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2.
Elife ; 122023 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-37874617

RESUMO

Leucine-rich repeat kinase 2 (LRRK2) variants associated with Parkinson's disease (PD) and Crohn's disease lead to increased phosphorylation of its Rab substrates. While it has been recently shown that perturbations in cellular homeostasis including lysosomal damage can increase LRRK2 activity and localization to lysosomes, the molecular mechanisms by which LRRK2 activity is regulated have remained poorly defined. We performed a targeted siRNA screen to identify regulators of LRRK2 activity and identified Rab12 as a novel modulator of LRRK2-dependent phosphorylation of one of its substrates, Rab10. Using a combination of imaging and immunopurification methods to isolate lysosomes, we demonstrated that Rab12 is actively recruited to damaged lysosomes and leads to a local and LRRK2-dependent increase in Rab10 phosphorylation. PD-linked variants, including LRRK2 R1441G and VPS35 D620N, lead to increased recruitment of LRRK2 to the lysosome and a local elevation in lysosomal levels of pT73 Rab10. Together, these data suggest a conserved mechanism by which Rab12, in response to damage or expression of PD-associated variants, facilitates the recruitment of LRRK2 and phosphorylation of its Rab substrate(s) at the lysosome.


Lysosomes are cellular compartments tasked with breaking down large molecules such as lipids or proteins. They perform an essential role in helping cells dispose of obsolete or harmful components; in fact, defects in lysosome function are associated with a range of health conditions. For instance, many genes associated with an increased risk of developing Parkinson's disease code for proteins required for lysosomes to work properly, such as the kinase LRRK2. Previous work has shown that this enzyme gets recruited to the surface of damaged lysosomes, where it can modulate the function of another set of molecular actors by modifying them through a chemical process known as phosphorylation. Such activity is increased in harmful versions of LRRK2 linked to Parkinson's disease. However, the molecular mechanisms which control LRRK2 activity or its recruitment to lysosomes remain unclear. To examine this question, Wang, Bondar et al. first performed a targeted screen to identify proteins that can regulate LRRK2 activity. This revealed that Rab12, one of molecular actors that LRRK2 phosphorylates, can in turn modulate the activity of the enzyme. Further imaging and biochemical experiments then showed that Rab12 is recruited to damaged lysosomes and that this step was in fact necessary for LRRK2 to also relocate to these compartments. The data suggest that this Rab12-driven recruitment process increases the local concentration of LRRK2 near its Rab targets on the membrane of damaged lysosomes, and therefore leads to enhanced LRRK2 activity. Crucially, Wang, Bondar et al. showed that Rab12 also plays a role in the increased LRRK2 activity observed with two Parkinson's disease-linked mutations (one in LRRK2 itself and one in another lysosomal regulator, VPS35), suggesting that increased LRRK2 concentration on lysosomes may be a conserved mechanism that leads to increased LRRK2 activity in disease. Overall, these results highlight a new, Rab12-dependent mechanism that results in enhanced activity at the lysosomal membrane with variants associated with Parkinson's disease, and for LRRK2 in general when lysosomes are damaged. This knowledge will be helpful to develop therapeutic strategies that target LRRK2, and to better understand how increased LRRK2 activity and lysosomal injury may be linked to Parkinson's disease.


Assuntos
Fenômenos Biológicos , Lisossomos , Proteínas rab de Ligação ao GTP , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Lisossomos/metabolismo , Mutação , Fosforilação , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo , Humanos
4.
Nat Commun ; 14(1): 5053, 2023 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-37598178

RESUMO

Brain exposure of systemically administered biotherapeutics is highly restricted by the blood-brain barrier (BBB). Here, we report the engineering and characterization of a BBB transport vehicle targeting the CD98 heavy chain (CD98hc or SLC3A2) of heterodimeric amino acid transporters (TVCD98hc). The pharmacokinetic and biodistribution properties of a CD98hc antibody transport vehicle (ATVCD98hc) are assessed in humanized CD98hc knock-in mice and cynomolgus monkeys. Compared to most existing BBB platforms targeting the transferrin receptor, peripherally administered ATVCD98hc demonstrates differentiated brain delivery with markedly slower and more prolonged kinetic properties. Specific biodistribution profiles within the brain parenchyma can be modulated by introducing Fc mutations on ATVCD98hc that impact FcγR engagement, changing the valency of CD98hc binding, and by altering the extent of target engagement with Fabs. Our study establishes TVCD98hc as a modular brain delivery platform with favorable kinetic, biodistribution, and safety properties distinct from previously reported BBB platforms.


