Participation of Rho, ROCK-2, and GAP activities during actin microfilament rearrangements in Entamoeba histolytica induced by fibronectin signaling

In Entamoeba histolytica little is known about the microfilament rearrangements formed by actin and ABPs. Fibronectin regulates many aspects of cell behavior involving the actin cytoskeleton and members of the Rho family of small GTPases. Using trophozoites interacted with fibronectin and glass, we present evidence related with the formation and regulation of different microfilament rearrangements and their cellular distribution, the effect of actin affecting drugs on these arrangements, and on trophozoites adhesion; we also demonstrate that actin isoforms are induced after adhesion, and also the selective participation of specific actin binding proteins such as ABP-120 and phospho-paxillin, regarding their location in the different actin structures. In addition, we show results that confirm the participation of EhRho, ROCK-2, and GAP activities. We propose that fibronectin induced signaling in E. histolytica trophozoites have important consequences in the actin cytoskeleton that may affect its behavior during the invasive process in the host.     

Demarcation of Viral Shelters Results in Destruction by Membranolytic GTPases: Antiviral Function of Autophagy Proteins and Interferon‐Inducible GTPases

A hallmark of positive‐sense RNA viruses is the formation of membranous shelters for safe replication in the cytoplasm. Once considered invisible to the immune system, these viral shelters are now found to be antagonized through the cooperation of autophagy proteins and anti‐microbial GTPases. This coordinated effort of autophagy proteins guiding GTPases functions against not only the shelters of viruses but also cytoplasmic vacuoles containing bacteria or protozoa, suggesting a broad immune‐defense mechanism against disparate vacuolar pathogens. Fundamental questions regarding this process remain: how the host recognizes these membranous structures as a target, how the autophagy proteins bring the GTPases to the shelters, and how the recruited GTPases disrupt these shelters. In this review, these questions are discussed, the answers to which will significantly advance our understanding of the response to vacuole‐like structures of pathogens, thereby paving the way for the development of broadly effective anti‐microbial strategies for public health.