Human Glial Cell Line-derived Neurotrophic Factor Receptor α4 Is the Receptor for Persephin and Is Predominantly Expressed in Normal and Malignant Thyroid Medullary Cells

Abstract

Glial cell line-derived neurotrophic factor (GDNF) family ligands signal through receptor complex consisting of a glycosylphosphatidylinositol-linked GDNF family receptor (GFR) α subunit and the transmembrane receptor tyrosine kinase RET. The inherited cancer syndrome multiple endocrine neoplasia type 2 (MEN2), associated with different mutations in RET, is characterized by medullary thyroid carcinoma. GDNF signals via GFRα1, neurturin via GFRα2, artemin via GFRα3, whereas the mammalian GFRα receptor for persephin (PSPN) is unknown. Here we characterize the human GFRα4 as the ligand-binding subunit required together with RET for PSPN signaling. Human and mouse GFRα4 lack the first Cys-rich domain characteristic of other GFRα receptors. Unlabeled PSPN displaces 125I-PSPN fromGFRA4-transfected cells, which express endogenous Ret. PSPN can be specifically cross-linked to mammalian GFRα4 and Ret, and is able to promote autophosphorylation of Ret inGFRA4-transfected cells. PSPN, but not other GDNF family ligands, promotes the survival of cultured sympathetic neurons microinjected with GFRA4. We identified different splice forms of human GFRA4 mRNA encoding for two glycosylphosphatidylinositol-linked and one putative soluble isoform that were predominantly expressed in the thyroid gland. Overlapping expression of RET and GFRA4 but not otherGFRA mRNAs in normal and malignant thyroid medullary cells suggests that GFRα4 may restrict the MEN2 syndrome to these cells.AJ291673AJ291674AJ291675 Glial cell line-derived neurotrophic factor (GDNF) family ligands signal through receptor complex consisting of a glycosylphosphatidylinositol-linked GDNF family receptor (GFR) α subunit and the transmembrane receptor tyrosine kinase RET. The inherited cancer syndrome multiple endocrine neoplasia type 2 (MEN2), associated with different mutations in RET, is characterized by medullary thyroid carcinoma. GDNF signals via GFRα1, neurturin via GFRα2, artemin via GFRα3, whereas the mammalian GFRα receptor for persephin (PSPN) is unknown. Here we characterize the human GFRα4 as the ligand-binding subunit required together with RET for PSPN signaling. Human and mouse GFRα4 lack the first Cys-rich domain characteristic of other GFRα receptors. Unlabeled PSPN displaces 125I-PSPN fromGFRA4-transfected cells, which express endogenous Ret. PSPN can be specifically cross-linked to mammalian GFRα4 and Ret, and is able to promote autophosphorylation of Ret inGFRA4-transfected cells. PSPN, but not other GDNF family ligands, promotes the survival of cultured sympathetic neurons microinjected with GFRA4. We identified different splice forms of human GFRA4 mRNA encoding for two glycosylphosphatidylinositol-linked and one putative soluble isoform that were predominantly expressed in the thyroid gland. Overlapping expression of RET and GFRA4 but not otherGFRA mRNAs in normal and malignant thyroid medullary cells suggests that GFRα4 may restrict the MEN2 syndrome to these cells. AJ291673AJ291674AJ291675 glial cell line-derived neurotrophic factor artemin follicular thyroid adenoma follicular thyroid carcinoma glial cell line-derived neurotrophic factor family receptor multiple endocrine neoplasia medullary thyroid carcinoma neurturin persephin papillary thyroid carcinoma, SCG, superior cervical ganglion persephin glycosylphosphatidylinositol reverse transcriptase-polymerase chain reaction rapid amplification of cDNA ends nerve growth factor base pair(s) The glial cell line-derived neurotrophic factor (GDNF)1 family ligands GDNF, neurturin (NRTN), artemin (ARTN), and persephin (PSPN) are structurally related neurotrophic factors that signal through a multicomponent receptor composed of the transmembrane receptor tyrosine kinase RET and high affinity glycosylphosphatidylinositol (GPI)-anchored proteins, the GDNF family α receptors 1–4 (GFRα1–4, reviewed in Refs. 1Airaksinen M.S. Titievsky A. Saarma M. Mol. Cell. Neurosci. 1999; 13: 313-325Crossref PubMed Scopus (388) Google Scholar and 2Baloh R.H. Enomoto H. Johnson Jr., E.M. Milbrandt J. Curr. Opin. Neurobiol. 