title: Purkinje cell protein 4 positively regulates neurite outgrowth and neurotransmitter release.
abstract: Purkinje cell protein 4 (PCP4), also called brain-specific polypeptide 19 (PEP19), is a neurospecific, small calmodulin-binding protein that binds both calcium-free and calcium-binding calmodulin to regulate the calmodulin-mediated signal. The expression level of this molecule is decreased in the brain in Alzheimer's disease, Huntington's disease, and alcoholism. However, little is known of the function of PCP4 regarding neuronal or neuroendocrine cell differentiation and neurotransmitter release. To address this, we established a PCP4 tetracycline-inducible rat chromaffin cell line, PC12. When PCP4 expression was induced with doxcycline, neurite outgrowth was significantly advanced in the presence of nerve growth factor (NGF) and dibutyryl cAMP, which was inhibited by W-7, a calmodulin inhibitor, and PD98059, an ERK inhibitor. In addition, size of the cell body also was increased by treatment with NGF in the PCP4-induced PC12 cells. Constitutive and potassium-evoked release of acetylcholine and dopamine was increased and apoptosis induced by hydrogen peroxide (H(2)O(2)) was inhibited in PCP4-induced PC12 cells. On the other hand, knockdown of PCP4 by siRNA transfection decreased neurite outgrowth and dopamine release and increased H(2)O(2)-induced apoptosis in PC12 cells. These results indicate that PCP4 promotes neuroendocrine cell differentiation and neurotransmitter release by activating calmodulin function.
authors.affiliation: Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan. harasima@metab.kuhp.kyoto-u.ac.jp
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Harashima
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Takahiko
authors.initials: T
authors.lastname: Horiuchi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Seino
authors.forename: Nobuya
authors.initials: N
authors.lastname: Inagaki
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology*; D016501:Neurites / Q000378:metabolism / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D016716:PC12 Cells; D051381:Rats
chemical_list: D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; C489090:Pcp4 protein, rat; D000109:Acetylcholine; D004298:Dopamine