FAMIN in dendritic cells biochemically restrains T cell priming
type: CreativeWork
description: FAMIN is a purine nucleoside enzyme that was first identified in genome-wide association studies (GWAS) as increasing risk for Crohn’s disease (CD). Defects in the enzyme that result in loss of catalytic activity are the only known monogenic cause of Still’s disease, a severe autoinflammatory condition that predisposes for the risk of developing macrophage activation syndrome (MAS). MAS can be triggered by common viral infections and result in hyperactivation of T lymphocytes. The work presented in this thesis builds on the discovery that FAMIN-sufficient mice are protected against influenza A infection, with dendritic cell (DC)- dependent excessive activation of CD8+ T cell responses in their FAMIN-deficient counterparts. Loss of FAMIN activity in DCs was shown to result in increased priming of both CD4+ and CD8+ T cells both in vitro and in vivo, resulting in enhanced antigen-specific cytotoxicity, IFNg secretion, and T cell expansion. Here, we discovered that FAMIN controls the pace of membrane trafficking and DC antigen processing to restrain T cell priming via a cytosolic NADH/ NAD+-dependent mechanism. We describe wide-reaching metabolic defects resulting from loss of FAMIN activity, including in the core pathways of glycolysis and TCA cycle activity, as well as upstream changes in glucose, fatty acid and amino acid metabolism. Notably, depressed rates of glycolysis and oxidative phosphorylation DCs lacking FAMIN function were not responsible for increased T cell priming capacity. Instead, we find that FAMIN balances flux through adenine-guanine nucleotide interconversion cycles to maintain the cytosolic NADH/ NAD+ ratio. We found that FAMIN additionally regulates T cell priming by DCs directly through the enzyme’s purine nucleoside phosphorylase (PNP) activity, converting exogenous hypoxanthine to inosine that acts on the T cell adenosine 2A receptor (A2AR). In summary, FAMIN is a multifunctional purine nucleoside enzyme enabling flux through purine interconv…
abstract: FAMIN is a purine nucleoside enzyme that was first identified in genome-wide association studies (GWAS) as increasing risk for Crohn’s disease (CD). Defects in the enzyme that result in loss of catalytic activity are the only known monogenic cause of Still’s disease, a severe autoinflammatory condition that predisposes for the risk of developing macrophage activation syndrome (MAS). MAS can be triggered by common viral infections and result in hyperactivation of T lymphocytes. The work presented in this thesis builds on the discovery that FAMIN-sufficient mice are protected against influenza A infection, with dendritic cell (DC)- dependent excessive activation of CD8+ T cell responses in their FAMIN-deficient counterparts. Loss of FAMIN activity in DCs was shown to result in increased priming of both CD4+ and CD8+ T cells both in vitro and in vivo, resulting in enhanced antigen-specific cytotoxicity, IFNg secretion, and T cell expansion. Here, we discovered that FAMIN controls the pace of membrane trafficking and DC antigen processing to restrain T cell priming via a cytosolic NADH/ NAD+-dependent mechanism. We describe wide-reaching metabolic defects resulting from loss of FAMIN activity, including in the core pathways of glycolysis and TCA cycle activity, as well as upstream changes in glucose, fatty acid and amino acid metabolism. Notably, depressed rates of glycolysis and oxidative phosphorylation DCs lacking FAMIN function were not responsible for increased T cell priming capacity. Instead, we find that FAMIN balances flux through adenine-guanine nucleotide interconversion cycles to maintain the cytosolic NADH/ NAD+ ratio. We found that FAMIN additionally regulates T cell priming by DCs directly through the enzyme’s purine nucleoside phosphorylase (PNP) activity, converting exogenous hypoxanthine to inosine that acts on the T cell adenosine 2A receptor (A2AR). In summary, FAMIN is a multifunctional purine nucleoside enzyme enabling flux through purine interconv…
author: Ramshorn, Katharina
language: eng
keywords: Autoimmunity, Crohn's disease, Dendritic cells, Immunometabolism, Purine metabolism, Still's disease, T cell priming
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/02677634-c56a-4e3b-b81b-410153c1f16d/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2022-10-01
date modified: 2026-07-22T22:24:23Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.96561