Leucine-rich Repeat Kinase 2 Expression Research Articles

Expression of G2019S LRRK2 in Rat Primary Astrocytes Mediates Neurotoxicity and Alters the Dopamine Synthesis Pathway in N27 Cells via Astrocytic Proinflammatory Cytokines and Neurotrophic Factors.

Astrocytes in the brain contribute to various essential functions, including maintenance of the neuronal framework, survival, communication, metabolic processes, and neurotransmitter levels. Leucine-rich repeat kinase 2 (LRRK2) is associated with the pathogenesis of Parkinson's disease (PD). LRRK2 is expressed in neurons, microglia, and astrocytes and plays diverse roles in these cell types. We aimed to determine the effects of mutant human G2019S-LRRK2 (GS-hLRRK2) in rat primary astrocytes (rASTROs). Transfection with GS-hLRRK2 significantly decreased cell viability compared to transfection with the vector and wild-type human LRRK2 (WT-hLRRK2). GS-hLRRK2 expression significantly reduced the levels of nerve growth factor and increased the levels of proinflammatory cytokines (interleukin-1β and tumor necrosis factor α) compared to the vector and WT-hLRRK2 expression. Furthermore, GS-hLRRK2 expression in rASTROs promoted astrogliosis, which was characterized by increased expression of glial fibrillary acidic protein and vimentin. Treatment with the conditioned medium of G2019S LRRK2-expressing rASTROs decreased N27 cell viability compared to treatment with that of WT-hLRRK2-expressing rASTROs. Consequently, the regulation of the dopamine synthesis pathway was affected in N27 cells, thereby leading to altered levels of tyrosine hydroxylase, dopamine transporter, Nurr1, and dopamine release. Overall, the G2019S LRRK2 mutation disrupted astrocyte function, thereby aggravating PD progression.

Suppression of Glioblastoma Stem Cell Potency and Tumor Growth via LRRK2 Inhibition.

Leucine-rich repeat kinase 2 (LRRK2), a large GTP-regulated serine/threonine kinase, is well-known for its mutations causing late-onset Parkinson's disease. However, the role of LRRK2 in glioblastoma (GBM) carcinogenesis has not yet been fully elucidated. Here, we discovered that LRRK2 was overexpressed in 40% of GBM patients, according to tissue microarray analysis, and high LRRK2 expression correlated with poor prognosis in GBM patients. LRRK2 and stemness factors were highly expressed in various patient-derived GBM stem cells, which are responsible for GBM initiation. Canonical serum-induced differentiation decreased the expression of both LRRK2 and stemness factors. Given that LRRK2 is a key regulator of glioma stem cell (GSC) stemness, we developed DNK72, a novel LRRK2 kinase inhibitor that penetrates the blood-brain barrier. DNK72 binds to the phosphorylation sites of active LRRK2 and dramatically reduced cell proliferation and stemness factors expression in in vitro studies. Orthotopic patient-derived xenograft mouse models demonstrated that LRRK2 inhibition with DNK72 effectively reduced tumor growth and increased survival time. We propose that LRRK2 plays a significant role in regulating the stemness of GSCs and that suppression of LRRK2 kinase activity leads to reduced GBM malignancy and proliferation. In the near future, targeting LRRK2 in patients with high LRRK2-expressing GBM could offer a superior therapeutic strategy and potentially replace current clinical treatment methods.

LRRK2 is involved in heat exposure-induced acute lung injury and alveolar type II epithelial cell dysfunction

Heat exposure induces excessive hyperthermia associated with systemic inflammatory response that leads to multiple organ dysfunction including acute lung injury. However, how heat impairs the lung remains elusive so far. We aimed to explore the underlying mechanism by focusing on leucine-rich repeat kinase 2 (LRRK2), which was associated with lung homeostasis. Both in vivo and in vitro models were induced by heat exposure. Firstly, heat exposure exerted core temperature (Tc) disturbance, pulmonary dysfunction, atelectasis, inflammation, impaired energy metabolism, and reduced surfactant proteins in the lung of mice. In addition, decreased LRRK2 expression and increased heat shock proteins (HSPs) 70 were observed with heat exposure in both the lung of mice and alveolar type II epithelial cells (AT2). Furthermore, LRRK2 inhibition aggravated heat exposure-initiated Tc dysregulation, injury in the lung and AT2 cells, and enhanced HSP70 expression. In conclusion, LRRK2 is involved in heat-induced acute lung injury and AT2 cell dysfunction.

