Cyclic ADP-ribose is a second messenger in the lipopolysaccharide- stimulated proliferation of human peripheral blood mononuclear cells

Santina Bruzzone, Antonio De Flora, Cesare Usai, Richard Graeff, Hon Cheung Lee

Research output: Contribution to journalArticlepeer-review

48 Scopus citations

Abstract

Cyclic ADP-ribose (cADPR), a universal calcium mobilizer from intracellular stores, was recently demonstrated to stimulate proliferation of various cell types. The role of cADPR in a specific process of monocyte- and plasma-mediated activation of T-lymphocytes by lipopolysaccharide (LPS) was addressed using human mononuclear cells from peripheral blood (PBMCs). Incubation of PBMCs with 0.1 μg/ml of LPS for 24 h provided a doubling in the intracellular levels of cADPR as compared with unstimulated PBMCs. The cADPR increase was abolished either by prior removal of monocytes or by pre-incubating a whole PBMC population with a monoclonal antibody against the monocyte marker CD14. The increased concentrations of intracellular cADPR elicited by LPS stimulation were paralleled by significant increases in NAD + levels and in the activities of ectocellular and membrane-bound fractions of ADP-ribosyl cyclase/ cADPR hydrolase activities. A cytosolic ADP-ribosyl cyclase was also detectable in PBMCs and its activity was comparably enhanced by LPS stimulation. This soluble cyclase is distinguished from the membrane-bound cyclase by both substrate and inhibitor sensitivities. LPS-stimulated PBMCs showed 2-3-fold increases of intracellular calcium ([Ca2+]), and these changes were prevented completely by the cADPR antagonist 8-Br-cADPR and by ryanodine. Both compounds, and the cyclase inhibitor nicotinamide, significantly inhibited the T-lymphocyte proliferation induced by LPS in PBMCs. These results demonstrate that cADPR plays a role of second messenger in the adaptive immune recognition process of LPS-stimulated proliferation of PBMCs.

Original languageEnglish (US)
Pages (from-to)395-403
Number of pages9
JournalBiochemical Journal
Volume375
Issue number2
DOIs
StatePublished - Oct 15 2003

Keywords

  • ADP-ribosyl cyclase
  • Cyclic ADP-ribose
  • Cyclic ADP-ribose hydrolase
  • Lipopolysaccharide
  • Nicotinamide-adenine dinucleotide (NAD)
  • Peripheral blood mononuclear cell

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