2000; 10: 103-110Crossref PubMed Scopus (407) Google Scholar). GFRα4 was first described from chicken and shown to be the preferential receptor for PSPN (3Enokido Y. de Sauvage F. Hongo J.-A. Ninkina N. Rosenthal A. Buchman V.L. Davies A.M. Curr. Biol. 1998; 8: 1019-1022Abstract Full Text Full Text PDF PubMed Google Scholar, 4Thompson J. Doxakis E. Piñon L.G.P. Strachan P. Buj-Bello A. Wyatt S. Buchman V.L. Davies A.M. Mol. Cell. Neurosci. 1998; 11: 117-126Crossref PubMed Scopus (82) Google Scholar). Recently, we characterized a mouse GFRα4 receptor (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). It differs from all other GFRα receptors, including chicken GFRα4, being smaller in size and lacking the first Cys-rich domain. Mouse Gfra4 transcripts are expressed in many embryonic and adult tissues but efficient splicing leading to a functional GPI-linked isoform, as well as putative transmembrane and soluble isoforms, occurs only in thyroid and adrenal medulla and in pituitary intermediate lobe (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). In mouse, Gfra4 andRet are coexpressed only in the thyroid C-cells and adrenal chromaffin cells. In chicken, Gfra4 mRNA is broadly expressed during embryonic development, including the spinal motoneurons and kidney (4Thompson J. Doxakis E. Piñon L.G.P. Strachan P. Buj-Bello A. Wyatt S. Buchman V.L. Davies A.M. Mol. Cell. Neurosci. 1998; 11: 117-126Crossref PubMed Scopus (82) Google Scholar). Chicken GFRα4 also binds mouse PSPN and confers survival response to PSPN in the presence of Ret (3Enokido Y. de Sauvage F. Hongo J.-A. Ninkina N. Rosenthal A. Buchman V.L. Davies A.M. Curr. Biol. 1998; 8: 1019-1022Abstract Full Text Full Text PDF PubMed Google Scholar). However, due to different structures of chicken and mammalian GFRα4, as well as the lack of information about the existence of chicken GFRα3, ligand specificity of mammalian GFRα4 cannot be directly extrapolated from experiments with chicken GFRα4. PSPN mRNA is expressed at low levels in many rat tissues, where two transcripts, an unspliced and a functional spliced form are produced (6Milbrandt J. de Sauvage F.J. Fahrner T.J. Baloh R.H. Leitner M.L. Tansey M.G. Lampe P.A. Heuckeroth R.O. Kotzbauer P.T. Simburger K.S. Golden J.P. Davies J.A. Vejsada R. Kato A.C. Hynes M. Sherman D Nishimura M Wang L.C. Vandlen R. Mottat B. Klein R.D. Poulson K. Gray C. Garces A. Henderson C, E. Phillips H, S. Johnson Jr., E.M. Neuron. 1998; 20: 245-253Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar, 7Jaszai J. Farkas L. Galter D. Reuss B. Strelau J. Unsicker K. Kriegelstein K. J. Neurosci. Res. 1998; 53: 494-501Crossref PubMed Scopus (32) Google Scholar). PSPN promotes the survival of embryonic motor neurons in vitro and rescues nigral dopamine neurons following neurotoxic injury in vivo but does not support the survival of any peripheral neurons tested (6Milbrandt J. de Sauvage F.J. Fahrner T.J. Baloh R.H. Leitner M.L. Tansey M.G. Lampe P.A. Heuckeroth R.O. Kotzbauer P.T. Simburger K.S. Golden J.P. Davies J.A. Vejsada R. Kato A.C. Hynes M. Sherman D Nishimura M Wang L.C. Vandlen R. Mottat B. Klein R.D. Poulson K. Gray C. Garces A. Henderson C, E. Phillips H, S. Johnson Jr., E.M. Neuron. 1998; 20: 245-253Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar). However, unlike GDNF and NRTN, PSPN does not induce neurite outgrowth of rat P8 motor axons in organotypic cultures (8Ho T.W. C. Y. Milbrandt J. Johnson Jr., E.M. L. 2000; PubMed Scopus Google Scholar). by the of RET in human papillary thyroid whereas mutations are for multiple endocrine neoplasia type 2 reviewed in Refs. P. C. A. S. PubMed Scopus Google Scholar, C. J. 1999; PubMed Google Scholar, Res. 1999; Google Scholar). The associated with these in cell However, RET is expressed at high levels in many other cell which not malignant in MEN2 T. M. N. T. M. J. 10: Google Scholar). is characterized by medullary thyroid carcinoma and whereas is characterized by associated with and is the only in medullary thyroid carcinoma. In in the domain of RET and of RET M. F. A. M. A. B. PubMed Scopus Google Scholar, T. N. H. M. M. Google which together with factors the malignant of cells. medullary thyroid carcinoma mutations are the but are also in the of RET. of a in the tyrosine