Preclinical Evaluation of Novel Positron Emission Tomography (PET) Probes for Imaging Leucine-Rich Repeat Kinase 2 (LRRK2).

Parkinson's disease (PD) is one of the most highly debilitating neurodegenerative disorders, which affects millions of people worldwide, and leucine-rich repeat kinase 2 (LRRK2) mutations have been involved in the pathogenesis of PD. Developing a potent LRRK2 positron emission tomography (PET) tracer would allow for in vivo visualization of LRRK2 distribution and expression in PD patients. In this work, we present the facile synthesis of two potent and selective LRRK2 radioligands [11C]3 ([11C]PF-06447475) and [18F]4 ([18F]PF-06455943). Both radioligands exhibited favorable brain uptake and specific bindings in rodent autoradiography and PET imaging studies. More importantly, [18F]4 demonstrated significantly higher brain uptake in the transgenic LRRK2-G2019S mutant and lipopolysaccharide (LPS)-injected mouse models. This work may serve as a roadmap for the future design of potent LRRK2 PET tracers.

Upregulation of LRRK2 following traumatic brain injury does not directly phosphorylate Thr175 tau.

Phosphorylated microtubule-associated protein tau (tau) aggregates are a pathological hallmark of various neurodegenerative diseases, including chronic traumatic encephalopathy and amyotrophic lateral sclerosis with cognitive impairment. While there are many residues phosphorylated on tau, phosphorylation of threonine 175 (pThr175 tau) has been shown to initiate fibril formation in vitro and is present in pathological tau aggregates in vivo. Given this, preventing Thr175 tau phosphorylation presents a potential approach to reduce fibril formation; however, the kinase(s) acting on Thr175 are not yet fully defined. Using a single controlled cortical impact rodent model of traumatic brain injury (TBI), which rapidly induces Thr175 tau phosphorylation, we observed an upregulation and alteration in subcellular localization of leucine-rich repeat kinase 2 (LRRK2), a kinase that has been implicated in tau phosphorylation. LRRK2 upregulation was evident by one-day post-injury and persisted to day 10. The most notable changes were observed in microglia at the site of injury in the cortex. To determine if the appearance of pThr175 tau was causally related to the upregulation of LRRK2 expression, we examined the ability of LRRK2 to phosphorylate Thr175in vitro by co-transfecting 2N4R human WT-tau with either LRRK2-WT, constitutively-active LRRK2-G2019S or inactive LRRK2-3XKD. We found no significant difference in the level of pThr175 tau between the overexpression of LRRK2-WT, -G2019S or -3XKD, suggesting LRRK2 does not phosphorylate tau at Thr175. Further, downstream events known to follow Thr175 phosphorylation and known to be associated with pathological tau fibril formation (pSer9-GSK3β and pThr231 tau induction) also remained unchanged. We conclude that while LRRK2 expression is altered in TBI, it does not contribute directly to pThr175 tau generation.

LINC00707 promotes multidrug resistance of ovarian cancer cells by targeting the miR-382-5p/LRRK2 axis.

