RESUMO
Alzheimer's disease (AD), a common form of dementia, is caused in part by the aggregation and accumulation in the brain of amyloid ß (Aß), a product of the proteolytic cleavage of amyloid precursor protein (APP) in endosomes. Trafficking of APP, such as surface-intracellular recycling, is an early critical step required for Aß generation. Less is known, however, about the molecular mechanism regulating APP trafficking. This study investigated the mechanism by which SPIN90, along with Rab11, modulates APP trafficking, Aß motility and accumulation, and synaptic functionality. Brain Aß deposition was lower in the progeny of 5xFAD-SPIN90KO mice than in 5xFAD-SPIN90WT mice. Analysis of APP distribution and trafficking showed that the surface fraction of APP was locally distinct in axons and dendrites, with these distributions differing significantly in 5xFAD-SPIN90WT and 5xFAD-SPIN90KO mice, and that neural activity-driven APP trafficking to the surface and intracellular recycling were more actively mobilized in 5xFAD-SPIN90KO neurons. In addition, SPIN90 was found to be cotrafficked with APP via axons, with ablation of SPIN90 reducing the intracellular accumulation of APP in axons. Finally, synaptic transmission was restored over time in 5xFAD-SPIN90KO but not in 5xFAD-SPIN90WT neurons, suggesting SPIN90 is implicated in Aß production through the regulation of APP trafficking.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Doença de Alzheimer , Precursor de Proteína beta-Amiloide , Proteínas do Tecido Nervoso , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Axônios/metabolismo , Modelos Animais de Doenças , Camundongos , Camundongos Transgênicos , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismoRESUMO
Myofibroblasts are the major cell type that is responsible for increase in the mechanical stiffness in fibrotic tissues. It has well documented that the TGF-ß/Smad axis is required for myofibroblast differentiation under the rigid substrate condition. However, the mechanism driving myofibroblast differentiation in soft substrates remains unknown. In this research, we demonstrated that interaction of yes-associated protein (YAP) and acetylated microtubule via dynein, a microtubule motor protein drives nuclear localization of YAP in the soft matrix, which in turn increased TGF-ß1-induced transcriptional activity of Smad for myofibroblast differentiation. Pharmacological and genetical disruption of dynein impaired the nuclear translocation of YAP and decreased the TGF-ß1-induced Smad activity even though phosphorylation and nuclear localization of Smad occurred normally in α-tubulin acetyltransferase 1 (α-TAT1) knockout cell. Moreover, microtubule acetylation prominently appeared in the fibroblast-like cells nearby the blood vessel in the fibrotic liver induced by CCl4 administration, which was conversely decreased by TGF-ß receptor inhibitor. As a result, quantitative inhibition of microtubule acetylation may be suggested as a new target for overcoming fibrotic diseases.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Ciclo Celular/metabolismo , Núcleo Celular/metabolismo , Dineínas/metabolismo , Fibroblastos/metabolismo , Microtúbulos/metabolismo , Transporte Proteico/fisiologia , Acetilação , Animais , Diferenciação Celular/fisiologia , Linhagem Celular , Células HEK293 , Humanos , Masculino , Camundongos Endogâmicos C57BL , Fosforilação/fisiologia , Transdução de Sinais/fisiologia , Proteínas Smad/metabolismo , Fator de Crescimento Transformador beta1/metabolismo , Proteínas de Sinalização YAPRESUMO
Mutations in DJ-1 (PARK7) are a known cause of early-onset autosomal recessive Parkinson's disease (PD). Accumulating evidence indicates that abnormalities of synaptic vesicle trafficking underlie the pathophysiological mechanism of PD. In the present study, we explored whether DJ-1 is involved in CNS synaptic function. DJ-1 deficiency impaired synaptic vesicle endocytosis and reavailability without inducing structural alterations in synapses. Familial mutants of DJ-1 (M26I, E64D, and L166P) were unable to rescue defective endocytosis of synaptic vesicles, whereas WT DJ-1 expression completely restored endocytic function in DJ-1 KO neurons. The defective synaptic endocytosis shown in DJ-1 KO neurons may be attributable to alterations in membrane cholesterol level. Thus, DJ-1 appears essential for synaptic vesicle endocytosis and reavailability, and impairment of this function by familial mutants of DJ-1 may be related to the pathogenesis of PD.
