L-type Ca V 1.3 calcium channels are expressed on the dendrites and soma of neurons, and there is a paucity of information about its role in hippocampal plasticity. Here, by genetic targeting to ablate Ca V 1.3 RNA editing, we demonstrate that unedited Ca V 1.3 ΔECS mice exhibited improved learning and enhanced long-term memory, supporting a functional role of RNA editing in behavior. Significantly, the editing paradox that functional recoding of Ca V 1.3 RNA editing sites slows Ca 2+ -dependent inactivation to increase Ca 2+ influx but reduces channel open probability to decrease Ca 2+ influx was resolved. Mechanistically, using hippocampal slice recordings, we provide evidence that unedited Ca V 1.3 channels permitted larger Ca 2+ influx into the hippocampal pyramidal neurons to bolster neuronal excitability, synaptic transmission, late long-term potentiation, and increased dendritic arborization. Of note, RNA editing of the Ca V 1.3 IQ-domain was found to be evolutionarily conserved in mammals, which lends support to the importance of the functional recoding of the Ca V 1.3 channel in brain function.

Abnormal lipid homeostasis has been observed in the brain of Parkinson’s disease (PD) patients and experimental models, although the mechanism underlying this phenomenon is unclear. Notably, previous studies have reported that the PD-linked protein Parkin functionally interacts with important lipid regulators, including Sterol Regulatory Element Binding Proteins (SREBPs) and Cluster of differentiation 36 (CD36). Here, we demonstrate a functional relationship between Parkin and Lipoprotein Lipase (LPL), a triglyceride lipase that is widely expressed in the brain. Using a human neuroblastoma cell line and a Parkin knockout (KO) mouse model, we demonstrate that Parkin expression level positively correlates with neuronal LPL protein level and activity. Importantly, our study identified SREBP2, a major regulator of sterol and fatty acid synthesis, as a potential mediator between Parkin and LPL. Supporting this, SREBP2 genetic ablation abolished Parkin effect on LPL expression. We further demonstrate that Parkin-LPL pathway regulates the formation of intracellular lipid droplets, and that this pathway is upregulated upon exposure to PD-linked oxidative stress induced by rotenone. Finally, we show that inhibition of either LPL or SREBP2 exacerbates rotenone-induced cell death. Taken together, our findings reveal a novel pathway linking Parkin, SREBP2, and LPL in neuronal lipid homeostasis that may be relevant to the pathogenesis of PD.

No abstract

No abstract