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1.
Cancer Cell ; 42(3): 358-377.e8, 2024 Mar 11.
Article in English | MEDLINE | ID: mdl-38215747

ABSTRACT

The evolutionary trajectory of glioblastoma (GBM) is a multifaceted biological process that extends beyond genetic alterations alone. Here, we perform an integrative proteogenomic analysis of 123 longitudinal glioblastoma pairs and identify a highly proliferative cellular state at diagnosis and replacement by activation of neuronal transition and synaptogenic pathways in recurrent tumors. Proteomic and phosphoproteomic analyses reveal that the molecular transition to neuronal state at recurrence is marked by post-translational activation of the wingless-related integration site (WNT)/ planar cell polarity (PCP) signaling pathway and BRAF protein kinase. Consistently, multi-omic analysis of patient-derived xenograft (PDX) models mirror similar patterns of evolutionary trajectory. Inhibition of B-raf proto-oncogene (BRAF) kinase impairs both neuronal transition and migration capability of recurrent tumor cells, phenotypic hallmarks of post-therapy progression. Combinatorial treatment of temozolomide (TMZ) with BRAF inhibitor, vemurafenib, significantly extends the survival of PDX models. This study provides comprehensive insights into the biological mechanisms of glioblastoma evolution and treatment resistance, highlighting promising therapeutic strategies for clinical intervention.


Subject(s)
Brain Neoplasms , Glioblastoma , Proteogenomics , Animals , Humans , Glioblastoma/genetics , Proto-Oncogene Proteins B-raf , Proteomics , Cell Line, Tumor , Neoplasm Recurrence, Local , Disease Models, Animal , Brain Neoplasms/genetics , Drug Resistance, Neoplasm , Xenograft Model Antitumor Assays
2.
Nanoscale Adv ; 5(6): 1636-1650, 2023 Mar 14.
Article in English | MEDLINE | ID: mdl-36926569

ABSTRACT

In biological studies and diagnoses, brightfield (BF), fluorescence, and electron microscopy (EM) are used to image biomolecules inside cells. When compared, their relative advantages and disadvantages are obvious. BF microscopy is the most accessible of the three, but its resolution is limited to a few microns. EM provides a nanoscale resolution, but sample preparation is time-consuming. In this study, we present a new imaging technique, which we termed decoration microscopy (DecoM), and quantitative investigations to address the aforementioned issues in EM and BF microscopy. For molecular-specific EM imaging, DecoM labels proteins inside cells using antibodies bearing 1.4 nm gold nanoparticles (AuNPs) and grows silver layers on the AuNPs' surfaces. The cells are then dried without buffer exchange and imaged using scanning electron microscopy (SEM). Structures labeled with silver-grown AuNPs are clearly visible on SEM, even they are covered with lipid membranes. Using stochastic optical reconstruction microscopy, we show that the drying process causes negligible distortion of structures and that less structural deformation could be achieved through simple buffer exchange to hexamethyldisilazane. Using DecoM, we visualize the nanoscale alterations in microtubules by microtubule-severing proteins that cannot be observed with diffraction-limited fluorescence microscopy. We then combine DecoM with expansion microscopy to enable sub-micron resolution BF microscopy imaging. We first show that silver-grown AuNPs strongly absorb white light, and the structures labeled with them are clearly visible on BF microscopy. We then show that the application of AuNPs and silver development must follow expansion to visualize the labeled proteins clearly with sub-micron resolution.

3.
Front Cell Neurosci ; 16: 1083159, 2022.
Article in English | MEDLINE | ID: mdl-36605616

ABSTRACT

Neurodegenerative diseases (NDDs) are characterized by the progressive loss of selectively vulnerable populations of neurons, which is responsible for the clinical symptoms. Although degeneration of neurons is a prominent feature that undoubtedly contributes to and defines NDD pathology, it is now clear that neuronal cell death is by no means mediated solely by cell-autonomous mechanisms. Oligodendrocytes (OLs), the myelinating cells of the central nervous system (CNS), enable rapid transmission of electrical signals and provide metabolic and trophic support to neurons. Recent evidence suggests that OLs and their progenitor population play a role in the onset and progression of NDDs. In this review, we discuss emerging evidence suggesting a role of OL lineage cells in the pathogenesis of age-related NDDs. We start with multiple system atrophy, an NDD with a well-known oligodendroglial pathology, and then discuss Alzheimer's disease (AD) and Parkinson's disease (PD), NDDs which have been thought of as neuronal origins. Understanding the functions and dysfunctions of OLs might lead to the advent of disease-modifying strategies against NDDs.