Assuntos
Endocitose/fisiologia , Terminações Nervosas/patologia , Proteína Desglicase DJ-1/fisiologia , Sinapses/patologia , Vesículas Sinápticas/patologia , Animais , Células Cultivadas , Camundongos , Camundongos Knockout , Mutação , Terminações Nervosas/metabolismo , Sinapses/metabolismo , Vesículas Sinápticas/metabolismoRESUMO
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a rapid accumulation of amyloid ß (Aß) protein in the hippocampus, which impairs synaptic structures and neuronal signal transmission, induces neuronal loss, and diminishes memory and cognitive functions. The present study investigated the impact of neuregulin 1 (NRG1)-ErbB4 signaling on the impairment of neural networks underlying hippocampal long-term potentiation (LTP) in 5xFAD mice, a model of AD with greater symptom severity than that of TG2576 mice. Specifically, we observed parvalbumin (PV)-containing hippocampal interneurons, the effect of NRG1 on hippocampal LTP, and the functioning of learning and memory. We found a significant decrease in the number of PV interneurons in 11-month-old 5xFAD mice. Moreover, synaptic transmission in the 5xFAD mice decreased at 6 months of age. The 11-month-old transgenic AD mice showed fewer inhibitory PV neurons and impaired NRG1-ErbB4 signaling than did wild-type mice, indicating that the former exhibit the impairment of neuronal networks underlying LTP in the hippocampal Schaffer-collateral pathway. In conclusion, this study confirmed the impaired LTP in 5xFAD mice and its association with aberrant NRG1-ErbB signaling in the neuronal network.
Assuntos
Envelhecimento/patologia , Doença de Alzheimer/patologia , Região CA1 Hipocampal/patologia , Potenciação de Longa Duração/fisiologia , Rede Nervosa/patologia , Neurônios/patologia , Envelhecimento/metabolismo , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Região CA1 Hipocampal/metabolismo , Cognição/fisiologia , Modelos Animais de Doenças , Feminino , Interneurônios/metabolismo , Interneurônios/patologia , Aprendizagem/fisiologia , Masculino , Memória/fisiologia , Camundongos , Camundongos Transgênicos , Rede Nervosa/metabolismo , Neuregulina-1/metabolismo , Neurônios/metabolismo , Parvalbuminas/metabolismo , Receptor ErbB-4/metabolismo , Transdução de Sinais/fisiologia , Transmissão Sináptica/fisiologiaRESUMO
Cancer-associated fibroblasts (CAFs) in the tumor microenvironment play major roles in supporting cancer progression. A previous report showed that SPIN90 downregulation is correlated with CAF activation and that SPIN90-deficient CAFs promote breast cancer progression. However, the mechanisms that mediate cancer-stroma interaction and how such interactions regulate cancer progression are not well understood. Here, we show that extra domain A (EDA)-containing fibronectin (FN), FN(+)EDA, produced by mouse embryonic fibroblasts (MEFs) derived from Spin90-knockout (KO) mice increases their own myofibroblast differentiation, which facilitates breast cancer progression. Increased FN(+)EDA in Spin90-KO MEFs promoted fibril formation in the extracellular matrix (ECM) and specifically interacted with integrin α4ß1 as the mediating receptor. Moreover, FN(+)EDA expression by Spin90-KO MEFs increased proliferation, migration, and invasion of breast cancer cells. Irigenin, a specific inhibitor of the interaction between integrin α4ß1 and FN(+)EDA, significantly blocked the effects of FN(+)EDA, such as fibril formation by Spin90-KO MEFs and proliferation, migration, and invasion of breast cancer cells. In orthotopic breast cancer mouse models, irigenin injection remarkably reduced tumor growth and lung metastases. It was supported by that FN(+)EDA in assembled fibrils was accumulated in cancer stroma of human breast cancer patients in which SPIN90 expression was downregulated. Our data suggest that SPIN90 downregulation increases FN(+)EDA and promotes ECM stiffening in breast cancer stroma through an assembly of long FN(+)EDA-rich fibrils; moreover, engagement of the Integrin α4ß1 receptor facilitates breast cancer progression. Inhibitory effects of irigenin on tumor growth and metastasis suggest the potential of this agent as an anticancer therapeutic.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Neoplasias da Mama/metabolismo , Fibronectinas/metabolismo , Proteínas Musculares/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Células Cultivadas , Feminino , Fibronectinas/genética , Deleção de Genes , Humanos , Neoplasias Mamárias Animais , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Musculares/genética , Neoplasias Experimentais , Proteínas do Tecido Nervoso/genética , Regulação para CimaRESUMO
