LRRK2 Research Articles

Using computer modeling to find new LRRK2 inhibitors for parkinson’s disease

Parkinson’s disease (PD) is a complex neurodegenerative disorder that affects multiple neurotransmitters, and its exact cause is still unknown. Developing new drugs for PD is a lengthy and expensive process, making it difficult to find new treatments. This study aims to create a detailed dataset to build strong predictive models with various machine learning algorithms. An ensemble modeling approach was employed to screen the DrugBank database, aiming to repurpose approved medications as potential treatments for Parkinson’s disease (PD). The dataset was constructed using pIC50 values of various compounds targeting the inhibition of leucine-rich repeat kinase 2 (LRRK2). The best ensemble model showed exceptional predictive performance, with five-fold cross-validation and external validation metrics exceeding 0.8 (Q2cv = 0.864 and Q2ext = 0.873). The DrugBank screening resulted in three promising drugs—triamterene, phenazopyridine, and CRA_1801—with predicted pIC50 values greater than 7, warranting further investigation as novel PD treatments. Molecular docking and molecular dynamics simulations were performed to provide a comprehensive understanding of the interactions between LRRK2 and the inhibitors in the data set and best molecules of the screening. Free energy of binding calculation along with hydrogen bond occupancy analysis and RMSD of the ligand in the pocket show CRA_1801 as the best candidate to be repurposed as LRRK2 inhibitor.

Endogenous LRRK2 and PINK1 function in a convergent neuroprotective ciliogenesis pathway in the brain

Mutations in Leucine-rich repeat kinase 2 (LRRK2) and PTEN-induced kinase 1 (PINK1) are associated with familial Parkinson's disease (PD). LRRK2 phosphorylates Rab guanosine triphosphatase (GTPases) within the Switch II domain while PINK1 directly phosphorylates Parkin and ubiquitin (Ub) and indirectly induces phosphorylation of a subset of Rab GTPases. Herein we have crossed LRRK2 [R1441C] mutant knock-in mice with PINK1 knock-out (KO) mice and report that loss of PINK1 does not impact endogenous LRRK2-mediated Rab phosphorylation nor do we see significant effect of mutant LRRK2 on PINK1-mediated Rab and Ub phosphorylation. In addition, we observe that a pool of the Rab-specific, protein phosphatase family member 1H phosphatase, is transcriptionally up-regulated and recruited to damaged mitochondria, independent of PINK1 or LRRK2 activity. Parallel signaling of LRRK2 and PINK1 pathways is supported by assessment of motor behavioral studies that show no evidence of genetic interaction in crossed mouse lines. Previously we showed loss of cilia in LRRK2 R1441C mice and herein we show that PINK1 KO mice exhibit a ciliogenesis defect in striatal cholinergic interneurons and astrocytes that interferes with Hedgehog induction of glial derived-neurotrophic factor transcription. This is not exacerbated in double-mutant LRRK2 and PINK1 mice. Overall, our analysis indicates that LRRK2 activation and/or loss of PINK1 function along parallel pathways to impair ciliogenesis, suggesting a convergent mechanism toward PD. Our data suggest that reversal of defects downstream of ciliogenesis offers a common therapeutic strategy for LRRK2 or PINK1 PD patients, whereas LRRK2 inhibitors that are currently in clinical trials are unlikely to benefit PINK1 PD patients.

Activating Sig-1R inhibits microvascular permeability by reducing LRRK2 expression in lipopolysaccharide-induced acute lung injury

