Parkin deficiency disrupts calcium homeostasis by modulating phospholipase C signalling.
Mutations in the E3 ubiquitin ligase parkin cause early-onset, autosomal-recessive juvenile parkinsonism (AJRP), presumably as a result of a lack of function that alters the level, activity, aggregation or localization of its substrates. Recently, we have reported that phospholipase Cgamma1 is a substrate for parkin. In this article, we show that parkin mutants and siRNA parkin knockdown cells possess enhanced levels of phospholipase Cgamma1 phosphorylation, basal phosphoinositide hydrolysis and intracellular Ca2+ concentration. The protein levels of Ca2+-regulated protein kinase Calpha were decreased in AJRP parkin mutant cells. Neomycin and dantrolene both decreased the intracellular Ca2+ levels in parkin mutants in comparison with those seen in wild-type parkin cells, suggesting that the differences were a consequence of altered phospholipase C activity. The protection of wild-type parkin against 6-hydroxydopamine (6OHDA) toxicity was also established in ARJP mutants on pretreatment with dantrolene, implying that a balancing Ca2+ release from ryanodine-sensitive stores decreases the toxic effects of 6OHDA. Our findings suggest that parkin is an important factor for maintaining Ca2+ homeostasis and that parkin deficiency leads to a phospholipase C-dependent increase in intracellular Ca2+ levels, which make cells more vulnerable to neurotoxins, such as 6OHDA.
Sandebring
Anna
A
Karolinska Institutet, Department of NVS, KI-Alzheimer's Disease Research Center, Stockholm, Sweden.
Dehvari
Nodi
N
Perez-Manso
Monica
M
Thomas
Kelly Jean
KJ
Karpilovski
Elena
E
Cookson
Mark R
MR
Cowburn
Richard F
RF
Cedazo-Mínguez
Angel
A
D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D003620:Dantrolene / Q000494:pharmacology; D006706:Homeostasis; D006801:Humans; D016627:Oxidopamine / Q000633:toxicity; D010716:Phosphatidylinositols / Q000378:metabolism; D051966:Phospholipase C gamma / Q000502:physiology*; D051571:Protein Kinase C-alpha / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000172:deficiency / Q000502:physiology*
D010716:Phosphatidylinositols; D016627:Oxidopamine; D044767:Ubiquitin-Protein Ligases; C111567:parkin protein; C496628:PRKCA protein, human; D051571:Protein Kinase C-alpha; D051966:Phospholipase C gamma; D003620:Dantrolene; D002118:Calcium