Identification of thymocyte regulators is a central issue in T cell biology. Interestingly, growing evidence indicates that common key molecules control neuronal and immune cell functions. The neurotrophic factor receptor RET mediates critical functions in foetal hematopoietic subsets, thus raising the possibility that RET-related molecules may also control T cell development. We show that Ret, Gfra1 and Gfra2 are abundantly expressed by foetal and adult immature DN thymocytes. Despite the developmentally regulated expression of these genes, analysis of foetal thymi from Gfra1, Gfra2 or Ret deficient embryos revealed that these molecules are dispensable for foetal T cell development. Furthermore, analysis of RET gain of function and Ret conditional knockout mice showed that RET is also unnecessary for adult thymopoiesis. Finally, competitive thymic reconstitution assays indicated that Ret deficient thymocytes maintained their differentiation fitness even in stringent developmental conditions. Thus, our data demonstrate that RET/GFRα signals are dispensable for thymic T cell development in vivo, indicating that pharmacological targeting of RET signalling in tumours is not likely to result in T cell production failure.
References
[1]
Petrie HT, Zuniga-Pflucker JC (2007) Zoned out: functional mapping of stromal signaling microenvironments in the thymus. Annu Rev Immunol 25: 649–679.
[2]
Hayday AC, Pennington DJ (2007) Key factors in the organized chaos of early T cell development. Nat Immunol 8: 137–144.
[3]
Rothenberg EV (2012) Transcriptional drivers of the T-cell lineage program. Curr Opin Immunol 24: 132–138.
[4]
David-Fung ES, Yui MA, Morales M, Wang H, Taghon T, et al. (2006) Progression of regulatory gene expression states in fetal and adult pro-T-cell development. Immunol Rev 209: 212–236.
[5]
Almeida AR, Borghans JA, Freitas AA (2001) T cell homeostasis: thymus regeneration and peripheral T cell restoration in mice with a reduced fraction of competent precursors. J Exp Med 194: 591–599.
[6]
Kreslavsky T, Gleimer M, Garbe AI, von Boehmer H (2010) alphabeta versus gammadelta fate choice: counting the T-cell lineages at the branch point. Immunol Rev 238: 169–181.
[7]
Radtke F, Fasnacht N, Macdonald HR (2010) Notch signaling in the immune system. Immunity 32: 14–27.
[8]
Godfrey DI, Kennedy J, Suda T, Zlotnik A (1993) A developmental pathway involving four phenotypically and functionally distinct subsets of CD3？CD4？CD8？ triple-negative adult mouse thymocytes defined by CD44 and CD25 expression. J Immunol 150: 4244–4252.
[9]
Porritt HE, Gordon K, Petrie HT (2003) Kinetics of steady-state differentiation and mapping of intrathymic-signaling environments by stem cell transplantation in nonirradiated mice. J Exp Med 198: 957–962.
[10]
Golden JP, DeMaro JA, Osborne PA, Milbrandt J, Johnson EM Jr (1999) Expression of neurturin, GDNF, and GDNF family-receptor mRNA in the developing and mature mouse. Exp Neurol 158: 504–528.
[11]
Kondo S, Kishi H, Tokimitsu Y, Muraguchi A (2003) Possible involvement of glial cell line-derived neurotrophic factor and its receptor, GFRalpha1, in survival and maturation of thymocytes. Eur J Immunol 33: 2233–2240.
[12]
Airaksinen MS, Saarma M (2002) The GDNF family: signalling, biological functions and therapeutic value. Nat Rev Neurosci 3: 383–394.
[13]
Arighi E, Borrello MG, Sariola H (2005) RET tyrosine kinase signaling in development and cancer. Cytokine Growth Factor Rev 16: 441–467.
[14]
Gattei V, Celetti A, Cerrato A, Degan M, De Iuliis A, et al. (1997) Expression of the RET receptor tyrosine kinase and GDNFR-alpha in normal and leukemic human hematopoietic cells and stromal cells of the bone marrow microenvironment. Blood 89: 2925–2937.
[15]
Houvras Y (2012) Completing the Arc: targeted inhibition of RET in medullary thyroid cancer. J Clin Oncol 30: 200–202.
[16]
Wells SA Jr, Robinson BG, Gagel RF, Dralle H, Fagin JA, et al. (2012) Vandetanib in patients with locally advanced or metastatic medullary thyroid cancer: a randomized, double-blind phase III trial. J Clin Oncol 30: 134–141.