Multidrug resistance severely limits the efficacy of ovarian cancer (OC) treatment. Recent studies have revealed the carcinogenic role of LINC00707 RNA. However, the role of LINC00707 in the development of multidrug resistance in OC has not been clarified. Therefore, the aim of this study was to investigate the relationship between LINC00707 and multidrug resistance in OC, which can facilitate the development of new therapeutic agents for effectively addressing this issue. The RNA expression of LINC00707, miR-382-5p and leucine-rich repeat kinase 2 (LRRK2) in SKOV3 (a human OC cell line) cells was detected by qRT-PCR. The effects of LINC00707 on the proliferation and viability of SKOV3 cells were determined by MTT assay and colony formation assay. The interaction of LINC00707, miR-382-5p, and LRRK2 was bioinformatically predicted and verified with dual-luciferase reporter assay. In addition, the effect of LINC00707 on drug resistance in SKOV3 cells through targeting the miR-382-5p/LRRK2 axis was explored. The expression of LINC00707 and LRRK2 was significantly increased in SKOV3 cells, while miR-382-5p expression was significantly decreased. The results of bioinformatic prediction and colony formation assay demonstrated that LINC00707 could regulate LRRK2 expression in SKOV3 cells by targeting miR-382-5p. Additionally, knockdown of LINC00707 markedly increased expression of miR-382-5p and decreased that of LRRK2, increased cell proliferation and viability, as well as sensitivity to chemotherapeutic agents in SKOV3 cells. Notably, these manifestations were more obvious with simultaneous knockdown of LINC00707 and miR-382-5p compared with knockdown of LINC00707 alone. LINC00707 is overexpressed in SKOV3 cells and promotes SKOV3 cell proliferation and resistance to chemotherapeutic drugs via targeting the miR-382-5p/LRRK2 axis.

Targeting leucine-rich repeat serine/threonine-protein kinase 2 sensitizes pancreatic ductal adenocarcinoma to anti-PD-L1 immunotherapy

Immune checkpoints blockade therapy is not sensitive in pancreatic ductal adenocarcinoma (PDAC) and negative feedback of tumor immune evasion might take part of responsibility. We isolated CD8+ T cells and cultured in vitro. Proteomic analysis was performed to compare changes of Panc02 cell lines cultured with conditional medium and leucine rich repeat kinase 2 (LRRK2) was identified as a differential gene. LRRK2 expression was related to CD8+ T cells spatial distribution in PDAC clinical samples and was upregulated by CD8+ T cells via interferon gamma (IFN-γ) simulation in vitro. Knocking down or pharmacologically inhibition of LRRK2 activated anti-pancreatic cancer immune response in mice which meant that LRRK2 acted as an immunosuppressive gene. Mechanically, LRRK2 phosphorylated PD-L1 at T210 to inhibit its ubiquitination-mediated proteasomal degradation. LRRK2 inhibition attenuated PD-1/PD-L1 blockade-mediated, T cell-induced, upregulation of LRRK2/PD-L1, thus sensitizing anti-PD therapy. In addition, Adenosylcobalamin, the activated form of Vitamin B12, which was found as a broad-spectrum inhibitor of LRRK2, could inhibited LRRK2 in vivo and sensitize immunotherapy in PDAC as well, which endowed LRRK2 inhibition a potential clinical translational value. Therefore, PD-L1 blockade combined with LRRK2 inhibition could be a novel therapy strategy for PDAC.

Secretion of VGF relies on the interplay between LRRK2 and post-Golgi v-SNAREs

The neuropeptide VGF was recently proposed as a neurodegeneration biomarker. The Parkinson's disease-related protein leucine-rich repeat kinase 2 (LRRK2) regulates endolysosomal dynamics, a process that involves SNARE-mediated membrane fusion and could regulate secretion. Here we investigate potential biochemical and functional links between LRRK2 and v-SNAREs. We find that LRRK2 directly interacts withthe v-SNAREs VAMP4 and VAMP7. Secretomics reveals VGF secretory defects in VAMP4 and VAMP7knockout (KO) neuronal cells. In contrast, VAMP2 KO "regulated secretion-null" and ATG5 KO "autophagy-null" cells release more VGF. VGF is partially associated with extracellular vesicles and LAMP1+ endolysosomes. LRRK2 expression increases VGF perinuclear localization and impairs its secretion. Retention using selective hooks (RUSH) assays show that a pool of VGF traffics through VAMP4+ and VAMP7+ compartments, and LRRK2 expression delays its transport to the cell periphery. Overexpression of LRRK2 or VAMP7-longin domain impairs VGF peripheral localization in primary cultured neurons. Altogether, our results suggest that LRRK2 might regulate VGF secretion via interaction with VAMP4 and VAMP7.

