Identification of a Novel Pathway of Transforming Growth Factor-β1 Regulation by Extracellular NAD+ in Mouse Macrophages

• Published in: The Journal of biological chemistry 2012-09, Vol.287 (37), p.31003-31014
• Main Authors: Zamora, Ruben, Azhar, Nabil, Namas, Rajaie, Metukuri, Mallikarjuna R., Clermont, Thierry, Gladstone, Chase, Namas, Rami A., Hermus, Linda, Megas, Cristina, Constantine, Gregory, Billiar, Timothy R., Fink, Mitchell P., Vodovotz, Yoram
• Format: Article
• Language: English
• Subjects: cADPR; Calcium; Computational Biology; Gene Regulation; Macrophages; Transforming Growth Factor β (TGFβ)
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.344309

Extracellular β-nicotinamide adenine dinucleotide (NAD+) is anti-inflammatory. We hypothesized that NAD+ would modulate the anti-inflammatory cytokine Transforming Growth Factor (TGF)-β1. Indeed, NAD+ led to increases in both active and latent cell-associated TGF-β1 in RAW 264.7 mouse macrophages as well as in primary peritoneal macrophages isolated from both C3H/HeJ (TLR4-mutant) and C3H/HeOuJ (wild-type controls for C3H/HeJ) mice. NAD+ acts partially via cyclic ADP-ribose (cADPR) and subsequent release of Ca2+. Treatment of macrophages with the cADPR analog 3-deaza-cADPR or Ca2+ ionophores recapitulated the effects of NAD+ on TGF-β1, whereas the cADPR antagonist 8-Br-cADPR, Ca2+ chelation, and antagonism of L-type Ca2+ channels suppressed these effects. The time and dose effects of NAD+ on TGF-β1 were complex and could be modeled both statistically and mathematically. Model-predicted levels of TGF-β1 protein and mRNA were largely confirmed experimentally but also suggested the presence of other mechanisms of regulation of TGF-β1 by NAD+. Thus, in vitro and in silico evidence points to NAD+ as a novel modulator of TGF-β1. Background: Both extracellular NAD+ and the cytokine TGF-β1 are anti-inflammatory. Results: NAD+ increases both active and latent TGF-β1 in mouse macrophages. A mathematical model partially explains the complex effects of NAD+ on TGF-β1. Conclusion: NAD+ is a novel modulator of TGF-β1. Significance: Combined in vitro and in silico approaches may help elucidate novel pathways of TGF-β1 regulation.