1 Department of Preclinical Veterinary Sciences, Royal (Dick) School of Veterinary Studies, Summerhall Square, Edinburgh EH9 1QH, UK
2 Department of Molecular Oncology, Genentech, 1 DNA Way, South San Francisco, California CA 94010, USA
*Author for correspondence (e-mail: alun.davies{at}ed.ac.uk)
Accepted July 2, 2001
![]() |
SUMMARY |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: Artemin, Sympathetic neurones, Mouse, Neurotrophins
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Members of the GDNF family use multicomponent receptors that consist of a common receptor tyrosine kinase signalling component Ret (Durbec et al., 1996; Trupp et al., 1996; Vega et al., 1996; Worby et al., 1996), plus one of a family of GPI-linked receptors (GFR1 to 4) that confers ligand specificity. Studies of ligand binding, Ret phosphorylation and the responses of cells expressing these receptors have indicated that Ret/GFR
1 is the preferred receptor for GDNF (Klein et al., 1997; Jing et al., 1996; Treanor et al., 1996), Ret/GFR
2 is the preferred receptor for neurturin (Buj-Bello et al., 1997; Baloh et al., 1997; Creedon et al., 1997; Jing et al., 1997; Sanicola et al., 1997; Suvanto et al., 1997; Widenfalk et al., 1997; Trupp et al., 1998), Ret/GFR
3 is the preferred receptor for artemin (Baloh et al., 1998) and Ret/GFR
4 is the receptor for persephin (Enokido et al., 1998).
The defective formation and maintenance of the sympathetic nervous system in mice with a disrupted GFR3 (Gfra3 Mouse Genome Informatics) gene (Nishino et al., 1999) prompted our present study to clarify the role of artemin in sympathetic neurone development. GFR
3-deficient mice survive to adulthood but exhibit the characteristic features of defective cranial sympathetic function. Although the number of cells in the superior cervical ganglion (SCG) of GFR
3-/- embryos is apparently normal at E11.5 and continues to increase between E12.5 and birth, the number is only 60 to 80% of the number in wild-type SCG during this period of embryonic development. The SCG is also displaced more caudally in GFR
3-/- embryos at E12.5 and later stages, possibly owing to failure of SCG precursors to complete the last step in their rostral migration from lower cervical levels (Nishino et al., 1999). It is unclear, however, whether this defect in precursor cell migration in GFR
3-deficient embryos is the cause of the reduced number of cells in the early SCG or whether artemin-GFR
3 signalling plays a role in sympathetic neuroblast proliferation or differentiation. By birth, the sympathetic innervation of several tissues is defective in GFR
3-/- mice, and during the postnatal period there is progressive death of neurones in the SCG so that by P60 fewer than 5% of the neurones remain (Nishino et al., 1999). It is unclear, however, whether this loss of SCG neurones is because sympathetic neurones depend on artemin for survival or whether the neurones fail to obtain other target-derived neurotrophic factors because artemin/GFR
3 signalling plays a key role in establishing sympathetic innervation. To shed light on these issues, we have examined the effects of artemin on sympathetic neurone generation, survival and growth in dissociated sympathetic ganglion cultures established over a broad range of ages from E12 to adulthood. We show that artemin promotes neuroblast proliferation and neurone generation, and that it enhances neurite growth and sustains sympathetic neurone survival at different stages of development.
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
To obtain a simple estimate of the number of neurones surviving in these cultures under different experimental conditions, the number of attached neurones within a 12x12 mm grid in the centre of each dish was initially counted 6 hours after plating and was counted again at time intervals thereafter. The number of neurones present in the grid at these later times is expressed as a percentage of the initial count at 6 hours. In each experiment, triplicate cultures were set up for all conditions.