Alterations in mechanical properties in the extracellular matrix are modulated by myofibroblasts and are required for progressive fibrotic diseases. Recently, we reported that fibroblasts depleted of SPIN90 showed enhanced differentiation into myofibroblasts via increased acetylation of microtubules in the soft matrix; the mechanisms of the underlying signaling network, however, remain unclear. In this study, we determine the effect of depletion of SPIN90 on FAK/ROCK signaling modules. Transcriptome analysis of Spin90 KO mouse embryonic fibroblasts (MEF) and fibroblasts activated by TGF-ß revealed that Postn is the most significantly upregulated gene. Knockdown of Postn by small interfering RNA suppressed cell adhesion and myofibroblastic differentiation and downregulated FAK activity in Spin90 KO MEF. Our results indicate that SPIN90 depletion activates FAK/ROCK signaling, induced by Postn expression, which is critical for myofibroblastic differentiation on soft matrices mimicking the mechanical environment of a normal tissue.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Moléculas de Adesão Celular/metabolismo , Regulação para Baixo/genética , Fibroblastos/metabolismo , Quinase 1 de Adesão Focal/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Transdução de Sinais , Quinases Associadas a rho/metabolismo , Animais , Diferenciação Celular , Adesões Focais/metabolismo , Camundongos Knockout , Miofibroblastos/metabolismoRESUMO
BACKGROUND: To describe a case of highly suspected primary intraocular lymphoma (PIOL) in a patient using etanercept for the treatment of rheumatoid arthritis. CASE PRESENTATION: A 50-year-old female patient presented with decreased vision in her left eye that lasted for a week. She had a 15-year history of seropositive rheumatoid arthritis (RA), and had been taking weekly etanercept for the preceding 8 months. Funduscopic examination and SD-OCT showed a swollen ellipsoid zone (EZ) and a retinal pigment epithelium (RPE) irregularity of the right eye. We also noted EZ disruption and a RPE irregularity in the left eye. As subretinal infiltration was aggravated in the right eye after the initial treatment, we completed a vitrectomy. Vitreous cytology revealed PIOL with positive CD20 immunostaining. She was treated with serial intravitreal methotrexate injections and systemic chemotherapy. After the treatment, subretinal infiltration and subRPE deposits were decreased in the right eye with no evidence of recurrence in either eye. CONCLUSIONS: This case suggests a potential relationship between immunosuppression with anti-TNFα medication, and increased risk for lymphoma, especially in patients with underlying rheumatologic disorders and especially in patients with suspected chronic refractory uveitis.
Assuntos
Antirreumáticos/efeitos adversos , Artrite Reumatoide/tratamento farmacológico , Etanercepte/efeitos adversos , Neoplasias Oculares/induzido quimicamente , Imunossupressores/efeitos adversos , Linfoma/induzido quimicamente , Feminino , Humanos , Pessoa de Meia-IdadeRESUMO
EF-hand domain-containing protein D2/Swiprosin-1 (EFhd2) is an actin-binding protein mainly expressed in the central nervous and the immune systems of mammals. Intracellular events linked to EFhd2, such as membrane protrusion formation, cell adhesion, and BCR signaling, are triggered by the association of EFhd2 and F-actin. We previously reported that Ca2+ enhances the F-actin-bundling ability of EFhd2 through maintaining a rigid parallel EFhd2-homodimer structure. It was also reported that the F-actin-bundling ability of EFhd2 is regulated by a phosphorylation-dependent mechanism. EGF-induced phosphorylation at Ser183 of EFhd2 has been shown to inhibit F-actin-bundling, leading to irregular actin dynamics at the leading edges of cells. However, the underlying mechanism of this inhibition has remained elusive. Here, we report the crystal structure of a phospho-mimicking mutant (S183E) of the EFhd2 core domain, where the actin-binding sites are located. Although the overall structure of the phospho-mimicking mutant is similar to the one of the unphosphorylated form, we observed a conformational transition from ordered to disordered structure in the linker region at the C-terminus of the mutant. Based on our structural and biochemical analyses, we suggest that phosphorylation at Ser183 of EFhd2 causes changes in the local conformational dynamics and the surface charge distribution of the actin-binding site, resulting in a re-coordination of the actin-binding sites in the dimer structure and a reduction of F-actin-bundling activity without affecting the F-actin-binding capacity.