BackgroundEndothelial cells are the first and most damaged target cells during acute lung injury (ALI). Endothelial dysfunction increases pulmonary microvascular permeability, subsequently leading to pulmonary oedema and organ dysfunction; however, clinical treatments against microvascular permeability show poor efficacy. Herein, we aimed to explore the role of the Sigma-1 receptor (Sig-1R) in pulmonary microvascular permeability by constructing ALI animal and cell models, and further investigated the specific mechanisms. MethodsThe effects of Sig-1R on lung injury and endothelial barrier disruption were examined in lipopolysaccharide (LPS)-induced mice and human umbilical vein endothelial cells (HUVECs), respectively. Transcriptome sequencing was carried out to identify possible targets of Sig-1R, and the specific mechanisms of Sig-1R action were investigated using RNA interference and plasmid transfection. ResultsAnalysis of a Gene expression omnibus dataset suggested that Sig-1R plays a protective role against vascular hyperpermeability in ALI. Downregulation of Sig-1R expression and endothelial barrier disruption were both observed in mice and HUVECs upon LPS stimulation. Sig-1R agonists attenuated vascular hyperpermeability in vivo and in vitro, further improving ALI. Sig-1R activation downregulated Leucine-rich repeat kinase 2 (LRRK2) expression in mice and HUVECs. LRRK2 knockdown ameliorated endothelial barrier disruption in mice and HUVECs. Overexpression of LRRK2 reversed the protective effect of Sig-1R activation on LPS-induced endothelial hyperpermeability. Furthermore, Sig1r knockdown exacerbated LPS-induced microvascular hyperpermeability, which was rescued by inhibition of LRRK2. ConclusionsSig-1R activation exerts a protective effect against LPS-induced microvascular hyperpermeability by downregulating LRRK2 expression, which could lead to the development of novel therapeutic strategies for treating ALI.

Executive dysfunction in Parkinson's disease: From neurochemistry to circuits, genetics and neuroimaging.

Cognitive decline is one of the most significant non-motor symptoms of Parkinson's disease (PD), with executive dysfunction (EDF) being the most prominent characteristic of PD-associated cognitive deficits. Currently, lack of uniformity in the conceptualization and assessment scales for executive functions impedes the early and accurate diagnosis of executive dysfunction in PD. The neurobiological mechanisms of executive dysfunction in PD remain poorly understood. Moreover, the treatment of cognitive impairment in PD has progressed slowly and with limited efficacy. Thus, this review explores the characteristics and potential mechanisms of executive dysfunction in PD from multiple perspectives, including the concept of executive function, commonly used neuropsychological tests, neurobiochemistry, genetics, neuroelectrophysiology and neuroimaging. The available evidence indicates that degeneration of the frontal-striatal circuit, along with mutations in the Catechol-O-methyltransferase (COMT) gene and Leucine-rich repeat kinase 2 (LRRK2) gene, may contribute to executive dysfunction in patients with PD. The increase in theta and delta waves, along with the decrease in alpha waves, offers potential biomarkers for the early identification and monitoring of executive dysfunction, as well as the development of dementia in patients with PD. The PD cognition-related pattern (PDCP) pattern may serve as a tool for monitoring and assessing cognitive function progression in these patients and is anticipated to become a biomarker for cognitive disorders associated with PD. The aim is to provide new insights for the early and precise diagnosis and treatment of executive dysfunction in PD.

Structural insights into the novel Parkinson’s-linked R1501W mutation in the Roc domain of leucine-rich repeat kinase 2

ABSTRACT Missense mutations in the Leucine-rich repeat kinase 2 (LRRK2) protein are strongly linked to the pathogenicity of both sporadic and familial Parkinson's Disease (PD). Considering their prevalence and functional consequence, mutations causing kinase dysfunction have experienced the greatest exploration. However, variants of LRRK2 with unaltered kinase activity have also been found to cause PD. This study focuses on one such case: the novel R1501W mutation in the Roc-COR (GTPase) domain of LRRK2. Given its novelty, there are scarcely any studies inspecting this variant. Thus, we employed molecular dynamics simulations of 200 ns alongside structural analyses such as root-mean-square (RMS) fluctuation, RMS deviation, radius of gyration, solvent-accessible surface-area, principal component analysis, and free energy landscape to characterise the structural changes occurring in the R1501W mutant in comparison to the wild-type. Our results reveal the introduction of a closed hydrophobic nest in the mutated region, as well as an increase in flexibility, instability, and compactness of the tertiary structure. We speculate that these alterations contribute to a kinase-independent mechanism for pathogenesis. Overall, our investigation showcases the structural dynamics of R1501W mutant LRRK2, providing a backbone for the design of future studies to further inspect the pathogenic pathway employed by this novel variant.

The design and development of LRRK2 inhibitors as novel therapeutics for Parkinson's disease.