Because neurones are generated from proliferating progenitor cells in cultures of early SCG and SG, the number of neurones surviving in these cultures at intervals following plating is influenced not only by the length of time individual differentiated neurones survive, but also by the rate at which neurones are generated from their progenitors. To quantify both of these parameters in the same experiment, we followed the survival of the neurones that comprised an initial cohort identified shortly after plating, monitored the generation of new neurones at intervals and followed the survival of these newly generated neurones. In these cumulative cohort experiments, the initial cohort was identified within a 12x12 mm grid in the centre of 60 mm culture dishes 6 hours after plating. The survival of these neurones was monitored at 6 hourly intervals and is expressed as a percentage of the starting number of neurones in the initial cohort. In addition to following the survival of neurones in the initial cohort, the generation of new neurones in the same grid was monitored at each time point. This established new cohorts of neurones that were generated between 6 and 12 hours, 12 and 18 hours, 18 and 24 hours, 24 and 30 hours, and 30 and 36 hours. The survival of neurones in each of these newly identified cohorts was subsequently monitored at 6 hourly intervals after their identification. The number of neurones in these cohorts is expressed as a percentage of the number of neurones in the initial cohort identified 6 hours after plating. The results of each experiment are plotted in stacking bar charts.
Neuroblast proliferation in vitro
Neuroblast proliferation was measured in vitro by determining the number of neuroblasts that incorporated bromodeoxyuridine (BrdU) into their nuclei using immunocytochemistry. Cells were plated in 24-well multiwell plates (Costar), BrdU was added at various times after plating the cells and the cultures were incubated for a further period to permit incorporation of BrdU into S-phase cell nuclei. The cells were then fixed in methanol (-20°C for 15 minutes) and were stained for nuclear BrdU incorporation using an anti-BrdU monoclonal antibody (Sigma) diluted 1:500 in phosphate-buffered saline (PBS) for 48 hours at 4°C. The cells were then labelled using biotinylated secondary antibody (1:200), avidin and biotinylated horseradish peroxidase macromolecular complex (Vectastain ABC Kit, Vector Labs). The substrate used for the reaction was diaminobenzidine tetrachloride (DAB substrate kit, Vector Labs). The number of BrdU-positive cells is expressed as a percentage of total cell number.
Generation of GFR3-/- mice
A BAC clone containing the GFR3 gene was isolated and used to construct a targeting vector. A pGK1-neo cassette flanked 5' by a 1.6 kb PCR fragment located approximately 1.5 kb upstream of the initiation ATG and 3' by a 5.3 kb EcoRI-XhoI fragment immediately downstream of exon 1 was used to delete a 2 kb fragment containing the first exon of GFR
3. Linearised DNA (20 µg) was used to electroporate 1x107 ES R1 cells. G418/Gancyclovir resistant clones were screened for homologous recombination by Southern analysis. Genomic DNA was digested with HindIII and hybridised with a 1.5 kb EcoRI-PstI fragment located upstream of the 1.6 kb short arm. Homologous recombination was detected at a frequency of 1/100 clones. Three independent targeted clones were used to generate chimeric animals by injection into C57BL/6 blastocysts. Male chimeras were bred with C57BL/6 females, and heterozygous offspring were interbred to generate GFR
3-/- mice. These mice were back-crossed into a CD1 background (the same in which all other experiments were carried out).
Neuroblast proliferation in GFR3-deficient embryos
Embryos were obtained from overnight matings of GFR3+/- mice. Pregnant females were killed by cervical dislocation after 14 days gestation, and the genotypes of the embryos were determined by a PCR-based technique using DNA isolated from embryonic bodies. The heads were fixed for 30 minutes in Carnoys fluid (60% ethanol, 30% chloroform and 10% glacial acetic acid). After dehydration through a graded alcohol series, the tissue was paraffin wax embedded. Serial sections of the heads in the region of the SCG were cut at 8 µm and were mounted onto poly-lysine-coated slides (BDH) or Gold Seal Ultrastick Slides (Erie Scientific).
To monitor neuroblast proliferation, the sections were stained for the presence of the proliferating cell nuclear antigen (PCNA). Because expression of PCNA is not restricted to dividing neuronal cells, the sections were double stained for ßIII tubulin to identify all neuroblasts and neurones in the SCG. The sections were cleared in xylene and rehydrated before quenching in 3% hydrogen peroxide in methanol for 20 minutes. Nonspecific antibody binding was blocked in 10% horse serum, 0.5% Triton X-100 in PBS before incubation with anti-PCNA monoclonal antibody (Sigma) diluted 1:1000 in blocking buffer for 1 hour at room temperature. The cells were then labelled using biotinylated secondary antibody (1:200), avidin and biotinylated horseradish peroxidase macromolecular complex (Vectastain ABC Kit, Vector Labs). The substrate used for the reaction was 1mg/ml diaminobenzidine tetrachloride (FastDAB, Sigma). The sections were then incubated with mouse anti-ßIII tubulin antibody (Promega) diluted 1:5000 in blocking buffer overnight at 4°C. The cells were then labelled using biotinylated secondary antibody (1:200), avidin, biotinylated horseradish peroxidase macromolecular complex (Vectastain ABC Kit, Vector Labs) and visualised using a VIP substrate kit (Vector Labs) which produced an intense purple reaction product.
