Generation of gene-corrected iPSCs line (KEIUi001-A) from a PARK8 patient iPSCs with familial Parkinson's disease carrying the I2020T mutation in LRRK2.

Leucine-rich repeat kinase 2 (LRRK2) is the causal gene of the autosomal dominant hereditary form of Parkinson's disease (PD), PARK8. We have previously reported that induced pluripotent stem cells (iPSCs) from a PARK8 patient with I2020T LRRK2 mutation replicated to some extent the pathologic phenotype evident in the brain of PD patients. In the present study, we generated gene-corrected iPSCs line, KEIUi001-A, using TALEN-mediated genome editing. KEIUi001-A retained a normal karyotype and pluripotency, i.e. the capacity to differentiate into cell types of the three germ layers. This iPSCs will be valuable for clarifying various aspects of LRRK2-related pathology.

Leucine-Rich Repeat Kinase 2 Controls Inflammatory Cytokines Production through NF-κB Phosphorylation and Antigen Presentation in Bone Marrow-Derived Dendritic Cells.

Leucine-rich repeat kinase 2 (LRRK2) is the causal molecule of familial Parkinson's disease. Although the characteristics of LRRK2 have gradually been revealed, its true physiological functions remain unknown. LRRK2 is highly expressed in immune cells such as B2 cells and macrophages, suggesting that it plays important roles in the immune system. In the present study, we investigate the roles of LRRK2 in the immune functions of dendritic cells (DCs). Bone marrow-derived DCs from both C57BL/6 wild-type (WT) and LRRK2 knockout (KO) mice were induced by culture with granulocyte/macrophage-colony stimulating factor (GM/CSF) in vitro. We observed the differentiation of DCs, the phosphorylation of the transcriptional factors NF-κB, Erk1/2, and p-38 after lipopolysaccharide (LPS) stimulation and antigen-presenting ability by flow cytometry. We also analyzed the production of inflammatory cytokines by ELISA. During the observation period, there was no difference in DC differentiation between WT and LRRK2-KO mice. After LPS stimulation, phosphorylation of NF-κB was significantly increased in DCs from the KO mice. Large amounts of inflammatory cytokines were produced by DCs from KO mice after both stimulation with LPS and infection with Leishmania. CD4+ T-cells isolated from antigen-immunized mice proliferated to a significantly greater degree upon coculture with antigen-stimulated DCs from KO mice than upon coculture with DCs from WT mice. These results suggest that LRRK2 may play important roles in signal transduction and antigen presentation by DCs.

Enhanced activated T cell subsets in prostate cancer patients receiving iodine-125 low-dose-rate prostate brachytherapy.

Radiotherapy (RT) is one of the most important treatments for prostate cancer. Although RT can kill cancer cells through direct and indirect effects of radiation, it occasionally induces an abscopal effect whereby localized radiation treatment is associated with elimination of metastatic cancer at a distance from the irradiated area. Thus, RT may induce an effective antitumor immune response, although the mechanism involved has remained unclear. The present was designed to evaluate this effect of RT in 36 patients with prostate cancer who provided informed consent prior to enrollment in this clinical trial. Peripheral blood samples were collected periodically after low-dose-rate (LDR) prostate brachytherapy, and lymphocyte subsets were analyzed by flow cytometry. The proportion of activated T cells (CD3+HLA-DR+, CD4+HLA-DR+ and CD8+HLA-DR+) in peripheral blood revealed a gradual and bimodal increase after LDR brachytherapy, whereas memory CD8+ T cells bimodally decreased after treatment. The ratios of activated T cells and regulatory T cells gradually increased after the treatment. Thus, LDR brachytherapy was demonstrated to induce effective immune responses in patients. This increase of activated T cells may contribute to maintenance of remission and reduction of relapse rates.

Establishment of DYT5 patient-specific induced pluripotent stem cells with a GCH1 mutation.

Peripheral blood mononuclear cells (PBMCs) were collected from a clinically diagnosed 20-year-old dystonia patient with a GCH1 mutation (DYT5). Episomal vectors were used to introduce reprogramming factors (OCT3/4, SOX2, KLF4, L-MYC, LIN28, and p53 carboxy-terminal dominant-negative fragment) to the PBMCs. The generated iPSCs expressed pluripotency markers, and were capable of differentiating into derivates of all three germ layers in vitro. The iPSC line also showed a normal karyotype and preserved the GCH1 mutation. This cellular model can provide opportunities to perform pathophysiological studies for aberrant dopamine metabolism-related disorders.

