Iannotta Lucia, Emanuele Marco, Favetta Giulia, Tombesi Giulia, Vandewynckel Laurine, Lara Ordóñez Antonio Jesús, Saliou Jean-Michel, Drouyer Matthieu, Sibran William, Civiero Laura, Nichols R Jeremy, Athanasopoulos Panagiotis S, Kortholt Arjan, Chartier-Harlin Marie-Christine, Greggio Elisa, Taymans Jean-Marc
Department of Biology, University of Padova, Padua, Italy.
National Research Council, c/o Humanitas Research Hospital, Institute of Neuroscience, Rozzano, Italy.
Front Mol Neurosci. 2023 Dec 18;16:1269387. doi: 10.3389/fnmol.2023.1269387. eCollection 2023.
Mutations in leucine-rich repeat kinase 2 (LRRK2) are a common cause of inherited and sporadic Parkinson's disease (PD) and previous work suggests that dephosphorylation of LRRK2 at a cluster of heterologous phosphosites is associated to disease. We have previously reported subunits of the PP1 and PP2A classes of phosphatases as well as the PAK6 kinase as regulators of LRRK2 dephosphorylation. We therefore hypothesized that PAK6 may have a functional link with LRRK2's phosphatases. To investigate this, we used PhosTag gel electrophoresis with purified proteins and found that PAK6 phosphorylates the PP2A regulatory subunit PPP2R2C at position S381. While S381 phosphorylation did not affect PP2A holoenzyme formation, a S381A phosphodead PPP2R2C showed impaired binding to LRRK2. Also, PAK6 kinase activity changed PPP2R2C subcellular localization in a S381 phosphorylation-dependent manner. Finally, PAK6-mediated dephosphorylation of LRRK2 was unaffected by phosphorylation of PPP2R2C at S381, suggesting that the previously reported mechanism whereby PAK6-mediated phosphorylation of 14-3-3 proteins promotes 14-3-3-LRRK2 complex dissociation and consequent exposure of LRRK2 phosphosites for dephosphorylation is dominant. Taken together, we conclude that PAK6-mediated phosphorylation of PPP2R2C influences the recruitment of PPP2R2C to the LRRK2 complex and PPP2R2C subcellular localization, pointing to an additional mechanism in the fine-tuning of LRRK2 phosphorylation.
富含亮氨酸重复激酶2（LRRK2）的突变是遗传性和散发性帕金森病（PD）的常见病因，先前的研究表明，LRRK2在一组异源磷酸化位点的去磷酸化与疾病相关。我们之前报道过，磷酸酶PP1和PP2A家族的亚基以及PAK6激酶是LRRK2去磷酸化的调节因子。因此，我们推测PAK6可能与LRRK2的磷酸酶存在功能联系。为了研究这一点，我们使用PhosTag凝胶电泳对纯化的蛋白质进行分析，发现PAK6在第381位丝氨酸处磷酸化PP2A调节亚基PPP2R2C。虽然第381位丝氨酸的磷酸化不影响PP2A全酶的形成，但S381A磷酸化失活的PPP2R2C与LRRK2的结合受损。此外，PAK6激酶活性以第381位丝氨酸磷酸化依赖的方式改变PPP2R2C的亚细胞定位。最后，PAK6介导的LRRK2去磷酸化不受PPP2R2C在第381位丝氨酸处磷酸化的影响，这表明先前报道的机制，即PAK6介导的14-3-3蛋白磷酸化促进14-3-3-LRRK2复合物解离，从而使LRRK2磷酸化位点暴露以进行去磷酸化，是主要机制。综上所述，我们得出结论，PAK6介导的PPP2R2C磷酸化影响PPP2R2C向LRRK2复合物的募集以及PPP2R2C的亚细胞定位，这表明在LRRK2磷酸化的微调中存在另一种机制。
