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1.
Sensors (Basel) ; 23(13)2023 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-37447693

RESUMEN

The major problem in Thailand related to parking is time violation. Vehicles are not allowed to park for more than a specified amount of time. Implementation of closed-circuit television (CCTV) surveillance cameras along with human labor is the present remedy. However, this paper presents an approach that can introduce a low-cost time violation tracking system using CCTV, Deep Learning models, and object tracking algorithms. This approach is fairly new because of its appliance of the SOTA detection technique, object tracking approach, and time boundary implementations. YOLOv8, along with the DeepSORT/OC-SORT algorithm, is utilized for the detection and tracking that allows us to set a timer and track the time violation. Using the same apparatus along with Deep Learning models and algorithms has produced a better system with better performance. The performance of both tracking algorithms was well depicted in the results, obtaining MOTA scores of (1.0, 1.0, 0.96, 0.90) and (1, 0.76, 0.90, 0.83) in four different surveillance data for DeepSORT and OC-SORT, respectively.

2.
Mol Ther Nucleic Acids ; 32: 937-948, 2023 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-37346979

RESUMEN

Dominant missense mutations in DNAJB6, a co-chaperone of HSP70, cause limb girdle muscular dystrophy (LGMD) D1. No treatments are currently available. Two isoforms exist, DNAJB6a and DNAJB6b, each with distinct localizations in muscle. Mutations reside in both isoforms, yet evidence suggests that DNAJB6b is primarily responsible for disease pathogenesis. Knockdown treatment strategies involving both isoforms carry risk, as DNAJB6 knockout is embryonic lethal. We therefore developed an isoform-specific knockdown approach using morpholinos. Selective reduction of each isoform was achieved in vitro in primary mouse myotubes and human LGMDD1 myoblasts, as well as in vivo in mouse skeletal muscle. To assess isoform specific knockdown in LGMDD1, we created primary myotube cultures from a knockin LGMDD1 mouse model. Using mass spectrometry, we identified an LGMDD1 protein signature related to protein homeostasis and myofibril structure. Selective reduction of DNAJB6b levels in LGMDD1 myotubes corrected much of the proteomic disease signature toward wild type levels. Additional in vivo functional data is required to determine if selective reduction of DNAJB6b is a viable therapeutic target for LGMDD1.

3.
Diagnostics (Basel) ; 12(12)2022 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-36552910

RESUMEN

White blood cells (WBCs) in the human immune system defend against infection and protect the body from external hazardous objects. They are comprised of neutrophils, eosinophils, basophils, monocytes, and lymphocytes, whereby each accounts for a distinct percentage and performs specific functions. Traditionally, the clinical laboratory procedure for quantifying the specific types of white blood cells is an integral part of a complete blood count (CBC) test, which aids in monitoring the health of people. With the advancements in deep learning, blood film images can be classified in less time and with high accuracy using various algorithms. This paper exploits a number of state-of-the-art deep learning models and their variations based on CNN architecture. A comparative study on model performance based on accuracy, F1-score, recall, precision, number of parameters, and time was conducted, and DenseNet161 was found to demonstrate a superior performance among its counterparts. In addition, advanced optimization techniques such as normalization, mixed-up augmentation, and label smoothing were also employed on DenseNet to further refine its performance.

4.
Front Immunol ; 13: 984302, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36172375

RESUMEN

The microRNA, miR-146a, is a negative feedback regulator of the central immune transcription factor, nuclear factor kappa B (NFkB). MiR-146a plays important roles in the immune system, and miR-146a deficient mice show a complex phenotype with features of chronic inflammation and autoimmune disease. In this study, we examined the role of miR-146a in extrafollicular B-cell responses, finding that miR-146a suppresses cellular responses in vivo and in vitro. Gene expression profiling revealed that miR-146a-deficient B-cells showed upregulation of interferon pathway genes, including Traf6, a known miR-146a target. We next interrogated the role of TRAF6 in these B-cell responses, finding that TRAF6 is required for proliferation by genetic and pharmacologic inhibition. Together, our findings demonstrate a novel role for miR-146a and TRAF6 in the extrafollicular B-cell responses, which have recently been tied to autoimmune disease pathogenesis. Our work highlights the pathogenetic role of miR-146a and the potential of pharmacologic inhibition of TRAF6 in autoimmune diseases in which miR-146a is deregulated.


Asunto(s)
Enfermedades Autoinmunes , Linfocitos B , MicroARNs , Factor 6 Asociado a Receptor de TNF , Animales , Linfocitos B/inmunología , Interferones/metabolismo , Ratones , MicroARNs/genética , FN-kappa B/metabolismo , Factor 6 Asociado a Receptor de TNF/metabolismo
5.
Entropy (Basel) ; 24(1)2022 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-35052160

RESUMEN

Multiple myeloma is a condition of cancer in the bone marrow that can lead to dysfunction of the body and fatal expression in the patient. Manual microscopic analysis of abnormal plasma cells, also known as multiple myeloma cells, is one of the most commonly used diagnostic methods for multiple myeloma. However, as it is a manual process, it consumes too much effort and time. Besides, it has a higher chance of human errors. This paper presents a computer-aided detection and segmentation of myeloma cells from microscopic images of the bone marrow aspiration. Two major contributions are presented in this paper. First, different Mask R-CNN models using different images, including original microscopic images, contrast-enhanced images and stained cell images, are developed to perform instance segmentation of multiple myeloma cells. As a second contribution, a deep-wise augmentation, a deep learning-based data augmentation method, is applied to increase the performance of Mask R-CNN models. Based on the experimental findings, the Mask R-CNN model using contrast-enhanced images combined with the proposed deep-wise data augmentation provides a superior performance compared to other models. It achieves a mean precision of 0.9973, mean recall of 0.8631, and mean intersection over union (IOU) of 0.9062.

6.
Entropy (Basel) ; 24(10)2022 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-37420378

RESUMEN

Caries prevention is essential for oral hygiene. A fully automated procedure that reduces human labor and human error is needed. This paper presents a fully automated method that segments tooth regions of interest from a panoramic radiograph to diagnose caries. A patient's panoramic oral radiograph, which can be taken at any dental facility, is first segmented into several segments of individual teeth. Then, informative features are extracted from the teeth using a pre-trained deep learning network such as VGG, Resnet, or Xception. Each extracted feature is learned by a classification model such as random forest, k-nearest neighbor, or support vector machine. The prediction of each classifier model is considered as an individual opinion that contributes to the final diagnosis, which is decided by a majority voting method. The proposed method achieved an accuracy of 93.58%, a sensitivity of 93.91%, and a specificity of 93.33%, making it promising for widespread implementation. The proposed method, which outperforms existing methods in terms of reliability, and can facilitate dental diagnosis and reduce the need for tedious procedures.

7.
Leukemia ; 36(1): 68-79, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34321607

RESUMEN

Despite recent advances in therapeutic approaches, patients with MLL-rearranged leukemia still have poor outcomes. Here, we find that the RNA-binding protein IGF2BP3, which is overexpressed in MLL-translocated leukemia, strongly amplifies MLL-Af4-mediated leukemogenesis. Deletion of Igf2bp3 significantly increases the survival of mice with MLL-Af4-driven leukemia and greatly attenuates disease, with a minimal impact on baseline hematopoiesis. At the cellular level, MLL-Af4 leukemia-initiating cells require Igf2bp3 for their function in leukemogenesis. At the molecular level, IGF2BP3 regulates a complex posttranscriptional operon governing leukemia cell survival and proliferation. IGF2BP3-targeted mRNA transcripts include important MLL-Af4-induced genes, such as those in the Hoxa locus, and the Ras signaling pathway. Targeting of transcripts by IGF2BP3 regulates both steady-state mRNA levels and, unexpectedly, pre-mRNA splicing. Together, our findings show that IGF2BP3 represents an attractive therapeutic target in this disease, providing important insights into mechanisms of posttranscriptional regulation in leukemia.