Parkinson's disease (PD) is a common neurodegenerative disease affecting nearly 10 million people worldwide and placing a heavy medical burden on both society and families. However, due to the complexity of its pathological mechanisms, current treatments for PD can only alleviate patients' symptoms. Therefore, novel therapeutic strategies are urgently sought in clinical practice. Leucine-rich repeat kinase 2 (LRRK2) has emerged as a highly promising target for PD therapy. Missense mutations within the structural domain of LRRK2, the most common genetic risk factor for PD, lead to abnormally elevated kinase activity and increase the risk of developing PD. In this article, we provide a comprehensive overview of the structure, biological function, and pathogenic mutations of LRRK2, and examine recent advances in the development of LRRK2 inhibitors. We hope that this article will provide a reference for the design of novel LRRK2 inhibitors based on summarizing the facts and elucidating the viewpoints.

In vivo self-assembled siRNAs within small extracellular vesicles attenuate LRRK2-induced neurodegeneration in Parkinson's disease models.

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene play an important role in Parkinson's disease (PD) pathogenesis, and downregulation of LRRK2 has become a promising therapy for PD. Here, we developed a synthetic biology strategy for the self-assembly and delivery of small interfering RNAs (siRNAs) of LRRK2 into the substantia nigra via small extracellular vesicles (sEVs) using a genetic circuit (in the form of naked DNA plasmid) to attenuate PD-like phenotypes in mouse model. We generated the genetic circuit encoding both a neuron-targeting rabies virus glycoprotein (RVG) tag and a LRRK2 siRNA under the control of a cytomegalovirus (CMV) promoter, and assessed its therapeutic effects using LRRK2R1441G mouse models of PD. After intravenous injection, the genetic circuit was taken up by the host liver to reprogram liver cells to produce and self-assemble LRRK2 siRNAs into sEVs, and then the sEV-enclosed LRRK2 siRNAs were further transferred by the endogenous circulating system of sEVs and guided by the RVG tag to the substantia nigra. Intravenous injection of this genetic circuit reduced total and phosphorylated LRRK2 levels in the substantia nigra, and attenuated PD-like phenotypes in two mouse models by rescuing LRRK2R1441G-induced dopaminergic neurodegeneration and reducing microgliosis. This study provides an efficient therapeutic strategy to attenuate LRRK2-induced neurodegeneration and neuroinflammation in PD mouse models, and may open a new avenue to safely deliver siRNA into brain after peripheral intravenous injection and facilitate PD treatment.

α-Synuclein Gene Hypomethylation in LRRK2 Parkinson's Disease Patients.

α-Synuclein (SNCA) gene hypomethylation was reported in idiopathic Parkinson's disease (iPD). Based on a high clinical resemblance between iPD and leucine-rich repeat kinase 2 (LRRK2)-driven Parkinson's disease (L2PD), we investigated the epigenetic status of SNCA in an extensive LRRK2 clinical cohort from Spain. We assessed the methylation levels of 23 CpG sites in the SNCA promoter region using peripheral blood DNA from L2PD patients (n = 151), LRRK2 nonmanifesting carriers (n = 55), iPD patients (n = 115), and healthy control subjects (n = 154) (total: N = 475). Compared with control subjects, we found significant SNCA hypomethylation in 11 of 23 CpGs in L2PD (48%), whereas 22 CpGs (96%) were hypomethylated in iPD. In line with a healthy status, asymptomatic mutation carriers had similar SNCA methylation profiles to control subjects. This study shows for the first time that SNCA hypomethylation occurs in patients with L2PD. Further studies addressing SNCA methylation status in additional worldwide LRRK2 cohorts are warranted. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

In-depth mass-spectrometry reveals phospho-RAB12 as a blood biomarker of G2019S LRRK2-driven Parkinson's disease.