Assuntos
Proteínas de Ligação ao Cálcio/química , Proteínas de Ligação ao Cálcio/metabolismo , Actinas/metabolismo , Sítios de Ligação , Proteínas de Ligação ao Cálcio/genética , Cristalografia por Raios X , Humanos , Modelos Moleculares , Mutação , Fosforilação , Conformação Proteica , Multimerização Proteica , Serina/metabolismoRESUMO
Intracellular membrane fusion requires not only SNARE proteins but also other regulatory proteins such as the Rab and Sec1/Munc18 (SM) family proteins. Although neuronal SNARE proteins alone can drive the fusion between synthetic liposomes, it remains unclear whether they are also sufficient to induce the fusion of biological membranes. Here, through the use of engineered yeast vacuoles bearing neuronal SNARE proteins, we show that neuronal SNAREs can induce membrane fusion between yeast vacuoles and that this fusion does not require the function of the Rab protein Ypt7p or the SM family protein Vps33p, both of which are essential for normal yeast vacuole fusion. Although excess vacuolar SNARE proteins were also shown to mediate Rab-bypass fusion, this fusion required homotypic fusion and vacuole protein sorting complex, which bears Vps33p and was accompanied by extensive membrane lysis. We also show that this neuronal SNARE-driven vacuole fusion can be stimulated by the neuronal SM protein Munc18 and blocked by botulinum neurotoxin serotype E, a well-known inhibitor of synaptic vesicle fusion. Taken together, our results suggest that neuronal SNARE proteins are sufficient to induce biological membrane fusion, and that this new assay can be used as a simple and complementary method for investigating synaptic vesicle fusion mechanisms.
Assuntos
Bioensaio/métodos , Fusão de Membrana/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Proteínas SNARE/metabolismo , Vacúolos/metabolismo , Animais , Toxinas Botulínicas , Proteínas Munc18/metabolismo , Células PC12 , Ratos , Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Proteínas rab de Ligação ao GTP/metabolismoRESUMO
Spinal muscular atrophy (SMA) is an autosomal recessive genetic disease, which causes death of motor neurons in the anterior horn of the spinal cord. Genetic cause of SMA is the deletion or mutation of SMN1 gene, which encodes the SMN protein. Although SMA patients include SMN2 gene, a duplicate of SMN1 gene, predominant production of exon 7 skipped isoform from SMN2 pre-mRNA, fails to rescue SMA patients. Here we show that hnRNP M, a member of hnRNP protein family, when knocked down, promotes exon 7 skipping of both SMN2 and SMN1 pre-mRNA. By contrast, overexpression of hnRNP M promotes exon 7 inclusion of both SMN2 and SMN1 pre-mRNA. Significantly, hnRNP M promotes exon 7 inclusion in SMA patient cells. Thus, we conclude that hnRNP M promotes exon 7 inclusion of both SMN1 and SMN2 pre-mRNA. We also demonstrate that hnRNP M contacts an enhancer on exon 7, which was previously shown to provide binding site for tra2ß. We present evidence that hnRNP M and tra2ß contact overlapped sequence on exon 7 but with slightly different RNA sequence requirements. In addition, hnRNP M promotes U2AF65 recruitment on the flanking intron of exon 7. We conclude that hnRNP M promotes exon 7 inclusion of SMN1 and SMN2 pre-mRNA through targeting an enhancer on exon 7 through recruiting U2AF65. Our results provide a clue that hnRNP M is a potential therapeutic target for SMA.
Assuntos
Elementos Facilitadores Genéticos/genética , Ribonucleoproteínas Nucleares Heterogêneas Grupo M/metabolismo , Atrofia Muscular Espinal/genética , Células do Corno Anterior/metabolismo , Células do Corno Anterior/patologia , Técnicas de Cultura de Células , Éxons/genética , Regulação da Expressão Gênica , Ribonucleoproteínas Nucleares Heterogêneas Grupo M/genética , Terapia de Alvo Molecular , Neurônios Motores/metabolismo , Neurônios Motores/patologia , Atrofia Muscular Espinal/etiologia , Atrofia Muscular Espinal/patologia , Proteínas do Tecido Nervoso/metabolismo , Proteínas Nucleares/metabolismo , Precursores de RNA/metabolismo , Proteínas de Ligação a RNA/metabolismo , Ribonucleoproteínas/metabolismo , Fatores de Processamento de Serina-Arginina , Medula Espinal/metabolismo , Medula Espinal/patologia , Fator de Processamento U2AF , Proteína 1 de Sobrevivência do Neurônio Motor/metabolismo , Proteína 2 de Sobrevivência do Neurônio Motor/genética , Proteína 2 de Sobrevivência do Neurônio Motor/metabolismoRESUMO
Katanin is a heterodimeric enzyme that severs and disassembles microtubules. While the p60 subunit has the enzyme activity, the p80 subunit regulates the p60 activity. The microtubule-severing activity of katanin plays an essential role in axonal growth. However, the mechanisms by which neuronal cells regulate the expression of katanin-p60 remains unknown. Here we showed that USP47 and C terminus of Hsp70-interacting protein (CHIP) antagonistically regulate the stability of katanin-p60 and thereby axonal growth. USP47 was identified as a katanin-p60-specific deubiquitinating enzyme for its stabilization. We also identified CHIP as a ubiquitin E3 ligase that promotes proteasome-mediated degradation of katanin-p60. Moreover, USP47 promoted axonal growth of cultured rat hippocampal neurons, whereas CHIP inhibited it. Significantly, treatment with basic fibroblast growth factor (bFGF), an inducer of axonal growth, increased the levels of USP47 and katanin-p60, but not CHIP. Consistently, bFGF treatment resulted in a marked decrease in the level of ubiquitinated katanin-p60 and thereby in the promotion of axonal growth. On the other hand, the level of USP47, but not CHIP, decreased concurrently with that of katanin-p60 as axons reached their target cells. These results indicate that USP47 plays a crucial role in the control of axonal growth during neuronal development by antagonizing CHIP-mediated katanin-p60 degradation.