4.
J Neurosci Res ; 99(11): 2874-2887, 2021 11.
Article in English | MEDLINE | ID: mdl-34510521

ABSTRACT

Axons in the adult mammalian central nervous system fail to regenerate after injury. By contrast, spontaneous axon regeneration occurs in the peripheral nervous system (PNS) due to a supportive PNS environment and an increase in the intrinsic growth potential induced by injury via cooperative activation of multifaceted biological pathways. This study compared axon regeneration and injury responses in C57BL/6 male and female mice after sciatic nerve crush (SNC) injury. The extent of axon regeneration in vivo was indistinguishable in male and female mice when observed at 3 days after SNC injury, and primary dorsal root ganglion (DRG) neurons from injured, male and female mice extended axons to a similar length. Moreover, the induction of selected regeneration-associated genes (RAGs), such as Atf3, Sprr1a, Gap43, Sox11, Jun, Gadd45a, and Smad1 were comparable in male and female DRGs when assessed by quantitative real-time reverse transcription polymerase chain reaction. Furthermore, the RNA-seq analysis of male and female DRGs revealed that differentially expressed genes (DEGs) in SNC groups compared to sham-operated groups included many common genes associated with neurite outgrowth. However, we also found that a large number of genes in the DEGs were sex dependent, implicating the involvement of distinct gene regulatory network in the two sexes following peripheral nerve injury. In conclusion, we found that male and female mice mounted a comparable axon regeneration response and many RAGs were commonly induced in response to SNC. However, given that many DEGs were sex-dependently expressed, future studies are needed to investigate whether they contribute to peripheral axon regeneration, and if so, to what extent.


Subject(s)
Peripheral Nerve Injuries , Animals , Axons/physiology , Female , Ganglia, Spinal/metabolism , Male , Mammals , Mice , Mice, Inbred C57BL , Nerve Regeneration/physiology , Peripheral Nerve Injuries/metabolism , Sciatic Nerve
5.
J Med Chem ; 64(16): 11886-11903, 2021 08 26.
Article in English | MEDLINE | ID: mdl-34355886

ABSTRACT

The PKC-θ isoform of protein kinase C is selectively expressed in T lymphocytes and plays an important role in the T cell antigen receptor (TCR)-triggered activation of mature T cells, T cell proliferation, and the subsequent release of cytokines such as interleukin-2 (IL-2). Herein, we report the synthesis and structure-activity relationship (SAR) of a novel series of PKC-θ inhibitors. Through a combination of structure-guided design and exploratory SAR, suitable replacements for the basic C4 amine of the original lead (3) were identified. Property-guided design enabled the identification of appropriately substituted C2 groups to afford potent analogs with metabolic stability and permeability to support in vivo testing. With exquisite general kinase selectivity, cellular inhibition of T cell activation as assessed by IL-2 expression, a favorable safety profile, and demonstrated in vivo efficacy in models of acute and chronic T cell activation with oral dosing, CC-90005 (57) was selected for clinical development.


Subject(s)
Cyclohexanols/therapeutic use , Graft vs Host Disease/drug therapy , Immunologic Factors/therapeutic use , Protein Kinase C-theta/antagonists & inhibitors , Protein Kinase Inhibitors/therapeutic use , Pyrimidines/therapeutic use , Animals , Caco-2 Cells , Cell Proliferation/drug effects , Cyclohexanols/chemical synthesis , Cyclohexanols/metabolism , Humans , Immunologic Factors/chemical synthesis , Immunologic Factors/metabolism , Lymphocyte Activation/drug effects , Male , Mice, Inbred C57BL , Molecular Docking Simulation , Molecular Structure , Protein Binding , Protein Kinase C-delta/antagonists & inhibitors , Protein Kinase C-delta/metabolism , Protein Kinase C-theta/metabolism , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/metabolism , Pyrimidines/chemical synthesis , Pyrimidines/metabolism , Structure-Activity Relationship , T-Lymphocytes/drug effects
6.
Genes (Basel) ; 12(4)2021 03 29.
Article in English | MEDLINE | ID: mdl-33805527