Asunto(s)
Carcinogénesis/patología , Proteínas de Unión al ADN/genética , Regulación Leucémica de la Expresión Génica , N-Metiltransferasa de Histona-Lisina/genética , Leucemia Experimental/patología , Proteína de la Leucemia Mieloide-Linfoide/genética , Proteínas Nucleares/genética , Proteínas de Fusión Oncogénica/genética , Proteínas de Unión al ARN/fisiología , Animales , Apoptosis , Carcinogénesis/genética , Carcinogénesis/metabolismo , Proliferación Celular , Femenino , Leucemia Experimental/etiología , Leucemia Experimental/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados
8.
Front Physiol ; 12: 640374, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34335286

RESUMEN

Cyclopentenone prostaglandins (cyPGs) are biologically active lipid mediators, including PGA2, PGA1, PGJ2, and its metabolites. cyPGs are essential regulators of inflammation, cell proliferation, apoptosis, angiogenesis, cell migration, and stem cell activity. cyPGs biologically act on multiple cellular targets, including transcription factors and signal transduction pathways. cyPGs regulate the inflammatory response by interfering with NF-κB, AP-1, MAPK, and JAK/STAT signaling pathways via both a group of nuclear receptor peroxisome proliferator-activated receptor-gamma (PPAR-γ) dependent and PPAR-γ independent mechanisms. cyPGs promote the resolution of chronic inflammation associated with cancers and pathogen (bacterial, viral, and parasitic) infection. cyPGs exhibit potent effects on viral infections by repressing viral protein synthesis, altering viral protein glycosylation, inhibiting virus transmission, and reducing virus-induced inflammation. We summarize their anti-proliferative, pro-apoptotic, cytoprotective, antioxidant, anti-angiogenic, anti-inflammatory, pro-resolution, and anti-metastatic potential. These properties render them unique therapeutic value, especially in resolving inflammation and could be used in adjunct with other existing therapies. We also discuss other α, ß -unsaturated carbonyl lipids and cyPGs like isoprostanes (IsoPs) compounds.

9.
Sensors (Basel) ; 21(6)2021 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-33802223

RESUMEN

Automated segmentation methods are critical for early detection, prompt actions, and immediate treatments in reducing disability and death risks of brain infarction. This paper aims to develop a fully automated method to segment the infarct lesions from T1-weighted brain scans. As a key novelty, the proposed method combines variational mode decomposition and deep learning-based segmentation to take advantages of both methods and provide better results. There are three main technical contributions in this paper. First, variational mode decomposition is applied as a pre-processing to discriminate the infarct lesions from unwanted non-infarct tissues. Second, overlapped patches strategy is proposed to reduce the workload of the deep-learning-based segmentation task. Finally, a three-dimensional U-Net model is developed to perform patch-wise segmentation of infarct lesions. A total of 239 brain scans from a public dataset is utilized to develop and evaluate the proposed method. Empirical results reveal that the proposed automated segmentation can provide promising performances with an average dice similarity coefficient (DSC) of 0.6684, intersection over union (IoU) of 0.5022, and average symmetric surface distance (ASSD) of 0.3932, respectively.


Asunto(s)
Aprendizaje Profundo , Humanos , Procesamiento de Imagen Asistido por Computador , Infarto , Imagen por Resonancia Magnética
10.
Infect Immun ; 87(4)2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30642904

RESUMEN

Plasmodium falciparum erythrocyte-binding antigen 140 (EBA-140) plays a role in tight junction formation during parasite invasion of red blood cells and is a potential vaccine candidate for malaria. Individuals in areas where malaria is endemic possess EBA-140-specific antibodies, and individuals with high antibody titers to this protein have a lower rate of reinfection by parasites. The red blood cell binding segment of EBA-140 is comprised of two Duffy-binding-like domains, called F1 and F2, that together create region II. The sialic acid-binding pocket of F1 is essential for binding, whereas the sialic acid-binding pocket in F2 appears dispensable. Here, we show that immunization of mice with the complete region II results in poorly neutralizing antibodies. In contrast, immunization of mice with the functionally relevant F1 domain of region II results in antibodies that confer a 2-fold increase in parasite neutralization compared to that of the F2 domain. Epitope mapping of diverse F1 and F2 monoclonal antibodies revealed that the functionally relevant F1 sialic acid-binding pocket is a privileged site inaccessible to antibodies, that the F2 sialic acid-binding pocket contains a nonneutralizing epitope, and that two additional epitopes reside in F1 on the opposite face from the sialic acid-binding pocket. These studies indicate that focusing the immune response to the functionally important F1 sialic acid binding pocket improves the protective immune response of EBA-140. These results have implications for improving future vaccine designs and emphasize the importance of structural vaccinology for malaria.


