RESUMO
This work analyzes the role of the tight junction (TJ) protein ZO-2 on mechanosensation. We found that the lack of ZO-2 reduced apical membrane rigidity measured with atomic force microscopy, inhibited the association of γ-actin and JAM-A to the cell border, and instead facilitated p114RhoGEF and afadin accumulation at the junction, leading to an enhanced mechanical tension at the TJ measured by FRET, with a ZO-1 tension probe, and increased tricellular TJ tension. Simultaneously, adherens junction tension measured with an E-cadherin probe was unaltered. The stability of JAM-A and ZO-2 binding was assessed by a collaborative in silico study. The absence of ZO-2 also impacted the cell response to the substrate, as monolayers plated in 20 kPa hydrogels developed holes not seen in parental cultures and displayed a retarded elongation and formation of cell aggregates. The absence of ZO-2 was sufficient to induce YAP and Snail nuclear accumulation in cells cultured over glass, but when ZO-2 KD cells were plated in nanostructured ridge arrays, they displayed an increased abundance of nuclear Snail and conspicuous internalization of claudin-4. These results indicate that the absence of ZO-2 also impairs the response of cells to substrate stiffness and exacerbates transformation triggered by substrate topography.
Assuntos
Actinas , Junções Íntimas , Actinas/metabolismo , Junções Íntimas/metabolismo , Proteína da Zônula de Oclusão-1/metabolismo , Fosfoproteínas/metabolismoRESUMO
Tight junctions (TJs) regulate the transit of ions and molecules through the paracellular pathway in epithelial cells. Zonula occludens 2 (ZO-2) is a cytoplasmic TJ protein. Here, we studied the ubiquitination of hZO-2 employing mutants of SUMOylation site K730 present in the GuK domain and the putative ubiquitination residues K759 and K992 located at the GuK domain and proline-rich region, respectively. In immunoprecipitation experiments done with MDCK cells transfected with wild-type (WT) hZO-2 or the ubiquitination-site mutants hZO-2-K759R or -K992R, we observed diminished ubiquitination of the mutants, indicating that residues K759 and K992 in hZO-2 are acceptors for ubiquitination. Moreover, using TUBES, we found that residues K759 and K992 of hZO-2 are targets of K48 polyubiquitination, a signal for proteasomal degradation. Accordingly, compared to WT hZO-2, the half-life of hZO-2 mutants K759R and K992R augmented from 19.9 to 37.3 and 23.3 h, respectively. Instead, the ubiquitination of hZO-2 mutant K730R increased, and its half-life diminished to 6.7 h. The lack of these lysine residues in hZO-2 affects TJ sealing as the peak of TER decreased in monolayers of MDCK cells transfected with any of these mutants. These results highlight the importance of ZO-2 ubiquitination and SUMOylation to maintain a healthy and stable pool of ZO-2 molecules at the TJ.
Assuntos
Sumoilação , Junções Íntimas , Proteína da Zônula de Oclusão-2/metabolismo , Junções Íntimas/metabolismo , Proteína da Zônula de Oclusão-1/genética , Proteína da Zônula de Oclusão-1/metabolismo , Lisina/metabolismo , Fosfoproteínas/metabolismo , Linhagem Celular , Prolina/metabolismoRESUMO
Tight junctions (TJs) are cellcell adhesion structures frequently altered by oncogenic transformation. In the present study the role of human papillomavirus (HPV) 16 E7 oncoprotein on the sealing of TJs was investigated and also the expression level of claudins in mouse cervix and in epithelial MadinDarby Canine Kidney (MDCK) cells. It was found that there was reduced expression of claudins 1 and 10 in the cervix of 7monthold transgenic K14E7 mice treated with 17ßestradiol (E2), with invasive cancer. In addition, there was also a transient increase in claudin1 expression in the cervix of 2monthold K14E7 mice, and claudin10 accumulated at the border of cells in the upper layer of the cervix in FvB mice treated with E2, and in K14E7 mice treated with or without E2. These changes were accompanied by an augmented paracellular permeability of the cervix in 2 and 7monthold FvB mice treated with E2, which became more pronounced in K14E7 mice treated with or without E2. In MDCK cells the stable expression of E7 increased the space between adjacent cells and altered the architecture of the monolayers, induced the development of an acute peak of transepithelial electrical resistance accompanied by a reduced expression of claudins 1, 2 and 10, and an increase in claudin4. Moreover, E7 enhances the ability of MDCK cells to migrate through a 3D matrix and induces cell stiffening and stress fiber formation. These observations revealed that cell transformation induced by HPV16 E7 oncoprotein was accompanied by changes in the pattern of expression of claudins and the degree of sealing of epithelial TJs.
