Lysosome Exocytosis and Invasion of Non-Phagocytic Host Cells by Trypanosoma Cruzi

Abstract

In recent years, significant progress has been made toward understanding the mechanisms of host cell invasion by the intracellular pathogen, Trypanosoma cruzi. Invasion of non-phagocytic cells by trypomastigotes, the mammalianinfective forms of T. cruzi, is achieved by a surprising mechanism whereby host cell lysosomes are recruited as a vehicle for parasite entry. These studies have revealed the existence of the lysosome exocytosis pathway, a previously unrecognised regulated secretion system in non-phagocytic mammalian cells. Host cell signalling pathways that regulate T. cruzi entry and lysosome recruitment were shown to involve the second messengers, Ca2+ and cAMP and require secreted agonist(s) generated by the parasite. In addition, the ability of T. cruzi to receive signals from the host cell in a contact-dependent manner is crucial to the invasive process. In this chapter, I will outline our current knowledge of the cellular and molecular bases for host cell invasion by T. cruzi as well as the experimental approaches taken to study this process.