Novel neurotrophin-1/B cell-stimulating factor-3 (cardiotrophin-like cytokine) stimulates corticotroph function via a signal transducer and activator of transcription-dependent mechanism negatively regulated by suppressor of cytokine signaling-3.
Novel neurotrophin-1/B cell-stimulating factor-3 (NNT-1/BSF-3) is a recently cloned gp130 cytokine, acting through the tripartite ciliary neurotrophic factor receptor (CNTFR) alpha/leukemia inhibitory factor receptor (LIFR)/gp130 receptor complex. The aim of the current study was to investigate the role of NNT-1/BSF-3 in corticotroph cell function and further characterize NNT-1/BSF-3 signaling pathways. Using RT-PCR, expression of ciliary neurotrophic factor receptor alpha, leukemia inhibitory factor receptor, and gp130 could be demonstrated in mRNA derived from murine corticotroph AtT-20 cells and murine pituitary tissue. Incubation of AtT-20 cells with 10 ng/ml recombinant human NNT-1/BSF-3 rapidly induced tyrosine-phosphorylation of signal transducer and activator of transcription (STAT)3 and STAT1 at 5 and 10 min. Proopiomelanocortin promoter activity and suppressor of cytokine signaling (SOCS)-3 promoter activity were significantly stimulated by NNT-1/BSF-3 4.0 +/- 0.3- and 5.9 +/- 0.2-fold, respectively. In comparison with untreated control, NNT-1/BSF-3 significantly stimulated ACTH secretion at 24 and 48 h 1.7 +/- 0.2-fold and 1.5 +/- 0.1-fold above baseline. In comparison with mock-transfected cells, stable overexpression of SOCS-3 in AtT-20 cells abolished NNT-1/BSF-3-induced STAT1 and STAT3 phosphorylation and almost completely inhibited STAT-dependent proopiomelanocortin promoter and SOCS-3 promoter activities. In addition, NNT-1/BSF-3-induced ACTH secretion at 48 h was significantly attenuated by SOCS-3 overexpression. In summary, we have shown that NNT-1/BSF-3 is a modulator of corticotroph cell function, which is negatively regulated by SOCS-3. Our data indicate that the activation of the Jak-STAT cascade is essential for corticotroph NNT-1/BSF-3 signaling. Further studies will have to investigate the possible in vivo role of NNT-1/BSF-3 as a neuroimmunoendocrine modulator of hypothalamus-pituitary-adrenal axis stress response.
Auernhammer
Christoph J
CJ
Department of Internal Medicine II, Klinikum Grosshadern, Ludwig-Maximilians-Universität, Munich 81366, Germany. christoph.auernhammer@med2.med.uni-muenchen.de
Isele
Nicola B
NB
Kopp
Florian B
FB
Spoettl
Gerald
G
Cengic
Neziha
N
Weber
Matthias M
MM
Senaldi
Giorgio
G
Engelhardt
Dieter
D
D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000235:genetics; D002478:Cells, Cultured; D050822:Cytokine Receptor gp130; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D008562:Membrane Glycoproteins / Q000235:genetics; D015213:Neuroimmunomodulation / Q000502:physiology; D010766:Phosphorylation; D010902:Pituitary Gland / Q000166:cytology* / Q000502:physiology; D011333:Pro-Opiomelanocortin / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020801:Receptor, Ciliary Neurotrophic Factor / Q000235:genetics; D018121:Receptors, Cytokine / Q000235:genetics; D053606:Receptors, OSM-LIF; D012097:Repressor Proteins; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000502:physiology*; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors
D015703:Antigens, CD; D016207:Cytokines; D004268:DNA-Binding Proteins; C494199:IL6ST protein, human; C507840:LIFR protein, human; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D008562:Membrane Glycoproteins; D011506:Proteins; D012333:RNA, Messenger; D020801:Receptor, Ciliary Neurotrophic Factor; D018121:Receptors, Cytokine; D053606:Receptors, OSM-LIF; D012097:Repressor Proteins; C106644:SOCS3 protein, human; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C121169:cardiotrophin-like cytokine; D050822:Cytokine Receptor gp130; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone