[en] Articular cartilage is a tissue that covers the surfaces of articular bones allowing the painless movement of the skeleton. Articular chondrocytes are the cells responsible for the synthesis and maintenance of cartilage during adult life. Osteoarthritis is characterized for the progressive degeneration of cartilage. Chondrocytes communicate each other through channels formed by connexin 43 (Cx43) called Gap Junctions (GJs). The presence of functional GJs channels might be essential to the maintenance of the homeostasis and proper functioning of the tissue by modulating the cell-cell and cell-matrix communication. Moreover, Cx43 has multiple functions independently of the activity of channels, and the overexpression of Cx43 was correlated with the degeneration of the extracellular matrix of articular cartilage. In this research work we have decided to investigate the functions of Cx43 in chondrocytes from healthy and osteoarthritic donors, with the goal of finding some functional impairment that might explain the change in the phenotype that it is observed in osteoarthritic chondrocytes. For this purpose, we have designed (i) a vector containing a siRNA sequence in order to reduce the Cx43 expression, and (ii) a vector to overexpress Cx43. We will investigate the role of Cx43 in gene expression, cell growth, proliferation and phenotype. Furthermore, we have also decided to study the effect of the glycosylation of glycoproteins, including Cx43, presented in the cartilage and in the membrane of chondrocytes, and related with cell adhesion and cell communication. We have used a lectin called MASL that specifically binds to terminal residues of α-2, 3 sialic acid, modification that has been previously associated with the development of osteoarthritis and rheumatoid arthritis. The results presented here show that nanomolar concentrations of MASL can preserve cartilage structure when cartilage or primary chondrocytes are treated with oligomycin, which triggers the extracellular matrix degradation through the increase of inflammatory cytokines or metalloproteinase.

[gl] A cartilaxe articular é un tecido que recobre a superficie dos ósos nas articulacións e permite o movemento do esqueleto sen que se produza dor ou rozamento entre as superficies óseas. Os condrócitos articulares son as células responsables do mantemento da cartilaxe durante a vida adulta. A artrose caracterízase pola dexeneración progresiva da cartilaxe articular. Os condrócitos comunícanse entre sí a través dos canais formados por conexina 43 (Cx43) e denominados Gap Junctions (GJs). A actividade e presencia destos canais podrían ser esenciais para manter a homeostase e correcto funcionamento do tecido modulando a comunicación célula-célula e célula-matriz. Ademáis, a Cx43 posúe múltiples funcións independentes da actividade dos canais, e a sobreexpresión de Cx43 correlacionouse coa dexeneración da matriz extracelular da cartilaxe articular. Neste traballo de Mestrado decidimos investigar as funcións da Cx43 en condrócitos de donantes sáns e artrósicos, co obxectivo de encontrar algunha alteración funcional que poida explicar o cambio de fenotipo celular que ocorre nos condrócitos dos pacientes que sofren artrose. Para levalo a cabo, deseñamos un vector que contén a secuencia de siRNA para disminuir a expresión da Cx43 e un segundo vector para sobreexpresar este xene, poidendo estudar desta maneira os efectos da Cx43 na expresión xénica, proliferación e fenotipo celular. Por outro lado, tamén decidimos estudar o efecto da glicosilación de proteínas, incluida a Cx43 de proteínas, incluida a Cx43, presentes na cartilaxe e na membrana dos condrócitos e implicadas en adhesión e comunicación celular. Para facelo utilizamos a lectina chamada MASL que se une específicamente a residuos termináis de ácido siálico α-2,3, modificación que foi relacionada co desenvolvemento da artrose e artrite reumatoide. Os resultados obtidos demostran que concentracións nanomolares de MASL protexen a estructura e composición da cartilaxe fronte a un dano que da lugar a unha degradación da matriz extracelular por incremento de mediadores proinflamatorios ou metaloproteasas.