Alterations in the LRRK2-Rab pathway in urinary extracellular vesicles as Parkinson’s disease and pharmacodynamic biomarkers

Expression or phosphorylation levels of leucine-rich repeat kinase 2 (LRRK2) and its Rab substrates have strong potential as disease or pharmacodynamic biomarkers. The main objective of this study is therefore to assess the LRRK2-Rab pathway for use as biomarkers in human, non-human primate (NHP) and rat urine. With urine collected from human subjects and animals, we applied an ultracentrifugation based fractionation protocol to isolate small urinary extracellular vesicles (uEVs). We used western blot with antibodies directed against total and phosphorylated LRRK2, Rab8, and Rab10 to measure these LRRK2 and Rab epitopes in uEVs. We confirm the presence of LRRK2 and Rab8/10 in human and NHP uEVs, including total LRRK2 as well as phospho-LRRK2, phospho-Rab8 and phospho-Rab10. We also confirm LRRK2 and Rab expression in rodent uEVs. We quantified LRRK2 and Rab epitopes in human cohorts and found in a first cohort that pS1292-LRRK2 levels were elevated in individuals carrying the LRRK2 G2019S mutation, without significant differences between healthy and PD groups, whether for LRRK2 G2019S carriers or not. In a second cohort, we found that PD was associated to increased Rab8 levels and decreased pS910-LRRK2 and pS935-LRRK2. In animals, acute treatment with LRRK2 kinase inhibitors led to decreased pT73-Rab10. The identification of changes in Rab8 and LRRK2 phosphorylation at S910 and S935 heterologous phosphosites in uEVs of PD patients and pT73-Rab10 in inhibitor-dosed animals further reinforces the potential of the LRRK2-Rab pathway as a source of PD and pharmacodynamic biomarkers in uEVs.

Pleiotropic effect of LRRK2 on Parkinson‐associated proteins and processing of pathological alpha‐synuclein in myeloid cells

AbstractBackgroundMutations in the LRRK2 gene, which encodes leucine‐rich repeat kinase 2 (LRRK2), are a cause of autosomal dominant Parkinson’s disease (PD). Single‐nucleotide polymorphisms (SNP) in the LRRK2 locus are one of the most consistently replicated in multiple genome‐wide association studies in sporadic PD and with inflammatory diseases. We recently found that a PD‐associated risk SNP (rs76904798, p = 2.0×10−28) in the LRRK2 locus is also associated with cerebrospinal fluid (CSF) levels of granulins (PGRN, p = 8.6×10−9), glycoprotein nmb (GPNMB, p = 2.3×10−9), Ectonucleoside triphosphate diphosphohydrolase‐1 (ENTPD1, p = 2.3×10−9) also known as CD39 and Cathepsin B (CTSB, p = 2.5×10−4). Yet, functional validation in cellular models is lacking.MethodsHuman monocytic cells (U937) were differentiated (dU937) into macrophages to test the effect of LRRK2 on CTSB, CD39, GPNMB, PGRN and alpha‐synuclein (aSyn). LRRK2 kinase activity and expression level were modulated using pharmacological inhibitors and lentivirus‐mediated overexpression. Protein levels were assessed using western blotting and ELISA. dU937 cells were treated with human aSyn pre‐formed fibrils (haSyn PFFs). We analyzed CSF somaLogic data from the Parkinson’s Progression Marker’s Initiative (PPMI) cohort (Data accessed November 2021).Results LRRK2 mutation (G2019S and R1441G) carriers from the PPMI cohort exhibit significantly increased CSF levels of PGRN (p = 2.1×10−22), GPNMB (p = 1.6×10−29), CTSB (p = 2.5×10−16) and CD39 (p = 1.8×10−18) compared to age and gender‐matched non‐carriers (N = 1158). dU937 cells overexpressing LRRK2 showed an increase in the phosphorylation of LRRK2‐Ser935 and Rab10‐T73 and intracellular levels of lysosomal proteins CTSB and Saposin D without affecting LAMP1 or M6PR. LRRK2 also reduced extracellular CD39, PGRN and GPNMB levels and the levels of intracellular endogenous aSyn dimers in dU937 cells. HaSyn PFF treatment induced a time‐dependent reduction of CTSB and GPNMB levels, increased PGRN levels and altered intracellular aSyn processing pattern in dU937 cells overexpressing LRRK2. Pharmacological LRRK2 kinase inhibition decreased intracellular CTSB levels. LRRK2 co‐immunoprecipitates with PGRN in cells and in human brain.ConclusionsLRRK2 modifies lysosome‐associated proteins and regulate aSyn proteostasis. Pathogenic LRRK2 mutations increased CSF levels of PGRN, GPNMB, CTSB and CD39 in the PPMI cohort. Our in vivo and in vitro data supports a pleotropic role of the LRRK2 locus as a genetic modifier of PD‐associated proteins.