Leucine-rich repeat kinase 2 (LRRK2) regulates α-synuclein clearance in microglia.

BACKGROUND: α-Synuclein (αSYN) has been genetically implicated in familial and sporadic Parkinson's disease (PD), and is associated with disease susceptibility, progression and pathology. Excess amounts of αSYN are toxic to neurons. In the brain, microglial αSYN clearance is closely related to neuronal survival. Leucine-rich repeat kinase 2 (LRRK2) is the one of the other genes implicated in familial and sporadic PD. While LRRK2 is known to be expressed in microglia, its true function remains to be elucidated. In this study, we investigated αSYN clearance by microglia isolated from LRRK2-knockout (KO) mice. RESULTS: In LRRK2-KO microglia, αSYN was taken up in larger amounts and cleared from the supernatant more effectively than for microglia isolated from wild-type (WT) mice. This higher clearance ability of LRRK2-KO microglia was thought to be due to an increase of Rab5-positive endosomes, but not Rab7- or Rab11-positive endosomes. Increased engagement between Rab5 and dynamin 1 was also observed in LRRK2-KO microglia. CONCLUSION: LRRK2 negatively regulates the clearance of αSYN accompanied by down-regulation of the endocytosis pathway. Our findings reveal a new functional role of LRRK2 in microglia and offer a new insight into the mechanism of PD pathogenesis.

Leucine-rich repeat kinase 2 is a regulator of B cell function, affecting homeostasis, BCR signaling, IgA production, and TI antigen responses.

LRRK2 is the causal molecule of autosomal dominant familial Parkinson's disease. B2 cells express a much higher LRRK2 mRNA level than B1 cells. To reveal the function of LRRK2 in B cells, we analyzed B cell functions in LRRK2-knockout (LRRK2(-/-)) mice. LRRK2(-/-) mice had significantly higher counts of peritoneal B1 cells than wild-type mice. After BCR stimulation, phosphor-Erk1/2 of splenic B2 cells was enhanced to a higher degree in LRRK2(-/-) mice. LRRK2(-/-) mice had a significantly higher serum IgA level, and TNP-Ficoll immunization increased the titer of serum anti-TNP IgM antibody. LRRK2 may play important roles in B cells.

Enhanced central memory cluster of differentiation 8+ and tumor antigen-specific T cells in prostate cancer patients receiving repeated in situ adenovirus-mediated suicide gene therapy.

The high relapse rate of prostate cancer following radical prostatectomy is clinically problematic, and various neoadjuvant therapies aimed at reducing the rate have been examined. A previous study has shown that immune responses are increased in patients treated by adenoviral vector-mediated herpes simplex virus-thymidine kinase (HSV-tk) gene delivery followed by ganciclovir (GCV) injection. However, details of the immune responses following this form of gene therapy remain unclear. Five patients who agreed to participate in the present phase I/II trial were repeatedly administered GCV intravenously for 2 weeks following intraprostatic injection of HSV-tk. Peripheral blood samples were periodically collected following the treatments, and lymphocyte subsets were analyzed by flow-cytometry. Intracellular interferon (IFN)-γ produced by T cells was further measured in response to prostatic acid phosphatase and NY-ESO-1 overlapping peptides. Central memory (CM) cluster of differentiation 8+ (CD8+) T cells were found to increase markedly during the second round of treatment. In three patients, tumor antigen-specific T cells were clearly increased following HSV-tk + GCV treatment. An increase in prostate cancer antigen-specific T cells and CM CD8+ T cells may contribute to a reduction of relapse rates in prostate cancer patients receiving this form of gene therapy, which shows promise in a neoadjuvant setting.

I2020T mutant LRRK2 iPSC-derived neurons in the Sagamihara family exhibit increased Tau phosphorylation through the AKT/GSK-3ß signaling pathway.

