Novel Transmembrane Receptor Involved in Phagosome Transport of Lysozymes and β-Hexosaminidase in the Enteric Protozoan Entamoeba histolytica

Atsushi Furukawa, Kumiko Nakada-Tsukui1, Tomoyoshi Nozaki

Speaker: Kai-Fei Chang (張凱斐)                                        Time: 14:00 ~15:00, Oct. 23, 2013

Commentator: Dr. Chih-Li Hsu (胥直利 老師)          Place: Room 601

Abstract:

Entamoeba histolytica is a human intestinal parasite that cause amoebic colits as well as liver, lung and brain abscess. Host tissue are damaged through a process involving adherence, contact-dependent cytolysis, and phagocytosis. Phagocytosis plays an essential role in the nutrient acquisition and constitutes one of the key virulence determinants.¹ E. histolytica is capable of ingesting microorganisms in the large intestine, as well as red blood cells and apoptotic immune cells during tissue invasion. Phagocytosis of certain bacteria by amoeba augments the cytopathic effect of E.histolytica.²In this study, the authors identified a receptor/carrier, cysteine proteinase binding protein family 8 (CPBF8), that binds to and transports the hydrolysis enzyme β-hexosaminidase and lysozymes to lysosome / phogosome when the E. histolytica ingest the cells or bacteria. From the results, repression of CPBF8 decreased the cytoplathic activity against the mammalian cells and delayed the degradation of ingested bacteria. Lysosome and β-hexosaminidase are abundant components found in phagosomes from E. histolytica.The authors verified CPBF8 protein have a stretch of serine-rich region for interacting with β-hexosaminidase. To summary, the authors have demonstrated that CPBF8 plays an important role in transporting lysosomal enzyme, the degradation of ingested bacteria, and cytopathy on host cells. This is the first time for understanding of these mechanism at molecular level.

References:

1.     Peterson KM, Shu J, Duggal P, Haque R, Mondal D, Petri WA Jr. (2010) Association between TNF-alpha and Entamoeba histolytica diarrhea. Am J Trop Med Hyg. 82(4):620-5

2.     Okada M, Huston CD, Mann BJ, Petri WA Jr, Kita K, Nozaki T. (2005) Proteomic analysis of phagocytosis in the enteric protozoan parasite Entamoeba histolytica. Eukaryot Cell. 4(4):827-31.