Assuntos
Adenosina Trifosfatases/metabolismo , Axônios/fisiologia , Proteínas de Choque Térmico HSP47/metabolismo , Neurônios/citologia , Ubiquitina-Proteína Ligases/metabolismo , Adenosina Trifosfatases/genética , Animais , Células Cultivadas , Embrião de Mamíferos , Feminino , Fatores de Crescimento de Fibroblastos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Proteínas de Choque Térmico HSP47/genética , Hipocampo/citologia , Humanos , Imunoprecipitação , Katanina , Masculino , Camundongos , Ratos , Ratos Sprague-Dawley , Fatores de Tempo , Transfecção , Ubiquitina-Proteína Ligases/genética , Ubiquitinação/genéticaRESUMO
Myogenesis is regulated by the basic helix-loop-helix (bHLH) myogenic regulatory factor MyoD, which induces muscle-specific gene expression by binding to the E-box sequence as a heterodimer with ubiquitous bHLH E2A (E12/E47) proteins. Here, we report that a 31-kDa caspase-generated cleavage product of Crk-associated substrate (p130Cas), herein called 31-kDa, is downregulated during muscle cell differentiation. 31-kDa contains a helix-loop-helix (HLH) domain that shows greater sequence homology with Id (inhibitor of DNA binding) proteins than with bHLH proteins. This HLH domain, lacking the basic region required for DNA binding, mediated the direct interaction of 31-kDa with MyoD. Overexpression of 31-kDa in C3H10T1/2 cells inhibited not only the transcriptional activation of p21(Waf1/Cip1) and E-box-dependent muscle-specific genes by MyoD and/or E2A but also MyoD-induced myosin heavy chain expression and myogenic conversion. In sum, our results suggest a role for 31-kDa as a negative regulator of MyoD in the muscle differentiation program.
Assuntos
Caspases/metabolismo , Proteína Substrato Associada a Crk/metabolismo , Desenvolvimento Muscular , Proteína MyoD/metabolismo , Animais , Caspases/química , Caspases/genética , Linhagem Celular , Regulação para Baixo , Regulação da Expressão Gênica no Desenvolvimento , Sequências Hélice-Alça-Hélice , CamundongosRESUMO
HBx acts as a multifunctional regulator that modulates various cellular responses, which can lead to development and progression of hepatocellular carcinoma (HCC). Here, we show that the HBx protein is also localized to peroxisomes, and this increases cellular reactive oxygen species (ROS) to levels that are higher than when HBx is localized to other organelles. The elevated ROS strongly activated nuclear factor (NF)-κB. In addition, the peroxisome-localized HBx increased the expressions of matrix metalloproteinases and decreased the expression of E-cadherin, which increased the invasive ability of HCC cells. Thus, a specific distribution of HBx to peroxisomes may contribute to HCC progression by increasing the invasive ability of HCC cells through elevation of the cellular ROS level.