Leucine-rich repeat kinase 2 (LRRK2) is the causative molecule of the autosomal dominant hereditary form of Parkinson's disease (PD), PARK8, which was originally defined in a study of a Japanese family (the Sagamihara family) harboring the I2020T mutation in the kinase domain. Although a number of reported studies have focused on cell death mediated by mutant LRRK2, details of the pathogenetic effect of LRRK2 still remain to be elucidated. In the present study, to elucidate the mechanism of neurodegeneration in PD caused by LRRK2, we generated induced pluripotent stem cells (iPSC) derived from fibroblasts of PD patients with I2020T LRRK2 in the Sagamihara family. We found that I2020T mutant LRRK2 iPSC-derived neurons released less dopamine than control-iPSC-derived neurons. Furthermore, we demonstrated that patient iPSC-derived neurons had a lower phospho-AKT level than control-iPSC-derived neurons, and that the former showed an increased incidence of apoptosis relative to the controls. Interestingly, patient iPSC-derived neurons exhibited activation of glycogen synthase kinase-3ß (GSK-3ß) and high Tau phosphorylation. In addition, the postmortem brain of the patient from whom the iPSC had been established exhibited deposition of neurofibrillary tangles as well as increased Tau phosphorylation in neurons. These results suggest that I2020T LRRK2-iPSC could be a promising new tool for reproducing the pathology of PD in the brain caused by the I2020T mutation, and applicable as a model in studies of targeted therapeutics.

Allo-antigen stimulated CD8+ T-cells suppress NF-κB and Ets-1 DNA binding activity, and inhibit phosphorylated NF-κB p65 nuclear localization in CD4+ T-cells.

CD8+ T-cells of asymptomatic HIV-1 carriers (AC) suppress human immunodeficiency virus type 1 (HIV-1) replication in a class I major histocompatibility complex (MHC-I)-restricted and -unrestricted manner. In order to investigate the mechanism of MHC-I-unrestricted CD8+ T-cell-mediated HIV-1 suppression, we previously established allo-antigen stimulated CD8+T-cells from HIV-1-uninfected donors. These allo-antigen stimulated CD8+ T-cells suppressed HIV-1 replication in acutely infected autologous CD4+ T-cells when directly co-cultured. To elucidate the mechanism of HIV-1 replication suppression, we analyzed DNA-binding activity and phosphorylation of transcriptional factors associated with HIV-1 replication by electrophoresis mobility shift assay and Western blotting. When CD4+ T-cells were cultured with allo-antigen stimulated CD8+ T-cells, the reduction of NF-κB and Ets-1 DNA-binding activity was observed. Nuclear localization of NF-κB p65 and Ets-1 was suppressed in CD4+ T-cells. Although NF-κB p65 and Ets-1 are known to be regulated by protein kinase A (PKA), no difference was observed in the expression and phosphorylation of the PKA catalytic subunit in CD4+ T-cells cultured with PHA-treated CD8+ T-cells or allo-antigen stimulated CD8+ T-cells. Cyclic AMP is also known to enter through gap junctions, but the suppression of HIV-1 replication mediated by allo-antigen stimulated CD8+ T-cells was not affected by the gap junction inhibitor. The nuclear transport of phosphorylated NF-κB p65 (Ser276) was inhibited only in CD4+ T-cells cultured with allo-antigen stimulated CD8+ T-cells. Our results indicate that allo-antigen stimulated CD8+ T-cells suppress the transcriptional activity of NF-κB p65 or Ets-1 in an antigen-nonspecific manner, and inhibit the nuclear transport of phosphorylated NF-κB p65 (Ser276).

Dominant-negative effects of LRRK2 heterodimers: a possible mechanism of neurodegeneration in Parkinson's disease caused by LRRK2 I2020T mutation.

Leucine-rich repeat kinase 2 (LRRK2) is the molecule responsible for autosomal-dominant Parkinson's disease (PD), PARK8, but the etiologic effects of its mutation remain unknown. In the present study, we investigated a novel mechanism for the neurodegeneration induced by I2020T mutant LRRK2. Using native gel electrophoresis and immunoprecipitation, we found that wild-type (WT) LRRK2 formed a heterodimer with I2020T LRRK2 in transfected cells, and that the heterodimer exhibited a markedly lower intracellular protein level than the WT/WT-homodimer. An increased amount of I2020T LRRK2 decreased the protein level of co-transfected WT LRRK2. A pulse-chase experiment revealed that the intracellular protein lifetime of WT LRRK2 was shortened by co-transfection with I2020T LRRK2. These results suggest that I2020T LRRK2 enhances the intracellular degradation of WT LRRK2 through WT/I2020T-heterodimer formation. Overexpression of WT LRRK2 in HEK293 cells increased the phosphorylation level of Akt1 (S473), a possible physiological substrate of LRRK2, and made cells resistant to hydrogen peroxide-induced apoptosis. However, both Akt1 phosphorylation and apoptosis resistance were reduced in WT/I2020T-expressing cells in comparison with WT/WT-expressing cells. Reduction of Akt1 phosphorylation and apoptosis resistance were also evident when a neuroblastoma SH-SY5Y clone overexpressing WT LRRK2 was transfected with the I2020T LRRK2. Altogether, these results suggest that the I2020T mutation enhances the intracellular degradation of LRRK2 through WT/I2020T-heterodimer formation, leading to reduced Akt1 phosphorylation and diminished protectivity against apoptosis. Our findings suggest the possibility of a dominant-negative mechanism of neurodegeneration in PD caused by I2020T LRRK2 mutation.