kinase which is also in to of RET with specificity in M. F. A. M. A. B. PubMed Scopus Google Scholar, T. N. H. M. M. Google Scholar). However, in cells, ligand to the of RET F. R. de Y. S. A. M. 1998; PubMed Scopus Google Scholar, E. L. M.G. B. A. P. 1998; PubMed Scopus Google Scholar). mouse of these mutations shown to of the malignant in human MEN2 S. B. A. M. R. J. M. S. A. PubMed Scopus Google Scholar, F. J. 2000; PubMed Scopus Google Scholar, D. 2000; PubMed Scopus Google Scholar). The and a MEN2 family and the in RET, suggests that are required to induce the In we characterized the human GFRα4 receptor and that is a functional for PSPN, which RET of GFRA4 in normal and malignant C-cells suggests is a in from different human tissues was from from was from the cell was with from human thyroid and adrenal and was from for and of by from human cells was the to the The RET of one from a family the one was for the but the was and were of which one was for the Human GFRA4 were identified from a human thyroid cDNA by the and the to the were were and PSPN, for and RET, and was for PSPN, and for RET, of human GFRA4 cDNA was together with were mammalian expression The in were the and a GFRA4 The of in two first a and a The the and was a and a of human was to the and and and a and an human were a and an in for mouse, and rat PSPN were as described in J. de Sauvage F.J. Fahrner T.J. Baloh R.H. Leitner M.L. Tansey M.G. Lampe P.A. Heuckeroth R.O. Kotzbauer P.T. Simburger K.S. Golden J.P. Davies J.A. Vejsada R. Kato A.C. Hynes M. Sherman D Nishimura M Wang L.C. Vandlen R. Mottat B. Klein R.D. Poulson K. Gray C. Garces A. Henderson C, E. Phillips H, S. Johnson Jr., E.M. Neuron. 1998; 20: 245-253Abstract Full Text Full Text PDF PubMed Scopus (440) Google in for human of of for of and for RET of The of in were by amplification of cells were with cDNA in and with PSPN was by to a of were as described A. J. S. Airaksinen M.S. E. Saarma M. J. Neurobiol. 2000; PubMed Scopus Google with in and for in the presence of different of human PSPN rat GDNF human human from J. Milbrandt and E. M. The to cells was at the was P. Scholar). cells were with for 2 and with in for the cells were with in at for were with at for were in The reaction for human and cells was as described but the cells were in 2 by at for with Ret and with The were with and by rat cells were with for and in for to with PSPN GDNF cells were and with at The were with cervical ganglion neurons from were for with cDNA of isoform of from M. and not were neurons a encoding was in were with and in and PSPN, GDNF, NRTN, all at of neurons neurons was neurons were for neurons with and were and expressed as of were for PSPN, for GDNF and NRTN, for In all and for a shown as a of were in the with GFRα4 and were and with other PSPN of the was by by at the of α In GFRA4 were as described J. K. D. A. T. S. R. M. H. Saarma M. Airaksinen M.S. Neuron. 1999; Full Text Full Text PDF PubMed Scopus Google of the thyroid by cDNA of the of human GFRA4 was as for and of and RET with the as in were and and as for and with not and of were and information from the mouse Gfra4 cDNA and (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google was to cDNA and the putative 2 to was by from human the of GFRA4 and were characterized by and of adult human thyroid cDNA and of to different of the putative of human GFRA4 and The of human GFRA4 encoding the signal high to the mouse Gfra4 (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). encoding with an signal to the signal in mouse, putative transmembrane and soluble in mouse (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google were not identified from human different spliced GFRA4 were identified and to the mouse Gfra4 (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). The a putative at and a of in the by a with a signal S. K. PubMed Scopus Google Scholar). The mouse and human is whereas the human and chicken GFRα4 is in chicken The other identified human GFRA4 transcripts in which the 2 and is in the and the of is of the splice in the The 2 and is also spliced in the of mouse of in transcripts with to a putative soluble isoform (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). In of the in human to a GPI-linked of In