LRRK2 expression in normal and pathologic human gut and in rodent enteric neural cell lines.

Leucine-rich repeat kinase 2 (LRRK2) gene, which is the gene most commonly associated with Parkinson's disease (PD), is also a susceptibility gene for Crohn's disease, thereby suggesting that LRRK2 may sit at the crossroads of gastrointestinal inflammation, Parkinson's, and Crohn's disease. LRRK2 protein has been studied intensely in both CNS neurons and in immune cells, but there are only few studies on LRRK2 in the enteric nervous system (ENS). LRRK2 is present in ENS ganglia and the existing studies on LRRK2 expression in colonic biopsies from PD subjects have yielded conflicting results. Herein, we propose to extend these findings by studying in more details LRRK2 expression in the ENS. LRRK2 expression was evaluated in full thickness segments of colon of 16 Lewy body, 12 non-Lewy body disorders cases, and 3 non-neurodegenerative controls and in various enteric neural cell lines. We showed that, in addition to enteric neurons, LRRK2 is constitutively expressed in enteric glial cells in both fetal and adult tissues. LRRK2 immunofluorescence intensity in the myenteric ganglia was not different between Lewy body and non-Lewy body disorders. Additionally, we identified the cAMP pathway as a key signaling pathway involved in the regulation of LRRK2 expression and phosphorylation in the enteric glial cells. Our study is the first detailed characterization of LRRK2 in the ENS and the first to show that enteric glial cells express LRRK2. Our findings provide a basis to unravel the functions of LRRK2 in the ENS and to further investigate the pathological changes in enteric synucleinopathies.

Leucine-rich repeat kinase 2 is protective during acute kidney injury through its activation of autophagy in podocytes.

Leucine-rich repeat kinase 2 (LRRK2) is a known regulator of autophagy in a range of cell types. Here, we investigated the role of LRRK2-associated autophagy during acute kidney injury (AKI) and its underlying mechanism(s) of action. Male mice aged 8-weeks were treated with the LRRK2 inhibitor MLi-2 and exposed to lipopolysaccharide (LPS) through intraperitoneal injection or ischemia-reperfusion (IR) surgery. Mice were sacrificed 12 or 24 h post-LPS injection or IR operation and blood was collected for serum creatinine measurements. Kidney cortical tissues were collected for western blot analysis of podocyte-specific markers and autophagy-associated proteins. Renal histopathology was observed through hematoxylin-eosin staining. For cell-based assays, immortalized mouse podocytes were silenced for LRRK2 through siRNA transfection and exposed to LPS or cobalt chloride. Changes in cell viability were investigated using cell counting kit-8, flow cytometry and MTT assays. Expression of podocyte-specific markers and autophagy-associated proteins were analyzed by western blotting. We observed an increase in LRRK2 expression at 12 h post-LPS injection and IR surgery that was accompanied by enhanced autophagy. At 24 h post-treatment, both LRRK2 expression and autophagy declined. Kidney injury was most pronounced in mice treated with MLi-2. Podocytes silenced for LRRK2 showed a loss of cell viability, decreased levels of podocyte-specific protein expression and a suppression of autophagy. Together, these data reveal the protective effects of LRRK2 during AKI through enhanced podocyte autophagy and cell viability.

The APP intracellular domain promotes LRRK2 expression to enable feed-forward neurodegenerative mechanisms in Parkinson's disease.