The total number of ßIII tubulin-positive cells and the number of ßIII tubulin-positive cells that were also PCNA positive were estimated using a digital stereology system that uses a combination of the optical dissector and volume fraction/Cavalieri methods (Kinetics Imaging).
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
Reduced neuroblast proliferation in GFR3-deficient embryos
To ascertain whether the effects of artemin on neuroblast proliferation observed in vitro are physiologically relevant, we generated GFR3-deficient mice by gene targeting and compared neuroblast proliferation in the E14 SCG of wild-type and GFR
3-/- embryos. A targeting vector where the first exon containing the signal sequence was replaced by a PGK1-neo cassette was transfected into embryonic stem cells (Fig. 4). Gene targeting was detected in 1/100 ES colonies and three clones were selected for microinjection into blastocysts. Chimeric mice with appropriate germline transmission were back-crossed into a CD1 background.
|
|
|
|
|
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The effect of artemin on enhancing neuroblast proliferation and the generation of post-mitotic sympathetic neurones was revealed by studying BrdU incorporation in dissociated cultures established from early sympathetic ganglia, and by detailed analysis of the generation of new neurones in cumulative cohort experiments set up throughout the phase of neurogenesis in the sympathetic chain. The physiological relevance of these in vitro observations was substantiated by our demonstration that there is a marked reduction in the proportion of sympathetic neuroblasts in the mitotic phase of the cell cycle in embryos deficient in the GFR3 subunit of the artemin receptor. Although a reduction in the size of the SCG has been reported in GFR
3-deficient embryos, this was attributed to a failure of SCG precursors to complete the last step in their rostral migration from lower cervical levels (Nishino et al., 1999). Although this is the likely reason for the more caudal location of the SCG in GFR
3-/- embryos, and may contribute to the reduced size of this ganglion in these embryos, our findings suggest that a major contributing factor to the decreased size of the SCG is a marked reduction in neuroblast proliferation. A local action of artemin on neuroblast proliferation within the early SCG is consistent with the in vivo expression of artemin and GFR
3. By in situ hybridisation, artemin mRNA is detectable in the SCG and in the region surrounding the SCG precursors, and GFR
3 mRNA is expressed by the majority of cells in the SCG during this early stage in development (Nishino et al., 1999).
What little is known about the signals that potentially regulate sympathetic neuroblast proliferation has been gleaned from in vitro studies of these cells obtained from mammalian and avian embryos. It has been reported that insulin, insulin-like growth factor 1, pituitary adenylate cyclase-activating polypeptide (PACAP), NT3 and retinoic acid promote the proliferation of rat sympathetic neuroblasts in culture (DiCicco-Bloom and Black, 1988; DiCicco-Bloom and Black, 1989; DiCicco-Bloom et al., 1993; Wyatt et al., 1999; DiCicco-Bloom et al., 2000). However, the physiological significance of these in vitro observations is unclear. In the case of NT3, appropriate numbers of sympathetic neurones are generated in NT3-deficient mouse embryos, and enhanced neuronal death occurs only after the phase of neurogenesis is over (Wyatt et al., 1997; Francis et al., 1999). Likewise, the demonstration that CNTF decreases neuroblast proliferation in cultures of embryonic chicken sympathetic chain (Ernsberger et al., 1989) is unclear because in rodents, at least, CNTF synthesis does not commence until after birth (Dobrea et al., 1992). By using complimentary in vitro and in vivo approaches, we have provided the first clear evidence that an identified growth factor plays a physiologically significant role in promoting the proliferation of sympathetic neuroblasts, leading to the increased generation of sympathetic neurones.