isoform, the and ends are to the but the of a of in different from 2 and is not to any in in which the 2 and and and are in the to a with a and of a putative soluble isoform of It is to that the of the of mouse and human and a with which is characteristic to spliced H. J. 1998; PubMed Scopus Google Scholar). of PSPN, was by in different adult and tissues 2 and not and expression of GFRA4 was at high levels in the adult thyroid at in the adrenal and thyroid whereas all other tissues not express levels of GFRA4. were with other of and not the of to the cDNA where all are spliced whereas the to the The to the cDNA 2 and encoding the putative soluble isoform The unspliced of PSPN was expressed in all human tissues the transcripts were was as a for which that the cDNA not levels of spliced PSPN transcripts encoding the functional were in adult human adrenal spinal and and were not in the thyroid gland. The for the spliced and unspliced PSPN transcripts were by RET mRNA was expressed at levels in tissues the of human PSPN to human GFRα4, we mouse cells which express Ret. cells cells not of PSPN from the cells, whereas GDNF to to and to were in the presence of Ret, human GFRα4 binds specifically PSPN, but not the other GDNF family PSPN binds to human GFRα4 with a of we the of PSPN to cells, which not express Ret. of the cells with by and by in a of and of and The a PSPN cross-linked to GFRα4 The and to PSPN cross-linked to GFRα4 and and PSPN and were from cells and The of was by PSPN by of the by of these two the of cross-linked to levels the human GFRα4 by a of the were also identified from cells In a of about was that be a complex of with Ret. the of PSPN with Ret, cross-linked in cells were with Ret 2 and The cross-linked of and as well as of about and size as in and also of were the was which the presence of cross-linked were cells and The of about and to the of and The of the complex of about be a of the PSPN to human GFRα4 Ret we cells with cells with GDNF as a PSPN Ret tyrosine autophosphorylation in cells, which a of to the form of Ret of Ret was in cells of Ret was at PSPN We of PSPN to mammalian complex functional as described for GFRα4 (3Enokido Y. de Sauvage F. Hongo J.-A. Ninkina N. Rosenthal A. Buchman V.L. Davies A.M. Curr. Biol. 1998; 8: 1019-1022Abstract Full Text Full Text PDF PubMed Google Scholar). We expressed the GPI-linked mouse Gfra4 human together with human RET in mouse neurons and the neurons with PSPN for neurons are but not PSPN by mouse expressed transcripts for Ret but not not of neurons mouse Gfra4 and RET was by PSPN PSPN, whereas of were with human was to PSPN to the neurons via endogenous Ret, whereas PSPN, the survival of neurons not from that of neurons GDNF and also of neurons and but these were not by of Gfra4 factors also neurons to neurons survival of mouse neurons complex PSPN, but not other GDNF family to a in and Ret in and mouse thyroid C-cells (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google and in adult human thyroid to the expression of RET, and PSPN mRNAs in human thyroid of GFRA4 that levels mRNAs encoding the two GPI-linked and levels of transcripts encoding the soluble isoform, are expressed in all first mRNA was not in any of the follicular thyroid follicular thyroid papillary thyroid mRNA was by in in the thyroid and was and expressed by all the malignant C-cells in the but not in the and expression was in the normal cells in thyroid including and not express GFRA4. of the thyroid expressed levels of spliced PSPN whereas the unspliced form of PSPN was in all levels of were in all of and RET mRNAs in thyroid by in of and RET to of different thyroid the of only the were and RET and mRNA levels were low in all including GFRA4 and RET were to and and were by GFRA4 and expressed in all malignant cells of the but not in the in in were for and mRNA by and in and In low levels and mRNAs were in of the cells. the GFRA4 is in the GFRA4 cDNA from the cell and normal thyroid were for a in the which not the of GFRα4, mutations were in the in the cell the of GFRA4 is not in of human and RET in thyroid and normal not expression is to expression The the the of of not in a mRNA expression is to expression The the the of of In we the of human GFRα4 encoding different of human GFRα4, two GPI-linked and one putative soluble isoform, from adult human thyroid gland. We described the and expression of mouse GFRα4 encoding different (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). in mouse, all human GFRα4 lack the first Cys-rich domain for all GFRα receptors, including chicken GFRα4 (4Thompson J. Doxakis E. Piñon L.G.P. Strachan P. Buj-Bello A. Wyatt S. Buchman V.L. Davies A.M. Mol. Cell. Neurosci. 