Asunto(s)
Anticuerpos Antiprotozoarios/inmunología , Proteínas Portadoras/inmunología , Epítopos/inmunología , Malaria Falciparum/inmunología , Plasmodium falciparum/inmunología , Proteínas Protozoarias/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos Neutralizantes/inmunología , Formación de Anticuerpos , Proteínas Portadoras/química , Proteínas Portadoras/genética , Mapeo Epitopo , Epítopos/química , Epítopos/genética , Humanos , Malaria Falciparum/parasitología , Masculino , Proteínas de la Membrana , Ratones Endogámicos BALB C , Plasmodium falciparum/genética , Dominios Proteicos , Proteínas Protozoarias/química , Proteínas Protozoarias/genética
11.
Elife ; 72018 12 17.
Artículo en Inglés | MEDLINE | ID: mdl-30556808

RESUMEN

Erythrocyte Binding Antigen of 175 kDa (EBA-175) has a well-defined role in binding to glycophorin A (GpA) during Plasmodium falciparum invasion of erythrocytes. However, EBA-175 is shed post invasion and a role for this shed protein has not been defined. We show that EBA-175 shed from parasites promotes clustering of RBCs, and EBA-175-dependent clusters occur in parasite culture. Region II of EBA-175 is sufficient for clustering RBCs in a GpA-dependent manner. These clusters are capable of forming under physiological flow conditions and across a range of concentrations. EBA-175-dependent RBC clustering provides daughter merozoites ready access to uninfected RBCs enhancing parasite growth. Clustering provides a general method to protect the invasion machinery from immune recognition and disruption as exemplified by protection from neutralizing antibodies that target AMA-1 and RH5. These findings provide a mechanistic framework for the role of shed proteins in RBC clustering, immune evasion, and malaria.


Asunto(s)
Antígenos de Protozoos/inmunología , Glicoforinas/inmunología , Evasión Inmune , Merozoítos/inmunología , Plasmodium falciparum/inmunología , Proteínas Protozoarias/inmunología , Anticuerpos Neutralizantes/farmacología , Antígenos de Protozoos/genética , Antígenos de Protozoos/metabolismo , Proteínas Portadoras/genética , Proteínas Portadoras/inmunología , Agregación Celular/inmunología , Células Cultivadas , Medios de Cultivo Condicionados/química , Eritrocitos/efectos de los fármacos , Eritrocitos/parasitología , Expresión Génica , Glicoforinas/metabolismo , Humanos , Proteínas de la Membrana/genética , Proteínas de la Membrana/inmunología , Merozoítos/genética , Merozoítos/crecimiento & desarrollo , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Plasmodium falciparum/crecimiento & desarrollo , Unión Proteica , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo
12.
Front Immunol ; 7: 670, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-28138326

RESUMEN

B-cell development in the bone marrow is followed by specification into functional subsets in the spleen, including marginal zone (MZ) B-cells. MZ B-cells are classically characterized by T-independent antigenic responses and require the elaboration of distinct gene expression programs for development. Given their role in gene regulation, it is not surprising that microRNAs are important factors in B-cell development. Recent work demonstrated that deficiency of the NFκB feedback regulator, miR-146a, led to a range of hematopoietic phenotypes, but B-cell phenotypes have not been extensively characterized. Here, we found that miR-146a-deficient mice demonstrate a reduction in MZ B-cells, likely from a developmental block. Utilizing high-throughput sequencing and comparative analysis of developmental stage-specific transcriptomes, we determined that MZ cell differentiation was impaired due to decreases in Notch2 signaling. Our studies reveal miR-146a-dependent B-cell phenotypes and highlight the complex role of miR-146a in the hematopoietic system.

