PCP4/PEP19 downregulates neurite outgrowth via transcriptional regulation of Ascl1 and NeuroD1 expression in human neuroblastoma M17 cells.

Ikumi Kitazono, Taiji Hamada, Takuya Yoshimura, Mari Kirishima, Seiya Yokoyama, Toshiaki Akahane, Akihide Tanimoto

Laboratory investigation; a journal of technical methods and pathology 2020 Dec

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Purkinje cell protein 4/peptide 19 (PCP4/PEP19) is 7.6 kDa peptide originally found in Purkinje cells. PCP4/PEP19 is a differentiation maker of Purkinje cells, where it functions as an antiapoptotic factor. Cerebral neuronal cells also express PCP4/PEP19, which may be related to neuronal cell survival. However, evidence suggests that PCP4/PEP19 may also be involved in neuronal differentiation. Here, we investigated the effects of PCP4/PEP19 expression on neuronal differentiation by analyzing neurite outgrowth, and expression of neuronal differentiation markers in cultured human neuroblastoma M17 cells. When PCP4/PEP19 expression was reduced by siRNA-mediated knockdown, neurite outgrowth was significantly increased. Among many differentiation markers tested, expression of NeuroD1 was increased, while that of Ascl1 was decreased upon PCP4/PEP19 knockdown. Furthermore, luciferase reporter assays revealed that PCP4/PEP19 knockdown upregulated NeuroD1 and downregulated Ascl1 expression, at the transcriptional level. These results suggest a new function of PCP4/PEP19, which suppresses neurite outgrowth and neuronal differentiation through the regulation of NeuroD1 and Ascl1 expression in M17 cells. Furthermore, immunohistochemical studies showed that PCP4/PEP19 localizes in the nuclei of human neuroblastoma cells. Therefore, PCP4/PEP19 may also be an intranuclear negative regulator of neuronal differentiation and may thus be a potential therapeutic target to promote cellular differentiation in human neuroblastoma.

Citation

Ikumi Kitazono, Taiji Hamada, Takuya Yoshimura, Mari Kirishima, Seiya Yokoyama, Toshiaki Akahane, Akihide Tanimoto. PCP4/PEP19 downregulates neurite outgrowth via transcriptional regulation of Ascl1 and NeuroD1 expression in human neuroblastoma M17 cells. Laboratory investigation; a journal of technical methods and pathology. 2020 Dec;100(12):1551-1563