Assuntos
Claudinas/biossíntese , Papillomavirus Humano 16/metabolismo , Proteínas E7 de Papillomavirus/metabolismo , Infecções por Papillomavirus/metabolismo , Junções Íntimas/metabolismo , Neoplasias do Colo do Útero/virologia , Animais , Células Cultivadas , Claudinas/genética , Claudinas/metabolismo , Modelos Animais de Doenças , Cães , Feminino , Papillomavirus Humano 16/isolamento & purificação , Humanos , Camundongos , Camundongos Transgênicos , Infecções por Papillomavirus/patologia , Infecções por Papillomavirus/virologia , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/patologiaRESUMO
The cytotrophoblast of human placenta transitions into an outer multinucleated syncytiotrophoblast (STB) layer that covers chorionic villi which are in contact with maternal blood in the intervillous space. During pregnancy, the Zika virus (ZIKV) poses a serious prenatal threat. STB cells are resistant to ZIKV infections, yet placental cells within the mesenchyme of chorionic villi are targets of ZIKV infection. We seek to determine whether ZIKV can open the paracellular pathway of STB cells. This route is regulated by tight junctions (TJs) which are present in the uppermost portion of the lateral membranes of STB cells. We analyzed the paracellular permeability and expression of E-cadherin, occludin, JAMs -B and -C, claudins -1, -3, -4, -5 and -7, and ZO-1, and ZO-2 in the STB of placentae from ZIKV-infected and non-infected women. In ZIKV-infected placentae, the pattern of expression of TJ proteins was preserved, but the amount of claudin-4 diminished. Placentae from ZIKV-infected women were permeable to ruthenium red, and had chorionic villi with a higher mean diameter and Hofbauer hyperplasia. Finally, ZIKV added to the basolateral surface of a trophoblast cell line reduced the transepithelial electrical resistance. These results suggest that ZIKV can open the paracellular pathway of STB cells.
Assuntos
Biomarcadores/metabolismo , Complicações Infecciosas na Gravidez/virologia , Proteínas de Junções Íntimas/metabolismo , Junções Íntimas/metabolismo , Trofoblastos/metabolismo , Infecção por Zika virus/metabolismo , Adulto , Linhagem Celular , Feminino , Humanos , Recém-Nascido , Permeabilidade , Gravidez , Trofoblastos/patologiaRESUMO
Zonula occludens-2 (ZO-2) is a tight junction (TJ) cytoplasmic protein, whose localization varies according to cell density and Ca2+ in the media. In cells cultured in low calcium (LC), ZO-2 displays a diffuse cytoplasmic distribution, but activation of the Ca2+ sensing receptor (CaSR) with Gd3+ triggers the appearance of ZO-2 at the cell borders. CaSR downstream signaling involves activation of protein kinase C, which phosphorylates and activates with no lysine kinase-4 that phosphorylates ZO-2 inducing its concentration at TJs. In LC, ZO-2 is protected from degradation by association to 14-3-3 proteins. When monolayers are transferred to normal calcium, the complexes ZO-2/14-3-3ζ and ZO-2/14-3-3σ move to the cell borders and dissociate. The 14-3-3 proteins are then degraded in proteosomes, whereas ZO-2 integrates to TJs. From the plasma membrane residual ZO-2 is endocyted and degradaded in lysosomes. The unique region 2 of ZO-2, and S261 located within a nuclear localization signal, are critical for the interaction with 14-3-3 ζ and σ and for the efficient nuclear importation of ZO-2. These results explain the molecular mechanism through which extracellular Ca2+ triggers the appearance of ZO-2 at TJs in epithelial cells and reveal the novel interaction between ZO-2 and 14-3-3 proteins, which is critical for ZO-2 protection and intracellular traffic.