Assuntos
Barreira Hematoencefálica , Encéfalo , Animais , Camundongos , Distribuição Tecidual , Anticorpos , Engenharia , Macaca fascicularis
5.
J Exp Med ; 219(3)2022 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-35226042

RESUMO

Delivery of biotherapeutics across the blood-brain barrier (BBB) is a challenge. Many approaches fuse biotherapeutics to platforms that bind the transferrin receptor (TfR), a brain endothelial cell target, to facilitate receptor-mediated transcytosis across the BBB. Here, we characterized the pharmacological behavior of two distinct TfR-targeted platforms fused to iduronate 2-sulfatase (IDS), a lysosomal enzyme deficient in mucopolysaccharidosis type II (MPS II), and compared the relative brain exposures and functional activities of both approaches in mouse models. IDS fused to a moderate-affinity, monovalent TfR-binding enzyme transport vehicle (ETV:IDS) resulted in widespread brain exposure, internalization by parenchymal cells, and significant substrate reduction in the CNS of an MPS II mouse model. In contrast, IDS fused to a standard high-affinity bivalent antibody (IgG:IDS) resulted in lower brain uptake, limited biodistribution beyond brain endothelial cells, and reduced brain substrate reduction. These results highlight important features likely to impact the clinical development of TfR-targeting platforms in MPS II and potentially other CNS diseases.


Assuntos
Iduronato Sulfatase , Mucopolissacaridose II , Receptores da Transferrina , Proteínas Recombinantes de Fusão , Animais , Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Iduronato Sulfatase/metabolismo , Iduronato Sulfatase/farmacologia , Lisossomos/metabolismo , Camundongos , Mucopolissacaridose II/metabolismo , Receptores da Transferrina/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes de Fusão/farmacologia , Distribuição Tecidual
6.
Cell ; 184(18): 4651-4668.e25, 2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-34450028

RESUMO

GRN mutations cause frontotemporal dementia (GRN-FTD) due to deficiency in progranulin (PGRN), a lysosomal and secreted protein with unclear function. Here, we found that Grn-/- mice exhibit a global deficiency in bis(monoacylglycero)phosphate (BMP), an endolysosomal phospholipid we identified as a pH-dependent PGRN interactor as well as a redox-sensitive enhancer of lysosomal proteolysis and lipolysis. Grn-/- brains also showed an age-dependent, secondary storage of glucocerebrosidase substrate glucosylsphingosine. We investigated a protein replacement strategy by engineering protein transport vehicle (PTV):PGRN-a recombinant protein linking PGRN to a modified Fc domain that binds human transferrin receptor for enhanced CNS biodistribution. PTV:PGRN rescued various Grn-/- phenotypes in primary murine macrophages and human iPSC-derived microglia, including oxidative stress, lysosomal dysfunction, and endomembrane damage. Peripherally delivered PTV:PGRN corrected levels of BMP, glucosylsphingosine, and disease pathology in Grn-/- CNS, including microgliosis, lipofuscinosis, and neuronal damage. PTV:PGRN thus represents a potential biotherapeutic for GRN-FTD.


Assuntos
Produtos Biológicos/uso terapêutico , Encéfalo/metabolismo , Doenças por Armazenamento dos Lisossomos/terapia , Progranulinas/uso terapêutico , Animais , Proteínas Morfogenéticas Ósseas/metabolismo , Endossomos/metabolismo , Feminino , Demência Frontotemporal/sangue , Demência Frontotemporal/líquido cefalorraquidiano , Gliose/complicações , Gliose/patologia , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Inflamação/patologia , Metabolismo dos Lipídeos , Lipofuscina/metabolismo , Lisossomos/metabolismo , Macrófagos/metabolismo , Masculino , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/metabolismo , Degeneração Neural/patologia , Fenótipo , Progranulinas/deficiência , Progranulinas/metabolismo , Receptores Imunológicos/metabolismo , Receptores da Transferrina/metabolismo , Distribuição Tecidual
7.
Sci Transl Med ; 12(545)2020 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-32461332