The I2020T Leucine-rich repeat kinase 2 transgenic mouse exhibits impaired locomotive ability accompanied by dopaminergic neuron abnormalities.

BACKGROUND: Leucine-rich repeat kinase 2 (LRRK2) is the gene responsible for autosomal-dominant Parkinson's disease (PD), PARK8, but the mechanism by which LRRK2 mutations cause neuronal dysfunction remains unknown. In the present study, we investigated for the first time a transgenic (TG) mouse strain expressing human LRRK2 with an I2020T mutation in the kinase domain, which had been detected in the patients of the original PARK8 family. RESULTS: The TG mouse expressed I2020T LRRK2 in dopaminergic (DA) neurons of the substantia nigra, ventral tegmental area, and olfactory bulb. In both the beam test and rotarod test, the TG mice exhibited impaired locomotive ability in comparison with their non-transgenic (NTG) littermates. Although there was no obvious loss of DA neurons in either the substantia nigra or striatum, the TG brain showed several neurological abnormalities such as a reduced striatal dopamine content, fragmentation of the Golgi apparatus in DA neurons, and an increased degree of microtubule polymerization. Furthermore, the tyrosine hydroxylase-positive primary neurons derived from the TG mouse showed an increased frequency of apoptosis and had neurites with fewer branches and decreased outgrowth in comparison with those derived from the NTG controls. CONCLUSIONS: The I2020T LRRK2 TG mouse exhibited impaired locomotive ability accompanied by several dopaminergic neuron abnormalities. The TG mouse should provide valuable clues to the etiology of PD caused by the LRRK2 mutation.

LRRK2 phosphorylates tubulin-associated tau but not the free molecule: LRRK2-mediated regulation of the tau-tubulin association and neurite outgrowth.

Leucine-rich repeat kinase 2 (LRRK2), a large protein kinase containing multi-functional domains, has been identified as the causal molecule for autosomal-dominant Parkinson's disease (PD). In the present study, we demonstrated for the first time that (i) LRRK2 interacts with tau in a tubulin-dependent manner; (ii) LRRK2 directly phosphorylates tubulin-associated tau, but not free tau; (iii) LRRK2 phosphorylates tau at Thr181 as one of the target sites; and (iv) The PD-associated LRRK2 mutations, G2019S and I2020T, elevated the degree of tau-phosphorylation. These results provide direct proof that tau is a physiological substrate for LRRK2. Furthermore, we revealed that LRRK2-mediated phosphorylation of tau reduces its tubulin-binding ability. Our results suggest that LRRK2 plays an important role as a physiological regulator for phosphorylation-mediated dissociation of tau from microtubules, which is an integral aspect of microtubule dynamics essential for neurite outgrowth and axonal transport.

Correlation of PU.1 and signal regulatory protein α1 expression in PU.1 transgenic K562 cells.

PU.1 is a key transcription factor for hematopoiesis and the reduction of this protein expression plays important roles in various hematological malignancies. To identify PU.1 downstream target genes, we recently reported dual microarray analyses, using PU.1 knockdown K562 (K562PU.1KD) cells stably expressing short inhibitory RNAs versus control cells and PU.1-overexpressing K562 (K562PU.1OE) cells versus control cells. Several PU.1 candidate target genes, including cell surface receptor, signal regulatory protein (SIRP) α1, were identified. In this study, we revealed that the expression of SIRPα1 is positively correlated with the expression of PU.1 in various K562PU.1KD and K562PU.1OE cells, shown by real-time PCR and flow cytometry analyses. SIRPα1 is a negative regulator of signaling and its reduced expression is considered to play a role in the pathogenesis of hematological malignancies through the activation of downstream signaling pathways. By comparing 3 different clones of K562PU.1KD cells to their controls, we found constitutive phosphorylation of the extracellular signal-regulated kinase (ERK), but not of Akt, in these cells. Taken together, the down-regulation of PU.1 expression suppresses the expression of SIRPα1, which may play a role in the aberrant activation of ERK in these cells.

LRRK2 directly phosphorylates Akt1 as a possible physiological substrate: impairment of the kinase activity by Parkinson's disease-associated mutations.

