Pj. Sansonetti, MOLECULAR AND CELLULAR BASES OF EPITHELIAL-CELL INVASION BY SHIGELLA-FLEXNERI, Comptes rendus de l'Academie des sciences. Serie 3, Sciences de la vie, 320(9), 1997, pp. 729-734
A key step in the pathogenesis of shigellosis is the capacity of the c
ausative bacteria, shigellae, to invade colonic and rectal epithelial
cells in humans. This invasive process encompasses several steps: entr
y into epithelial cells by induction of a macropinocytic event caused
by secreted Ipa proteins. The bacterium then escapes from the vacuole
and reaches the cytoplasmic compartment in which it divides rapidly an
d becomes motile via the expression of a surface protein, IcsA, whose
polar localization achieves directed polymerization of actin filaments
that push the bacterial body forward. Bacteria then engage the inner
face of the cellular membrane in the junctional area and form protrusi
ons allowing their passage into the adjacent cell. Lysis of the double
membrane eventually allows access to the cytoplasmic compartment of t
he adjacent cell, thus providing the bacterium with a very efficient m
echanism of epithelial colonization.