ABSTRACT

Parkinson's disease (PD) is a heterogeneous neurodegenerative disease characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta and the widespread occurrence of proteinaceous inclusions known as Lewy bodies and Lewy neurites. The etiology of PD is still far from clear, but aging has been considered as the highest risk factor influencing the clinical presentations and the progression of PD. Accumulating evidence suggests that aging and PD induce common changes in multiple cellular functions, including redox imbalance, mitochondria dysfunction, and impaired proteostasis. Age-dependent deteriorations in cellular dysfunction may predispose individuals to PD, and cellular damages caused by genetic and/or environmental risk factors of PD may be exaggerated by aging. Mutations in the LRRK2 gene cause late-onset, autosomal dominant PD and comprise the most common genetic causes of both familial and sporadic PD. LRRK2-linked PD patients show clinical and pathological features indistinguishable from idiopathic PD patients. Here, we review cellular dysfunctions shared by aging and PD-associated LRRK2 mutations and discuss how the interplay between the two might play a role in PD pathologies.


Subject(s)
Aging/pathology , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/genetics , Mutation , Parkinson Disease/pathology , Aging/genetics , Humans , Parkinson Disease/genetics
7.
Brain ; 144(2): 636-654, 2021 03 03.
Article in English | MEDLINE | ID: mdl-33479772

ABSTRACT

As the clinical failure of glioblastoma treatment is attributed by multiple components, including myelin-associated infiltration, assessment of the molecular mechanisms underlying such process and identification of the infiltrating cells have been the primary objectives in glioblastoma research. Here, we adopted radiogenomic analysis to screen for functionally relevant genes that orchestrate the process of glioma cell infiltration through myelin and promote glioblastoma aggressiveness. The receptor of the Nogo ligand (NgR1) was selected as the top candidate through Differentially Expressed Genes (DEG) and Gene Ontology (GO) enrichment analysis. Gain and loss of function studies on NgR1 elucidated its underlying molecular importance in suppressing myelin-associated infiltration in vitro and in vivo. The migratory ability of glioblastoma cells on myelin is reversibly modulated by NgR1 during differentiation and dedifferentiation process through deubiquitinating activity of USP1, which inhibits the degradation of ID1 to downregulate NgR1 expression. Furthermore, pimozide, a well-known antipsychotic drug, upregulates NgR1 by post-translational targeting of USP1, which sensitizes glioma stem cells to myelin inhibition and suppresses myelin-associated infiltration in vivo. In primary human glioblastoma, downregulation of NgR1 expression is associated with highly infiltrative characteristics and poor survival. Together, our findings reveal that loss of NgR1 drives myelin-associated infiltration of glioblastoma and suggest that novel therapeutic strategies aimed at reactivating expression of NgR1 will improve the clinical outcome of glioblastoma patients.


Subject(s)
Brain Neoplasms/metabolism , Brain Neoplasms/pathology , Glioblastoma/metabolism , Glioblastoma/pathology , Myelin Sheath/metabolism , Nogo Receptor 1/metabolism , Animals , Cell Line, Tumor , Female , Gene Expression Regulation, Neoplastic , Humans , Inhibitor of Differentiation Protein 1/metabolism , Inhibitor of Differentiation Proteins/metabolism , Mice, Inbred BALB C , Myelin Sheath/pathology , Ubiquitin-Specific Proteases/metabolism
8.
Int J Mol Sci ; 21(3)2020 Feb 05.
Article in English | MEDLINE | ID: mdl-32033476

ABSTRACT

Oligodendrocytes are specialized cells that myelinate axons in the central nervous system. Defects in oligodendrocyte function and failure to form or maintain myelin sheaths can cause a number of neurological disorders. Oligodendrocytes are differentiated from oligodendrocyte progenitor cells (OPCs), which extend several processes that contact, elaborate, and eventually wrap axonal segments to form multilayered myelin sheaths. These processes require extensive changes in the cytoarchitecture and must be regulated by reorganization of the cytoskeleton. Here, we established a simple protocol to isolate and differentiate mouse OPCs, and by using this method, we investigated a role of microtubules (MTs) in oligodendrocyte differentiation. Oligodendrocytes developed a complex network of MTs during differentiation, and treatment of differentiating oligodendrocytes with nanomolar concentrations of MT-targeting agents (MTAs) markedly affected oligodendrocyte survival and differentiation. We found that acute exposure to vincristine and nocodazole at early stages of oligodendrocyte differentiation markedly increased MT arborization and enhanced differentiation, whereas taxol and epothilone B treatment produced opposing outcomes. Furthermore, treatment of myelinating co-cultures of oligodendrocytes and neurons with nanomolar concentrations of MTAs at late stages of oligodendrocyte differentiation induced dysmyelination. Together, these results suggest that MTs play an important role in the survival, differentiation, and myelination of oligodendrocytes.


