KSHV encoded LANA upregulates Pim-1 and is a substrate for its kinase activity

Virology. 2006 Jul 20;351(1):18-28. doi: 10.1016/j.virol.2006.03.037. Epub 2006 Apr 27.

Abstract

Pim kinases are proto-oncogenes that are upregulated in a number of B cell cancers, including Epstein-Barr Virus (EBV) associated Burkitt's lymphoma. They have also been shown to be upregulated in Kaposi sarcoma-associated herpes virus (KSHV) infected primary B cells. Most cells in KSHV-associated tumors are latently infected and express only a small subset of viral genes, with KSHV latency associated nuclear antigen (LANA) being constitutively expressed. LANA regulates the transcription of a large number of cellular and viral genes. Here, we show that LANA upregulates transcription from the Pim-1 promoter (pPim-1) and map this activation to a region in the promoter located within the sequence (-681 to +37). We show that LANA expressing cells can proliferate faster and are better protected from drug induced apoptosis. Since transition through cell cycle check points and anti-apoptosis are functions associated with Pim-1, it is likely that higher Pim-1 expression in cells expressing LANA is responsible, at least in part, for this effect. A Pim-1 phosphorylation site was also identified within the amino-terminal domain of LANA. Using in vitro kinase assays, we confirmed that LANA was indeed a Pim-1 substrate, and the failure of Pim-1 to phosphorylate LANA mutated at SS205/6RR identified this site as the specific serine residues phosphorylated by Pim-1. This report provides valuable insight into yet another cellular signaling pathway subverted by KSHV LANA and suggests a contribution to KSHV related oncogenesis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Antigens, Viral / genetics
  • Antigens, Viral / metabolism*
  • Apoptosis
  • B-Lymphocytes / metabolism
  • Cell Line
  • Cell Proliferation
  • Epithelial Cells / metabolism
  • Herpesvirus 8, Human / genetics*
  • Herpesvirus 8, Human / metabolism*
  • Humans
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phosphorylation
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins c-pim-1 / genetics
  • Proto-Oncogene Proteins c-pim-1 / metabolism*
  • Signal Transduction
  • Substrate Specificity
  • Transcription, Genetic
  • Up-Regulation*

Substances

  • Antigens, Viral
  • Nuclear Proteins
  • latency-associated nuclear antigen
  • PIM1 protein, human
  • Proto-Oncogene Proteins c-pim-1