Gain-of-function mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are common in familial forms of Parkinson's disease (PD), which is characterized by progressive neurodegeneration that impairs motor and cognitive function. We previously demonstrated that LRRK2-mediated phosphorylation of β-amyloid precursor protein (APP) triggers the production and nuclear translocation of the APP intracellular domain (AICD). Here, we connected LRRK2 to AICD in a feed-forward cycle that enhanced LRRK2-mediated neurotoxicity. In cooperation with the transcription factor FOXO3a, AICD promoted LRRK2 expression, thus increasing the abundance of LRRK2 that promotes AICD activation. APP deficiency in LRRK2G2019S mice suppressed LRRK2 expression, LRRK2-mediated mitochondrial dysfunction, α-synuclein accumulation, and tyrosine hydroxylase (TH) loss in the brain, phenotypes associated with toxicity and loss of dopaminergic neurons in PD. Conversely, AICD overexpression increased LRRK2 expression and LRRK2-mediated neurotoxicity in LRRK2G2019S mice. In LRRK2G2019S mice or cultured dopaminergic neurons from LRRK2G2019S patients, treatment with itanapraced reduced LRRK2 expression and was neuroprotective. Itanapraced showed similar effects in a neurotoxin-induced PD mouse model, suggesting that inhibiting the AICD may also have therapeutic benefits in idiopathic PD. Our findings reveal a therapeutically targetable, feed-forward mechanism through which AICD promotes LRRK2-mediated neurotoxicity in PD.

Association of a common genetic variant with Parkinson's disease is mediated by microglia.

Studies of multiple neurodegenerative disorders have identified many genetic variants that are associated with risk of disease throughout a lifetime. For example, Parkinson's disease (PD) risk is attributed in part to both coding mutations in the leucine-rich repeat kinase 2 (LRRK2) gene and to a common noncoding variation in the 5' region of the LRRK2 locus, as identified by genome-wide association studies (GWAS). However, the mechanisms linking GWAS variants to pathogenicity are largely unknown. Here, we found that the influence of PD-associated noncoding variation on LRRK2 expression is specifically propagated through microglia and not by other cell types that express LRRK2 in the human brain. We find microglia-specific regulatory chromatin regions that modulate the LRRK2 expression in human frontal cortex and substantia nigra and confirm these results in a human-induced pluripotent stem cell-derived microglia model. We showed, using a large-scale clustered regularly interspaced short palindromic repeats interference (CRISPRi) screen, that a regulatory DNA element containing the single-nucleotide variant rs6581593 influences the LRRK2 expression in microglia. Our study demonstrates that cell type should be considered when evaluating the role of noncoding variation in disease pathogenesis and sheds light on the mechanism underlying the association of the 5' region of LRRK2 with PD risk.

Evaluation of Current Methods to Detect Cellular Leucine-Rich Repeat Kinase 2 (LRRK2) Kinase Activity.

Background:Coding variation in the Leucine rich repeat kinase 2 gene linked to Parkinson’s disease (PD) promotes enhanced activity of the encoded LRRK2 kinase, particularly with respect to autophosphorylation at S1292 and/or phosphorylation of the heterologous substrate RAB10.Objective:To determine the inter-laboratory reliability of measurements of cellular LRRK2 kinase activity in the context of wildtype or mutant LRRK2 expression using published protocols.Methods:Benchmark western blot assessments of phospho-LRRK2 and phospho-RAB10 were performed in parallel with in situ immunological approaches in HEK293T, mouse embryonic fibroblasts, and lymphoblastoid cell lines. Rat brain tissue, with or without adenovirus-mediated LRRK2 expression, and human brain tissues from subjects with or without PD, were also evaluated for LRRK2 kinase activity markers.Results:Western blots were able to detect extracted LRRK2 activity in cells and tissue with pS1292-LRRK2 or pT73-RAB10 antibodies. However, while LRRK2 kinase signal could be detected at the cellular level with over-expressed mutant LRRK2 in cell lines, we were unable to demonstrate specific detection of endogenous cellular LRRK2 activity in cell culture models or tissues that we evaluated.Conclusion:Further development of reliable methods that can be deployed in multiple laboratories to measure endogenous LRRK2 activities are likely required, especially at cellular resolution.

MiR-205 Regulates LRRK2 Expression in Dopamine Neurons in Parkinson's Disease through Methylation Modification.

