Molecular cloning and neurotrophic activities of a protein with structural similarities to nerve growth factor: developmental and topographical expression in the brain.

Abstract

We have used a pool of degenerate oligonucleotides representing all possible codons in regions of homology between brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) to prime rat hippocampal cDNAs in the polymerase chain reaction. The amplified DNA included a product with significant similarity to NGF and BDNF, which was used to isolate a 1020-nucleotide-long cDNA from a rat hippocampal library. From the nucleotide sequence, a 282-amino-acid-long protein with -45% amino acid similarity to both pig BDNF and rat NGF was deduced. In the adult brain, the mRNA for this protein was predominantly expressed in hippocampus, where it was confined to a subset of pyramidal and granular neurons. The developmental expression in brain showed a dear peak shortly after birth, 1 and 2 weeks earlier than maximal expression of BDNF and NGF, respectively. It was also expressed in several peripheral tissues with the highest level in kidney. The protein, transiently expressed in COS cells, was tested on chicken embryonic neurons and readily stimulated fiber outgrowth from explanted Remak's ganglion and, to a lesser extent, the nodose ganglion. A weak, but consistent, fiber outgrowth response was also seen in the ciliary ganglion and in paravertebral sympathetic ganglia. Moreover, the protein displaced binding of NGF to its receptor, suggesting that it can interact with the NGF receptor. Thus, this factor, although structurally and functionally related to NGF and BDNF, has unique biological activities and represents a member of a family of neurotrophic factors that may cooperate to support the development and maintenance of the vertebrate nervous system.

Cellular processing of the neurotrophin precursors of NT3 and BDNF by the mammalian proprotein convertases

“…This neurotrophin is well known to be expressed in a number of neuronal and non-neuronal tissues, including the hippocampus, Schwann cells and fibroblasts [4,23,24]. Similar to proNGF and proNT3 the predicted protein structure of human proBDNF [21] suggests that it contains a single Asn-glycosylation site 8 amino acids N-terminal to its presumed major cleavage site in the sequence Asn MetSerMetArgValArgArglHisSer.…”

“…Levi-Montalcini and coworkers discovered nerve growth factor (NGF), the first member of the family, over forty years ago (for review see [1]). Since the cDNA structure coding for the precursor of NGF (proNGF) was reported [2], four other members of the family have been identified and their cDNAs cloned: brain-derived neurotrophic factor (BDNF) [3], neurotrophin-3 (NT3) [4,5], neurotrophin-4/5 (NT-4/5) [6] and neurotrophin-6 (NT-6) [7]. Sequence data predict that all neurotrophins are generated from 31 35 kDa precursors that contain at their N-termini, hydrophobic signal peptides followed by proregions containing sequences of contiguous basic amino acids.…”

Two Restricted Sites on the Surface of the Nerve Growth Factor Molecule Independently Determine Specific TrkA Receptor Binding and Activation

“…First, we use a robust biological assay measuring fiber outgrowth from explanted embryonic chicken ganglia (30). For the analysis of NGF fiber outgrowth activity we use the sympathetic ganglia that express TrkA mRNA (35) and only weakly respond to NT-3 (36,37). To measure NT-3 fiber outgrowth activity we use Remak's ganglia, which do not respond to NGF and only express TrkC mRNA (38).…”

Inhibition of GABAASynaptic Responses by Brain-Derived Neurotrophic Factor (BDNF) in Rat Hippocampus

“…During brain development neurotrophins and their receptors display distinct stage-and tissue-specific patterns of expression (Ernfors et al, 1990a;Phillips et al, 1990;Merlio et al, 1992). BDNF mRNA is observed in the embryonic stage and is still present in the postnatal and adult stages (Ernfors et al, 1990b;Maisonpierre et al, 1990; Freidman et al, 1991).…”