The Leucine-Rich Repeat Kinase 2 Variant LRRK2G2019S Up-Regulates L-Type (CaV1.3) Calcium Channel via the CaVβ3 Subunit: Possible Role in the Pathogenesis of Parkinson’s Disease

Voltage-gated Ca²⁺ (Ca_V) channels are transmembrane proteins comprising the pore-forming subunit Ca_Vα₁ and the ancillary proteins Ca_Vα₂δ and Ca_Vβ. They are expressed in various tissues, including the nervous system, where they regulate Ca²⁺ entry in response to membrane potential changes. The increase in intracellular Ca²⁺ allows for regulating cell excitability and releasing neurotransmitters, among other cellular events. Leucine-rich repeat kinase 2 (LRRK2) is a serine-threonine kinase involved in vesicular mobilization. Previously, it has been shown that LRRK2 regulates neurotransmission by phosphorylating the Ca_Vβ auxiliary subunit of the Ca_V2.1 (P/Q-type) presynaptic channels. However, it is unknown whether the kinase can regulate the activity of other Ca_V channel subtypes, such as Ca_V1.3 (L-type), which play a significant role in the excitability of dopaminergic neurons in the substantia nigra pars compacta (SNc) and whose dysregulation contributes to neurodegeneration in Parkinson's disease (PD). Here, we found potential phosphorylation sites for LRRK2 in Ca_Vβ₃ and examined how these molecules interact. We used immunoprecipitation and electrophysiology in HEK-293 cells expressing recombinant Ca_V1.3 channels, both with and without wild-type LRRK2 or its LRRK2^G2019S mutation, which plays a role in familial PD through a possible gain-of-toxic-function mechanism. Our results show that LRRK2^G2019S significantly increases current density through Ca_V1.3 channels, and this effect depends on the presence of Ca_Vβ₃. Site-directed mutagenesis revealed that phosphorylation at S152 in the sequence of Ca_Vβ₃ is necessary and sufficient to explain the abnormal regulation of the channels mediated by LRRK2^G2019S. These data provide new insights into the molecular regulation that mutant LRRK2 may exert on L-type Ca_V1.3 channels, which determine pacemaker activity in dopaminergic neurons of the SNc and may, therefore, play a relevant role in the molecular pathophysiology of PD.