1998; 11: 117-126Crossref PubMed Scopus (82) Google Scholar). different adult and tissues were in the adult thyroid but also at low levels in the adrenal and thyroid However, high levels of Gfra4 are in the intermediate lobe of the mouse pituitary (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google we not mRNA in the adult human due to the of the pituitary intermediate lobe in levels of GFRA4 transcripts were also in but not in the adult human adrenal whereas high are in mouse (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). expression of human GFRA4 in thyroid and adrenal suggests a and a for GFRα4 in in chicken and where Gfra4 transcripts are expressed in many tissues (4Thompson J. Doxakis E. Piñon L.G.P. Strachan P. Buj-Bello A. Wyatt S. Buchman V.L. Davies A.M. Mol. Cell. Neurosci. 1998; 11: 117-126Crossref PubMed Scopus (82) Google Scholar, M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). with human were in in to mouse for Gfra4 (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). In with T. M. N. T. M. J. 10: Google Scholar, T. Y. M. M. T. J. PubMed Scopus Google Scholar, C. T.J. 10: Google was expressed at levels in many adult human tissues, including the thyroid and adrenal The functional mRNA not identified in human (6Milbrandt J. de Sauvage F.J. Fahrner T.J. Baloh R.H. Leitner M.L. Tansey M.G. Lampe P.A. Heuckeroth R.O. Kotzbauer P.T. Simburger K.S. Golden J.P. Davies J.A. Vejsada R. Kato A.C. Hynes M. Sherman D Nishimura M Wang L.C. Vandlen R. Mottat B. Klein R.D. Poulson K. Gray C. Garces A. Henderson C, E. Phillips H, S. Johnson Jr., E.M. Neuron. 1998; 20: 245-253Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar). In we the unspliced in all human tissues However, we also low levels of the spliced PSPN mRNA in human adrenal spinal and In levels of PSPN transcripts are in tissues in rat (6Milbrandt J. de Sauvage F.J. Fahrner T.J. Baloh R.H. Leitner M.L. Tansey M.G. Lampe P.A. Heuckeroth R.O. Kotzbauer P.T. Simburger K.S. Golden J.P. Davies J.A. Vejsada R. Kato A.C. Hynes M. Sherman D Nishimura M Wang L.C. Vandlen R. Mottat B. Klein R.D. Poulson K. Gray C. Garces A. Henderson C, E. Phillips H, S. Johnson Jr., E.M. Neuron. 1998; 20: 245-253Abstract Full Text Full Text PDF PubMed Scopus (440) Google Scholar, 7Jaszai J. Farkas L. Galter D. Reuss B. Strelau J. Unsicker K. Kriegelstein K. J. Neurosci. Res. 1998; 53: 494-501Crossref PubMed Scopus (32) Google Scholar). the spliced encoding functional PSPN is expressed in the rat thyroid we not expression in adult human mouse thyroid gland. was the only where the spliced PSPN was in all rat and the of ligand for GFRα4 in human thyroid It is that functional PSPN is expressed in the thyroid at not due to the lack of of a Gfra4 cDNA encoding a different GFRα4 isoform was from rat and as a GPI-linked receptor for PSPN S. M. E. R. P. P. R.D. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). However, the signal by the rat Gfra4 cDNA in that S. M. E. R. P. P. R.D. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google is and differs from the GFRα4 signal we identified by from rat thyroid and T. rat GFRα4 signal identified by is and high to the mouse and human signal by in mouse and by in that rat GFRα4 signal is also The putative rat GFRα4 signal identified by S. M. E. R. P. P. R.D. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google with the putative signal by the spliced of mouse M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google Scholar). that mouse and rat Gfra4 two encoding of the GFRα4 In GFRA4 encoding signal were not S. M. E. R. P. P. R.D. