Role of macrophage-stimulating protein and its receptor, RON tyrosine kinase, in ciliary motility.
Macrophage-stimulating protein (MSP) is an 80-kD serum protein with homology to hepatocyte growth factor (HGF). Its receptor, RON tyrosine kinase, is a new member of the HGF receptor family. The MSP-RON signaling pathway has been implicated in the functional regulation of mononuclear phagocytes. However, the function of this pathway in other types of cells has not been elucidated. Here we show that in contrast to the HGF receptor, which was expressed at the basolateral surface, RON was localized at the apical surface of ciliated epithelia in the airways and oviduct. In addition, MSP was found in the bronchoalveolar space at biologically significant concentrations. MSP bound to RON on normal human bronchial epithelial cells with a high affinity (Kd = 0.5 nM) and induced autophosphorylation of RON. Activation of RON by MSP led to a significant increase in ciliary beat frequency of human nasal cilia. These findings indicate that the ciliated epithelium of the mucociliary transport apparatus is a novel target of MSP. Ciliary motility is critical for mucociliary transport. Our findings suggest that the MSP-RON signaling pathway is a novel regulatory system of mucociliary function and might be involved in the host defense and fertilization.
Sakamoto
O
O
Department of Cell Differentiation, Institute of Molecular Embryology and Genetics, Kumamoto University School of Medicine, Japan.
Iwama
A
A
Amitani
R
R
Takehara
T
T
Yamaguchi
N
N
Yamamoto
T
T
Masuyama
K
K
Yamanaka
T
T
Ando
M
M
Suda
T
T
D000818:Animals; D001980:Bronchi / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002923:Cilia / Q000201:enzymology / Q000502:physiology / Q000648:ultrastructure; D004848:Epithelium / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D005187:Fallopian Tubes / Q000201:enzymology; D005260:Female; D006133:Growth Substances / Q000378:metabolism / Q000502:physiology*; D017228:Hepatocyte Growth Factor; D006801:Humans; D016676:Macrophages, Alveolar / Q000201:enzymology* / Q000502:physiology*; D009296:Nasal Cavity / Q000201:enzymology; D009928:Organ Specificity; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000502:physiology* / Q000648:ultrastructure; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000502:physiology* / Q000648:ultrastructure
D006133:Growth Substances; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; C082332:macrophage stimulating protein; D017228:Hepatocyte Growth Factor; C080835:RON protein; D020794:Receptor Protein-Tyrosine Kinases