Leucine-rich repeat kinase 2 (LRRK2) inhibition is a promising disease-modifying therapy for LRRK2-associated Parkinson's disease (L2PD) and idiopathic PD (iPD). However, pharmaco-dynamic readouts and progression biomarkers for clinical trials aiming for disease modification are insufficient since no endogenous marker reflecting enhanced kinase activity of the most common LRRK2 G2019S mutation has been reported yet in L2PD patients. Employing phospho-/proteomic analyses we assessed the impact that LRRK2 activating mutations had in peripheral blood mononuclear cells (PBMCs) from a LRRK2 clinical cohort from Spain (n=174). The groups of study encompassed G2019S L2PD patients (n=37), non-manifesting LRRK2 mutation carriers of G2019S, here, G2019S L2NMCs (n=27), R1441G L2PD patients (n=14), R1441G L2NMCs (n=11), iPD patients (n=40), and healthy controls (n=45). We identified 207 differential proteins in G2019S L2PD compared to controls (39 up/168 down) and 67 in G2019S L2NMCs (10 up/57 down). G2019S down-regulated proteins affected the endolysosomal pathway, proteostasis, and mitochondria, e.g., ATIC, RAB9A, or LAMP1. At the phospho-proteome level, we observed increases in endogenous phosphorylation levels of pSer106 RAB12 in G2019S carriers, which were validated by immunoblotting after 1 year of follow-up (n=48). Freshly collected PBMCs from 3 G2019S L2PD, 1 R1441G L2PD, 1 iPD, and 5 controls (n=10) showed strong diminishment of pSer106 RAB12 phosphorylation levels after in-vitro administration of the MLi-2 LRRK2 inhibitor. Using machine learning, we identified an 18-feature G2019S phospho-/protein signature discriminating G2019S L2PD, L2NMCs, and controls with 96% accuracy that correlated with disease severity, i.e., UPDRS-III motor scoring. Using easily accessible PBMCs from a LRRK2 clinical cohort, we identified elevated levels of pSer106 RAB12 as an endogenous biomarker of G2019S carriers. Our data suggest that monitoring pSer106 RAB12 phosphorylation could be a relevant biomarker for tracking LRRK2 activation, particularly in G2019S carriers. Future work may determine whether pSer106 RAB12 could help with patient enrichment and monitoring drug efficacy in LRRK2 clinical trials.

Widespread Distribution of α-Synuclein Oligomers in LRRK2-related Parkinson's Disease.

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common cause of familial and sporadic Parkinson's disease (PD). While the clinical features of LRRK2-PD patients resemble those of typical PD, there are significant differences in the pathological findings. The pathological hallmark of definite PD is the presence of α-synuclein (αSYN)-positive Lewy-related pathology; however, approximately half of LRRK2-PD cases do not have Lewy-related pathology. Lewy-related pathology is a late-stage αSYN aggregation that can be visualized with hematoxylin and eosin stains or conventional immunohistochemistry (IHC). Increasing evidence has indicated that αSYN oligomers, which represent the early-stage of αSYN aggregation, may have neurotoxicity. Visualization of αSYN oligomers requires specialized staining techniques, such as αSYN-proximity ligation assay (PLA). The distribution and severity of αSYN oligomers in the human brain of LRRK2-PD patients remain unknown. In this study, we performed phosphorylated αSYN-IHC and αSYN-PLA staining on postmortem brain sections of patients with three pathogenic LRRK2 mutants: p.G2019S (n=5), p.I2020T (n=5), and p.R1441C (n=4). The severity of Lewy-related pathology and αSYN oligomers were assessed semi-quantitatively in the brainstem, limbic lobe, basal ganglia, and cerebral cortex. αSYN oligomers were detected in LRRK2-PD cases even in cases without Lewy-related pathology; a negative correlation was observed between Lewy-related pathology and αSYN oligomers (r=-0.26 [-0.39, -0.12]; P<0.0001). Our findings suggest that αSYN oligomers may represent a common pathological feature of LRRK2-PD. Notably, patients harboring p.G2019S and p.I2020T had significantly higher levels of αSYN oligomers in those without Lewy-related pathology compared to those with Lewy-related pathology. These cases also had a trend toward shorter disease duration. These results imply that in LRRK2-PD, αSYN oligomers may initially accumulate in the brain but do not progress to form Lewy-related pathology. The present study suggests that targeting αSYN oligomers may be a therapeutic strategy for LRRK2-PD even if there is no Lewy-related pathology.

Intramolecular feedback regulation of the LRRK2 Roc G domain by a LRRK2 kinase-dependent mechanism.