Background:We explored the methylation modification in miR-205 promoter during the pathological changes of Parkinson’s disease (PD) and its regulation on Leucine-Rich Repeat Kinase 2 (LRRK2), clarified the important role of methylation in miR-205 promoter region in PD, explained the role of miR-205 methylation in the pathological changes of PD, and looked for new targets for PD.Methods:Methylation of miR-205 promoter regions was determined by cell genomic DNA, with model bisulfite treatment, and the transcription of miR-205 and LRRK2 in PD model cells was determined by qPCR, and LRRK2 expression was determined by Western blot. The binding sites of miRNAs in the non-coding region of LRRK2 were analyzed by the targetscan database, and miR-205 expression in 293T cells was controlled. The correlation between miR-205 expression and LRRK2 was determined to clarify the regulation mode of miR-205 on LRRK2.Results:The level of miR-205 were reduced in the SH-SY5Y Parkinson model cells, and its promoter region was highly methylated, while LRRK2 expression decreased in the model cells after 5-Azacytidine inhibition of methylation in miR-205 promoter region. According to the target scan database analysis, LRRK2 non-coding region is a miR-205-specific binding site. After further miR-205 overexpression in 293T cells, the transcription and translation of LRRK2 decreased in cells, which increased after the treatment of miR-205 inhibitor on LRRK2.Conclusion:The methylation modification of miR-205 promoter region could regulate the transcription and translation of LRRK2 in dopaminergic neurons, so miR-205 methylation regulation can serve as a new potential target for the treatment of PD.

Colonic Leucine-Rich Repeat Kinase 2 Expression Is Increased and Associated With Disease Severity in Patients With Parkinson's Disease.

BackgroundMutations in leucine-rich repeat kinase 2 (LRRK2) comprise a common genetic risk factor for Parkinson’s disease (PD) and inflammatory bowel disease (IBD). We investigated the expression of LRRK2 in colonic biopsies obtained from a cohort of PD patients and healthy controls.MethodsA cohort of 51 PD patients and 40 age- and gender-matched controls who have colonic biopsied samples were recruited. Among these participants, 26 individuals (12 PD patients and 14 controls) had a series of colon biopsies. For the patients with PD, the first biopsies were taken before the PD diagnosis. The colonic expression of LRRK2 was assayed by immunohistochemical staining.ResultsThe fraction of LRRK2-positive cells among the total cell count in biopsied colonic tissues was significantly higher in PD patients than controls (0.81% ± 0.53% vs. 0.45% ± 0.39%; P = 0.02). Colonic LRRK2 immunoreactivity was higher in those with LRRK2 genetic variants compared to those with wild type LRRK2 (2.44% ± 1.15% vs. 0.21 ± 0.13%, P < 0.01). Age had no effect on LRRK2 expression (P = 0.96). LRRK2 expression correlated with disease severity in regards to motor symptoms measured by the UPDRS part III scores (r = 6335, P < 0.001) and cognitive dysfunction measured by the mini-mental status examination scores (r = -0.5774, P < 0.001). PD patients in the prodromal phase had a steeper increase in colonic LRRK2 expression compared to controls during the serial colon biopsy assessment (P < 0.01).ConclusionColonic LRRK2 expression was increased in PD patients compared to controls, and the expression level correlated with disease severity.

Inhibition of LRRK2-Rab10 Pathway Improves Secondary Brain Injury After Surgical Brain Injury in Rats.

