Autocrine regulation of rat chondrocyte proliferation by natriuretic peptide C and its receptor, natriuretic peptide receptor-B.
Natriuretic peptide receptor-B (NPR-B) was identified in rat chondrocytes, and its physiological functions were investigated. Rat tissues, including the xiphoid cartilage, brain, lung, liver, adrenal gland, and kidney, were screened for NPR-B activity, which we assayed by receptor guanylate cyclase activity specifically stimulated by C-type natriuretic peptide (CNP), a known selective activator of NPR-B. Cartilage showed distinctly higher NPR-B activity. Furthermore, exposure of cultured rat chondrocytes to CNP (10(-6) M) resulted in a large increase in intracellular cGMP production (376 +/- 38 pmol/well), with threshold responses occurring between 10(-10) and 10(-9) M CNP. Atrial natriuretic peptide and brain natriuretic peptide also stimulated cGMP production in rat chondrocytes but with a potency that was at least 10 times less than that of CNP. Polymerase chain reaction analysis also demonstrated NPR-B gene expression in adult rat xiphisternum and cultured chondrocytes. These findings indicate that NPR-B is present in rat chondrocytes. In rat chondrocytes exposed to CNP, [3H]thymidine incorporation was inhibited in a dose-dependent manner (half-maximal response, 10(-11)M). However, much higher concentrations of atrial natriuretic peptide were required to induce the inhibition of thymidine incorporation. Interestingly, CNP-like immunoreactivity was detected in the conditioned medium from chondrocyte cultures. In addition, TGF-beta 1, a multifunctional cytokine, induced a marked increase in CNP secretion and CNP mRNA levels in chondrocytes. These results indicate that autocrine CNP inhibits mitogenesis in chondrocytes via NPR-B under the control of TGF-beta 1.
Hagiwara
H
H
Department of Biological Sciences, Tokyo Institute of Technology, Japan.
Sakaguchi
H
H
Itakura
M
M
Yoshimoto
T
T
Furuya
M
M
Tanaka
S
S
Hirose
S
S
D000818:Animals; D001483:Base Sequence; D002356:Cartilage / Q000166:cytology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D017077:Culture Media, Conditioned; D017931:DNA Primers; D006162:Guanylate Cyclase / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D020098:Natriuretic Peptide, C-Type; D009419:Nerve Tissue Proteins / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D017461:Receptors, Atrial Natriuretic Factor / Q000502:physiology*
D017077:Culture Media, Conditioned; D017931:DNA Primers; D009419:Nerve Tissue Proteins; D020098:Natriuretic Peptide, C-Type; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C073616:atrial natriuretic factor receptor C