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google identified only the rat Gfra4 and that high levels mRNA are in the to the that is in all spliced not transcripts expressed in functional with signal We shown that in mouse the transcripts are expressed at low levels in the we shown that high levels of Gfra4 mRNA are in the mouse and rat and of Gfra4 transcripts that of these transcripts a functional signal (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google not that the Gfra4 transcripts by S. M. E. R. P. P. R.D. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google in the rat The and that of PSPN with the Ret receptor kinase is by GFRα4. that in the presence of Ret, only PSPN but not GDNF, NRTN, was in from cells. The of about is of about for mouse PSPN, to chicken GFRα4 (3Enokido Y. de Sauvage F. Hongo J.-A. Ninkina N. Rosenthal A. Buchman V.L. Davies A.M. Curr. Biol. 1998; 8: 1019-1022Abstract Full Text Full Text PDF PubMed Google and the about for rat PSPN to rat GFRα4 S. M. E. R. P. P. R.D. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google but to for GFRα1, GFRα2, and and ligands R.D. Sherman D. D. B. Vandlen R. L. Hongo B. K. M. C. N. A. Phillips H. Henderson E. M. Rosenthal A. PubMed Scopus Google Scholar, M. C. N. Mol. Cell. Neurosci. 1998; 11: PubMed Scopus Google Scholar, R.H. Tansey M.G. Lampe P.A. Fahrner T.J. Enomoto H. Simburger K.S. Leitner M.L. T. Johnson Jr., E.M. Milbrandt J. Neuron. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). The of mammalian PSPN to chicken GFRα4 the in GFRα4 PSPN not characterized from chicken from the mammalian The that PSPN is able to GFRα4 also in the of Ret. is with the that a GDNF family ligand first binds to the GFRα receptor and the complex binds to Ret S. Y. Y. M. R. L. R. S. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar). However, also with the in which the ligand binds a complex M. C. D. P. C. L. S. H. R. A. R.D. S. A. PubMed Scopus Google Scholar). PSPN to chicken GFRα4 shown (3Enokido Y. de Sauvage F. Hongo J.-A. Ninkina N. Rosenthal A. Buchman V.L. Davies A.M. Curr. Biol. 1998; 8: 1019-1022Abstract Full Text Full Text PDF PubMed Google we for the first that the of PSPN with GFRα4 in of the Ret tyrosine PSPN of cells GFRα4 Ret autophosphorylation in a PSPN is to Ret autophosphorylation in cells that not express GFRα4. the isoform characterized in is a functional receptor for PSPN in Ret In to the rat GFRα4 isoform with a signal described by S. M. E. R. P. P. R.D. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google PSPN only as soluble and not to Ret We also that PSPN but not other GDNF family ligands, can promote the survival of cultured neurons and RET. In neurons RET GFRα4 an response to GDNF and but not to also the neurons to GDNF and We Ret, as well as but not Gfra4 transcripts in mouse that GDNF and these neurons via of endogenous receptors but not via GFRα4. of Ret in mouse SCG, in a A. J. Piñon L.G.P. A. J. Rosenthal A. M. Buchman V.L. Davies A.M. PubMed Scopus Google from different mouse the of PSPN to complex functional the RET an in the of a was to GFRα4 expression in these transcripts encoding the two were expressed at high in all In levels of encoding the putative soluble form of GFRα4 were in all In was in any other type of thyroid that the expression in thyroid is and GFRα4 be in It be to from and other endocrine as RET expression was also to the malignant C-cells with T. Y. M. M. T. J. PubMed Scopus Google Scholar, M. R. M. de A. Google Scholar). levels and transcripts were in of cells, that expression is not to thyroid cell is in with a expression in cells T. F. J. L. A. C. J. 2000; PubMed Scopus Google Scholar). However, low and expression also in normal in other thyroid and not in all does not support the that a in the of We that of GFRα4 with RET may tissues by MEN2 (5Lindahl M. Timmusk T. Rossi J. Saarma M. Airaksinen M.S. Mol. Cell. Neurosci. 2000; 15: 522-533Crossref PubMed Scopus (81) Google and GFRα4 be at for the of C-cells in the other as in a other GFRα receptors with the of RET receptors, and in tissues not in MEN2 K. T. H. N. A. M. K. K. A. M. Res. 2000; Google Scholar). It be to these by the is in different with MEN2 S. B. A. M. R. J. M. S. A. PubMed Scopus Google Scholar, F. J. 2000; PubMed Scopus Google Scholar, D. 2000; PubMed Scopus Google Scholar). in vitro are also to the for PSPN via different GFRα4 through normal and RET. We and for J. Milbrandt and E. M. Jr., for and M. for the human RET