ABSTRACT
Retinal pigment epithelium (RPE) is composed of a layer of highly specialized hexagonal pigment epithelial cells.The apical surface of RPE interacts with the photoreceptor, and RPE basal surface interacts with Bruch membrane and choroidal capillaries to maintain the function of retinal photoreceptor.A variety of junction proteins distributed between RPE cells are the basis for RPE to perform normal functions, ensuring the integrity and physiological function of RPE.Under pathological conditions, the abnormal function of RPE is first manifested by the abnormal junctional protein, which leads to the loss of adhesion between cells, cells and basement membrane, and then a series of abnormal biological behaviors, such as dissociation, migration, transdifferentiation and protein expression changes in RPE cells, which have become an important cause of many fundus diseases.The role of RPE junctional complexes during normal and pathological conditions, as well as their role in proliferative vitreoretinopathy, age-related macular degeneration and diabetic vitreoretinopathy was reviewed in this article from the composition and correlation of junctional proteins between RPE cells.
ABSTRACT
Durante a foliculogênese em mamíferos, ocorre um longo e complexo processo no qual o oócito adquire a competência necessária para a fecundação. Nesse processo ocorre uma comunicação metabólica bidirecional entre os oócitos e as células somáticas dentro do folículo que garante substratos para o oócito em desenvolvimento. Essa comunicação é mediada pelas junções celulares (junções comunicantes e junções aderentes) presentes nas projeções transzonais. As junções celulares e moléculas de adesão são responsáveis principalmente por promover a adesão entre as células foliculares; mas podem atuar em vias de sinalização celular e na regulação da transcrição gênica nas células somáticas e oócitos. Além disso, as junções comunicantes (junções gap) são canais intermembranares que intermediam a comunicação entre essas células através da passagem de pequenas moléculas. Essas junções comunicantes são compostas por proteínas denominadas conexinas; as conexinas 37 e 43 são as predominantes nos folículos ovarianos. Dessa forma, o conhecimento acerca das junções celulares é de extrema importância para o estudo da foliculogênese. A presente revisão teve como objetivo abordar os principais tipos de junções celulares existentes entre as células foliculares, com destaque para as junções gap e as principais proteínas de membranas (conexinas) presentes nos diferentes estágios do desenvolvimento folicular.
During the mammalian folliculogenesis, a long and complex process occurs, which the oocyte acquires the necessary competence for fecundation. In this process there is a metabolic bidirectional communication among the oocyte and somatic cells inside the follicle, which provides substrates for the oocyte developmental competence. This communication is mediated by cellular junctions (occlusions, adherens and gap junctions) localized in the transzonal projections. Cellular junctions and adhesion mollecules are responsable mainly for promoving the adhesion among follicular cells, however they can act in cellular signaling pathways and in regulation of genic transcription in the follicular cells and oocyte. Moreover, the communication junctions (gap junctions) are intermembrane channels that intermediate the communication among these cells through the passage of small molecules. These gap junctions are composed by connexins, of which the connexins 37 and 43 are the most frequently found in the ovarian follicle. Thus, knowledge of these cellular junctions are of great importance for studying the folliculogenesis process. The aim of this review was to report the main types of cellular junctions localized among the follicular cells, especially the gap junctions and the main membrane proteins (connexins) found in different stages of the follicular development.
Subject(s)
Humans , Gap Junctions , Intercellular Junctions , Ovarian Follicle , OvaryABSTRACT
Tunneling nanotubes (TNT) is a newly discovered connection mode between animal cells, and its formation is of great importance in physiological and pathological processes of animals and humans. The forming conditions and the promoting mechanism of TNT are not fully understood yet. It has been known that the state of cells (such as inflammatory conditions and stress reaction), molecular level (Fas ligand, cell adhesion molecules and the ligand interactions, M-Sec/TNFaip2/B94 and lipid molecules), and pathogenic infection are important for the formation of TNT. In this paper we reviewed the promoting mechanisms for TNT formation.
ABSTRACT
Tight junctions (TJs) form continuous intercellular contacts in intercellular junctions. TJs involve integral proteins such as occludin (OCLN) and claudins (CLDNs) as well as peripheral proteins such as zona occludens-1 (ZO-1) and junctional adhesion molecules (JAMs). TJs control paracellular transportation across cell-to-cell junctions. Although TJs have been studied for several decades, comparison of the transcriptional-translational levels of these molecules in canine organs has not yet been performed. In this study, we examined uterine expression of CLDNs, OCLN, junction adhesion molecule-A, and ZO-1 in canine. Expression levels of canine uterine TJ proteins, including CLDN1, 2, 4, 5, JAM-A, ZO-1, and OCLN, were measured using reverse transcription PCR, real-time PCR, and Western blotting, whereas TJs distribution was determined by immunohistochemistry. The mRNA and protein expression levels of OCLN, CLDN-1, 4, JAM-1, and ZO-1 were identified in the uterus. Immunohistochemistry demonstrated that TJs were localized to the endometrium and/or myometrium of the uterus. Our results show that canine TJ proteins, including CLDNs, OCLN, JAM-A, and ZO-1, were expressed in the canine uterus. Taken together, these proteins may perform unique physiological roles in the uterus. Therefore, these findings may serve as a basis for further studies on TJ proteins and their roles in the physiological or pathological condition of the canine uterus.
Subject(s)
Animals , Dogs , Female , Mice , Blotting, Western , Claudins , Endometrium , Herpes Zoster , Immunohistochemistry , Intercellular Junctions , Junctional Adhesion Molecules , Myometrium , Occludin , Physiology , Polymerase Chain Reaction , Real-Time Polymerase Chain Reaction , Reverse Transcription , RNA, Messenger , Tight Junctions , Transportation , UterusABSTRACT
A matriz extracelular foi considerada por muito tempo uma estrutura inerte constituída por várias proteínas e polissacarídeos sintetizados e secretados pelas células para o preenchimento do espaço extracelular. Atualmente sabe-se que, além de auxiliar na ligação das células para a formação dos tecidos, a matriz extracelular tem papel importante no controle do crescimento e na diferenciação celular e, nessa interação, moléculas como proteoglicanos, glicosaminoglicanos, proteases e glicosidases desencadeam eventos de sinalização celular. Os proteoglicanos presentes na matriz extracelular realizam importantes funções, dentre elas, regulação da atividade de moléculas sinalizadoras, controle do tráfego de células e moléculas, atuação como coreceptorese interação com proteínas fibrosas da matriz. Esta revisão tem enfoque nas características estruturais da matriz extracelular, de proteoglicanose do papel fundamental das interações celulares.
The extracellular matrix was considered for a long time as an inert structure consisting of various proteins and polysaccharides synthesized and secreted by cells to fill the extracellular space. Currently it is known that, in addition to helping cells connection for the tissue formation, theextracellular matrix has an important role in the growth control and in the cellular differentiation, and in this interaction, some molecules like theproteoglycans, glycosaminoglycans, proteases, and glycosidases may trigger cellular signaling events. Proteoglycans present in the extracellularmatrix perform important functions, such as: control of signaling molecules, the transit control of cells and molecules, co-receptors action and interaction with matrix fibrous proteins. This review is focused on the structural characteristics of extracellular matrix, of proteoglycans and of the fundamental role of cellular interactions.