The Parkinson's disease (PD)-linked protein Leucine-Rich Repeat Kinase 2 (LRRK2) consists of seven domains, including a kinase and a Roc G domain. Despite the availability of several high-resolution structures, the dynamic regulation of its unique intramolecular domain stack is nevertheless still not well understood. By in-depth biochemical analysis, assessing the Michaelis-Menten kinetics of the Roc G domain, we have confirmed that LRRK2 has, similar to other Roco protein family members, a KM value of LRRK2 that lies within the range of the physiological GTP concentrations within the cell. Furthermore, the R1441G PD variant located within a mutational hotspot in the Roc domain showed an increased catalytic efficiency. In contrast, the most common PD variant G2019S, located in the kinase domain, showed an increased KM and reduced catalytic efficiency, suggesting a negative feedback mechanism from the kinase domain to the G domain. Autophosphorylation of the G1+2 residue (T1343) in the Roc P-loop motif is critical for this phosphoregulation of both the KM and the kcat values of the Roc-catalyzed GTP hydrolysis, most likely by changing the monomer-dimer equilibrium. The LRRK2 T1343A variant has a similar increased kinase activity in cells compared to G2019S and the double mutant T1343A/G2019S has no further increased activity, suggesting that T1343 is crucial for the negative feedback in the LRRK2 signaling cascade. Together, our data reveal a novel intramolecular feedback regulation of the LRRK2 Roc G domain by a LRRK2 kinase-dependent mechanism. Interestingly, PD mutants differently change the kinetics of the GTPase cycle, which might in part explain the difference in penetrance of these mutations in PD patients.

PINK1 is a target of T cell responses in Parkinson's disease.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder. While there is no curative treatment, the immune system's involvement with autoimmune T cells that recognize the protein alpha-synuclein (α-syn) in a subset of individuals suggests new areas for therapeutic strategies. As not all patients with PD have T cells specific for α-syn, we explored additional autoantigenic targets of T cells in PD. We generated 15-mer peptides spanning several PD-related proteins implicated in PD pathology, including Glucosylceramidase Beta 1 (GBA), Superoxide dismutase 1 (SOD1), PTEN Induced Kinase 1 (PINK1), Parkin RBR E3 Ubiquitin Protein Ligase (parkin), Oxoglutarate Dehydrogenase (OGDH), and Leucine Rich Repeat Kinase 2 (LRRK2). Cytokine production (IFNγ, IL-5, IL-10) against these proteins was measured using a fluorospot assay and PBMCs from patients with PD and age-matched healthy controls. We identified PINK1, a regulator of mitochondrial stability, as an autoantigen targeted by T cells, as well as its unique epitopes, and their HLA restriction. The PINK1-specific T cell reactivity revealed sex-based differences as it was predominantly found in male patients with PD, which may contribute to the heterogeneity of PD. Identifying and characterizing PINK1 and other autoinflammatory targets may lead to antigen-specific diagnostics, progression markers, and/or novel therapeutic strategies for PD.

Effects of Calcium Ion Dyshomeostasis and Calcium Ion-Induced Excitotoxicity in Parkinson’s Disease

Calcium ions (Ca2+) are vital intracellular messengers that regulate a multitude of neuronal functions, including synaptic transmission, plasticity, exocytosis, and cell survival. Neuronal cell death can occur through a variety of mechanisms, including excitotoxicity, apoptosis, and autophagy. In the context of excitotoxicity, the excessive release of glutamate in the synapses can trigger the activation of postsynaptic receptors. Upon activation, Ca2+ influx into the cell from the extracellular space via their associated ion channels, most notably L-type Ca2+ channels. Previous studies have indicated that α-synuclein (α-syn), a typical cytosolic protein, plays a significant role in the pathogenesis of Parkinson’s disease (PD). It is also worth noting that the aggregated form of α-syn has the capacity to affect Ca2+ homeostasis by altering the function of Ca2+ regulation. The upregulation of leucine-rich repeat kinase 2 (LRRK2) is closely associated with PD pathogenesis. LRRK2 mutants exhibit a dysregulation of calcium signaling, resulting in dopaminergic neuronal degeneration. It could therefore be proposed that α-syn and LRRK2 play important roles in the mechanisms underlying Ca2+ dyshomeostasis and excitotoxicity in PD.