LRRK2 is the causal molecule for autosomal-dominant familial Parkinson's disease, although its true function, including its physiological substrates, remains unknown. Here, using in vitro kinase assay with recombinant proteins, we demonstrated for the first time that LRRK2 directly phosphorylates Akt1, a central molecule involved in signal transduction for cell survival and prevention of apoptosis. Ser473, one of two amino acids essential for Akt1 activation, was the target site for LRRK2. A knockdown experiment using intact cells also demonstrated LRRK2-mediated phosphorylation of Akt1 (Ser473), suggesting that Akt1 is a convincing candidate for the physiological substrate of LRRK2. The disease-associated mutations, R1441C, G2019S, and I2020T, exhibited reduced interaction with, and phosphorylation of, Akt1, suggesting one possible mechanism for the neurodegeneration caused by LRRK2 mutations.

LRRK2 is expressed in B-2 but not in B-1 B cells, and downregulated by cellular activation.

LRRK2, the causal molecule of familial Parkinson's disease, is expressed strongly by one of the B cell subsets, B-2 cells, but not by the other subset, B-1 cells, in the mouse peritoneal cavity, spleen, and peripheral blood. Bone marrow pre-B cells or T cells exhibited little LRRK2 expression. LRRK2 expression was dramatically downregulated upon activation of B-2 cells with various types of stimulation. These results suggest that LRRK2, whose true function has not yet been clarified, may play some important role(s) in the development and function of B cells, particularly the maintenance of B-2 cells in a resting status.

Age-dependent and cell-population-restricted LRRK2 expression in normal mouse spleen.

Leucine-rich repeat kinase 2 (LRRK2) is the causal molecule of familial Parkinson's disease (PD), but its true physiological function remains unknown. In the normal mouse, LRRK2 is expressed in kidney, spleen, and lung at much higher levels than in brain, suggesting that LRRK2 may play an important role in these organs. Analysis of age-related changes in LRRK2 expression demonstrated that expression in kidney, lung, and various brain regions was constant throughout adult life. On the other hand, expression of both LRRK2 mRNA and protein decreased markedly in spleen in an age-dependent manner. Analysis of purified spleen cells indicated that B lymphocytes were the major population expressing LRRK2, and that T lymphocytes showed no expression. Consistently, the B lymphocyte surface marker CD19 exhibited an age-dependent decrease of mRNA expression in spleen. These results suggest a possibly novel function of LRRK2 in the immune system, especially in B lymphocytes.

Prevention of intracellular degradation of I2020T mutant LRRK2 restores its protectivity against apoptosis.

Leucine-rich repeat kinase 2 (LRRK2) is the causal gene for autosomal dominant familial Parkinson's disease. We have previously reported a novel molecular feature characteristic to I2020T mutant LRRK2: higher susceptibility to post-translational degradation than the wild-type LRRK2. In the present study, we demonstrated that the protective effect of I2020T LRRK2 against hydrogen peroxide-induced apoptosis was impaired in comparison with the wild-type molecule. When the intracellular level of the protein had been allowed to recover by treatment with proteolysis inhibitors, the protective effect of I2020T LRRK2 against apoptosis was increased. We further confirmed that a decrease in the intracellular protein level of WT LRRK2 by knocking down resulted in a reduction of protectivity against apoptosis. These results suggest that higher susceptibility of I2020T mutant LRRK2 to intracellular degradation than the wild-type molecule may be one of the mechanisms involved in the neurodegeneration associated with this LRRK2 mutation.

Genome-wide association study identifies common variants at four loci as genetic risk factors for Parkinson's disease.

To identify susceptibility variants for Parkinson's disease (PD), we performed a genome-wide association study (GWAS) and two replication studies in a total of 2,011 cases and 18,381 controls from Japan. We identified a new susceptibility locus on 1q32 (P = 1.52 x 10(-12)) and designated this as PARK16, and we also identified BST1 on 4p15 as a second new risk locus (P = 3.94 x 10(-9)). We also detected strong associations at SNCA on 4q22 (P = 7.35 x 10(-17)) and LRRK2 on 12q12 (P = 2.72 x 10(-8)), both of which are implicated in autosomal dominant forms of parkinsonism. By comparing results of a GWAS performed on individuals of European ancestry, we identified PARK16, SNCA and LRRK2 as shared risk loci for PD and BST1 and MAPT as loci showing population differences. Our results identify two new PD susceptibility loci, show involvement of autosomal dominant parkinsonism loci in typical PD and suggest that population differences contribute to genetic heterogeneity in PD.