Nerve growth factor (NGF) receptors in a central nervous system glial cell line: upregulation by NGF and brain-derived neurotrophic factor.
The neurotrophic proteins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are related in their primary amino acid structures. In this study we investigated the extent to which the low-affinity NGF receptor (LNGFR) in C6 glioma cells can discriminate between the neurotrophins NGF and BDNF. LNGFR-immunoreactivity (IR) was studied in C6 cells treated for 16 hr with NGF (50 ng/ml) or BDNF (10 ng/ml), using immunogold labelling and electron microscopic morphometric analysis. The cells were exposed to the anti-NGFR antibody 192-IgG, followed by immunoglobulin conjugated with colloidal gold. Untreated C6 cells exhibited some surface gold label (positive LNGFR-IR). Cells treated with NGF or BDNF displayed significantly increased LNGFR-IR on all surfaces in terms of gold labeling, which was more pronounced in NGF-treated cells. LNGFR-IR was also localized in coated endocytotic vesicles, in smooth endoplasmic reticulum, and in secondary multivesicular lysosomes in neurotrophin-treated and untreated cells. The increase in LNGFR protein was further substantiated by a correspondingly higher content of LNGFR mRNA detected after 15 hr of either NGF or BDNF treatment. These results suggest that the LNGFR in glial cells can be upregulated by the structurally related neurotrophins NGF and BDNF.
Spoerri
P E
PE
Department of Cellular Biology, Fidia Research Laboratories, Abano Terme, Italy.
Romanello
S
S
Petrelli
L
L
Negro
A
A
Dal Toso
R
R
Leon
A
A
Skaper
S D
SD
D000818:Animals; D015152:Blotting, Northern; D001932:Brain Neoplasms / Q000378:metabolism; D019208:Brain-Derived Neurotrophic Factor; D002460:Cell Line; D005910:Glioma / Q000378:metabolism; D007457:Iodine Radioisotopes; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D009457:Neuroglia / Q000378:metabolism*; D051381:Rats; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects*
D019208:Brain-Derived Neurotrophic Factor; D007457:Iodine Radioisotopes; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D017475:Receptors, Nerve Growth Factor