title: Internalization of a non-pathogenic mycobacteria by macropinocytosis in human alveolar epithelial A549 cells.
abstract: Mycobacterium smegmatis (MSM) a non-pathogenic mycobacterium is often employed as a tool to understand many aspects of the mycobacterial infections. However, its own biology and particularly its mechanism of entry into non-phagocytic cells are not well known. Previously, we demonstrated that Mycobacterium tuberculosis (MTB) invades epithelial cells by macropinocytosis. In the present study, we investigated whether MSM also invades human epithelial type II pneumocytes (A549) by macropinocytosis. Infection of A549 cells with MSM elicited actin filaments redistribution, lamellipodia formation and increased fluid phase uptake, suggesting macropinocytosis. Furthermore, macropinocytosis inhibitors like cytochalasin D and amiloride caused inhibition of fluid phase and bacterial uptake. We can conclude that MSM, like MTB, takes advantage of macropinocytosis for entry into epithelial cells, however, unlike MTB, internalized MSM are killed by host cells. These findings suggest that induction of macropinocytosis and cell invasion is not an exclusive feature of pathogenic organisms.
authors.affiliation: Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, 11340 México City, D.F., Mexico. abrilestela@hotmail.com
authors.forename: Blanca Estela
authors.initials: BE
authors.lastname: García-Pérez
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Hernández-González
authors.forename: Samuel
authors.initials: S
authors.lastname: García-Nieto
authors.forename: Julieta
authors.initials: J
authors.lastname: Luna-Herrera
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival; D015638:Cytochalasin D / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000382:microbiology* / Q000502:physiology; D006801:Humans; D009165:Mycobacterium Infections, Nontuberculous / Q000382:microbiology*; D020102:Mycobacterium smegmatis / Q000187:drug effects / Q000502:physiology*; D010873:Pinocytosis / Q000187:drug effects; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects / Q000382:microbiology* / Q000502:physiology
chemical_list: D015638:Cytochalasin D; D000584:Amiloride