The cellular and extracellular proteomic signature of human dopaminergic neurons carrying the LRRK2 G2019S mutation.

Extracellular vesicles are easily accessible in various biofluids and allow the assessment of disease-related changes in the proteome. This has made them a promising target for biomarker studies, especially in the field of neurodegeneration where access to diseased tissue is very limited. Genetic variants in the LRRK2 gene have been linked to both familial and sporadic forms of Parkinson's disease. With LRRK2 inhibitors entering clinical trials, there is an unmet need for biomarkers that reflect LRRK2-specific pathology and target engagement. In this study, we used induced pluripotent stem cells derived from a patient with Parkinson's disease carrying the LRRK2 G2019S mutation and an isogenic gene-corrected control to generate human dopaminergic neurons. We isolated extracellular vesicles and neuronal cell lysates and characterized their proteomic signature using data-independent acquisition proteomics. Then, we performed differential expression analysis to identify dysregulated proteins in the mutated line. We used Metascape and gene ontology enrichment analysis on the dysregulated proteomes to identify changes in associated functional networks. We identified 595 significantly differentially regulated proteins in extracellular vesicles and 3,205 in cell lysates. We visualized functionally relevant protein-protein interaction networks and identified key regulators within the dysregulated proteomes. Using gene ontology, we found a close association with biological processes relevant to neurodegeneration and Parkinson's disease. Finally, we focused on proteins that were dysregulated in both the extracellular and cellular proteomes. We provide a list of ten biomarker candidates that are functionally relevant to neurodegeneration and linked to LRRK2-associated pathology, for example, the sonic hedgehog signaling molecule, a protein that has tightly been linked to LRRK2-related disruption of cilia function. In conclusion, we characterized the cellular and extracellular proteome of dopaminergic neurons carrying the LRRK2 G2019S mutation and proposed an experimentally based list of biomarker candidates for future studies.

The kinase LRRK2 is required for the physiological function and expression of the glial glutamate transporter EAAT2 (SLC1A2).

Neurotransmitter transporters (NTTs) control synaptic responses by modulating the concentration of neurotransmitters at the synaptic cleft. Glutamate is the most abundant excitatory neurotransmitter in the brain and needs to be finely tuned in time and space to maintain a healthy brain and precise neurotransmission. The glutamate transporter EAAT2 (SLC1A2) is primarily responsible for glutamate clearance. EAAT2 impairment has been associated with Alzheimer's disease (AD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD). Mutations in leucine-rich repeat kinase 2 (LRRK2) contribute to both monogenic and sporadic forms of PD, of which the common substitution Gly2019Ser is associated with a significant deficit in EAAT2 expression. The role of pathological mutants of the LRRK2 is intensively studied and reviewed. Here we have focused the attention on the physiological role of LRRK2 on EAAT2, comparing the activity of NTTs with or without the LRRK2 kinase. By heterologous expression in Xenopus laevis oocytes and two-electrode voltage clamp, the current amplitudes of the selected NTTs and kinetic parameters have been collected in the presence and absence of LRRK2. The results show that EAAT2 expression and function are impaired in the absence of the kinase and also under its pharmacological inhibition via MLi-2 treatment. LRRK2 stabilizes EAAT2 expression increasing the amount of transporter at the plasma membrane. Interestingly, the LRRK2 action is EAAT2-specific, as we observed no significant changes in the transport current amplitude and kinetic parameters obtained for the other excitatory and inhibitory NTTs studied. This study, for the first time, demonstrates the physiological importance of LRRK2 in EAAT2 function, highlighting the specificity of LRRK2-mediated modulation of EAAT2 and suggesting a potential role for the kinase as a checkpoint for preserving neurons from excitotoxicity. In brain conditions associated with impaired glutamate clearance, targeting LRRK2 for EAAT2 regulation may offer novel therapeutic opportunities.

