Expression of neurotrophins and their receptors in peripheral lung cells of mice.
Neurotrophins play an essential role in nerve systems. Recent reports indicated that neurotrophins [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5)] have numerous effects on non-neural cells, especially on immune cells. However, whether lung cells express neurotrophins and/or their receptors (TrkA for NGF, TrkB for BDNF and NT-4/5, and TrkC for NT-3) has never been systematically investigated. We investigated constitutive expression of neurotrophin family and their Trk receptor family in alveolar macrophages and other peripheral lung cells of mice. New findings were: (1) RT-PCR for neurotrophins and their receptors detected NT-3 and NT-4/5 in alveolar macrophages, BDNF, NT-4/5, trkA, the truncated form of trkB, and trkC in lung homogenate, but no trks in alveolar macrophages, (2) immunohistochemistry for neurotrophin receptors detected TrkA in capillary cells, the truncated form of TrkB, and TrkC in interstitial macrophages, (3) immunoelectron microscopy for TrkC revealed expression of TrkC on the surface of interstitial macrophages, and (4) in situ hybridization for neurotrophins detected BDNF in interstitial macrophages and alveolar type I cells, NT-3 in alveolar macrophages, and NT-4/5 in alveolar and interstitial macrophages. These findings indicate that a previously unknown signal trafficking occurs through neurotrophins in peripheral lung.
Hikawa
Shiori
S
Department of Medicine, Kitasato University School of Medicine, Kitasato 1-15-1, Sagamihara, Kanagawa 228-8555, Japan.
Kobayashi
Hirosuke
H
Hikawa
Naoshi
N
Kusakabe
Tatsumi
T
Hiruma
Hiromi
H
Takenaka
Toshifumi
T
Tomita
Tomoyuki
T
Kawakami
Tadashi
T
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000032:analysis / Q000235:genetics; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics; D007150:Immunohistochemistry; D008168:Lung / Q000166:cytology*; D016676:Macrophages, Alveolar / Q000737:chemistry*; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D009414:Nerve Growth Factors / Q000032:analysis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D020933:Neurotrophin 3 / Q000032:analysis / Q000235:genetics; D021381:Protein Transport; D012333:RNA, Messenger / Q000032:analysis; D020917:Receptor, trkA; D020813:Receptor, trkB / Q000032:analysis / Q000235:genetics; D020812:Receptor, trkC / Q000032:analysis / Q000235:genetics; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
D019208:Brain-Derived Neurotrophic Factor; D002352:Carrier Proteins; D008565:Membrane Proteins; D009414:Nerve Growth Factors; D020933:Neurotrophin 3; D012333:RNA, Messenger; D017475:Receptors, Nerve Growth Factor; C071951:neurotrophin 5; D020917:Receptor, trkA; D020813:Receptor, trkB; D020812:Receptor, trkC; C073922:neurotrophin 4