Bone morphogenetic protein-5 (BMP-5) promotes dendritic growth in cultured sympathetic neurons
1 Division of Toxicology, Dept of Environmental Health Sciences, Johns Hopkins University, Baltimore, MD, USA
2 Dept of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, NY, USA
3 Division of Pulmonary and Critical Care Medicine, Dept of Medicine, Johns Hopkins University, Baltimore, MD, USA
BMC Neuroscience 2001, 2:12 doi:10.1186/1471-2202-2-12Published: 11 September 2001
BMP-5 is expressed in the nervous system throughout development and into adulthood. However its effects on neural tissues are not well defined. BMP-5 is a member of the 60A subgroup of BMPs, other members of which have been shown to stimulate dendritic growth in central and peripheral neurons. We therefore examined the possibility that BMP-5 similarly enhances dendritic growth in cultured sympathetic neurons.
Sympathetic neurons cultured in the absence of serum or glial cells do not form dendrites; however, addition of BMP-5 causes these neurons to extend multiple dendritic processes, which is preceded by an increase in phosphorylation of the Smad-1 transcription factor. The dendrite-promoting activity of BMP-5 is significantly inhibited by the BMP antagonists noggin and follistatin and by a BMPR-IA-Fc chimeric protein. RT-PCR and immunocytochemical analyses indicate that BMP-5 mRNA and protein are expressed in the superior cervical ganglia (SCG) during times of initial growth and rapid expansion of the dendritic arbor.
These data suggest a role for BMP-5 in regulating dendritic growth in sympathetic neurons. The signaling pathway that mediates the dendrite-promoting activity of BMP-5 may involve binding to BMPR-IA and activation of Smad-1, and relative levels of BMP antagonists such as noggin and follistatin may modulate BMP-5 signaling. Since BMP-5 is expressed at relatively high levels not only in the developing but also the adult nervous system, these findings suggest the possibility that BMP-5 regulates dendritic morphology not only in the developing, but also the adult nervous system.