Serum deprivation leads to growth inhibition and protein tyrosine phosphorylation in Entamoeba histolytica

摘要

Growth of Entamoeba histolytica in culture was found to be entirely dependent upon the presence of serum in the culture media. Very little protein phosphorylation was detected in growing E. histolytica cells by quantitative immunofluorescence and immunoblotting. Intense augumentation of antiphosphotyrosine immunofluorescence was observed after 1 h of serum deprivation. Antiphosphotyrosine immunofluorescence levels increased moderately between 1 h and 1.5 h of serum deprivation, after which no further increase was observed till 4 h serum deprivation. At 1 h of serum deprivation, a very high tyrosine kinase activity was detected. Sodium orthovanadate, a potent tyrosine phosphatase inhibitor, increased tyrosine phosphorylation of a 38 kDa protein after 1 h of incubation and also inhibited the growth of E. histolytica in culture. Our data demonstrated that protein tyrosine phosphorylation was associated with growth inhibition of E. histolytica. [References: 8]