Involvement of the Mitogen-Activated Protein (MAP) kinase signalling pathway in host cell invasion by Toxoplasma gondii

Little is known about signalling in Toxoplasma gondii, but it is likely tha t protein kinases might play a key role in the parasite proliferation, diff erentiation and probably invasion. We previously characterized Mitogen-Acti vated Protein (MAP) kinases in T. gondii lysates. in this study, cultured c ells were tested for their susceptibility to Toxoplasma gondii infection af ter tachyzoite pretreatment with drugs interfering with MAP kinase activati on pathways. Protein kinases inhibitors, i.e. genistein, RO31-8220 and PD09 8059, reduced tachyzoite infectivity by 38 +/- 4.5 %, 85.5 +/- 9 % and 56 /- 10 %, respectively. Conversely, protein kinases activators, i.e. bombesi n and PMA, markedly increased infectivity (by 202 +/- 37 % and 258 +/- 14 % , respectively). These results suggest that signalling pathways involving P KC and MAP kinases play a role in host cell invasion by Toxoplasma.