RESUMO
Entamoeba histolytica trophozoites do interact with extracellular matrix components in order to invade and finally destroy tissue. An important step in this interaction involves the binding of a 140-kDa membrane protein that binds to fibronectin. The similarity of this amoebic receptor to fibronectin receptors from higher eukaryotic cells was defined by indirect immunofluorescence, western blot and immunohistochemistry, using polyclonal monospecific antibodies raised against the amoebic protein. These results suggest that lower eukaryotic cells have and use a beta 1 integrin-like molecule as well as mechanisms similar to those present in higher eukaryotic cells during interaction with extracellular matrix components.
Assuntos
Entamoeba histolytica/imunologia , Integrina beta1/análise , Proteínas de Membrana/análise , Proteínas de Protozoários/análise , Receptores de Fibronectina/análise , Animais , Anticorpos Antiprotozoários , Antígenos de Protozoários/imunologia , Western Blotting , Embrião de Galinha , Cricetinae , Entamoeba histolytica/crescimento & desenvolvimento , Entamoeba histolytica/patogenicidade , Fibroblastos , Técnica Indireta de Fluorescência para Anticorpo , Cobaias , Imuno-Histoquímica , Integrina beta1/imunologia , Integrina beta1/isolamento & purificação , Fígado/citologia , Macrófagos , Proteínas de Membrana/imunologia , Proteínas de Membrana/isolamento & purificação , Mesocricetus , Camundongos , Camundongos Endogâmicos BALB C , Proteínas de Protozoários/imunologia , Proteínas de Protozoários/isolamento & purificação , Receptores de Fibronectina/imunologia , Receptores de Fibronectina/isolamento & purificaçãoRESUMO
Entamoeba histolytica cells secrete electron-dense granules (EDGs) that have collagenase activity. To study the possible involvement of calmodulin (CaM) on EDG secretion, the effect of several CaM antagonists (TFP, R24571, W-7, W-5, dibucaine and DL-propranolol) was tested on this cellular function. Except for W-5 and dibucaine, the rest of these compounds inhibited EDG secretion. Transmission electron microscopy of collagen-activated trophozoites showed numerous EDGs located in or near the surface membrane. In contrast, trophozoites incubated with TFP showed no EDGs. Protein kinase C inhibitors (H-7, ML-9) had no effect on EDG secretion, suggesting that CaM antagonists acted by selectively inhibiting CaM. These results suggest that a CaM-dependent process is involved in EDG secretion.