Subject(s)
Cell Differentiation/physiology , Microtubules/physiology , Oligodendroglia/physiology , Animals , Axons/metabolism , Axons/physiology , Cells, Cultured , Central Nervous System/metabolism , Central Nervous System/physiology , Coculture Techniques/methods , Cytoskeleton/metabolism , Cytoskeleton/physiology , Mice , Mice, Inbred ICR , Microtubules/metabolism , Myelin Basic Protein/metabolism , Myelin Sheath/metabolism , Myelin Sheath/physiology , Neurogenesis/physiology , Neurons/metabolism , Neurons/physiology , Oligodendrocyte Precursor Cells/metabolism , Oligodendrocyte Precursor Cells/physiology , Oligodendroglia/metabolism
9.
Rheumatol Ther ; 7(1): 101-119, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31721017

ABSTRACT

INTRODUCTION: Spebrutinib (CC-292) is an orally administered, covalent, small-molecule inhibitor of Bruton's tyrosine kinase (BTK), part of the B-cell and Fc receptor signaling pathways. This study evaluated spebrutinib pharmacology and mechanism of action over a 4-week treatment period in patients with active rheumatoid arthritis (RA). METHODS: Primary human B cells, T cells, natural killer cells, macrophages, dendritic cells, basophils, and osteoclasts were treated with spebrutinib in vitro. Clinical pharmacodynamics were studied in 47 patients with active RA on background methotrexate therapy randomized to oral spebrutinib 375 mg/day or placebo. RESULTS: In vitro, spebrutinib inhibited B-cell proliferation more potently than T-cell proliferation and reduced both lymphoid and myeloid cytokine production and degranulation, as well as osteoclastogenesis. Clinical efficacy trended higher in spebrutinib-treated RA patients, with 41.7% (10/24) achieving ≥ 20% improvement in ACR response criteria (ACR20) versus 21.7% (5/23) of placebo patients at week 4 (P = 0.25). Treatment-emergent adverse events were comparable between treatment groups. In spebrutinib-treated patients, median BTK occupancy in peripheral blood was 83%, and significant increases in total CD19+ and mature-naive CD27-CD38-IgD+ B cells and decreases in transitional CD27-CD38+ B cells were observed. Spebrutinib significantly reduced serum chemokines chemokine ligand 13 (CXCL13), macrophage inflammatory protein-1ß (MIP-1ß), and the bone resorption biomarker carboxy-terminal collagen cross-linking telopeptide (CTX-I) (P < 0.05). Clinical response to spebrutinib was associated with lower increases in CD19+ B cells and greater decreases in CXCL13 and MIP-1ß from baseline to week 4. High CD19+ B cells and low CTX-I at baseline were associated with better spebrutinib clinical response. CONCLUSIONS: Spebrutinib inhibited various leukocyte responses in vitro, including those of B cells and osteoclasts. In this small study in RA patients, spebrutinib was well tolerated, showed a downward trend for symptoms, significantly modulated B-cell populations, and reduced markers of chemotaxis and osteoclast activity. TRIAL REGISTRATION: NCT01975610.

10.
BMB Rep ; 52(9): 533-539, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31383252

ABSTRACT

Recent evidence from genetics, animal model systems and biochemical studies suggests that defects in membrane trafficking play an important part in the pathophysiology of Parkinson's disease (PD). Mutations in leucine-rich repeat kinase 2 (LRRK2) constitute the most frequent genetic cause of both familial and sporadic PD, and LRRK2 has been suggested as a druggable target for PD. Although the precise physiological function of LRRK2 remains largely unknown, mounting evidence suggests that LRRK2 controls membrane trafficking by interacting with key regulators of the endosomal-lysosomal pathway and synaptic recycling. In this review, we discuss the genetic, biochemical and functional links between LRRK2 and membrane trafficking. Understanding the mechanism by which LRRK2 influences such processes may contribute to the development of disease-modifying therapies for PD. [BMB Reports 2019; 52(9): 533-539].


