Tryptophan hydroxylase 2 (TPH2) is an isozyme of tryptophan hydroxylase found in vertebrates. In humans, TPH2 is primarily expressed in the serotonergicneurons of the brain, with the highest expression in the raphe nucleus of the midbrain. Until the discovery of TPH2 in 2003,[1] serotonin levels in the central nervous system were believed to be regulated by serotonin synthesis in peripheral tissues, in which tryptophan hydroxylase is the dominant form.[2]
Tryptophan hydroxylase (TPH; EC 1.14.16.4) is the rate-limiting enzyme in the synthesis of serotonin (5-hydroxytryptamine, or 5HT). 5HT is causally involved in numerous central nervous activities, and it has several functions in peripheral tissues, including the maintenance of vascular tone and gut motility.[supplied by OMIM][3]
↑Walther DJ, Peter JU, Bashammakh S, Hörtnagl H, Voits M, Fink H, Bader M (Jan 2003). "Synthesis of serotonin by a second tryptophan hydroxylase isoform". Science. 299 (5603): 76. doi:10.1126/science.1078197. PMID12511643.
↑Zill P, Büttner A, Eisenmenger W, Möller HJ, Ackenheil M, Bondy B (2005). "Analysis of tryptophan hydroxylase I and II mRNA expression in the human brain: a post-mortem study". Journal of Psychiatric Research. 41 (1–2): 168–73. doi:10.1016/j.jpsychires.2005.05.004. PMID16023677.
Walther DJ, Peter JU, Bashammakh S, Hörtnagl H, Voits M, Fink H, Bader M (Jan 2003). "Synthesis of serotonin by a second tryptophan hydroxylase isoform". Science. 299 (5603): 76. doi:10.1126/science.1078197. PMID12511643.
Zill P, Baghai TC, Zwanzger P, Schüle C, Eser D, Rupprecht R, Möller HJ, Bondy B, Ackenheil M (Nov 2004). "SNP and haplotype analysis of a novel tryptophan hydroxylase isoform (TPH2) gene provide evidence for association with major depression". Molecular Psychiatry. 9 (11): 1030–6. doi:10.1038/sj.mp.4001525. PMID15124006.
Breidenthal SE, White DJ, Glatt CE (Jun 2004). "Identification of genetic variants in the neuronal form of tryptophan hydroxylase (TPH2)". Psychiatric Genetics. 14 (2): 69–72. doi:10.1097/01.ypg.0000107929.32051.58. PMID15167691.
De Luca V, Mueller DJ, Tharmalingam S, King N, Kennedy JL (Oct 2004). "Analysis of the novel TPH2 gene in bipolar disorder and suicidality". Molecular Psychiatry. 9 (10): 896–7. doi:10.1038/sj.mp.4001531. PMID15197398.
Harvey M, Shink E, Tremblay M, Gagné B, Raymond C, Labbé M, Walther DJ, Bader M, Barden N (Nov 2004). "Support for the involvement of TPH2 gene in affective disorders". Molecular Psychiatry. 9 (11): 980–1. doi:10.1038/sj.mp.4001557. PMID15263906.
Zill P, Büttner A, Eisenmenger W, Möller HJ, Bondy B, Ackenheil M (Oct 2004). "Single nucleotide polymorphism and haplotype analysis of a novel tryptophan hydroxylase isoform (TPH2) gene in suicide victims". Biological Psychiatry. 56 (8): 581–6. doi:10.1016/j.biopsych.2004.07.015. PMID15476687.
Zhang X, Gainetdinov RR, Beaulieu JM, Sotnikova TD, Burch LH, Williams RB, Schwartz DA, Krishnan KR, Caron MG (Jan 2005). "Loss-of-function mutation in tryptophan hydroxylase-2 identified in unipolar major depression". Neuron. 45 (1): 11–6. doi:10.1016/j.neuron.2004.12.014. PMID15629698.
Coon H, Dunn D, Lainhart J, Miller J, Hamil C, Battaglia A, Tancredi R, Leppert MF, Weiss R, McMahon W (May 2005). "Possible association between autism and variants in the brain-expressed tryptophan hydroxylase gene (TPH2)". American Journal of Medical Genetics Part B. 135B (1): 42–6. doi:10.1002/ajmg.b.30168. PMID15768392.
Sheehan K, Lowe N, Kirley A, Mullins C, Fitzgerald M, Gill M, Hawi Z (Oct 2005). "Tryptophan hydroxylase 2 (TPH2) gene variants associated with ADHD". Molecular Psychiatry. 10 (10): 944–9. doi:10.1038/sj.mp.4001698. PMID15940290.
Shamir A, Shaltiel G, Levi I, Belmaker RH, Agam G (2005). "Postmortem parietal cortex TPH2 expression is not altered in schizophrenic, unipolar-depressed, and bipolar patients vs control subjects". Journal of Molecular Neuroscience. 26 (1): 33–7. doi:10.1385/JMN:26:1:033. PMID15968084.
Brown SM, Peet E, Manuck SB, Williamson DE, Dahl RE, Ferrell RE, Hariri AR (Sep 2005). "A regulatory variant of the human tryptophan hydroxylase-2 gene biases amygdala reactivity". Molecular Psychiatry. 10 (9): 884–8, 805. doi:10.1038/sj.mp.4001716. PMID16044172.
Walitza S, Renner TJ, Dempfle A, Konrad K, Wewetzer CH, Halbach A, Herpertz-Dahlmann B, Remschmidt H, Smidt J, Linder M, Flierl L, Knölker U, Friedel S, Schäfer H, Gross C, Hebebrand J, Warnke A, Lesch KP (Dec 2005). "Transmission disequilibrium of polymorphic variants in the tryptophan hydroxylase-2 gene in attention-deficit/hyperactivity disorder". Molecular Psychiatry. 10 (12): 1126–32. doi:10.1038/sj.mp.4001734. PMID16116490.
Canli T, Congdon E, Gutknecht L, Constable RT, Lesch KP (Nov 2005). "Amygdala responsiveness is modulated by tryptophan hydroxylase-2 gene variation". Journal of Neural Transmission. 112 (11): 1479–85. doi:10.1007/s00702-005-0391-4. PMID16245070.
Mössner R, Freitag CM, Gutknecht L, Reif A, Tauber R, Franke P, Fritze J, Wagner G, Peikert G, Wenda B, Sand P, Rietschel M, Garritsen H, Jacob C, Lesch KP, Deckert J (Jul 2006). "The novel brain-specific tryptophan hydroxylase-2 gene in panic disorder". Journal of Psychopharmacology. 20 (4): 547–52. doi:10.1177/0269881106059704. PMID16401665.
De Luca V, Hlousek D, Likhodi O, Van Tol HH, Kennedy JL, Wong AH (Feb 2006). "The interaction between TPH2 promoter haplotypes and clinical-demographic risk factors in suicide victims with major psychoses". Genes, Brain, and Behavior. 5 (1): 107–10. doi:10.1111/j.1601-183X.2005.00182.x. PMID16436194.
Carkaci-Salli N, Flanagan JM, Martz MK, Salli U, Walther DJ, Bader M, Vrana KE (Sep 2006). "Functional domains of human tryptophan hydroxylase 2 (hTPH2)". The Journal of Biological Chemistry. 281 (38): 28105–12. doi:10.1074/jbc.M602817200. PMID16864580.