Leucine-rich repeat kinase 2 (LRRK2) is considered as a potential target for the treatment of Parkinson's disease. This protein is expressed in the brain and has been associated with various diseases and lysosomal maintenance. Rab10 is a member of the Rab protein GTPase family that has been recently shown to be a kinase substrate of LRRK2. In addition, LRRK2 and its kinase substrate Rab10 constitute a key stress response pathway during lysosomal overload stress. This study aimed to investigate the potential role and mechanism underlying LRRK2 and its kinase substrate Rab10 involving surgical brain injury (SBI). One hundred and forty-four male Sprague-Dawley rats were examined using an SBI model, and some had received the LRRK2-specific inhibitor PF-06447475. Thereafter, western blotting, immunofluorescence, brain water content analysis, neuronal apoptosis assay, and neurological score analysis were conducted. The results showed that after SBI, LRRK2 and phosphorylated Rab10 (p-Rab10) expression in neuronal cells were upregulated, and administration of PF-06447475 significantly reduced neuronal apoptosis, neuroinflammation, and brain water content 12 h after SBI and improved neurological deficit 72 h after SBI, which is related to the decreased expression of LRRK2 and p-Rab10, and the lessening of lysosomal overload stress. Our research suggests that the inhibition of LRRK2 can effectively interfere with the role of p-Rab10 in promoting the secretion of lysosomal hydrolase in lysosomal overload stress after SBI, thereby reducing neuronal apoptosis and inflammation after SBI and playing a major role in brain protection.

LRRK2 correlates with macrophage infiltration in pan-cancer

Leucine-rich repeat kinase2 (LRRK2) influences the host immune responses and correlates with the pathogenesis of inflammation, cancer as well as Parkinson’ Disease. Herein, we explored the oncogenic role of LRRK2 at pan-cancer level and validated the analysis by single cell RNA-sequencing and in-vitro experiments. As a result, LRRK2 significantly correlated with the survival events. Specifically, LRRK2 increased the risk of Low-Grade Glioma whereas improved the survival probability of patients with Skin Cutaneous Melanoma. Gene set enrichment analysis demonstrated the involvement of LRRK2 in the host immune responses. Within the tumor microenvironment, LRRK2 was positively associated with the recruitment of macrophages. Furthermore, scRNA-seq and co-culture experiments demonstrated that LRRK2 deficiency impaired macrophage functions, and influenced the neoplastic progression in a cancer type-specific manner. Therefore, the present study provided a therapeutic strategy for LGG based on the interference with LRRK2 expression and activity to prevent macrophage recruitment and promote tumor eradication.

Assessing stimulation-dependent changes in LRRK2 and GCase expression/activity and convergence at the lysosome in cryopreserved monocytes.

Both leucine-rich repeat kinase 2 (LRRK2) and glucocerebrosidase (GCase) are promising targets for the treatment of Parkinson's disease (PD). Evidence suggests that both proteins are involved in similar biological pathways, including lysosomal function. However, studies to date have largely investigated the enzymes in isolation and any relationship between LRRK2 and GCase remains unclear. Recent data suggest that it is the response to immunological challenges that is altered in PD and that circulating baseline cytokine levels are not useful diagnostic or predictive biomarkers in PD. Taken together, this project aims to optimize a blood collection and cryopreservation protocol to facilitate the collection and study of monocytes from PD patients and healthy controls, with a particular focus on measuring stimulation-dependent changes in LRRK2 and GCase protein activity levels and lysosomal function. Human PBMCs were isolated from whole blood and plated fresh or post-cryopreservation. PBMCs were treated with MLi2 or CBE +/- IFN-γ. Treatment effects on cathepsin activity, LRRK2 and GCase enzymatic activity, and antigen presentation were assessed in monocytes via flow cytometry. Media was collected RESULT: We first assessed the effects of cryopreservation on our read-outs. Despite cryopreservation having a small effect at baseline, both fresh and cryopreserved monocytes gated from total PBMCs exhibited comparable changes in response to IFN-γ. We observed that LRRK2 kinase inhibition decreases cathepsin activity in monocytes in a stimulation-dependent manner. This was coupled with increased LRRK2 expression and alterations in immune cell activation with LRRK2 kinase inhibition. Similarly, an increase in GCase activity levels were observed in monocytes upon IFN-γ treatment. These results show that cryopreservation of PBMCs doesn't affect our ability to measure stimulation-dependent changes in both LRRK2 and GCase expression/activity levels. These assays are therefore to be repeated in idiopathic PD PBMCs. Furthermore, these results suggest a fundamental role of LRRK2, specifically LRRK2 kinase activity, in lysosomal function in immune cells. Given the parallel increases in GCase activity, future research aims to investigate how these two enzymes interact and converge on biological pathways regulating inflammation and the lysosome in patient monocytes.