Subject(s)
Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/metabolism , Parkinson Disease/metabolism , Synaptic Vesicles/metabolism , Animals , Cell Membrane/metabolism , Humans , Protein Transport/physiology
11.
Cell Rep ; 26(5): 1357-1367.e5, 2019 01 29.
Article in English | MEDLINE | ID: mdl-30699360

ABSTRACT

Katanin was the first microtubule (MT)-severing enzyme discovered, but how katanin executes MT severing remains poorly understood. Here, we report X-ray crystal structures of the apo and ATPγS-bound states of the catalytic AAA domain of human katanin p60 at 3.0 and 2.9 Å resolution, respectively. Comparison of the two structures reveals conformational changes induced by ATP binding and how such changes ensure hexamer stability. Moreover, we uncover structural details of pore loops (PLs) and show that Arg283, a residue unique to katanin among MT-severing enzymes, protrudes from PL1 and lines the entry of the catalytic pore. Functional studies suggest that PL1 and Arg283 play essential roles in the recognition and remodeling of the glutamylated, C-terminal tubulin tail and regulation of axon growth. In addition, domain-swapping experiments in katanin and spastin suggest that the non-homologous N-terminal region, which contains the MT-interacting and trafficking domain and a linker, confers specificity to the severing process.


Subject(s)
Glutamates/metabolism , Katanin/chemistry , Katanin/metabolism , Microtubules/metabolism , Adenosine Triphosphate/metabolism , Amino Acid Sequence , Animals , Arginine/metabolism , Axons/metabolism , HeLa Cells , Humans , Mice, Inbred ICR , Models, Molecular , Mutation/genetics , Protein Domains , Protein Multimerization , Sensory Receptor Cells/metabolism , Spastin/metabolism
12.
Glia ; 67(2): 360-375, 2019 02.
Article in English | MEDLINE | ID: mdl-30444070

ABSTRACT

Schwann cells (SCs), the primary glia in the peripheral nervous system (PNS), display remarkable plasticity in that fully mature SCs undergo dedifferentiation and convert to repair SCs upon nerve injury. Dedifferentiated SCs provide essential support for PNS regeneration by producing signals that enhance the survival and axon regrowth of damaged neurons, but the identities of neurotrophic factors remain incompletely understood. Here we show that SCs express and secrete progranulin (PGRN), depending on the differentiation status of SCs. PGRN expression and secretion markedly increased as primary SCs underwent dedifferentiation, while PGRN secretion was prevented by administration of cAMP, which induced SC differentiation. We also found that sciatic nerve injury, a physiological trigger of SC dedifferentiation, induced PGRN expression in SCs in vivo. These results suggest that dedifferentiated SCs express and secrete PGRN that functions as a paracrine factor to support the survival and axon growth of neighboring neurons after injury.


Subject(s)
Axons/pathology , Cell Proliferation/drug effects , Motor Neurons/pathology , Progranulins/metabolism , Schwann Cells/metabolism , Sciatic Neuropathy/pathology , Animals , Axons/drug effects , Bucladesine/pharmacology , Cell Survival/drug effects , Cells, Cultured , Coculture Techniques , Culture Media, Conditioned/pharmacology , Disease Models, Animal , Dose-Response Relationship, Drug , Fluoresceins/metabolism , Mass Spectrometry , Mice , Mice, Inbred ICR , Motor Neurons/drug effects , Progranulins/pharmacology , RNA, Messenger/metabolism , Schwann Cells/chemistry , Spinal Cord/cytology
13.
Cell Death Dis ; 9(11): 1125, 2018 11 12.
Article in English | MEDLINE | ID: mdl-30420654

ABSTRACT

Leucine-rich repeat kinase 2 (LRRK2), originally identified as a causative genetic factor in Parkinson's disease, is now associated with a number of pathologies. Here, we show that brain injury induces a robust expression of endogenous LRRK2 and suggest a role of LRRK2 after injury. We found that various in vitro and in vivo models of traumatic brain injury (TBI) markedly enhanced LRRK2 expression in neurons and also increased the level of hypoxia-inducible factor (HIF)-1α. Luciferase reporter assay and chromatin immunoprecipitation revealed direct binding of HIF-1α in LRRK2 proximal promoter. We also found that HIF-1α-dependent transcriptional induction of LRRK2 exacerbated neuronal cell death following injury. Furthermore, application of G1023, a specific, brain-permeable inhibitor of LRRK2, substantially prevented brain tissue damage, cell death, and inflammatory response and alleviated motor and cognitive defects induced by controlled cortical impact injury. Together, these results suggest HIF-1α-LRRK2 axis as a potential therapeutic target for brain injury.