Assuntos
Carcinoma Hepatocelular/patologia , Neoplasias Hepáticas/patologia , Peroxissomos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transativadores/metabolismo , Caderinas/biossíntese , Linhagem Celular Tumoral , Transformação Celular Neoplásica/patologia , Progressão da Doença , Células HEK293 , Células Hep G2 , Hepatite B/virologia , Vírus da Hepatite B/patogenicidade , Humanos , Metaloproteinase 1 da Matriz/biossíntese , Metaloproteinase 1 da Matriz/genética , Metaloproteinase 7 da Matriz/biossíntese , Metaloproteinase 7 da Matriz/genética , Metaloproteinase 9 da Matriz/biossíntese , Metaloproteinase 9 da Matriz/genética , Potencial da Membrana Mitocondrial , Mitocôndrias/patologia , NF-kappa B/biossíntese , Invasividade Neoplásica , RNA Mensageiro/biossíntese , Proteínas Virais Reguladoras e AcessóriasRESUMO
Membrane protrusions, like lamellipodia, and cell movement are dependent on actin dynamics, which are regulated by a variety of actin-binding proteins acting cooperatively to reorganize actin filaments. Here, we provide evidence that Swiprosin-1, a newly identified actin-binding protein, modulates lamellipodial dynamics by regulating the accessibility of F-actin to cofilin. Overexpression of Swiprosin-1 increased lamellipodia formation in B16F10 melanoma cells, whereas knockdown of Swiprosin-1 inhibited EGF-induced lamellipodia formation, and led to a loss of actin stress fibers at the leading edges of cells but not in the cell cortex. Swiprosin-1 strongly facilitated the formation of entangled or clustered F-actin, which remodeled the structural organization of actin filaments making them in accessible to cofilin. EGF-induced phosphorylation of Swiprosin-1 at Ser183, a phosphorylation site newly identified using mass spectrometry, effectively inhibited clustering of actin filaments and permitted cofilin access to F-actin, resulting in actin depolymerization. Cells over expressing a Swiprosin-1 phosphorylation-mimicking mutant or a phosphorylation-deficient mutant exhibited irregular membrane dynamics during the protrusion and retraction cycles of lamellipodia. Taken together, these findings suggest that dynamic exchange of Swiprosin-1 phosphorylation and dephosphorylation is a novel mechanism that regulates actin dynamics by modulating the pattern of cofilin activity at the leading edges of cells.
Assuntos
Fatores de Despolimerização de Actina/metabolismo , Actinas/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas dos Microfilamentos/metabolismo , Animais , Membrana Celular/metabolismo , Fator de Crescimento Epidérmico/metabolismo , Humanos , Camundongos , Fosforilação , Serina/metabolismo , Transdução de Sinais , Células Tumorais CultivadasRESUMO
Actin plays a fundamental role in the regulation of spine morphology (both shrinkage and enlargement) upon synaptic activation. In particular, actin depolymerization is crucial for the spine shrinkage in NMDAR-mediated synaptic depression. Here, we define the role of SPIN90 phosphorylation/dephosphorylation in regulating actin depolymerization via modulation of cofilin activity. When neurons were treated with NMDA, SPIN90 was dephosphorylated by STEP61 (striatal-enriched protein tyrosine phosphatase) and translocated from the spines to the dendritic shafts. In addition, phosphorylated SPIN90 bound cofilin and then inhibited cofilin activity, suggesting that SPIN90 dephosphorylation is a prerequisite step for releasing cofilin so that cofilin can adequately sever actin filaments into monomeric form. We found that SPIN90 YE, a phosphomimetic mutant, remained in the spines after NMDAR activation where it bound cofilin, thereby effectively preventing actin depolymerization. This led to inhibition of the activity-dependent redistribution of cortactin and drebrin A, as well as of the morphological changes in the spines that underlie synaptic plasticity. These findings indicate that NMDA-induced SPIN90 dephosphorylation and translocation initiates cofilin-mediated actin dynamics and spine shrinkage within dendritic spines, thereby modulating synaptic activity.