Assuntos
Proteínas 14-3-3/metabolismo , Junções Íntimas/metabolismo , Proteína da Zônula de Oclusão-2/metabolismo , Animais , Cálcio/metabolismo , Linhagem Celular , Membrana Celular/metabolismo , Proliferação de Células , Cães , Células Epiteliais/metabolismo , Células Madin Darby de Rim Canino , Fosfoproteínas/metabolismo , Fosforilação , Proteína Quinase C/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Detecção de Cálcio/metabolismo , Células Receptoras Sensoriais/metabolismo , Transdução de Sinais , Proteína da Zônula de Oclusão-1/metabolismoRESUMO
Methamidophos (MET) is an organophosphate (OP) pesticide widely used in agriculture in developing countries. MET causes adverse effects in male reproductive function in humans and experimental animals, but the underlying mechanisms remain largely unknown. We explored the effect of MET on mice testes (5â¯mg/kg/day/4â¯days), finding that this pesticide opens the blood-testis barrier and perturbs spermatogenesis, generating the appearance of immature germ cells in the epididymis. In the seminiferous tubules, MET treatment changed the level of expression or modified the stage-specific localization of tight junction (TJ) proteins ZO-1, ZO-2, occludin, and claudin-3. In contrast, claudin-11 was barely altered. MET also modified the shape of claudin-11, and ZO-2 at the cell border, from a zigzag to a more linear pattern. In addition, MET diminished the expression of ZO-2 in spermatids present in seminiferous tubules, induced the phosphorylation of ZO-2 and occludin in testes and reduced the interaction between these proteins assessed by co-immunoprecipitation. MET formed covalent bonds with ZO-2 in serine, tyrosine and lysine residues. The covalent modifications formed on ZO-2 at putative phosphorylation sites might interfere with ZO-2 interaction with regulatory molecules and other TJ proteins. MET bonds formed at ZO-2 ubiquitination sites likely interfere with ZO-2 degradation and TJ sealing, based on results obtained in cultured epithelial cells transfected with ZO-2 mutated at a MET target lysine residue. Our results shed light on MET male reproductive toxicity and are important to improve regulations regarding the use of OP pesticides and to protect the health of agricultural workers.
Assuntos
Barreira Hematotesticular/efeitos dos fármacos , Inseticidas/farmacologia , Organofosfatos/farmacologia , Compostos Organotiofosforados/farmacologia , Proteína da Zônula de Oclusão-2/metabolismo , Animais , Barreira Hematotesticular/metabolismo , Claudinas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos ICR , Ocludina/metabolismo , Fosfoproteínas/metabolismo , Fosforilação/efeitos dos fármacos , Túbulos Seminíferos/efeitos dos fármacos , Túbulos Seminíferos/metabolismo , Espermatogênese/efeitos dos fármacos , Junções Íntimas/efeitos dos fármacos , Junções Íntimas/metabolismo , Proteína da Zônula de Oclusão-1/metabolismoRESUMO
Silencing Zonula occludens 2 (ZO-2), a tight junctions (TJ) scaffold protein, in epithelial cells (MDCK ZO-2 KD) triggers: 1) Decreased cell to substratum attachment, accompanied by reduced expression of claudin-7 and integrin ß1, and increased vinculin recruitment to focal adhesions and stress fibers formation; 2) Lowered cell-cell aggregation and appearance of wider intercellular spaces; 3) Increased RhoA/ROCK activity, mediated by GEF-HI recruitment to cell borders by cingulin; 4) Increased Cdc42 activity, mitotic spindle disorientation and the appearance of cysts with multiple lumens; 5) Increased Rac and cofilin activity, multiple lamellipodia formation and random cell migration but increased wound closure; 6) Diminished cingulin phosphorylation and disappearance of planar network of microtubules at the TJ region; and 7) Increased transepithelial electrical resistance at steady state, coupled to an increased expression of ZO-1 and claudin-4 and a decreased expression of claudin-2 and paracingulin. Hence, ZO-2 is a crucial regulator of Rho proteins activity and the development of epithelial cytoarchitecture and barrier function.
Assuntos
Junções Íntimas/metabolismo , Proteína da Zônula de Oclusão-1/genética , Proteína da Zônula de Oclusão-2/genética , Proteínas rac1 de Ligação ao GTP/genética , Proteína rhoA de Ligação ao GTP/genética , Animais , Claudina-2/metabolismo , Claudina-4/genética , Claudina-4/metabolismo , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Cães , Células Epiteliais/metabolismo , Humanos , Células Madin Darby de Rim Canino , Fosforilação , Junções Íntimas/genética , TransfecçãoRESUMO
Introducción: la notificación de reacciones adversas a medicamentos es una obligación a nivel mundial. Aunque se han establecido muchas metodologías para esta acción, en la actualidad existen problemas. Objetivo: determinar la frecuencia de sospecha de reacciones adversas a la administración de medicamentos en pacientes y comparar la accesibilidad del llenado del formato de la NOM220 de la Secretaría de Salud y la Tarjeta Amarilla propuesta por la Organización Mundial de la Salud. Métodos: estudio transversal y observacional. Participaron 50 médicos responsables de las clínicas de diabetes del Estado de Hidalgo. Inicialmente, los médicos fueron capacitados para identificar las sospechas de reacciones adversas a la administración de medicamentos en los pacientes atendidos. Se realizó un diseño cruzado, en el que el 50 por ciento de los médicos utilizaron por tres meses el formato de la NOM220 y 50 por ciento la Tarjeta Amarilla. Después intercambiaron formatos y los utilizaron