Subject(s)
Brain Injuries, Traumatic/genetics , Cerebral Cortex/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/genetics , Transcription, Genetic , Animals , Apoptosis/drug effects , Apoptosis/genetics , Base Sequence , Brain Injuries, Traumatic/metabolism , Brain Injuries, Traumatic/pathology , Brain Injuries, Traumatic/prevention & control , Cerebral Cortex/drug effects , Cerebral Cortex/pathology , Female , Gene Expression Regulation , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/antagonists & inhibitors , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/metabolism , Mice , Mice, Inbred ICR , Mitochondria/drug effects , Mitochondria/metabolism , Mitochondria/pathology , Neurons/drug effects , Neurons/metabolism , Neurons/pathology , Neuroprotective Agents/pharmacology , Primary Cell Culture , Promoter Regions, Genetic , Protein Binding , Protein Kinase Inhibitors/pharmacology , Psychomotor Performance/drug effects , Signal Transduction
14.
Mol Neurodegener ; 13(1): 8, 2018 02 13.
Article in English | MEDLINE | ID: mdl-29439717

ABSTRACT

BACKGROUND: Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common cause of familial and sporadic Parkinson's disease (PD). Elevated kinase activity is associated with LRRK2 toxicity, but the substrates that mediate neurodegeneration remain poorly defined. Given the increasing evidence suggesting a role of LRRK2 in membrane and vesicle trafficking, here we systemically screened Rab GTPases, core regulators of vesicular dynamics, as potential substrates of LRRK2 and investigated the functional consequence of such phosphorylation in cells and in vivo. METHODS: In vitro LRRK2 kinase assay with forty-five purified human Rab GTPases was performed to identify Rab family proteins as substrates of LRRK2. We identified the phosphorylation site by tandem mass-spectrometry and confirmed it by assessing phosphorylation in the in vitro LRRK2 kinase assay and in cells. Effects of Rab phosphorylation on neurodegeneration were examined in primary cultures and in vivo by intracranial injection of adeno-associated viral vectors (AAV) expressing wild-type or phosphomutants of Rab35. RESULTS: Our screening revealed that LRRK2 phosphorylated several Rab GTPases at a conserved threonine residue in the switch II region, and by using the kinase-inactive LRRK2-D1994A and the pathogenic LRRK2-G2019S along with Rab proteins in which the LRRK2 site was mutated, we verified that a subset of Rab proteins, including Rab35, were authentic substrates of LRRK2 both in vitro and in cells. We also showed that phosphorylation of Rab regulated GDP/GTP-binding property in cells. Moreover, in primary cortical neurons, mutation of the LRRK2 site in several Rabs caused neurotoxicity, which was most severely induced by phosphomutants of Rab35. Furthermore, intracranial injection of the AAV-Rab35 -T72A or AAV-Rab35-T72D into the substantia nigra substantially induced degeneration of dopaminergic neurons in vivo. CONCLUSIONS: Here we show that a subset of Rab GTPases are authentic substrates of LRRK2 both in vitro and in cells. We also provide evidence that dysregulation of Rab phosphorylation in the LRRK2 site induces neurotoxicity in primary neurons and degeneration of dopaminergic neurons in vivo. Our study suggests that Rab GTPases might mediate LRRK2 toxicity in the progression of PD.


Subject(s)
Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/metabolism , Nerve Degeneration/metabolism , Parkinson Disease/metabolism , rab GTP-Binding Proteins/metabolism , Animals , Dopaminergic Neurons/metabolism , Dopaminergic Neurons/pathology , Humans , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/genetics , Mice , Mutation , Nerve Degeneration/pathology , Parkinson Disease/genetics , Parkinson Disease/pathology , Phosphorylation
15.
Front Mol Neurosci ; 10: 391, 2017.
Article in English | MEDLINE | ID: mdl-29234272

ABSTRACT

Glycogen synthase kinases 3 (GSK3) α and ß are expressed in the nervous system, and disruption of GSK3 signaling has been implicated in a wide range of neurodevelopmental and psychiatric disorders. Although several studies have established a role of GSK3 signaling in the nervous system, much less is known about isoform-specific functions. Here, we have examined the role of GSK3α and GSK3ß in the developing neocortex by performing in utero electroporation with specific small interfering RNAs targeting each isoform. We found that depletion of either GSK3α or GSK3ß commonly promoted the proliferation of neural progenitor cells in the ventricular zone, but at later stages, knocking down of each isoform resulted in distinct outcomes. In particular, the transformation of radial progenitors to intermediate progenitor cells was promoted in GSK3α-depleted cells, but markedly prevented in GSK3ß-depleted cells. Moreover, knocking down of GSK3ß but not GSK3α prevented the generation of upper-layer Cux1+ neurons. Consistent with the distinct outcomes, protein levels of c-Myc and ß-catenin, well-known substrates of GSK3, were differentially affected by depletion of GSK3α and GSK3ß. Together, these results suggest that GSK3α and GSK3ß might play distinct roles in the genesis and differentiation of neuronal lineage cells during neocortex development by differential regulation of downstream signaling pathways.

