ReviewFrontiers in molecular biosciences2022
Systemic tryptophan homeostasis.
Review in Frontiers in molecular biosciences, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 76 papers, 5 of them syntheses that pooled it.
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Who cites it
76 citing papers in PubMed, 5 syntheses or guidelines pooled it.
- Conserved hepatic RNA signatures across multiple cohorts reveal novel mechanistic clues for advanced fibrosis in human MASLD.Hepatology communications · 2026Pooled it
- Multimodal microglial and kynurenine pathway alterations across the affective-psychosis spectrum: a systematic review of patterns, heterogeneity, and dimensional implications.Molecular psychiatry · 2026Pooled it
- Phytochemical Modulation of the Kynurenine Pathway (KYNP) and Its Emerging Mechanistic Insights into Cancer Progression: A Systematic Review.International journal of molecular sciences · 2026Pooled it
- Pooled it
- Metabolomics biomarkers and related pathways in acute renal injury: a bibliometric investigation, meta-analysis, and systematic review.Frontiers in medicine · 2025Pooled it
- Chicken IDO2 and TDO2: Biochemical Characteristics and Regulatory Roles in Avian Tryptophan Metabolism and Inflammatory Response.Animals : an open access journal from MDPI · 2026Article
- Tryptophan Metabolism in Digestive and Extra-Digestive Diseases: Mechanisms, Clinical Implications, and Therapeutic Perspectives.Nutrients · 2026Review
- Lactoferrin alleviates non-alcoholic steatohepatitis via remodeling gut microbiota to regulate serotonin-related pathways.Journal of advanced research · 2026Article
- Characterization of multi-stage metabolic alterations in hepatitis B virus-related acute-on-chronic liver failure using high-coverage metabolomics.Metabolomics : Official journal of the Metabolomic Society · 2026Article
- NADThe Journal of general virology · 2026Review
- Cysteine availability tunes ubiquitin signaling via inverse stability of LRRC58 E3 ligase and its substrate CDO1.Nature communications · 2026Article
- Cell Signaling by Tryptophan Catabolism.Biochemistry · 2026Review
- Glioblastoma region-specific metabolic signatures reflect patient survival duration.Journal of neuro-oncology · 2026Article
- Not so cold after all: tumor infiltrating CD8+ T cells in EBV-positive Burkitt lymphoma are quiescent, not exhausted.bioRxiv : the preprint server for biology · 2026Article
- Artemether and Euphorbia factor L9 suppress kynurenine production through distinct effects on tryptophan metabolism.The Biochemical journal · 2026Article
- Kidney Function Modulates Gut Microbial Metabolism.Toxins · 2026Article
- Disrupted Tryptophan Metabolism Mediates Manganese-Induced Neurogenesis and Neuroinflammatory Impairments: Rescue by Exogenous Melatonin.Environment & health (Washington, D.C.) · 2026Article
- Article
- Modulation of the Kynurenine Pathway: A New Approach for Treating Neurodegeneration.Life (Basel, Switzerland) · 2026Review
- Serotonin, Kynurenine, and Indole Pathways of Tryptophan Metabolism in Humans in Health and Disease.Nutrients · 2026Review
16 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
4 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Tryptophan is an essential amino acid, which is not only a building block for protein synthesis, but also a precursor for the biosynthesis of co-enzymes and neuromodulators, such as NAD/NADP(H), kynurenic acid, melatonin and serotonin. It also plays a role in immune homeostasis, as local tryptophan catabolism impairs T-lymphocyte mediated immunity. Therefore, tryptophan plasmatic concentration needs to be stable, in spite of large variations in dietary supply. Here, we review the main checkpoints accounting for tryptophan homeostasis, including absorption, transport, metabolism and elimination, and we discuss the physiopathology of disorders associated with their dysfunction. Tryptophan is catabolized along the kynurenine pathway through the action of two enzymes that mediate the first and rate-limiting step of the pathway: indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO). While IDO1 expression is restricted to peripheral sites of immune modulation, TDO is massively expressed in the liver and accounts for 90% of tryptophan catabolism. Recent data indicated that the stability of the TDO protein is regulated by tryptophan and that this regulation allows a tight control of tryptophanemia. TDO is stabilized when tryptophan is abundant in the plasma, resulting in rapid degradation of dietary tryptophan. In contrast, when tryptophan is scarce, TDO is degraded by the proteasome to avoid excessive tryptophan catabolism. This is triggered by the unmasking of a degron in a non-catalytic tryptophan-binding site, resulting in TDO ubiquitination by E3 ligase SKP1-CUL1-F-box. Deficiency in TDO or in the hepatic aromatic transporter SLC16A10 leads to severe hypertryptophanemia, which can disturb immune and neurological homeostasis.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.