durante los tres meses siguientes. Al cabo de este periodo, respondieron un cuestionario para determinar la utilidad, claridad, tiempo de llenado y practicidad de ambos formatos. Se realizó estadística descriptiva y análisis bivariado para determinar los factores asociados a las sospecha de reacciones adversas a medicamentos, con el software SPSS (versión 17). Resultados: se registraron 46 sospechas de reacciones adversas a medicamentos en 46 pacientes con el formato de la NOM220 y 78 sospechas de reacciones adversas a medicamentos con la Tarjeta Amarilla en 78 pacientes. Todas las sospechas de reacciones adversas a la administración de medicamentos fueron tipo A. Los médicos recomiendan la utilización de la Tarjeta Amarilla, consideran claro el formato, sencillo, legible, fácil de llenar, entendible y accesible (p< 0,05). Conclusiones: los resultados permiten proponer la Tarjeta Amarilla como una alternativa más accesible para la notificación de sospechas de reacciones adversas a medicamentos, o se hagan adecuaciones al formato de la NOM220(AU)
Introduction: the reporting of adverse drug reactions is a global obligation. Although many methods have been implemented, there are still problems at present. Objective: to determine the frequency of suspected adverse reactions in patients and to compare the access to filling out the NOM220 formats of the Secretaría de Salud and the Yellow Card suggested by the World Health Organization. Methods: a cross-sectional and observational study was made. Fifty physicians responsible for the diabetes clinics in the state of Hidalgo participated in the study. First, the physicians were trained to identify the suspected adverse drug reactions in their patients. A crossover design was created where 50 percent of physicians used the NOM220 format and 50 percent the Yellow Card. Three months later, they exchanged the formats and used them during the following three months. After this period, questionnaire was administered to determine the usefulness, clarity, filling out time and convenience of the formats. Descriptive statistics and bivariate analyses were applied to determine the factors associated with the suspected adverse drug reactions with SPSS software (version 17). Results: a total of 46 suspected adverse reactions were registered in 46 patients using NOM220 format and 78 with the Yellow Card in 78 patients. All the suspected adverse reactions were type A. The physicians recommended the use of Yellow Card since they considered that it is practical, simple, readable, understandable, accessible and requires less time to fill it out (p< 0.05). Conclusions: the results allow selecting the Yellow Card as the most accessible choice for reporting suspected drug adverse reactions; additionally, they suggest that adjustments should be also made in the NOM220 format(AU)
Assuntos
Humanos , Animais , Masculino , Diabetes Mellitus/etnologia , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/epidemiologia , Farmacovigilância , Estudos Transversais , Estudos Prospectivos , Estudo Observacional , MéxicoRESUMO
The aim of this study was to compare the efficacy of diclofenac, for the treatment of acute pain originated by lower-limb fracture and surgery, with that of diclofenac plus B vitamins. This was a single-center, prospective, randomized, and double-blinded clinical trial. Patients with lower-limb closed fractures rated their pain on a 10 cm visual analog scale (VAS). Patients were then randomized to receive diclofenac or diclofenac plus B vitamins (thiamine, pyridoxine, and cyanocobalamin) intramuscularly twice daily. Patient evaluations of pain intensity were recorded throughout two periods: twenty-four hours presurgery and twenty-four hours postsurgical. One hundred twenty-two patients completed the study. The subjects' assessments of limb pain on the VAS showed a significant reduction from baseline values regardless of the treatment group. Diclofenac plus B vitamins combination was more effective to reduce the pain than diclofenac alone. The results showed that the addition of B vitamins to diclofenac increased its analgesic effect. The novelty of this paper consists in that diclofenac and diclofenac plus B vitamins were useful for treatment of acute pain originated by lower-limb fracture and surgery.
RESUMO
With the aim of discovering new molecular interactions of the tight junction protein ZO-2, a two-hybrid screen was performed on a human kidney cDNA library using as bait the middle segment of ZO-2. Through this assay we identified a 24-kDa novel protein herein named ZASP for ZO-2 associated speckle protein. ZO-2/ZASP interaction further confirmed by pull down and immunoprecipitation experiments, requires the presence of the intact PDZ binding motif SQV of ZASP and the third PDZ domain of ZO-2. ZASP mRNA and protein are present in the kidney and in several epithelial cell lines. Endogenous ZASP is expressed primarily in nuclear speckles in co-localization with splicing factor SC-35. Nocodazole treatment and wash out reveals that ZASP disappears from the nucleus during mitosis in accordance with speckle disassembly during metaphase. ZASP amino acid sequence exhibits a canonical nuclear exportation signal and in agreement the protein exits the nucleus through a process mediated by exportin/CRM1. ZASP over-expression blocks the inhibitory activity of ZO-2 on cyclin D1 gene transcription and protein expression. The identification of ZASP helps to unfold the complex nuclear molecular arrays that form on ZO-2 scaffolds.