16.
J Immunol ; 199(7): 2388-2407, 2017 10 01.
Article in English | MEDLINE | ID: mdl-28848067

ABSTRACT

BAFF is a B cell survival and maturation factor implicated in the pathogenesis of systemic lupus erythematosus (SLE). In this in vitro study, we describe that soluble BAFF in combination with IL-2 and IL-21 is a T cell contact-independent inducer of human B cell proliferation, plasmablast differentiation, and IgG secretion from circulating CD27+ memory and memory-like CD27-IgD- double-negative (DN) B cells, but not CD27-IgD+ naive B cells. In contrast, soluble CD40L in combination with IL-2 and IL-21 induces these activities in both memory and naive B cells. Blood from healthy donors and SLE patients have similar circulating levels of IL-2, whereas SLE patients exhibit elevated BAFF and DN B cells and reduced IL-21. B cell differentiation transcription factors in memory, DN, and naive B cells in SLE show elevated levels of Aiolos, whereas Ikaros levels are unchanged. Treatment with CC-220, a modulator of the cullin ring ligase 4-cereblon E3 ubiquitin ligase complex, reduces Aiolos and Ikaros protein levels and BAFF- and CD40L-induced proliferation, plasmablast differentiation, and IgG secretion. The observation that the soluble factors BAFF, IL-2, and IL-21 induce memory and DN B cell activation and differentiation has implications for extrafollicular plasmablast development within inflamed tissue. Inhibition of B cell plasmablast differentiation by reduction of Aiolos and Ikaros may have utility in the treatment of SLE, where elevated levels of BAFF and Aiolos may prime CD27+ memory and DN memory-like B cells to become Ab-producing plasmablasts in the presence of BAFF and proinflammatory cytokines.


Subject(s)
B-Cell Activating Factor/blood , B-Cell Activating Factor/immunology , B-Lymphocyte Subsets/immunology , Ikaros Transcription Factor/genetics , Immunologic Memory , Lupus Erythematosus, Systemic/immunology , Peptide Hydrolases/metabolism , Adaptor Proteins, Signal Transducing , Antibody Formation/drug effects , B-Cell Activating Factor/metabolism , B-Lymphocyte Subsets/drug effects , CD40 Ligand/pharmacology , Cell Differentiation , Heterocyclic Compounds, 4 or More Rings/pharmacology , Humans , Ikaros Transcription Factor/blood , Immunologic Memory/drug effects , Interleukin-2/blood , Interleukin-2/pharmacology , Interleukins/pharmacology , Morpholines , Phthalimides , Piperidones , Tumor Necrosis Factor Receptor Superfamily, Member 7/deficiency , Tumor Necrosis Factor Receptor Superfamily, Member 7/genetics , Tumor Necrosis Factor Receptor Superfamily, Member 7/immunology , Ubiquitin-Protein Ligases
17.
Exp Neurobiol ; 26(3): 158-167, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28680301

ABSTRACT

Brain is a rich environment where neurons and glia interact with neighboring cells as well as extracellular matrix in three-dimensional (3D) space. Astrocytes, which are the most abundant cells in the mammalian brain, reside in 3D space and extend highly branched processes that form microdomains and contact synapses. It has been suggested that astrocytes cultured in 3D might be maintained in a less reactive state as compared to those growing in a traditional, two-dimensional (2D) monolayer culture. However, the functional characterization of the astrocytes in 3D culture has been lacking. Here we cocultured neurons and astrocytes in 3D and examined the morphological, molecular biological, and electrophysiological properties of the 3D-cultured hippocampal astrocytes. In our 3D neuron-astrocyte coculture, astrocytes showed a typical morphology of a small soma with many branches and exhibited a unique membrane property of passive conductance, more closely resembling their native in vivo counterparts. Moreover, we also induced reactive astrocytosis in culture by infecting with high-titer adenovirus to mimic pathophysiological conditions in vivo. Adenoviral infection induced morphological changes in astrocytes, increased passive conductance, and increased GABA content as well as tonic GABA release, which are characteristics of reactive gliosis. Together, our study presents a powerful in vitro model resembling both physiological and pathophysiological conditions in vivo, and thereby provides a versatile experimental tool for studying various neurological diseases that accompany reactive astrocytes.

