title: Parkin potentiates ATP-induced currents due to activation of P2X receptors in PC12 cells.
abstract: Loss-of-function mutations of the parkin gene causes an autosomal recessive juvenile-onset form of Parkinson's disease (AR-JP). Parkin was shown to function as a RING-type E3 ubiquitin protein ligase. However, the function of parkin in neuronal cells remains elusive. Here, we show that expression of parkin-potentiated adenosine triphosphate (ATP)-induced currents that result from activation of the P2X receptors which are widely distributed in the brain and involved in neurotransmission. ATP-induced inward currents were measured in mock-, wild-type or mutant (T415N)-parkin-transfected PC12 cells under the conventional whole-cell patch clamp configuration. The amplitude of ATP-induced currents was significantly greater in wild-type parkin-transfected cells. However, the immunocytochemical study showed no apparent increase in the number of P2X receptors or in ubiquitin levels. The increased currents were attenuated by inhibition of cAMP-dependent protein kinase (PKA) but not protein kinase C (PKC) or Ca2+ and calmodulin-dependent protein kinase (CaMKII). ATP-induced currents were also regulated by phosphatases and cyclin-dependent protein kinase 5 (CDK5) via dopamine and cyclic AMP-regulated phosphoprotein (DARPP-32), though the phosphorylation at Thr-34 and Thr-75 were unchanged or rather attenuated. We also tried to investigate the effect of alpha-synuclein, a substrate of parkin and also forming Lysine 63-linked multiubiquitin chains. Expression of alpha-synuclein did not affect the amplitude of ATP-induced currents. Our finding provides the evidence for a relationship between parkin and a neurotransmitter receptor, suggesting that parkin may play an important role in synaptic activity.
authors.affiliation: Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Sato
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Arimura
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Manago
authors.forename: Kaori
authors.initials: K
authors.lastname: Nishikawa
authors.forename: Kumiko
authors.initials: K
authors.lastname: Aoki
authors.forename: Etsuko
authors.initials: E
authors.lastname: Wada
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Osaka
authors.forename: Rieko
authors.initials: R
authors.lastname: Setsuie
authors.forename: Mikako
authors.initials: M
authors.lastname: Sakurai
authors.forename: Taiju
authors.initials: T
authors.lastname: Amano
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Aoki
authors.forename: Keiji
authors.initials: K
authors.lastname: Wada
authors.forename: Mami
authors.initials: M
authors.lastname: Noda
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000378:metabolism / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects*; D008954:Models, Biological; D016716:PC12 Cells; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051844:alpha-Synuclein / Q000502:physiology
chemical_list: D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; C497928:PPP1R1B protein, human; D018048:Receptors, Purinergic P2; C497604:SNCA protein, human; D025801:Ubiquitin; D051844:alpha-Synuclein; D000255:Adenosine Triphosphate; D044767:Ubiquitin-Protein Ligases; C111567:parkin protein; D011494:Protein Kinases