Molecular dynamics studies reveal the structural impacts of LRRK2 R1441C and LRRK2 D1994A mutations in Parkinson's disease

Parkinson's Disease (PD) is a continuingly deteriorating neurological ailment affecting over 8.5 million patients globally as of 2019, and the numbers are expected to keep rising. To aid in identifying therapeutic targets, molecular dynamics simulations are convenient and cost-effective methods for enriching our knowledge of the molecular pathophysiology of diseases. Many proteins and their corresponding mutations have been identified to contribute to this disease, of which Leucine-rich repeat kinase 2 (LRRK2) is accountable for a significant percentage. Several mutations involving the domains in LRRK2 have been studied, which are known to interfere with various enzymatic processes, ultimately leading to trademark features of PD like aggregation of protein inclusions called Lewy Bodies (LBs), mitochondrial dysfunctions, etc. The precise molecular mechanism of the mutations' pathophysiology is still unclear. This research article looks at the structural effects of mutations, namely the R1441C and D1994A mutations, on the surrounding residues in the protein, offering novel insights into pathophysiological changes at an atomistic level. Our results indicate a gain of electrostatic interactions with a stable αβ motif within the LRR-Roc linker, amongst other changes. This article also highlights the potential involvement and importance of the αβ motif in LRRK2 associated PD.

Autophagy Deficits Underly Selective Neuronal Vulnerability to Alpha Synuclein Fibrils in Alzheimer’s and Parkinson’s iPSC Derived Neurons

AbstractBackgroundAlzheimer’s (AD) and Parkinson’s disease (PD) feature progressive neurodegeneration in a remarkably regionally selective manner. Post mortem studies have posited a role for cell autonomous mechanisms driving this, so we aimed to examine a live human induced pluripotent stem cell (iPSC) model to see whether it can replicate the phenomenon of selective neuronal vulnerability, so to better determine disease mechanisms and therapeutic targets.MethodiPSC‐derived neurons offer a rare opportunity to examine cell autonomous vulnerability in live human cells. iPSCs from patients with AD‐related presenilin‐1 mutations (n = 6), PD‐related leucine rich repeat kinase 2 mutations (n = 6), and isogenic corrected (n = 4) and healthy controls (n = 4) have been differentiated into both cortical and midbrain dopaminergic neurons to enable comparison of pre‐formed fibril induced pathology in different neuronal subtypes from the same patient. We then examined lysosomal number, morphology, degradation, pH, and calcium using live imaging assays, alongside mitochondrial biology, and electrophysiology to understand underlying drivers of vulnerability in the cell types.ResultUpon insult with alpha‐synuclein PFFs, AD and PD dopaminergic neurons produce substantial Lewy‐like pathology, whereas cortical neurons remain relatively resilient to alpha‐synuclein aggregation, suggesting cell‐type vulnerability. PSEN1‐Intron‐4‐Deletion cortical neurons, however, had significantly elevated pathology. These lines displayed hyperactivity on microelectrode arrays and abnormal lysosomal biology, including increased LAMP1 and dysregulated calcium. PFF‐insulted AD cortical neurons also have impaired neurite outgrowth, while PD cortical neurons are resilient.ConclusionThese preliminary results show relative vulnerability of AD against PD cortical neurons, and dopaminergic against cortical neurons to alpha‐synuclein aggregates for the first time. These suggest the selective vulnerability to proteinopathy in these diseases is reflected by the iPSC neuronal model and support the notion that cell intrinsic factors like autophagy drive vulnerability.

Circular RNA circ_0004630 promotes malignancy and glycolysis of nonsmall cell lung cancer by sponging microRNA-1208 and regulating leucine-rich repeat kinase 2 expression.

