Apoptotic mimicry: an altruisticbehavior in host/Leishmania interplay
Wanderley, J. L. M. ; Benjamin, A. ; Real, F. ; Bonomo, A. ; Moreira, M. E. C. ; Barcinski, M. A. .
Braz J Med Biol Res
; 38(6): 807-812, jun. 2005. ilus
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Apoptosis is the most common phenotype observed when cells diethrough programmed cell death. The morphologic and biochemicalchanges that characterize apoptotic cells depend on the activation of adiverse set of genes. Apoptosis is essential for multicellular organismssince their development and homeostasis are dependent on extensivecell renewal. In fact, there is strong evidence for the correlationbetween the emergence of multicellular organisms and apoptosisduring evolution. On the other hand, no obvious advantages can beenvisaged for unicellular organisms to carry the complex machineryrequired for programmed cell death. However, accumulating evidenceshows that free-living and parasitic protozoa as well as yeasts displayapoptotic markers. This phenomenon has been related to altruisticbehavior, when a subpopulation of protozoa or yeasts dies by apoptosis,with clear benefits for the entire population. Recently, phosphatidylserine(PS) exposure and its recognition by a specific receptor(PSR) were implicated in the infectivity of amastigote forms ofLeishmania, an obligatory vertebrate intramacrophagic parasite, showingfor the first time that unicellular organisms use apoptotic featuresfor the establishment and/or maintenance of infection. Here we focuson PS exposure in the outer leaflet of the plasma membrane - an earlyhallmark of apoptosis - and how it modulates the inflammatoryactivity of phagocytic cells. We also discuss the possible mechanismsby which PS exposure can define Leishmania survival inside host cellsand the evolutionary implications of apoptosis at the unicellular level.(AU)
Biblioteca responsable:
BR440.1
Ubicación: BR440.1
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