S-Nitrosylation of G protein-coupled receptor kinase 6 and Casein kinase 2 alpha modulates their kinase activity toward alpha-synuclein phosphorylation in an animal model of Parkinson’s disease

Abstract

Parkinson's disease (PD) is a common neurodegenerative disorder which is mostly sporadic but familial-linked PD (FPD) cases have also been found. The first reported gene mutation that linked to PD is α-synuclein (α-syn). Studies have shown that mutations, increased expression or abnormal processing of α-syn can contribute to PD, but it is believed that multiple mechanisms are involved. One of the contributing factors is post-translational modification (PTM), such as phosphorylation of α-syn at serine 129 by G-protein-coupled receptor kinases (GRKs) and casein kinase 2α (CK2α). Another known important contributing factor to PD pathogenesis is oxidative and nitrosative stress. In this study, we found that GRK6 and CK2α can be S-nitrosylated by nitric oxide (NO) both in vitro and in vivo. S-nitrosylation of GRK6 and CK2α enhanced their kinase activity towards the phosphorylation of α-syn at S129. In an A53T α-syn transgenic mouse model of PD, we found that increased GRK6 and CK2α S-nitrosylation were observed in an age dependent manner and it was associated with an increased level of pSer129 α-syn. Treatment of A53T α-syn transgenic mice with Nω-Nitro-L-arginine (L-NNA) significantly reduced the S-nitrosylation of GRK6 and CK2α in the brain. Finally, deletion of neuronal nitric oxide synthase (nNOS) in A53T α-syn transgenic mice reduced the levels of pSer129 α-syn and α-syn in an age dependent manner. Our results provide a novel mechanism of how NO through S-nitrosylation of GRK6 and CK2α can enhance the phosphorylation of pSer129 α-syn in an animal model of PD.

Pathogenic Impact of α-Synuclein Phosphorylation and Its Kinases in α-Synucleinopathies

“…Interestingly, the α-synuclein C-terminal tail contains the majority of phosphorylation sites ( Figure 3 ). Phosphorylation of α-synuclein Ser129 is mediated by several kinases such as G-protein-coupled receptor kinases (GRKs) [ 54 , 55 , 56 ], casein kinase II [ 56 , 57 , 58 ], polo-like kinases [ 59 , 60 , 61 ], and leucine-rich repeat kinase 2 (LRRK2) [ 62 , 63 ]. Below, we summarize the α-synuclein phosphorylation kinases and describe the associated pathogenic neurotoxicity.…”

“…Wu et al reported that CK2α can be S-nitrosylated by nitric oxide (NO). Intriguingly, S-nitrosylation of CK2α enhanced the kinase activity of this catalytic subunit towards the phosphorylation of α-synuclein at Ser129 [ 56 ]. These data indicate that CK2α can enhance the phosphorylation of pSer129 α-synuclein.…”

“…Focusing on the kinases that have the ability to phosphorylate α-synuclein ( Figure 3 ), GRK, CK2, and PLK indeed alter the activity by their modification in Lewy body diseases. As introduced in Section 4 , GRK6 and CK2α can be S-nitrosylated by NO, with S-nitrosylation enhancing their kinase activity towards the phosphorylation of α-synuclein at Ser129 [ 56 ]. Notably, in an A53T α-synuclein transgenic mouse, a familial Parkinson’s disease model, Wu et al demonstrated that increased GRK6 and CK2α S-nitrosylation was age-dependent and associated with an increased level of p-Ser129 α-synuclein, which suggests GRK6 and CK2α S-nitrosylation as a potential therapeutic target of α-synucleinopathy.…”

Nitric Oxide and S-Nitrosylation in Cardiac Regulation: G Protein-Coupled Receptor Kinase-2 and β-Arrestins as Targets

“…Inhibitory GRK2 S-nitrosylation confirms the prior findings showing that NO/SNO can promote GPCR signaling [ 116 , 117 ] since GRK2 inhibition will prevent desensitization of receptors. GRK6 is also reported to be S-nitrosylated in an age-dependent manner resulting in enhanced kinase activity and this modification was suggested to contribute Parkinson’s disease [ 118 ] ( Figure 2 ).…”

Lovastatin Alleviates α-Synuclein Aggregation and Phosphorylation in Cellular Models of Synucleinopathy

“…The phosphorylation of α-syn at S129 regulates physiological function and remarkably promotes their aggregation, critically participates in the pathogenesis of PD as an important molecular event. Casein kinase 2 (CK2) is the major one of the kinases that mediate α-syn phosphorylation at S129 ( Perez et al, 2011 ; Wu et al, 2020 ). It consists of two regulatory subunits β and two catalytic subunits α that mainly contribute to the catalytic activity.…”