13.
mBio ; 5(5): e01606-14, 2014 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-25205096

RESUMEN

UNLABELLED: Erythrocyte invasion is an essential step in the pathogenesis of malaria. The erythrocyte binding-like (EBL) family of Plasmodium falciparum proteins recognizes glycophorins (Gp) on erythrocytes and plays a critical role in attachment during invasion. However, the molecular basis for specific receptor recognition by each parasite ligand has remained elusive, as is the case with the ligand/receptor pair P. falciparum EBA-175 (PfEBA-175)/GpA. This is due largely to difficulties in producing properly glycosylated and functional receptors. Here, we developed an expression system to produce recombinant glycosylated and functional GpA, as well as mutations and truncations. We identified the essential binding region and determinants for PfEBA-175 engagement, demonstrated that these determinants are required for the inhibition of parasite growth, and identified the glycans important in mediating the PfEBA-175-GpA interaction. The results suggest that PfEBA-175 engages multiple glycans of GpA encoded by exon 3 and that the presentation of glycans is likely required for high-avidity binding. The absence of exon 3 in GpB and GpE due to a splice site mutation confers specific recognition of GpA by PfEBA-175. We speculate that GpB and GpE may have arisen due to selective pressure to lose the PfEBA-175 binding site in GpA. The expression system described here has wider application for examining other EBL members important in parasite invasion, as well as additional pathogens that recognize glycophorins. The ability to define critical binding determinants in receptor-ligand interactions, as well as a system to genetically manipulate glycosylated receptors, opens new avenues for the design of interventions that disrupt parasite invasion. IMPORTANCE: Plasmodium falciparum uses distinct ligands that bind host cell receptors for invasion of red blood cells (RBCs) during malaria infection. A key entry pathway involves P. falciparum EBA-175 (PfEBA-175) recognizing glycophorin A (GpA) on RBCs. Despite knowledge of this protein-protein interaction, the complete mechanism for specific receptor engagement is not known. PfEBA-175 recognizes GpA but is unable to engage the related RBC receptor GpB or GpE. Understanding the necessary elements that enable PfEBA-175 to specifically recognize GpA is critical in developing specific and potent inhibitors of PfEBA-175 that disrupt host cell invasion and aid in malaria control. Here, we describe a novel system to produce and manipulate the host receptor GpA. Using this system, we probed the elements in GpA necessary for engagement and thus for host cell invasion. These studies have important implications for understanding how ligands and receptors interact and for the future development of malaria interventions.


Asunto(s)
Antígenos de Protozoos/metabolismo , Eritrocitos/parasitología , Exones , Glicoforinas/genética , Plasmodium falciparum/genética , Proteínas Protozoarias/metabolismo , Secuencia de Aminoácidos , Antígenos de Protozoos/genética , Sitios de Unión , Glicoforinas/metabolismo , Glicosilación , Células HEK293 , Humanos , Datos de Secuencia Molecular , Mutación , Plasmodium falciparum/crecimiento & desarrollo , Unión Proteica/genética , Dominios y Motivos de Interacción de Proteínas , Proteínas Protozoarias/genética , Sitios de Empalme de ARN , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
15.
PLoS Pathog ; 9(5): e1003390, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23717209

RESUMEN

Disrupting erythrocyte invasion by Plasmodium falciparum is an attractive approach to combat malaria. P. falciparum EBA-175 (PfEBA-175) engages the host receptor Glycophorin A (GpA) during invasion and is a leading vaccine candidate. Antibodies that recognize PfEBA-175 can prevent parasite growth, although not all antibodies are inhibitory. Here, using x-ray crystallography, small-angle x-ray scattering and functional studies, we report the structural basis and mechanism for inhibition by two PfEBA-175 antibodies. Structures of each antibody in complex with the PfEBA-175 receptor binding domain reveal that the most potent inhibitory antibody, R217, engages critical GpA binding residues and the proposed dimer interface of PfEBA-175. A second weakly inhibitory antibody, R218, binds to an asparagine-rich surface loop. We show that the epitopes identified by structural studies are critical for antibody binding. Together, the structural and mapping studies reveal distinct mechanisms of action, with R217 directly preventing receptor binding while R218 allows for receptor binding. Using a direct receptor binding assay we show R217 directly blocks GpA engagement while R218 does not. Our studies elaborate on the complex interaction between PfEBA-175 and GpA and highlight new approaches to targeting the molecular mechanism of P. falciparum invasion of erythrocytes. The results suggest studies aiming to improve the efficacy of blood-stage vaccines, either by selecting single or combining multiple parasite antigens, should assess the antibody response to defined inhibitory epitopes as well as the response to the whole protein antigen. Finally, this work demonstrates the importance of identifying inhibitory-epitopes and avoiding decoy-epitopes in antibody-based therapies, vaccines and diagnostics.


