User:SourisSourit/sandbox/IAM



Infection-Associated Macropinosomes (IAMs) are fluid-filled intracellular compartment formed upon pathogen infection. They have been studied mainly in the context of epithelial cell invasion by Gram-negative bacteria such as Salmonella and Shigella. However, they appear to be involved in virus infection as well.

Identity
Their common characteristic with the physiological macropinosome are the followings:


 * size of the compartment
 * resulting from membrane protrusion
 * non-receptor specifique (opposite to phagosome)
 * containing extracellular liquid
 * early endocytic marker Rab5, PI3P, EEA1
 * their formation can be inhibited using the specific inhibitor Amiloride

Their difference from physiological macropinosome:


 * Their formation is triggered by a pathogen and its effectors
 * Their maturation and interaction with the intracellular pathogen are driven by pathogen effectors.

Currently, little is known about the IAM identity and their similarities and differences with physiological macropinosome remain to be further explored.

Formation
While entering in non-phagocytic epithelial cells, pathogens may trigger their uptake by inducing the formation of membrane protrusion called ruffles. The closure of the ruffles can result in (1) the engulfment of the pathogen within an intracellular vacuole, and (2) the formation of fluid-filled IAMs.