Latent membrane protein 2A-mediated effects on the phosphatidylinositol 3-Kinase/Akt pathway

J Virol. 2000 Nov;74(22):10838-45. doi: 10.1128/jvi.74.22.10838-10845.2000.

Abstract

Epstein-Barr virus (EBV) latent membrane protein 2A (LMP2A) is expressed on the membranes of B lymphocytes and blocks B-cell receptor (BCR) signaling in EBV-transformed B lymphocytes in vitro. The phosphotyrosine motifs at positions 74 or 85 and 112 within the LMP2A amino-terminal domain are essential for the LMP2A-mediated block of B-cell signal transduction. In vivo studies indicate that LMP2A allows B-cell survival in the absence of normal BCR signals. A possible role for Akt in the LMP2A-mediated B-cell survival was investigated. The protein kinase Akt is a crucial regulator of cell survival and is activated within B lymphocytes upon BCR cross-linking. LMP2A expression resulted in the constitutive phosphorylation of Akt, and this LMP2A effect is dependent on phosphatidylinositol 3-kinase activity. In addition, recruitment of Syk and Lyn protein tyrosine kinases (PTKs) to tyrosines 74 or 85 and 112, respectively, are critical for LMP2A-mediated Akt phosphorylation. However, the ability of LMP2A to mediate a survival phenotype downstream of Akt could not be detected in EBV-negative Akata cells. This would indicate that LMP2A is not responsible for EBV-dependent Burkitt's lymphoma cell survival.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • B-Lymphocytes / physiology*
  • B-Lymphocytes / transplantation
  • B-Lymphocytes / virology
  • Burkitt Lymphoma / pathology
  • Cell Line, Transformed
  • Gene Expression Regulation
  • Herpesvirus 4, Human / metabolism
  • Humans
  • Mice
  • Mice, SCID
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphorylation
  • Protein Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • Viral Matrix Proteins / physiology*

Substances

  • EBV-associated membrane antigen, Epstein-Barr virus
  • Proto-Oncogene Proteins
  • Viral Matrix Proteins
  • AKT1 protein, human
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt