title: Mature pig oligodendrocytes rapidly process human recombinant pro-nerve growth factor and do not undergo cell death.
abstract: The neurotrophin family with its first member, nerve growth factor (NGF), binds two classes of receptors, more specifically to Trk receptors and to a shared p75NTR receptor. It has been shown that proNGF rather than NGF is predominant in the mature central nervous system. A recent finding indicated that a furin-resistant proNGF preferentially binds to p75NTR, initiating a pro-apoptotic cascade even in the presence of TrkA. In this context, rodent oligodendrocytes were reported to undergo cell death when exposed to proNGF. We have investigated the effect of a non-mutated 32 kDa human recombinant proNGF (rhproNGF) on cultured pig oligodendrocytes which express TrkA, p75NTR and sortilin. Pig oligodendrocytes respond to rhproNGF (50 ng/mL) with an enhanced regeneration of their processes as already observed for NGF. Activity of mitogen-activated protein kinase (MAPK), which plays an important role in oligodendroglial process formation, was increased even when rhproNGF processing was inhibited by the furin inhibitor Decanoyl-RVKR-CMK. Similarly, a cleavage-resistant proNGF (R-1G) activated MAPK and promoted oligodendroglial process regeneration. High concentrations of rhproNGF (300 ng/mL) did not induce cell death. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis and Western blotting revealed that oligodendrocytes process rhproNGF to NGF. NGF was detected in Western blots of oligodendroglial lysates already 10 min after rhproNGF exposure, followed by a release of NGF into the culture medium. Indirect evidence indicates that rhproNGF processing occurs via an endocytotic route.
authors.affiliation: Max-Planck Institute for Experimental Medicine, RG Neural Regeneration, Goettingen, Germany. althaus@em.mpg.de
authors.forename: Hans H
authors.initials: HH
authors.lastname: Althaus
authors.forename: Sabine
authors.initials: S
authors.lastname: Klöppner
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016923:Cell Death / Q000502:physiology; D002478:Cells, Cultured; D004705:Endocytosis / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D020932:Nerve Growth Factor / Q000378:metabolism* / Q000494:pharmacology*; D009416:Nerve Regeneration / Q000502:physiology; D009836:Oligodendroglia / Q000378:metabolism* / Q000502:physiology*; D011498:Protein Precursors / Q000378:metabolism* / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology; D013552:Swine; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D011498:Protein Precursors; D011994:Recombinant Proteins; D013778:Tetrazolium Salts; D013844:Thiazoles; C061397:pro-nerve growth factor, human; D020932:Nerve Growth Factor; D020928:Mitogen-Activated Protein Kinases; C022616:thiazolyl blue