Asunto(s)
Anticuerpos Neutralizantes/química , Anticuerpos Antiprotozoarios/química , Antígenos de Protozoos/química , Glicoforinas/química , Plasmodium falciparum/química , Proteínas Protozoarias/química , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/genética , Antígenos de Protozoos/inmunología , Epítopos/química , Epítopos/genética , Epítopos/inmunología , Eritrocitos/inmunología , Eritrocitos/parasitología , Glicoforinas/genética , Glicoforinas/inmunología , Glicoforinas/metabolismo , Humanos , Plasmodium falciparum/genética , Plasmodium falciparum/inmunología , Estructura Cuaternaria de Proteína , Estructura Terciaria de Proteína , Proteínas Protozoarias/antagonistas & inhibidores , Proteínas Protozoarias/genética , Proteínas Protozoarias/inmunología , Relación Estructura-Actividad
16.
Mol Biol Cell ; 23(18): 3612-23, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22833563

RESUMEN

The sorting of signaling receptors within the endocytic system is important for appropriate cellular responses. After activation, receptors are trafficked to early endosomes and either recycled or sorted to lysosomes and degraded. Most receptors trafficked to lysosomes are modified with ubiquitin and recruited into an endosomal subdomain enriched in hepatocyte growth factor-regulated tyrosine kinase substrate (HRS), a ubiquitin-binding component of the endosomal-sorting complex required for transport (ESCRT) machinery, and then sorted into intraluminal vesicles (ILVs) of multivesicular bodies (MVBs)/lysosomes. However, not all receptors use ubiquitin or the canonical ESCRT machinery to sort to MVBs/lysosomes. This is exemplified by protease-activated receptor-1 (PAR1), a G protein-coupled receptor for thrombin, which sorts to lysosomes independent of ubiquitination and HRS. We recently showed that the adaptor protein ALIX binds to PAR1, recruits ESCRT-III, and mediates receptor sorting to ILVs of MVBs. However, the mechanism that initiates PAR1 sorting at the early endosome is not known. We now report that the adaptor protein complex-3 (AP-3) regulates PAR1 ubiquitin-independent sorting to MVBs through an ALIX-dependent pathway. AP-3 binds to a PAR1 cytoplasmic tail-localized tyrosine-based motif and mediates PAR1 lysosomal degradation independent of ubiquitination. Moreover, AP-3 facilitates PAR1 interaction with ALIX, suggesting that AP-3 functions before PAR1 engagement of ALIX and MVB/lysosomal sorting.


Asunto(s)
Complejo 3 de Proteína Adaptadora/metabolismo , Proteínas de Unión al Calcio/metabolismo , Proteínas de Ciclo Celular/metabolismo , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Lisosomas/metabolismo , Cuerpos Multivesiculares/metabolismo , Receptor PAR-1/metabolismo , Complejo 3 de Proteína Adaptadora/genética , Subunidades delta de Complexo de Proteína Adaptadora/genética , Subunidades delta de Complexo de Proteína Adaptadora/metabolismo , Proteínas de Unión al Calcio/genética , Proteínas de Ciclo Celular/genética , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Células HeLa , Humanos , Immunoblotting , Microscopía Confocal , Modelos Biológicos , Unión Proteica , Transporte de Proteínas , Interferencia de ARN , Receptor PAR-1/genética , Transducción de Señal , Ubiquitina/metabolismo , Ubiquitinación
17.
J Cell Biol ; 197(3): 407-19, 2012 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-22547407