Analysis of neuronal survival in cohort experiments established from early sympathetic ganglia clearly shows that artemin sustains the survival of newly generated sympathetic neurones for a brief period after they have undergone their terminal mitosis. This survival effect is no longer evident after E16, and no survival effect of artemin was observed on SCG neurones cultured between this stage and P8. However, by P12, a marked survival response to artemin was observed which was sustained through later ages. The appearance of this late survival response to artemin coincides with the ability of an increasing proportion of sympathetic neurones to survive in culture without added neurotrophic factors. However, the possibility that the production and release of artemin within cultures of mature sympathetic neurones is responsible for the appearance of neurotrophic factor-independent survival is excluded by the lack of effect of function-blocking anti-GFR3 antibodies on the survival of mature sympathetic neurones.
Previous in vitro studies have reported that artemin promotes the survival of newborn rat sympathetic and sensory neurones (Baloh et al., 1998), and postnatal mouse sensory neurones (Baudet et al., 2000). However, our detailed developmental study has revealed a novel phenomenon that has not previously been described for any other neurotrophic factor, namely, that the same population of neurones exhibits two distinct phases of responsiveness to a factor separated by an extended period during which the factor has no effect on survival. These two phases in the survival-promoting action of artemin on embryonic and late postnatal sympathetic neurones observed in vitro might correspond to local and target-derived actions of artemin, respectively, on sympathetic neurone survival in vivo.
Curiously, although artemin did not promote the survival of cultured SCG neurones between birth and P8 (Figs 6 and 7), these neurones start to die at an abnormally high rate in GFR3-deficient mice during this period of development (Nishino et al., 1999). It is possible that this abnormal death of SCG neurones may be because absence of artemin/GFR
3 signalling earlier in development might have affected the ability of the neurones to innervate their targets appropriately and to obtain an adequately supply of target-derived NGF and NT3 on which they depend for their survival (Levi-Montalcini and Booker, 1960; Zhou and Rush, 1995). It should be noted that the SCG of GFR
3-/- mice forms in an abnormal anatomical location (Nishino et al., 1999) that might affect the subsequent guidance of sympathetic axons to their correct targets.
In addition to enhancing the survival of late postnatal sympathetic neurones, artemin increased neurite growth from these neurones to a greater extent than NGF. The effects of NGF on promoting neurite growth are well documented both in vitro and in vivo (Edwards et al., 1989; Purves et al., 1988; Scott and Davies, 1993; Snider, 1988). Recently, other neurotrophic factors have been shown to synergise with NGF in promoting neurite outgrowth. For example, HGF enhances neurite growth from embryonic sensory and sympathetic neurones in the presence of NGF (Maina et al., 1998; Maina et al., 1997) and enhances neurite growth from postnatal SCG neurones (Yang et al., 1998). It is possible that the effect of artemin on neurite growth observed in vitro may reflect a role for artemin in establishing and maintaining target field innervation in vivo. Indeed, the loss of this effect of artemin in GFR3-deficient mice may at least be partly responsible for the observed deficiency of sympathetic axons in several tissues in the postnatal period (Nishino et al., 1999).
In summary, we have defined the roles of artemin at different stages in the development of the sympathetic nervous system by studying its effects on neuroblasts and neurones in culture and by analysing embryos defective in artemin signalling. We have shown that artemin increases sympathetic neuroblast division, and provide the first evidence that a growth factor is a physiologically relevant regulator of the proliferation of these neuroblasts. Artemin subsequently promotes the survival of newly differentiated sympathetic neurones for a brief period after they have undergone their terminal mitosis. Then, uniquely for a neurotrophic factor, artemin promotes the survival of these neurones for a second time several weeks after birth. During this late stage in their development, artemin also enhances neurite growth to a greater extent than NGF. Our results provide a clear illustration of how a single factor can exert a diversity of actions on a population of neurones at different stages in its development and raise interesting questions about the nature of the signalling pathways mediating these different responses.