RESUMO

Effective delivery of protein therapeutics to the central nervous system (CNS) has been greatly restricted by the blood-brain barrier (BBB). We describe the development of a BBB transport vehicle (TV) comprising an engineered Fc fragment that exploits receptor-mediated transcytosis for CNS delivery of biotherapeutics by binding a highly expressed brain endothelial cell target. TVs were engineered using directed evolution to bind the apical domain of the human transferrin receptor (hTfR) without the use of amino acid insertions, deletions, or unnatural appendages. A crystal structure of the TV-TfR complex revealed the TV binding site to be away from transferrin and FcRn binding sites, which was further confirmed experimentally in vitro and in vivo. Recombinant expression of TVs fused to anti-ß-secretase (BACE1) Fabs yielded antibody transport vehicle (ATV) molecules with native immunoglobulin G (IgG) structure and stability. Peripheral administration of anti-BACE1 ATVs to hTfR-engineered mice and cynomolgus monkeys resulted in substantially improved CNS uptake and sustained pharmacodynamic responses. The TV platform readily accommodates numerous additional configurations, including bispecific antibodies and protein fusions, yielding a highly modular CNS delivery platform.


Assuntos
Secretases da Proteína Precursora do Amiloide , Barreira Hematoencefálica , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Ácido Aspártico Endopeptidases/metabolismo , Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Haplorrinos/metabolismo , Fragmentos Fc das Imunoglobulinas , Camundongos , Receptores da Transferrina/metabolismo
9.
Sci Rep ; 6: 34379, 2016 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-27682269

RESUMO

Dengue virus (DENV) is a mosquito-borne Flavivirus classified into four serotypes (DENV-1-4) that causes Dengue fever (DF), Dengue hemorrhagic Fever (DHF) or Dengue shock syndrome (DSS). An estimated 390 million people are at risk for infection with DENV and there are no effective vaccines or therapeutics. We utilized RNA chromatography coupled with quantitative mass spectrometry (qMS) to identify host RNA binding proteins (RBPs) that interact with DENV-2 RNA. We identified ERI3 (also PRNPIP and PINT1), a putative 3'-5' RNA exonuclease, which preferentially associates with DENV-2 genomic RNA via interactions with dumbbell structures in the 3' UTR. ERI3 is required for accumulation of DENV-2 genomic RNA and production of infectious particles. Furthermore, the mosquito homologue of ERI3 is required for DENV-2 replication in adult Aedes aegypti mosquitos implying that the requirement for ERI3 is conserved in both DENV hosts. In human cells ERI3 localizes to the Golgi in uninfected cells, but relocalizes near sites of DENV-2 replication in infected cells. ERI3 is not required for maintaining DENV-2 RNA stability or translation of the viral polyprotein, but is required for viral RNA synthesis. Our results define a specific role for ERI3 and highlight the importance of Golgi proteins in DENV-2 replication.

11.
J Vis Exp ; (110)2016 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-27168110

RESUMO

Unlike mammals, insects such as Drosophila have multiple taste organs. The chemosensory neurons on the legs, proboscis, wings and ovipositor of Drosophila express gustatory receptors(1,2), ion channels(3-6), and ionotropic receptors(7) that are involved in the detection of volatile and non-volatile sensory cues. These neurons directly contact tastants such as food, noxious substances and pheromones and therefore influence many complex behaviors such as feeding, egg-laying and mating. Electrode recordings and calcium imaging have been widely used in insects to quantify the neuronal responses evoked by these tastants. However, electrophysiology requires specialized equipment and obtaining measurements from a single taste sensillum can be technically challenging depending on the cell-type, size, and position. In addition, single neuron resolution in Drosophila can be difficult to achieve since taste sensilla house more than one type of chemosensory neuron. The live calcium imaging method described here allows responses of single gustatory neurons in live flies to be measured. This method is especially suitable for imaging neuronal responses to lipid pheromones and other ligand types that have low solubility in water-based solvents.


