Pituitary Adenylyl Cyclase‐Activating Polypeptide and Nerve Growth Factor Use the Proteasome to Rescue Nerve Growth Factor‐Deprived Sympathetic Neurons Cultured From Chick Embryos

• Published in: Journal of neurochemistry 1998-11, Vol.71 (5), p.1889-1897
• Main Authors: Przywara, Dennis A., Kulkarni, Jayant S., Wakade, Taruna D., Leontiev, Dmitry V., Wakade, Arun R.
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Apoptosis - drug effects; Biological and medical sciences; Caspase 3; Caspases - metabolism; Cells, Cultured; Chick Embryo; CPP32; Cysteine Endopeptidases - physiology; Fundamental and applied biological sciences. Psychology; Ganglia, Sympathetic - cytology; Ganglia, Sympathetic - embryology; Ganglia, Sympathetic - metabolism; Lactacystin; Multienzyme Complexes - physiology; Nerve growth factor; Nerve Growth Factors - deficiency; Nerve Growth Factors - physiology; Neurons - drug effects; Neurons - physiology; Neuropeptide; Neuropeptides - pharmacology; Neuropeptides - physiology; Neuroprotective Agents - pharmacology; Neurotransmitter Agents - pharmacology; Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ; Pituitary Adenylate Cyclase-Activating Polypeptide; Pituitary adenylyl cyclase‐activating polypeptide; Proteasome; Proteasome Endopeptidase Complex; Signal Transduction - drug effects; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.1998.71051889.x

: Removal of nerve growth factor (NGF) from sympathetic neurons initiates a neuronal death program and apoptosis. We show that pituitary adenylyl cyclase‐activating polypeptide (PACAP) prevents apoptosis in NGF‐deprived sympathetic neurons. PACAP (100 nM) added to culture medium at the time of plating failed to support neuronal survival. However, in neurons grown for 2 days with NGF and then deprived of NGF, PACAP prevented cell death for the next 24–48 h. Uptake of [3H]norepinephrine ([3H]NE) was used as an index of survival and decreased >50% in NGF‐deprived cultures within 24 h. PACAP (1–100 nM) restored [3H]NE uptake to 92 ± 8% of that of NGF‐supported controls. Depolarization‐induced [3H]NE release in neurons rescued by PACAP was the same as that in NGF‐supported neurons. PACAP rescue was not mimicked by forskolin or 8‐bromo‐cyclic AMP and was not blocked by the protein kinase A inhibitor Rp‐adenosine 3′,5′‐cyclic monophosphothioate. Mobilization of phosphatidylinositol by muscarine failed to support NGF‐deprived neurons. Thus, PACAP may use novel signaling to promote survival of sympathetic neurons. The apoptosis‐associated caspase CPP32 activity increased approximately fourfold during 6 h of NGF withdrawal (145 ± 40 versus 38 ± 17 nmol of substrate cleaved/min/mg of protein) and returned to even below the control level in NGF‐deprived, PACAP‐rescued cultures (14 ± 7 nmol/min/mg of protein). Readdition of NGF or PACAP to NGF‐deprived cultures reversed CPP32 activation, and this was blocked by lactacystin, a potent and specific inhibitor of the 20S proteasome, suggesting that NGF and PACAP target CPP32 for destruction by the proteasome. As PACAP is a preganglionic neurotransmitter in autonomic ganglia, we propose a novel function for this transmitter as an apoptotic rescuer of sympathetic neurons when the supply of NGF is compromised.