![]() |
ACKNOWLEDGMENTS |
---|
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Acheson, A., Conover, J. C., Fandl, J. P., DeChlara, T. M., Russell, M., Thadani, A., Squinto, S. P., Yancopoulos, G. D. and Lindsay, R. M. (1995). A BDNF autocrine loop in adult sensory neurons prevents cell death. Nature 374, 450-453.[Medline]
Arenas, E., Trupp, M., Akerud, P. and Ibanez, C. F. (1995). GDNF prevents degeneration and promotes the phenotype of brain noradrenergic neurons in vivo. Neuron 15, 1465-1473.[Medline]
Baloh, R. H., Tansey, M. G., Lampe, P. A., Fahrner, T. J., Enomoto, H., Simburger, K. S., Leitner, M. L., Araki, T., Johnson, E. M. and Milbrandt, J. (1998). Artemin, a novel member of the GDNF ligand family, supports peripheral and central neurons and signals through the GFR3-RET receptor complex. Neuron 21, 1291-1302.[Medline]
Baloh, R. H., Tansey, M. G., Golden, J. P., Creedon, D. J., Heuckeroth, R. O., Keck, C. L., Zimonjic, D. B., Popescu, N. C., Johnson, E. M. J. and Milbrandt, J. (1997). TrnR2, a novel receptor that mediates neurturin and GDNF signaling through Ret. Neuron 18, 793-802.[Medline]
Baudet, C., Mikaels, A., Westphal, H., Johansen, J., Johansen, T. E. and Ernfors, P. (2000). Positive and negative interactions of GDNF, NTN and ART in developing sensory neuron subpopulations, and their collaboration with neurotrophins. Development 127, 4335-4344.
Buj-Bello, A., Buchman, V. L., Horton, A., Rosenthal, A. and Davies, A. M. (1995). GDNF is an age-specific survival factor for sensory and autonomic neurons. Neuron 15, 821-828.[Medline]
Buj-Bello, A., Adu, J., Piñón, L. G. P., Horton, A., Thompson, J., Rosenthal, A., Chinchetru, M., Buchman, V. L. and Davies, A. M. (1997). Neurturin responsiveness requires a GPI-linked receptor plus the Ret receptor tyrosine kinase. Nature 387, 721-724.[Medline]
Cacalano, G., Farinas, I., Wang, L., Hagler, K., Forgie, A., Moore, M., Armanini, M., Phillips, H., Ryan, A. M., Reichardt, L. F. et al. (1998). GFRalpha1 is an essential receptor component for GDNF in the developing nervous system and kidney. Neuron 21, 53-62.[Medline]
Creedon, D. J., Tansey, M. G., Baloh, R. H., Osborne, P. A., Lampe, P. A., Fahrner, T. J., Heuckeroth, R. O., Milbrandt, J. and Johnson, E. M. J. (1997). Neurturin shares receptors and signal transduction pathways with glial cell line-derived neurotrophic factor in sympathetic neurons. Proc. Natl. Acad. Sci. USA 94, 7018-7023.
Davies, A. M., Lee, K. F. and Jaenisch, R. (1993). p75-deficient trigeminal sensory neurons have an altered response to NGF but not to other neurotrophins. Neuron 11, 565-574.[Medline]
DiCicco-Bloom, E., Deutsch, P. J., Maltzman, J., Zhang, J., Pintar, J. E., Zheng, J., Friedman, W. F., Zhou, X. and Zaremba, T. (2000). Autocrine expression and ontogenetic functions of the PACAP ligand/receptor system during sympathetic development. Dev. Biol. 219, 197-213.[Medline]
DiCicco-Bloom, E. and Black, I. B. (1988). Insulin growth factors regulate the mitotic cycle in cultured rat sympathetic neuroblasts. Proc. Natl. Acad. Sci. USA 85, 4066-4070.[Abstract]
DiCicco-Bloom, E. and Black, I. B. (1989). Depolarisation and insulin-like growth factor-I differentially regulate the mitotic cycle in cultured rat sympathetic neuroblasts. Brain Res. 491, 403-406.[Medline]
DiCicco-Bloom, E., Friedman, W. J. and Black, I. B. (1993). NT-3 stimulates sympathetic neuroblast proliferation by promoting precursor cell survival. Neuron 11, 1101-1111.[Medline]
Dobrea, G. M., Unnerstall, J. R. and Rao, M. S. (1992). The expression of CNTF message and immunoreactivity in the central and peripheral nervous system of the rat. Dev. Brain Res. 66, 209-219.[Medline]
Durbec, P., Marcos-Gutierrez, C. V., Kilkenny, C., Grigoriou, M., Wartiowaara, K., Suvanto, P., Smith, D., Ponder, B., Costantini, F., Saarma, M. et al. (1996). GDNF signalling through the Ret receptor tyrosine kinase. Nature 381, 789-793.[Medline]
Edwards, R. H., Rutter, W. J. and Hanahan, D. (1989). Directed expression of NGF to pancreatic beta cells in transgenic mice leads to selective hyperinnervation of the islets. Cell 58, 161-170.[Medline]
Enokido, Y., de Sauvage, F., Hongo, J., Ninkina, N., Rosenthal, A., Buchman, V. and Davies, A. M. (1998). GFR-4 and the tyrosine kinase Ret form a functional receptor complex for persephin. Curr. Biol. 8, 1019-1022.[Medline]
Enomoto, H., Araki, T., Jackman, A., Heuckeroth, R. O., Snider, W. D., Johnson, E. M., Jr. and Milbrandt, J. (1998). GFR alpha1-deficient mice have deficits in the enteric nervous system and kidneys. Neuron 21, 317-324.[Medline]
Enomoto, H., Heuckeroth, R. O., Golden, J. P., Johnson, E. M. and Milbrandt, J. (2000). Development of cranial parasympathetic ganglia requires sequential actions of GDNF and neurturin. Development 127, 4877-4889.