Assuntos
Drosophila/fisiologia , Feromônios/química , Paladar/fisiologia , Animais , Cálcio , Fenômenos Eletrofisiológicos , Lipídeos , Células Receptoras Sensoriais
12.
Elife ; 4: e06914, 2015 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-26083710

RESUMO

Gustatory pheromones play an essential role in shaping the behavior of many organisms. However, little is known about the processing of taste pheromones in higher order brain centers. Here, we describe a male-specific gustatory circuit in Drosophila that underlies the detection of the anti-aphrodisiac pheromone (3R,11Z,19Z)-3-acetoxy-11,19-octacosadien-1-ol (CH503). Using behavioral analysis, genetic manipulation, and live calcium imaging, we show that Gr68a-expressing neurons on the forelegs of male flies exhibit a sexually dimorphic physiological response to the pheromone and relay information to the central brain via peptidergic neurons. The release of tachykinin from 8 to 10 cells within the subesophageal zone is required for the pheromone-triggered courtship suppression. Taken together, this work describes a neuropeptide-modulated central brain circuit that underlies the programmed behavioral response to a gustatory sex pheromone. These results will allow further examination of the molecular basis by which innate behaviors are modulated by gustatory cues and physiological state.


Assuntos
Drosophila/fisiologia , Neurônios/fisiologia , Feromônios/metabolismo , Taquicininas/metabolismo , Animais , Proteínas de Drosophila/análise , Neurônios/química , Receptores de Superfície Celular/análise , Percepção Gustatória
13.
Stem Cell Reports ; 4(1): 61-73, 2015 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-25434820

RESUMO

As complete absence of germ cells leads to sterile males in zebrafish, we explored the relationship between primordial germ cell (PGC) number and sexual development. Our results revealed dimorphic proliferation of PGCs in the early zebrafish larvae, marking the beginning of sexual differentiation. We applied morpholino-based gene knockdown and cell transplantation strategies to demonstrate that a threshold number of PGCs is required for the stability of ovarian fate. Using histology and transcriptomic analyses, we determined that zebrafish gonads are in a meiotic ovarian stage at 14 days postfertilization and identified signaling pathways supporting meiotic oocyte differentiation and eventual female fate. The development of PGC-depleted gonads appears to be restrained and delayed, suggesting that PGC number may directly regulate the variability and length of gonadal transformation and testicular differentiation in zebrafish. We propose that gonadal transformation may function as a developmental buffering mechanism to ensure the reproductive outcome.


Assuntos
Células Germinativas/citologia , Células Germinativas/metabolismo , Gônadas/embriologia , Gônadas/metabolismo , Peixe-Zebra/embriologia , Peixe-Zebra/metabolismo , Animais , Diferenciação Celular , Proliferação de Células , Análise por Conglomerados , Embrião não Mamífero , Feminino , Perfilação da Expressão Gênica , Gônadas/citologia , Larva , Masculino , Meiose , Modelos Biológicos , Reprodutibilidade dos Testes , Caracteres Sexuais , Diferenciação Sexual , Transdução de Sinais , Fatores de Tempo , Transcriptoma , Fator de Crescimento Transformador beta/metabolismo , Peixe-Zebra/genética
15.
J Cell Biol ; 195(5): 799-813, 2011 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-22123864

RESUMO

In eukaryotes, cytokinesis is accomplished by an actomyosin-based contractile ring. Although in Caenorhabditis elegans embryos larger cells divide at a faster rate than smaller cells, it remains unknown whether a similar mode of scalability operates in other cells. We investigated cytokinesis in the filamentous fungus Neurospora crassa, which exhibits a wide range of hyphal circumferences. We found that N. crassa cells divide using an actomyosin ring and larger rings constricted faster than smaller rings. However, unlike in C. elegans, the total amount of myosin remained constant throughout constriction, and there was a size-dependent increase in the starting concentration of myosin in the ring. We predict that the increased number of ring-associated myosin motors in larger rings leads to the increased constriction rate. Accordingly, reduction or inhibition of ring-associated myosin slows down the rate of constriction. Because the mechanical characteristics of contractile rings are conserved, we predict that these findings will be relevant to actomyosin ring constriction in other cell types.


Assuntos
Actomiosina/metabolismo , Citocinese/fisiologia , Miosinas/metabolismo , Neurospora crassa/citologia , Actinas/metabolismo , Actinas/fisiologia , Actomiosina/genética , Membrana Celular/metabolismo , Membrana Celular/fisiologia , Tamanho Celular , Miosinas/genética , Neurospora crassa/genética , Neurospora crassa/fisiologia
16.
Curr Protoc Cytom ; Chapter 9: Unit 9.32.1-16, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20373497

RESUMO

In studies of eukaryotic cell cycle regulation, the budding yeast Saccharoymyces cerevisiae offers many advantages as a model system. Due to its simple growth requirements and genetic tractability, this organism is a powerful tool for investigating the molecular regulation of cell cycle control. One earlier disadvantage to performing cell cycle analyses in yeast was that existing methods were restricted to either visual analysis or flow cytometry, both of which present limitations in the scope and accuracy of the data obtained. This unit demonstrates the combined use of DNA content measurements and bright-field image analysis using multispectral imaging flow cytometry (MIFC) to provide a more precise quantitation of yeast cell cycle distribution. The advantage of this method is the ability to analyze large numbers of cells using multiple cell cycle indicators in a relatively short amount of time.