Emerging evidence has discovered that circular RNAs play important regulators of nonsmall cell lung cancer (NSCLC), but the role and potential molecular mechanism of hsa_circ_100549 (circ_0004630) involved in NSCLC is poorly defined. In this study, circ_0004630, microRNA-1208 (miR-1208), and leucine-rich repeat kinase 2 (LRRK2) expression were detected using real-time quantitative polymerase chain reaction. Cell proliferation, colony formation, apoptosis, and invasion were assessed using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine, colony formation, flow cytometry, and transwell assays. Protein levels of glucose transporter 1, Hexokinase 2, and LRRK2 were detected using western blot assay. Glucose consumption, lactate production, and adenosine triphosphatecontent were assessed using the corresponding kits. After predicting via bioinformatics software Circinteractome and Targetscan, the binding between miR-1208 and circ_0004630 or LRRK2 was verified by a dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assay. The xenograft tumor model analyzed the biological role circ_000460 on tumor growth in vivo. It was found that circ_0004630 and LRRK2 were increased, and miR-1208 was low expression in NSCLC tissues and cells. Functionally, the downregulation of circ_0004630 inhibited NSCLC cell proliferation, invasion, glycolysis, and accelerated apoptosis in vitro. In mechanism, circ_0004630 might work as a sponge of miR-1208 to modulate LRRK2 expression. In addition, DUXAP8 deficiency cured neuroblastoma tumor growth in vivo. In conclusion, circ_0004630 knockdown might suppress NSCLC cell proliferation, metastasis, and glycolysis partly by the miR-1208/LRRK2 axis. Our findings hinted at an important theoretical basis for further elucidating the pathogenesis of NSCLC and targeted therapy.

Exploring environmental modifiers of LRRK2-associated Parkinson’s disease penetrance: An exposomics and metagenomics pilot study on household dust

Pathogenic variants in the Leucine-rich repeat kinase 2 (LRRK2) gene are a primary monogenic cause of Parkinson’s disease (PD). However, the likelihood of developing PD with inherited LRRK2 pathogenic variants differs (a phenomenon known as “reduced penetrance”), with factors including age and geographic region, highlighting a potential role for lifestyle and environmental factors in disease onset. To investigate this, household dust samples from four different groups of individuals were analyzed using metabolomics/exposomics and metagenomics approaches: PD+/LRRK2+ (PD patients with pathogenic LRRK2 variants; n = 11), PD-/LRRK2+ (individuals with pathogenic LRRK2 variants but without PD diagnosis; n = 8), iPD (PD of unknown cause; n = 11), and a matched, healthy control group (n = 11). The dust was complemented with metabolomics and lipidomics of matched serum samples, where available. A total of 1,003 chemicals and 163 metagenomic operational taxonomic units (mOTUs) were identified in the dust samples, of which ninety chemicals and ten mOTUs were statistically significant (ANOVA p-value < 0.05). Reduced levels of 2-benzothiazolesulfonic acid (BThSO3) were found in the PD-/LRRK2+ group compared to the PD+/LRRK2+ . Among the significant chemicals tentatively identified in dust, two are hazardous chemical replacements: Bisphenol S (BPS), and perfluorobutane sulfonic acid (PFBuS). Furthermore, various lipids were found altered in serum including different lysophosphatidylethanolamines (LPEs), and lysophosphatidylcholines (LPCs), some with higher levels in the PD+/LRRK2+ group compared to the control group. A cellular study on isogenic neurons generated from a PD+/LRRK2+ patient demonstrated that BPS negatively impacts mitochondrial function, which is implicated in PD pathogenesis. This pilot study demonstrates how non-target metabolomics/exposomics analysis of indoor dust samples complemented with metagenomics can prioritize relevant chemicals that may be potential modifiers of LRRK2 penetrance.

Clinical features and progression of Parkinson's disease with LRRK2 variants: A prospective study.

We established a prospective cohort study to investigate the differences in motor and non-motor symptoms between idiopathic Parkinson's disease (IPD) and Parkinson's disease in carriers of leucine-rich repeat kinase 2 (LRRK2) gene risk variants (LRRK2-PD). The study included 1407 individuals with IPD and 649 individuals with LRRK2-PD (comprising 304 with LRRK2-G2385R, 220 with LRRK2-R1628P, and 105 with LRRK2-A419V). Differences in symptoms between LRRK2-PD and IPD were analyzed using LCMM modeling and Cox regression analysis. The LRRK2-G2385R variant showed slower progression in tremor symptoms and excessive daytime sleepiness compared with IPD. In contrast, symptoms associated with LRRK2-R1628P and LRRK2-A419V were more similar to those of IPD. Survival analysis revealed that LRRK2-PD does not affect life expectancy compared with IPD. Our extended longitudinal follow-up of LRRK2-PD in the Chinese population provided valuable insights, further confirming the clinical characteristics of the three LRRK2 variants.