to the mdm-1 promoter region.
  • ICP22 binding interfered with the trans-transcriptional activating effect of P53 on the mdm-1 promoter.
  • This interaction led to MDM-2 binding to P53, reducing P53 degradation.
  • Consequently, cellular P53 levels increased, facilitating S phase entry.

Conclusions:

  • ICP22 manipulates host cell cycle machinery to favor viral replication.
  • The interaction of ICP22 with the mdm-1 promoter and P53/MDM-2 pathway is a key mechanism for cell cycle dysregulation.
  • ICP22's ability to increase P53 levels indirectly highlights its complex role in modulating cellular processes during HSV-1 infection.

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