Ernsberger, U., Sendtner, M. and Rohrer, H. (1989). Proliferation and differentiation of embryonic chick sympathetic neurons: effects of ciliary neurotrophic factor. Neuron 2, 1275-1284.[Medline]
Forgie, A., Doxakis, E., Buj-Bello, A., Wyatt, S. and Davies, A. M. (1999). Differences and developmental changes in the responsiveness of PNS neurons to GDNF and neurturin. Mol. Cell. Neurosci. 13, 430- 440.[Medline]
Francis, N., Farinas, I., Brennan, C., Rivas-Plata, K., Backus, C., Reichardt, L. and Landis, S. (1999). NT-3, like NGF, is required for survival of sympathetic neurons, but not their precursors. Dev. Biol. 210, 411-427.[Medline]
Ha, D. H., Robertson, R. T., Ribak, C. E. and Weiss, J. H. (1996). Cultured basal forebrain cholinergic neurons in contact with cortical cells display synapses, enhanced morphological features, and decreased dependence on nerve growth factor. J. Comp. Neurol. 373, 451-465.[Medline]
Henderson, C. E., Phillips, H. S., Pollock, R. A., Davies, A. M., Lemeulle, C., Armanini, M. P., Simpson, L. C., Moffet, B., Vandlen, R. A., Koliatsos, V. E. et al. (1994). GDNF: a potent survival factor for motoneurons present in peripheral nerve and muscle. Science 266, 1062-1064.[Medline]
Heuckeroth, R. O., Lampe, P. A., Johnson, E. M. and Milbrandt, J. (1998). Neurturin and GDNF promote proliferation and survival of enteric neuron and glial progenitors in vitro. Dev. Biol. 200, 116-129.[Medline]
Jing, S., Wen, D., Yu, Y., Holst, P. L., Luo, Y., Fang, M., Tamir, R., Antonio, L., Hu, Z., Cupples, R. et al. (1996). GDNF-induced activation of the ret protein tyrosine kinase is mediated by GDNFR-alpha, a novel receptor for GDNF. Cell 85, 1113-1124.[Medline]
Jing, S., Yu, Y., Fang, M., Hu, Z., Holst, P. L., Boone, T., Delaney, J., Schultz, H., Zhou, R. and Fox, G. M. (1997). GFR-2 and GFR
-3 are two new receptors for ligands of the GDNF family. J. Biol. Chem. 272, 33111-33117.
Klein, R. D., Sherman, D., Ho, W., Stone, D., Bennett, G. L., Moffat, B., Vandlen, R., Simmons, L., Gu, Q., Hongo, J. et al. (1997). A GPI-linked protein that interacts with Ret to form a candidate neurturin receptor. Nature 387, 717-721.[Medline]
Kotzbauer, P. T., Lampe, P. A., Heuckeroth, R. O., Golden, J. P., Creedon, D. J., Johnson, E. M. J. and Milbrandt, J. (1996). Neurturin, a relative of glial-cell-line-derived neurotrophic factor. Nature 384, 467-470.[Medline]
Kurki, P., Vanderlaan, M., Dolbeare, F., Gray, J. and Tan, E. M. (1986). Expression of proliferating cell nuclear antigen (PCNA)/cyclin during the cell cycle. Exp Cell Res 166, 209-219.[Medline]
Levi-Montalcini, R. and Booker, B. (1960). Destruction of the sympathetic ganglia in mammals by an antiserum to the nerve growth-promoting factor. Proc. Natl. Acad. Sci. USA 42, 384-391.