[17]
Patel A, Harker N, Moreira-Santos L, Ferreira M, Alden K, et al. (2012) Differential RET Signaling Pathways Drive Development of the Enteric Lymphoid and Nervous Systems. Sci Signal 5: ra55.
[18]
Veiga-Fernandes H, Coles MC, Foster KE, Patel A, Williams A, et al. (2007) Tyrosine kinase receptor RET is a key regulator of Peyer's patch organogenesis. Nature 446: 547–551.
[19]
Vargas-Leal V, Bruno R, Derfuss T, Krumbholz M, Hohlfeld R, et al. (2005) Expression and function of glial cell line-derived neurotrophic factor family ligands and their receptors on human immune cells. J Immunol 175: 2301–2308.
[20]
Cacalano G, Farinas I, Wang LC, Hagler K, Forgie A, et al. (1998) GFRalpha1 is an essential receptor component for GDNF in the developing nervous system and kidney. Neuron 21: 53–62.
[21]
Rossi J, Luukko K, Poteryaev D, Laurikainen A, Sun YF, et al. (1999) Retarded growth and deficits in the enteric and parasympathetic nervous system in mice lacking GFR alpha2, a functional neurturin receptor. Neuron 22: 243–252.
[22]
Schuchardt A, D'Agati V, Larsson-Blomberg L, Costantini F, Pachnis V (1994) Defects in the kidney and enteric nervous system of mice lacking the tyrosine kinase receptor Ret. Nature 367: 380–383.
[23]
de Boer J, Williams A, Skavdis G, Harker N, Coles M, et al. (2003) Transgenic mice with hematopoietic and lymphoid specific expression of Cre. Eur J Immunol 33: 314–325.
[24]
Smith-Hicks CL, Sizer KC, Powers JF, Tischler AS, Costantini F (2000) C-cell hyperplasia, pheochromocytoma and sympathoadrenal malformation in a mouse model of multiple endocrine neoplasia type 2B. EMBO J 19: 612–622.
[25]
Nakayama S, Iida K, Tsuzuki T, Iwashita T, Murakami H, et al. (1999) Implication of expression of GDNF/Ret signalling components in differentiation of bone marrow haemopoietic cells. Br J Haematol 105: 50–57.
[26]
Trupp M, Belluardo N, Funakoshi H, Ibanez CF (1997) Complementary and overlapping expression of glial cell line-derived neurotrophic factor (GDNF), c-ret proto-oncogene, and GDNF receptor-alpha indicates multiple mechanisms of trophic actions in the adult rat CNS. J Neurosci 17: 3554–3567.
[27]
Carlomagno F, Melillo RM, Visconti R, Salvatore G, De Vita G, et al. (1998) Glial cell line-derived neurotrophic factor differentially stimulates ret mutants associated with the multiple endocrine neoplasia type 2 syndromes and Hirschsprung's disease. Endocrinology 139: 3613–3619.
[28]
Ledda F, Paratcha G, Ibanez CF (2002) Target-derived GFRalpha1 as an attractive guidance signal for developing sensory and sympathetic axons via activation of Cdk5. Neuron 36: 387–401.
[29]
Paratcha G, Ledda F, Baars L, Coulpier M, Besset V, et al. (2001) Released GFRalpha1 potentiates downstream signaling, neuronal survival, and differentiation via a novel mechanism of recruitment of c-Ret to lipid rafts. Neuron 29: 171–184.
[30]
Anderson G, Jenkinson EJ (2008) Bringing the thymus to the bench. J Immunol 181: 7435–7436.
[31]
Bleul CC, Boehm T (2005) BMP signaling is required for normal thymus development. J Immunol 175: 5213–5221.
[32]
Ciofani M, Zuniga-Pflucker JC (2007) The thymus as an inductive site for T lymphopoiesis. Annu Rev Cell Dev Biol 23: 463–493.
[33]
Paratcha G, Ledda F, Ibanez CF (2003) The neural cell adhesion molecule NCAM is an alternative signaling receptor for GDNF family ligands. Cell 113: 867–879.
[34]
Trupp M, Arenas E, Fainzilber M, Nilsson AS, Sieber BA, et al. (1996) Functional receptor for GDNF encoded by the c-ret proto-oncogene. Nature 381: 785–789.
[35]
Mombaerts P, Iacomini J, Johnson RS, Herrup K, Tonegawa S, et al. (1992) RAG-1-deficient mice have no mature B and T lymphocytes. Cell 68: 869–877.
[36]
Peixoto A, Monteiro M, Rocha B, Veiga-Fernandes H (2004) Quantification of multiple gene expression in individual cells. Genome Res 14: 1938–1947.