Assuntos
Núcleo Celular/metabolismo , DNA Fúngico/metabolismo , Fungos/fisiologia , Saccharomyces cerevisiae/genética , Algoritmos , Calibragem , Ciclo Celular , Citometria de Fluxo/métodos , Fungos/citologia , Microscopia/métodos , Saccharomyces cerevisiae/fisiologia , Software
17.
Cytometry A ; 73(9): 825-33, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18613038

RESUMO

Budding yeast Saccharoymyces cerevisiae is a powerful model system for analyzing eukaryotic cell cycle regulation. Yeast cell cycle analysis is typically performed by visual analysis or flow cytometry, and both have limitations in the scope and accuracy of data obtained. This study demonstrates how multispectral imaging flow cytometry (MIFC) provides precise quantitation of cell cycle distribution and morphological phenotypes of yeast cells in flow. Cell cycle analysis of wild-type yeast, nap1Delta, and yeast overexpressing NAP1, was performed visually, by flow cytometry and by MIFC. Quantitative morphological analysis employed measurements of cellular length, thickness, and aspect ratio in an algorithm to calculate a novel feature, bud length. MIFC demonstrated reliable quantification of the yeast cell cycle compared to morphological and flow cytometric analyses. By employing this technique, we observed both the G2/M delay and elongated buds previously described in the nap1Delta strain. Using MIFC, we demonstrate that overexpression of NAP1 causes elongated buds yet only a minor disruption in the cell cycle. The different effects of NAP1 expression level on cell cycle and morphology suggests that these phenotypes are independent. Unlike conventional yeast flow cytometry, MIFC generates complete cell cycle profiles and concurrently offers multiple parameters for morphological analysis.


Assuntos
Ciclo Celular , Citometria de Fluxo/métodos , Citometria por Imagem/métodos , Saccharomyces cerevisiae/citologia , Proteínas de Ciclo Celular/metabolismo , Proteínas do Citoesqueleto/metabolismo , Proteínas Nucleares/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
18.
Mol Cell Biol ; 28(4): 1313-25, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18086883

RESUMO

In Saccharomyces cerevisiae, the evolutionarily conserved nucleocytoplasmic shuttling protein Nap1 is a cofactor for the import of histones H2A and H2B, a chromatin assembly factor and a mitotic factor involved in regulation of bud formation. To understand the mechanism by which Nap1 function is regulated, Nap1-interacting factors were isolated and identified by mass spectrometry. We identified several kinases among these proteins, including casein kinase 2 (CK2), and a new bud neck-associated protein, Nba1. Consistent with our identification of the Nap1-interacting kinases, we showed that Nap1 is phosphorylated in vivo at 11 sites and that Nap1 is phosphorylated by CK2 at three substrate serines. Phosphorylation of these serines was not necessary for normal bud formation, but mutation of these serines to either alanine or aspartic acid resulted in cell cycle changes, including a prolonged S phase, suggesting that reversible phosphorylation by CK2 is important for cell cycle regulation. Nap1 can shuttle between the nucleus and cytoplasm, and we also showed that CK2 phosphorylation promotes the import of Nap1 into the nucleus. In conclusion, our data show that Nap1 phosphorylation by CK2 appears to regulate Nap1 localization and is required for normal progression through S phase.


Assuntos
Caseína Quinase II/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas Nucleares/metabolismo , Saccharomyces cerevisiae/enzimologia , Transporte Ativo do Núcleo Celular , Ciclo Celular , Núcleo Celular/metabolismo , Ciclina B/metabolismo , Histonas/metabolismo , Proteína 1 de Modelagem do Nucleossomo , Fosfoproteínas/metabolismo , Fosforilação , Ligação Proteica , Transporte Proteico , Saccharomyces cerevisiae/citologia , Proteínas de Saccharomyces cerevisiae/metabolismo
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