Lin, L. H., Doherty, D. H., Lile, J. D., Bektesh, S. and Collins, F. (1993). GDNF: A glial cell-derived neurotrophic factor for midbrain dopaminergic neurons. Science 260, 1130-1132.[Medline]
Maina, F., Hilton, M. C., Ponzetto, C., Davies, A. M. and Klein, R. (1997). Met receptor signalling is required for sensory nerve development. Genes Dev. 11, 3341-3350.
Maina, F., Hilton, M. C., Andres, R., Wyatt, S., Klein, R. and Davies, A. M. (1998). Multiple roles for hepatocyte growth factor in sympathetic neuron development. Neuron 20, 835-846.[Medline]
Milbrandt, 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. et al. (1998). Persephin, a novel neurotrophic factor related to GDNF and neurturin. Neuron 20, 245-253.[Medline]
Molliver, D. C., Wright, D. E., Leitner, M. L., Parsadanian, A. S., Doster, K., Wen, D., Yan, Q. and Snider, W. D. (1997). IB4-binding DRG neurons switch from NGF to GDNF dependence in early postnatal life. Neuron 19, 849-861.[Medline]
Moore, M. W., Klein, R. D., Farinas, I., Sauer, H., Armanini, M., Phillips, H., Reicherdt, L. F., Ryan, A. M., Carver-Moore, K. and Rosenthal, A. (1996). Renal and neuronal abnormalities in mice lacking GDNF. Nature 382, 76-79.[Medline]
Nishino, J., Mochida, K., Ohfuji, Y., Shimazaki, T., Meno, C., Ohishi, S., Matsuda, Y., Fujii, H., Saijoh, Y. and Hamada, H. (1999). GFR alpha3, a component of the artemin receptor, is required for migration and survival of the superior cervical ganglion. Neuron 23, 725-736.[Medline]
Pichel, J. G., Shen, L., Sheng, H. Z., Granholm, A., Drago, J., Grinberg, A., Lee, E. J., Huang, S. P., Saarma, M., Hoffer, B. J. et al. (1996). Defects in enteric innervation and kidney development in mice lacking GDNF. Nature 382, 73-76.[Medline]
Purves, D., Snider, W. D. and Voyvodic, J. T. (1988). Trophic regulation of nerve cell morphology and innervation in the autonomic nervous system. Nature 336, 123-128.[Medline]
Rohrer, H. and Thoenen, H. (1987). Relationship between differentiation and terminal mitosis: chick sensory and ciliary neurons differentiate after terminal mitosis of precursor cells, whereas sympathetic neurons continue to divide after differentiation. J. Neurosci. 7, 3739-3748.[Abstract]
Sanchez, M. P., Silos-Santiago, I., Frisen, J., He, B., Sergio, S. A. and Barbacid, M. (1996). Renal agenesis and the absence of enteric neurons in mice lacking GDNF. Nature 382, 70-73.[Medline]
Sanicola, M., Hession, C., Worley, D., Carmillo, P., Ehrenfels, C., Walus, L., Robinson, S., Jaworski, G., Wei, H., Tizard, R. et al. (1997). Glial cell line-derived neurotrophic factor-dependent RET activation can be mediated by two different cell-surface accessory proteins. Proc. Natl. Acad. Sci. USA 94, 6238-6243.
Scott, S. A. and Davies, A. M. (1993). Age-related effects of nerve growth factor on the morphology of embryonic sensory neurons in vitro. J. Comp. Neurol. 337, 277-285.[Medline]
Snider, W. D. (1988). Nerve growth factor enhances dendritic arborization of sympathetic ganglion cells in developing mammals. J. Neurosci. 8, 2628-2634.[Abstract]
Suter-Crazzolara, C. and Unsicker, K. (1994). GDNF is expressed in two forms in many tissues outside the CNS. NeuroReport 5, 2486-2488.[Medline]
Suvanto, P., Wartiovaara, K., Lindahl, M., Arumae, U., Moshnyakov, M., Horelli-Kuitunen, N., Airaksinen, M. S., Palotie, A., Sariola, H. and Saarma, M. (1997). Cloning, mRNA distribution and chromosomal localisation of the gene for glial cell line-derived neurotrophic factor receptor beta, a homologue to GDNFR-alpha. Hum. Mol. Genet. 6, 1267-1273.
