Protein kinase C remains functionally active during TPA induced neuronal differentiation of SH-SY5Y human neuroblastoma cells

✍ Scribed by Vendela Parrow; Eewa Nånberg; Jari Heikkilä; Ulf Hammerling; Sven Påhlman

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 1019 KB
• Volume: 152
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041520313

✦ Synopsis

20500 h o , Finland (1.H.I SH-SY5Y human neuroblastoma cells can be induced to differentiate into a neuronal phenotype by treatment with 12-O-tetradecanoylphorbol-13-acctatc UPA).

In other cell systems, TPA treatment frequently leads to down-regulation of protein kinase C (PKC). However, we now report that TPA-treated and non-treated SH-SYSY cells express PKC-a, but not PKC-P and PKC-y, mRNA. Furthermore, only a dight down-regulation of the PKC-a protein could be seen during prolonged treatment with 16 n M TPA, the concentration giving optimal differentiation. In contrast, a higher concentration of TPA (1.6 pM) results in a poor neuronal differentiation and a complete down-regulation of PKC-a. PKC-a was rapidly translocated to the particulate fraction and remained membrane bound for at least 4 days during treatment with 16 nM TPA. In such cells a sustained increased level of the phosphorylated form of a 80,000 Dalton PKC-substrate was found. In addition to this sustained augmented phosphorylation, administration of fresh TPA at day 4 caused a small but reproducible further increased level of phosphorylatcd substrate. When the PKC activity was measured by the histone phosphorylation assay a substantial fraction of the initial enzyme activity could still be detected after 4 days of TPA treatment. Taken together. the data demonstrate that PKC remains functionally active during TPA induced diiferentidtion of SH-SYSY cells, which may suggest a continuous role for the enzyme during the differentiation process. 0 1992 Wlley-Lls~. lric