Influence of the Paracoccidioides brasiliensis 14-3-3 and gp43 proteins on the induction of apoptosis in A549 epithelial cells

The fungal strain Paracoccidioides brasiliensis remains viableinside of epithelial cells and can induce apoptosis in this population. However,until now, the molecules that participate in this process remained unknown. Thus,this study evaluated the contribution of two P. brasiliensismolecules, the 14-3-3 and glycoprotein of 43 kDa proteins, which had been previouslydescribed as extracellular matrix adhesins and apoptosis inductors in humanpneumocytes. Accordingly, epithelial cells were treated with these molecules fordifferent periods of time and the expression of the apoptosis regulating-proteinsBak, Bax, Bcl-2, p53 and caspases were evaluated by terminal deoxynucleotidyltransferase dUTP nick end labelling, flow cytometry and real-time polymerase chainreaction analysis. Our results demonstrated that treatment with these moleculesinduces apoptosis signalling in pulmonary epithelial cells, showing the same patternof programmed cell-death as that observed during infection with P.brasiliensis. Thus, we could conclude that P.brasiliensis uses these molecules as virulence factors that participatenot only in the fungal adhesion process to host cells, but also in other importantcellular mechanisms such as apoptosis.