18.
Nat Commun ; 8: 14346, 2017 02 01.
Article in English | MEDLINE | ID: mdl-28146148

ABSTRACT

In native tissues, cellular and acellular components are anisotropically organized and often aligned in specific directions, providing structural and mechanical properties for actuating biological functions. Thus, engineering alignment not only allows for emulation of native tissue structures but might also enable implementation of specific functionalities. However, achieving desired alignment is challenging, especially in three-dimensional constructs. By exploiting the elastomeric property of polydimethylsiloxane and fibrillogenesis kinetics of collagen, here we introduce a simple yet effective method to assemble and align fibrous structures in a multi-modular three-dimensional conglomerate. Applying this method, we have reconstructed the CA3-CA1 hippocampal neural circuit three-dimensionally in a monolithic gel, in which CA3 neurons extend parallel axons to and synapse with CA1 neurons. Furthermore, we show that alignment of the fibrous scaffold facilitates the establishment of functional connectivity. This method can be applied for reconstructing other neural circuits or tissue units where anisotropic organization in a multi-modular structure is desired.


Subject(s)
Cell Culture Techniques/methods , Hippocampus/physiology , Nerve Net/physiology , Neurons/physiology , Tissue Scaffolds/chemistry , Animals , Anisotropy , Cells, Cultured , Collagen/chemistry , Hippocampus/cytology , Mice, Inbred ICR , Microscopy, Confocal , Nerve Net/cytology , Neurons/cytology , Rats, Sprague-Dawley , Synapses/physiology , Time-Lapse Imaging/methods , Tissue Engineering/methods
19.
Neural Plast ; 2016: 5056418, 2016.
Article in English | MEDLINE | ID: mdl-27872763

ABSTRACT

Several studies have demonstrated the therapeutic potential of applying microtubule- (MT-) stabilizing agents (MSAs) that cross the blood-brain barrier to promote axon regeneration and prevent axonal dystrophy in rodent models of spinal cord injury and neurodegenerative diseases. Paradoxically, administration of MSAs, which have been widely prescribed to treat malignancies, is well known to cause debilitating peripheral neuropathy and axon degeneration. Despite the growing interest of applying MSAs to treat the injured or degenerating central nervous system (CNS), consequences of MSA exposure to neurons in the central and peripheral nervous system (PNS) have not been thoroughly investigated. Here, we have examined and compared the effects of a brain-penetrant MSA, epothilone B, on cortical and sensory neurons in culture and show that epothilone B exhibits both beneficial and detrimental effects, depending on not only the concentration of drug but also the type and age of a neuron, as seen in clinical settings. Therefore, to exploit MSAs to their full benefit and minimize unwanted side effects, it is important to understand the properties of neuronal MTs and strategies should be devised to deliver minimal effective concentration directly to the site where needed.


Subject(s)
Epothilones/pharmacology , Microtubules/physiology , Neurons/physiology , Tubulin Modulators/pharmacology , Age Factors , Animals , Animals, Newborn , Brain/cytology , Brain/drug effects , Brain/physiology , Cells, Cultured , Female , Mice , Mice, Inbred ICR , Microtubules/drug effects , Neurons/drug effects
20.
Neuron ; 92(3): 607-611, 2016 Nov 02.
Article in English | MEDLINE | ID: mdl-27810002

ABSTRACT

This article introduces the history and the long-term goals of the Korea Brain Initiative, which is centered on deciphering the brain functions and mechanisms that mediate the integration and control of brain functions that underlie decision-making. The goal of this initiative is the mapping of a functional connectome with searchable, multi-dimensional, and information-integrated features. The project also includes the development of novel technologies and neuro-tools for integrated brain mapping. Beyond the scientific goals this grand endeavor will ultimately have socioeconomic ramifications that not only facilitate global collaboration in the neuroscience community, but also develop various brain science-related industrial and medical innovations.


Subject(s)
Brain/physiology , Decision Making/physiology , Neurosciences/organization & administration , Brain Mapping , Connectome , Humans , International Cooperation , Public-Private Sector Partnerships , Republic of Korea
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