RESUMEN

The sorting of signaling receptors to lysosomes is an essential regulatory process in mammalian cells. During degradation, receptors are modified with ubiquitin and sorted by endosomal sorting complex required for transport (ESCRT)-0, -I, -II, and -III complexes into intraluminal vesicles (ILVs) of multivesicular bodies (MVBs). However, it remains unclear whether a single universal mechanism mediates MVB sorting of all receptors. We previously showed that protease-activated receptor 1 (PAR1), a G protein-coupled receptor (GPCR) for thrombin, is internalized after activation and sorted to lysosomes independent of ubiquitination and the ubiquitin-binding ESCRT components hepatocyte growth factor-regulated tyrosine kinase substrate and Tsg101. In this paper, we report that PAR1 sorted to ILVs of MVBs through an ESCRT-III-dependent pathway independent of ubiquitination. We further demonstrate that ALIX, a charged MVB protein 4-ESCRT-III interacting protein, bound to a YPX(3)L motif of PAR1 via its central V domain to mediate lysosomal degradation. This study reveals a novel MVB/lysosomal sorting pathway for signaling receptors that bypasses the requirement for ubiquitination and ubiquitin-binding ESCRTs and may be applicable to a subset of GPCRs containing YPX(n)L motifs.


Asunto(s)
Proteínas de Unión al Calcio/metabolismo , Proteínas de Ciclo Celular/metabolismo , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Cuerpos Multivesiculares/metabolismo , Receptor PAR-1/metabolismo , Ubiquitina/metabolismo , ATPasas Asociadas con Actividades Celulares Diversas , Adenosina Trifosfatasas/antagonistas & inhibidores , Adenosina Trifosfatasas/genética , Adenosina Trifosfatasas/metabolismo , Secuencias de Aminoácidos , Western Blotting , Proteínas de Unión al Calcio/antagonistas & inhibidores , Proteínas de Unión al Calcio/genética , Proteínas de Ciclo Celular/antagonistas & inhibidores , Proteínas de Ciclo Celular/genética , Complejos de Clasificación Endosomal Requeridos para el Transporte/antagonistas & inhibidores , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Endosomas/metabolismo , Ensayo de Inmunoadsorción Enzimática , Técnica del Anticuerpo Fluorescente , Células HeLa , Humanos , Inmunoprecipitación , Lisosomas/metabolismo , Unión Proteica , Transporte de Proteínas , ARN Mensajero/genética , ARN Interferente Pequeño/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptor PAR-1/genética , Ubiquitinación , ATPasas de Translocación de Protón Vacuolares/antagonistas & inhibidores , ATPasas de Translocación de Protón Vacuolares/genética , ATPasas de Translocación de Protón Vacuolares/metabolismo
18.
Proc Natl Acad Sci U S A ; 106(15): 6393-7, 2009 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-19332793

RESUMEN

Protease-activated receptor-1 (PAR(1)) is a G-protein-coupled receptor uniquely activated by proteolysis. Thrombin, a coagulant protease, induces inflammatory responses and endothelial barrier permeability through the activation of PAR(1). Activated protein C (APC), an anti-coagulant protease, also activates PAR(1). However, unlike thrombin, APC elicits anti-inflammatory responses and protects against endothelial barrier dysfunction induced by thrombin. We found that thrombin and APC signaling were lost in PAR(1)-deficient endothelial cells, indicating that PAR(1) is the major effector of protease signaling. To delineate the mechanism responsible for protease-selective signaling by PAR(1), we examined the effect of APC and thrombin on the activation of RhoA and Rac1, small GTPases that differentially regulate endothelial barrier permeability. Thrombin caused robust RhoA signaling but not Rac1 activation, whereas APC stimulated a marked increase in Rac1 activation but not RhoA signaling, consistent with the opposing functions of these proteases on endothelial barrier integrity. Strikingly, APC signaling and endothelial barrier protection effects were abolished in cells lacking caveolin-1, whereas thrombin signaling remained intact. These findings suggest that compartmentalization of PAR(1) in caveolae is critical for APC selective signaling to Rac1 activation and endothelial barrier protection. We further report that APC induces PAR(1) phosphorylation and desensitizes endothelial cells to thrombin signaling but promotes limited receptor cleavage and negligible internalization and degradation even after prolonged APC exposure. Thus, APC selective signaling and endothelial barrier protective effects are mediated through compartmentalization of PAR(1) in caveolae and a novel mechanism of PAR(1) signal regulation.


