Differential action of nerve growth factor and phorbol ester TPA on rat synaptosomal PKC isoenzymes

• Published in: Neurochemistry international 1999-10, Vol.35 (4), p.281-291
• Main Authors: Gil, Carles, Pelliccioni, Patricia, Itarte, Emili, Aguilera, José
• Format: Article
• Language: English
• Subjects: Animals; Biochemistry and metabolism; Biological and medical sciences; Brain - drug effects; Brain - enzymology; Brain - metabolism; Central nervous system; Fundamental and applied biological sciences. Psychology; Isoenzymes - metabolism; Isoforms; Nerve growth factor; Nerve Growth Factors - pharmacology; phorbol 12-myristate 13-acetate diester; Phosphatidylinositols - metabolism; Phospholipid hydrolysis; Protein kinase C; Protein Kinase C - metabolism; Rat brain; Rats; Rats, Sprague-Dawley; Synaptosomes; Synaptosomes - drug effects; Synaptosomes - enzymology; Synaptosomes - metabolism; Tetradecanoylphorbol Acetate - pharmacology; Vertebrates: nervous system and sense organs
• ISSN: 0197-0186; 1872-9754
• DOI: 10.1016/S0197-0186(99)00076-5

The subcellular redistribution of protein kinase C family members (α, β, γ, δ, ε and ζ isoforms) was examined in response to treatment with 12- O-tetradecanoyl-phorbol-13 acetate (TPA) or nerve growth factor (NGF) in a synaptosomal-enriched P 2 fraction from rat brain. Treatment with TPA affected members of the classical-PKC family (α, β and γ), resulting in a final loss of total protein of each isoenzyme. The kinetics of changes of members of the novel-PKC family are different, the δ isoform being translocated, but not down-regulated, while the ε isoform showing only a slight diminishing of immunoreactivity in the soluble and particulate fractions. The atypical-PKC ζ isoform was not translocated in response to TPA. Incubation with NGF induced a loss of immunoreactivity of the cytosolic α, β and ε isoforms, but the membrane fractions of these isoforms were not appreciably affected. In contrast, a marked translocation from cytosol to membrane was observed in the case of the γ and δ isoforms. The ζ isoform presented a slight translocation from the particulate fraction to the soluble fraction. Thus, the results show that the effects of TPA and NGF on PKC isoforms are not coincident in synaptosomes, the δ isoform being activated and not down-regulated by both treatments, whereas the γ isoform is only down-regulated in the case of TPA, but presents sustained translocation with NGF, indicating that PKC isoform-specific degradation pathways exist in synaptic terminals. The effects of NGF on PKC isoforms coexist with an increase in NGF-induced polyphosphoinositide hydrolysis, suggesting the participation of phospholipases.