Treanor, J., Goodman, L., de Sauvage, F., Stone, D., Poulsen, K., Beck, K., Gary, C., Armanini, M., Pollock, R., Hefti, F. et al. (1996). Characterization of a receptor for glial cell line-derived neurotrophic factor. Nature 382, 80-83.[Medline]
Trupp, M., Ryden, M., Jornvall, H., Funakoshi, H., Timmusk, T., Arenas, E. and Ibanez, C. F. (1995). Peripheral expression and biological activities of GDNF, a new neurotrophic factor for avian and mammalian peripheral neurons. J. Cell Biol. 130, 137-148.[Abstract]
Trupp, M., Arenas, E., Fainzilber, M., Nilsson, A., Sieber, B., Grigoriou, M., Kilkenny, C., Salazar-Grueso, E., Pachnis, V., Arumae, U. et al. (1996). Functional receptor for GDNF encoded by the c-ret proto-oncogene. Nature 381, 785-789.[Medline]
Trupp, M., Raynoschek, C., Belluardo, N. and Ibanez, C. F. (1998). Multiple GPI-anchored receptors control GDNF-dependent and independent activation of the c-ret receptor tyrosine kinase. Mol. Cell. Neurosci. 11, 47-63.[Medline]
Vega, Q. C., Worby, C. A., Lechner, M. S., Dixon, J. E. and Dressler, G. R. (1996). Glial cell line-derived neurotrophic factor activates the receptor tyrosine kinase RET and promotes kidney morphogenesis. Proc. Natl. Acad. Sci. USA 93, 10657-10661.
Widenfalk, J., Nosrat, C., Tomac, A., Westphal, H., Hoffer, B. and Olson, L. (1997). Neurturin and glial cell line-derived neurotrophic factor receptor-beta (GDNFR-beta), novel proteins related to GDNF and GDNFR-alpha with specific cellular patterns of expression suggesting roles in the developing and adult nervous system and in peripheral organs. J. Neurosci. 17, 8506-8519.
Williams, L. R., Inouye, G., Cummins, V. and Pelleymounter, M. A. (1996). Glial cell line-derived neurotrophic factor sustains axotomized basal forebrain cholinergic neurons in vivo: dose-response comparison to nerve growth factor and brain-derived neurotrophic factor. J. Pharmacol. Exp. Ther. 277, 1140-1151.[Abstract]
Worby, C. A., Vega, Q. C., Zhao, Y., Chao, H. H. J., Seasholtz, A. F. and Dixon, J. E. (1996). Glial cell line-derived neurotrophic factor signals through the RET receptor and activates mitogen-activated protein kinase. J. Biol. Chem. 271, 23619-23622.
Wright, E. M., Vogel, K. S. and Davies, A. M. (1992). Neurotrophic factors promote the maturation of developing sensory neurons before they become dependent on these factors for survival. Neuron 9, 139-150.[Medline]
Wright, D. E. and Snider, W. D. (1996). Focal expression of glial cell line-derived neurotrophic factor in developing mouse limb bud. Cell Tissue Res. 286, 209-217.[Medline]
Wyatt, S., Piñón, L. G. P., Ernfors, P. and Davies, A. M. (1997). Sympathetic neuron survival and TrkA expression in NT3-deficient mouse embryos. EMBO J. 16, 3115-3123.
Wyatt, S., Andres, R., Rohrer, H. and Davies, A. M. (1999). Regulation of neurotrophin receptor expression by retinoic acid in mouse sympathetic neuroblasts. J. Neurosci. 19, 1062-1071.
Yang, X. M., Toma, J. G., Bamji, S. X., Belliveau, D. J., Kohn, J., Park, M. and Miller, F. D. (1998). Autocrine hepatocyte growth factor provides a local mechanism for promoting axonal growth. J. Neurosci. 18, 8369-8381.
Zhou, X. and Rush, R. A. (1995). Sympathetic neurons in neonatal rats require endogenous neurotrophin-3 for survival. J. Neurosci. 15, 6521-6530.[Medline]