Characterization of the Bone Morphogenetic Protein-2 as a Neurotrophic Factor

doi:10.1074/jbc.271.29.17360

Characterization of the Bone Morphogenetic Protein-2 as a Neurotrophic Factor

INDUCTION OF NEURONAL DIFFERENTIATION OF PC12 CELLS IN THE ABSENCE OF MITOGEN-ACTIVATED PROTEIN KINASE ACTIVATION*

From the ^‡ Laboratory of Cell Biology, Gifu Pharmaceutical University, 5-6-1, Mitahora-higashi, Gifu 502, Japan and the
^∥ Suntory Institute for Biomedical Research, Mishima, Osaka 618, Japan

” To whom all correspondence should be addressed. Tel.: 81-58-237-3931 (ext. 207); Fax: 81-58-237-5979.

Abstract

Rat pheochromocytoma PC12 cells are shown to express a single class of high affinity binding sites for bone morphogenetic protein (BMP)-2 (1,300 receptors/cell, K_d = 31.3 pM). Affinity cross-linking using radiolabeled BMP-2 demonstrated the presence of six components with apparent molecular masses of 170, 155, 105, 90, 80, and 70 kDa. BMP-2 induced morphological changes in PC12 cells with the concomitant expression of three neurofilament proteins. Thus, BMP-2 would appear to be another neurotrophic factor that, like nerve growth factor or basic fibroblast growth factor, stimulates the neuronal differentiation of PC12 cells. Unlike nerve growth factor and basic fibroblast growth factor, however, BMP-2 failed to induce the activation of either 41- and 43-kDa mitogen-activated protein (MAP) kinases or the MAP kinase/extracellular signal-regulated kinase kinase (MEK). Also, BMP-2 did not induce the expression of the c-fos gene in PC12 cells. Activin A was also capable of inducing the neuronal differentiation of PC12 cells without activating MAP kinases and MEK. These findings show a clear dissociation between the requirement for the activation of the MAP kinase cascade and the ability of BMP-2 and activin A to induce PC12 cell neuronal differentiation. In addition, these results suggest that the activation of MAP kinases and MEK is not an absolute requirement for PC12 cell differentiation.

Footnotes

↵^§ Contributed equally to this work.
↵^¶ Recipient of a fellowship from the Japan Society for the Promotion of Science for Japanese Junior Scientists.
↵* This work was supported in part by grants-in-aid from the Ministry of Education, Science, Sports, and Culture of Japan and by grants from the Research Foundation for Pharmaceutical Sciences of Japan and CIBA-GEIGY Foundation (Japan) for the Promotion of Science. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

BMP

bone morphogenetic protein

TGF-β

transforming growth factor-β

MAP kinase

mitogen-activated protein kinase

MEK

MAP kinase/ERK kinase

ERK

extracellular signal-regulated kinase

NGF

nerve growth factor

bFGF

basic fibroblast growth factor

PAGE

polyacrylamide gel electrophoresis

NF

neurofilament

MBP

myelin basic protein

GST

glutathione S-transferase.
↵² S. Iwasaki, M. Katayama, A. Hattori, M. Tsujimoto, K. Ishii, and M. Kohno, manuscript in preparation.
↵³ S. Iwasaki, S. Tanimura, A. Hattori, M. Tsujimoto, and M. Kohno, manuscript in preparation.
- Received February 26, 1996.
- Revision received April 24, 1996.