Adenosine Kinase Inhibition Promotes Survival of Fetal Adenosine Deaminase-Deficient Thymocytes by Blocking dATP Accumulation

J Clin Invest. 2002 Aug;110(3):395-402. doi: 10.1172/JCI15683.

Abstract

Thymocyte development past the CD4(-)CD8(-) stage is markedly inhibited in adenosine deaminase-deficient (ADA-deficient) murine fetal thymic organ cultures (FTOCs) due to the accumulation of ADA substrates derived from thymocytes failing developmental checkpoints. Such cultures can be rescued by overexpression of Bcl-2, suggesting that apoptosis is an important component of the mechanism by which ADA deficiency impairs thymocyte development. Consistent with this conclusion, ADA-deficient FTOCs were partially rescued by a rearranged T cell receptor beta transgene that permits virtually all thymocytes to pass the beta-selection checkpoint. ADA-deficient cultures were also rescued by the adenosine kinase inhibitor 5'-amino-5'-deoxyadenosine (5'A5'dAdo), indicating that the metabolite responsible for the inhibition of thymocyte development is not adenosine or deoxyadenosine, but a phosphorylated derivative of an ADA substrate. Correction of ADA-deficient FTOCs by 5'A5'dAdo correlated with reduced accumulation of dATP, implicating this compound as the toxic metabolite. In ADA-inhibited FTOCs rescued with a Bcl-2 transgene, however, dATP levels were superelevated, suggesting that cells failing positive and negative selection continued to contribute to the accumulation of ADA substrates. Our data are consistent with dATP-induced mitochondrial cytochrome c release followed by apoptosis as the mechanism by which ADA deficiency leads to reduced thymic T cell production.

Publication types

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

MeSH terms

  • Adenosine Deaminase / metabolism*
  • Adenosine Kinase / antagonists & inhibitors*
  • Adenosylhomocysteinase
  • Animals
  • CD4-Positive T-Lymphocytes / cytology
  • CD8-Positive T-Lymphocytes / cytology
  • Cell Differentiation
  • Cell Survival
  • Deoxyadenine Nucleotides / metabolism*
  • Deoxyadenosines / pharmacology
  • Hydrolases / antagonists & inhibitors
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Purinergic P1 Receptor Agonists
  • Purinergic P1 Receptor Antagonists
  • Receptor, Adenosine A2A
  • Receptor, Adenosine A2B
  • Receptor, Adenosine A3
  • Receptors, Antigen, T-Cell, alpha-beta / genetics
  • Receptors, Antigen, T-Cell, alpha-beta / physiology
  • Receptors, Purinergic P1 / genetics
  • Thymus Gland / cytology*

Substances

  • Deoxyadenine Nucleotides
  • Deoxyadenosines
  • Proto-Oncogene Proteins c-bcl-2
  • Purinergic P1 Receptor Agonists
  • Purinergic P1 Receptor Antagonists
  • Receptor, Adenosine A2A
  • Receptor, Adenosine A2B
  • Receptor, Adenosine A3
  • Receptors, Antigen, T-Cell, alpha-beta
  • Receptors, Purinergic P1
  • 5'-amino-5'-deoxyadenosine
  • Adenosine Kinase
  • Hydrolases
  • Adenosylhomocysteinase
  • Adenosine Deaminase
  • 2'-deoxyadenosine triphosphate