Assuntos
Actinas/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Cofilina 1/metabolismo , Hipocampo/metabolismo , Proteínas Musculares/metabolismo , N-Metilaspartato/farmacologia , Neurônios/efeitos dos fármacos , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Espinhas Dendríticas/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HEK293 , Células HeLa , Humanos , Proteínas Musculares/genética , Mutação , Neurônios/metabolismo , Fosforilação/efeitos dos fármacos , Ligação Proteica , Proteínas Tirosina Fosfatases não Receptoras/metabolismo , Ratos , TransfecçãoRESUMO
PRECIS: Different mechanisms of angle closure represented distinct aspects of intraocular pressure (IOP) control after phacoemulsification. Classification of angle closure mechanisms is necessary for postoperative IOP management and glaucoma progression in primary angle closure eyes. PURPOSE: To investigate the relationship between the anterior chamber angle (ACA) characteristics, measured by swept-source anterior segment optical coherence tomography (SS AS-OCT), and intraocular pressure (IOP) control after phacoemulsification in eyes with primary angle closure disease (PACD) with different angle closure mechanisms. METHODS: PACD eyes were classified into 3 groups according to angle closure mechanisms using preoperative SS AS-OCT images; pupillary block (PB), plateau iris configuration (PIC), exaggerated lens vault (ELV). This retrospective, clinical cohort study included eighty-five eyes of 85 PACD patients: 34 with PB, 23 with PIC, and 28 with ELV. ACA parameters were measured preoperatively and 1 month postoperatively using SS AS-OCT. IOP measurements were performed preoperatively and during six months postoperatively. Postoperative IOP reduction and fluctuation were calculated, and their correlations with SS AS-OCT parameters were analyzed. RESULTS: PIC group showed the lowest postoperative IOP reduction compared to the other groups (P=0.023). Preoperative ACA measurements were significantly associated with postoperative IOP reduction in ELV and PB groups, while postoperative measurements were in PIC group. Preoperative and postoperative change of iridotrabecular contact (ITC) index and area were correlated with postoperative IOP reduction in PB and ELV groups but not in PIC group. Postoperative ITC index (P=0.031) and area (P=0.003) showed significant correlations with postoperative IOP fluctuation only in PIC group. CONCLUSIONS: SS AS-OCT parameters including ITC index and area showed different associations with postoperative IOP control, which should be considered in determination of lens extraction and treatment of PACD eyes.
RESUMO
PURPOSE: To investigate the association between the longitudinal changes in both macular vessel density (mVD) and macular ganglion cell-inner plexiform layer thickness (mGCIPLT) and visual field (VF) progression (including central VF progression) in open-angle glaucoma (OAG) patients with central visual field (CVF) damage at different glaucoma stages. DESIGN: Retrospective longitudinal study. PARTICIPANTS: This study enrolled 223 OAG eyes with CVF loss at baseline classified as early-to-moderate (133 eyes) or advanced (90 eyes) stage based on the VF mean deviation (MD) (-10 dB). METHODS: Serial mVDs at parafoveal and perifoveal sectors and mGCIPLT measurements were obtained using OCT angiography and OCT during a mean follow-up of 3.5 years. Visual field progression was determined using both the event- and trend-based analyses during follow-up. MAIN OUTCOME MEASURES: Linear mixed-effects models were used to compare the rates of change in each parameter between VF progressors and nonprogressors. Logistic regression analyses were performed to determine the risk factors for VF progression. RESULTS: In early-to-moderate stage, progressors showed significantly faster rates of change in the mGCIPLT (-1.02 vs. -0.47 µm/year), parafoveal (-1.12 vs. -0.40%/year), and perifoveal mVDs (-0.83 vs. -0.44%/year) than nonprogressors (all P < 0.05). In advanced stage cases, only the rates of change in mVDs (parafoveal: -1.47 vs. -0.44%/year; perifoveal: -1.04 vs. -0.27%/year; all P < 0.05) showed significant differences between the groups. By multivariable logistic regression analyses, the faster rate of mVD loss was a predictor of VF progression regardless of glaucoma stage, while the rate of mGCIPLT loss was significantly associated with VF progression only in early-to-moderate stage cases. CONCLUSIONS: Progressive mVD loss is significantly associated with VF progression (including central VF progression) in the OAG eyes with CVF loss regardless of the glaucoma stage. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Assuntos
Glaucoma de Ângulo Aberto , Glaucoma , Humanos , Glaucoma de Ângulo Aberto/complicações , Glaucoma de Ângulo Aberto/diagnóstico , Campos Visuais , Estudos Retrospectivos , Estudos Longitudinais , Testes de Campo Visual , Pressão Intraocular , Fibras Nervosas , Tomografia de Coerência Óptica , Células Ganglionares da RetinaRESUMO
OBJECTIVES: To evaluate the clinical utility of trend-based analysis of the targeted mean total deviation (TMTD) by comparing its rates of visual field (VF) change and sensitivities of detecting VF progression with those of the mean total deviation (mTD) in the global and hemifield VF area in early to-moderate glaucoma patients. METHODS: A single eye from 139 open-angle glaucoma patients with hemifield VF defects and a minimum two year follow-up were retrospectively evaluated. The TMTD was estimated by averaging the total deviation (TD) values after excluding VF points that had a threshold sensitivity of <0 dB in three baseline tests, and the mTD by averaging the entire VF TD values. The study patients were classified as VF progressors vs. non-progressors using both event- and trend-based analysis. The rates of change and ratios of progression detection were compared between TMTD and mTD. RESULTS: This study included 49 VF progressors and 90 non-progressors. Slopes for the global and VF-affected hemifield TMTD were significantly faster than those for the mTD in each subgroup and in the entire cohort (P < 0.001). Trend-based TMTD analysis detected VF progression in greater proportion than either trend-based mTD or event-based analysis (38.1% vs. 30.2% vs. 27.3%, respectively: VF affected hemifields). CONCLUSIONS: The rates of change in the TMTD are significantly faster than those for the mTD globally and in the VF-affected hemifields. Trend-based TMTD analysis shows greater sensitivity for detecting VF progression than trend-based mTD or event-based analysis in early-to-moderate glaucoma patients with hemifield VF loss.
