RT Journal Article
SR Electronic
T1 NGF/BDNF chimeric proteins: analysis of neurotrophin specificity by homolog-scanning mutagenesis
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 306
OP 318
DO 10.1523/JNEUROSCI.12-01-00306.1992
VO 12
IS 1
A1 U Suter
A1 C Angst
A1 CL Tien
A1 CC Drinkwater
A1 RM Lindsay
A1 EM Shooter
YR 1992
UL http://www.jneurosci.org/content/12/1/306.abstract
AB Despite their extensive sequence identities at the amino acid level (approximately 55%), NGF and brain-derived neurotrophic factor (BDNF) display distinct neuronal specificity toward neurons of both the PNS and CNS. To explore which region(s) within these neurotrophic factors might determine their differential actions on various subpopulations of peripheral neurons, a systematic series (homolog-scanning mutagenesis) of chimeric NGF/BDNF molecules was prepared using PCR overlap-extension techniques. After expression in COS-7 cells, the chimeric proteins were tested for their biological activities in neurite outgrowth and neuronal survival assays. This approach led to the functional expression of 12 NGF/BDNF chimeras. Surprisingly, despite replacing successive amino acid segments throughout the entire length of NGF with the corresponding parts of BDNF, all chimeras displayed full NGF-like activity in bioassays carried out with PC12 cells, embryonic chick dorsal root ganglion explants, sympathetic ganglion explants, and dissociated cultures of dorsal root ganglion neurons. Most of the chimeras additionally showed BDNF-like activity as defined by neurite outgrowth on chick nodose ganglion explants. However, none of the chimeras supported the survival of dissociated nodose ganglion neurons. Our results suggest that NGF and BDNF must share very similar higher- order protein structures, and we propose that the overall structure or conformation of NGF, in contrast to short amino acid –active-site” segments, may determine its exact neuronal specificity.