Asunto(s)
Caveolas/metabolismo , Receptor PAR-1/metabolismo , Transducción de Señal , Células Cultivadas , Activación Enzimática , Humanos , Fosforilación , Proteína C/metabolismo , Receptor PAR-1/genética , Especificidad por Sustrato , Trombina/metabolismo , Proteína de Unión al GTP rac1/metabolismo , Proteínas de Unión al GTP rho/metabolismo
19.
Annu Rev Pharmacol Toxicol ; 48: 601-29, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-17995450

RESUMEN

The heptahelical G protein-coupled receptors (GPCRs) belong to the largest family of cell surface signaling receptors encoded in the human genome. GPCRs signal to diverse extracellular stimuli and control a vast number of physiological responses, making this receptor class the target of nearly half the drugs currently in use. In addition to rapid desensitization, receptor trafficking is crucial for the temporal and spatial control of GPCR signaling. Sorting signals present in the intracytosolic domains of GPCRs regulate trafficking through the endosomal-lysosomal system. GPCR internalization is mediated by serine and threonine phosphorylation and arrestin binding. Short, linear peptide sequences including tyrosine- and dileucine-based motifs, and PDZ ligands that are recognized by distinct endocytic adaptor proteins also mediate internalization and endosomal sorting of GPCRs. We present new data from bioinformatic searches that reveal the presence of these types of sorting signals in the cytoplasmic tails of many known GPCRs. Several recent studies also indicate that the covalent modification of GPCRs with ubiquitin serves as a signal for internalization and lysosomal sorting, expanding the diversity of mechanisms that control trafficking of mammalian GPCRs.


Asunto(s)
Endosomas/metabolismo , Lisosomas/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Arrestinas/metabolismo , Humanos , Ligandos , Fosforilación , Señales de Clasificación de Proteína/fisiología , Ubiquitina/metabolismo
20.
Mol Cell Biol ; 26(8): 3231-42, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16581796

RESUMEN

Protease-activated receptor 1 (PAR1), a G protein-coupled receptor for the coagulant protease thrombin, is irreversibly activated by proteolysis. Unactivated PAR1 cycles constitutively between the plasma membrane and intracellular stores, thereby providing a protected receptor pool that replenishes the cell surface after thrombin exposure and leads to rapid resensitization to thrombin signaling independent of de novo receptor synthesis. Here, we show that AP2, a clathrin adaptor, binds directly to a tyrosine-based motif in the cytoplasmic tail of PAR1 and is essential for constitutive receptor internalization and cellular recovery of thrombin signaling. Expression of a PAR1 tyrosine mutant or depletion of AP2 by RNA interference leads to significant inhibition of PAR1 constitutive internalization, loss of intracellular uncleaved PAR1, and failure of endothelial cells and other cell types to regain thrombin responsiveness. Our findings establish a novel role for AP2 in direct regulation of PAR1 trafficking, a process critically important to the temporal and spatial aspects of thrombin signaling.


Asunto(s)
Complejo 2 de Proteína Adaptadora/metabolismo , Endotelio Vascular/metabolismo , Receptores de Trombina/metabolismo , Complejo 2 de Proteína Adaptadora/química , Complejo 2 de Proteína Adaptadora/genética , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Anticuerpos Monoclonales/metabolismo , Calcio/análisis , Línea Celular , Endotelio Vascular/citología , Técnica del Anticuerpo Fluorescente , Glutatión Transferasa/metabolismo , Células HeLa , Histidina/química , Humanos , Immunoblotting , Microscopía Confocal , Datos de Secuencia Molecular , Subunidades de Proteína/química , Subunidades de Proteína/metabolismo , ARN Interferente Pequeño/metabolismo , Receptor PAR-1/química , Receptor PAR-1/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Resonancia por Plasmón de Superficie , Tirosina/química , Venas Umbilicales/citología
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