Assuntos
Glaucoma de Ângulo Aberto , Glaucoma , Humanos , Campos Visuais , Glaucoma de Ângulo Aberto/diagnóstico , Estudos Retrospectivos , Tiram , Glaucoma/diagnóstico , Testes de Campo Visual , Transtornos da Visão/diagnóstico , Pressão Intraocular , Progressão da DoençaRESUMO
PURPOSE: To investigate the predictive capabilities of peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) thinning to detect visual field (VF) progression in normal-tension glaucoma patients with an initial parafoveal scotoma (IPFS) or nasal step (INS). DESIGN: Retrospective cohort study. METHODS: A total of 185 early-stage glaucoma eyes, followed for 10 years, were retrospectively stratified into IPFS and INS groups. Progressive pRNFL and mGCIPL thinning were assessed using spectral-domain optical coherence tomography and VF progression using both event- or trend-based analysis. Kaplan-Meier survival analysis compared VF survival in each VF phenotype with or without progressive pRNFL and mGCIPL thinning. Cox proportional regression analysis identified VF progression factors. RESULTS: VF progression was detected in 42 IPFS (n = 86) and 47 INS (n = 99) eyes. Among VF progressors, pRNFL thinning was significantly faster in INS group compared to IPFS group (P < .01), while mGCIPL thinning was similar (P = .16). At 5 years, eyes with progressive mGCIPL thinning showed significantly lower VF survival in both VF phenotypes (all P < .05). Progressive pRNFL thinning showed significantly lower VF survival only in INS eyes (P = .015). Cox multivariate regression revealed that mGCIPL thinning predicted subsequent VF progression in IPFS eyes, while mGCIPL and pRNFL thinning had significant associations with VF progression in INS eyes. CONCLUSIONS: mGCIPL outperforms pRNFL at early follow-up in detecting VF progression in IPFS eyes but not INS eyes. Appropriate selection of structural parameters (mGCIPL vs. pRNFL) maximizes early VF progression detection according to initial VF defect location.
RESUMO
Purpose: This study investigated the global and regional correlations between longitudinal structure-function (S-F) and vasculature-function (V-F) data using circumpapillary retinal nerve fiber layer thickness (cpRNFLT) measurements from optical coherence tomography (OCT), circumpapillary vessel density (cpVD) from OCT angiography (OCTA), and the corresponding visual field mean sensitivities at different glaucoma stages. Methods: A total of 107 eyes from 107 glaucoma patients with progressive visual field (VF) changes followed up for an average of 3.33 ± 1.39 years were enrolled, including early-to-moderate (51 eyes) and advanced (56 eyes) stages. The rates of longitudinal change in the VF mean deviation (MD), cpRNFLT, and cpVD were evaluated using linear mixed-effects models and compared between different glaucoma stages. Longitudinal global and regional S-F and V-F relationships were assessed by repeated measures correlation analysis by glaucoma stage. Results: No significant differences were found in the rates of VF MD and cpVD changes (P > 0.05) between the two glaucoma stage groups. CpRNFLT decreased more rapidly in the early-to-moderate stage group (P < 0.001) in which significant longitudinal global and regional correlations were found in both S-F and V-F relationships (all P < 0.05), except for the nasal sector. Significant global and regional correlations were only found in V-F relationship in advanced stage cases (all P < 0.05). Conclusions: Significant longitudinal V-F relationships exist globally and regionally regardless of glaucoma stage but no longitudinal S-F relationship is present in advanced glaucoma. Longitudinal follow-up of cpVD parameters may be useful for monitoring glaucomatous VF progression at all disease stages.