title: Endocytosis in the shiitake mushroom Lentinula edodes and involvement of GTPase LeRAB7.
abstract: Endocytosis is the process by which substrates enter a cell without passing through the plasma membrane but rather invaginate the cell membrane and form intracellular vesicles. Rab7 regulates endocytic trafficking between early and late endosomes and between late endosomes and lysosomes. LeRab7 in Lentinula edodes is strongly homologous to Rab7 in Homo sapiens. Receptors for activated C kinase-1 (LeRACK1) and Rab5 GTPase (LeRAB5) were isolated as interacting partners of LeRab7, and the interactions were confirmed by in vivo and in vitro protein interaction assays. The three genes showed differential expression in the various developmental stages of the mushroom. In situ hybridization showed that the three transcripts were localized in regions of active growth, such as the outer region of trama cells, and the subhymenium of the hymenophore of mature fruiting bodies and the prehymenophore of young fruiting bodies. The existence of endocytosis in the mycelium and hymenophores was confirmed by the internalization of FM4-64. LeRAB7 was partially colocalized with the AM4-64 and was located in the late endocytic pathway. This is the first report of the presence of endocytosis in homobasidiomycetes. LeRAB7, LeRAB5, and LeRACK1 may contribute to the growth of L. edodes and cell differentiation in hymenophores.
authors.affiliation: Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, SAR, People's Republic of China.
authors.forename: Ming Tsung
authors.initials: MT
authors.lastname: Lee
authors.forename: Carol Ying Ying
authors.initials: CY
authors.lastname: Szeto
authors.forename: Tak Pan
authors.initials: TP
authors.lastname: Ng
authors.forename: Hoi Shan
authors.initials: HS
authors.lastname: Kwan
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry; D020558:GTP Phosphohydrolases / Q000737:chemistry*; D015966:Gene Expression Regulation, Fungal; D008954:Models, Biological; D009693:Nucleic Acid Hybridization; D011485:Protein Binding; D021381:Protein Transport; D020942:Shiitake Mushrooms / Q000378:metabolism*; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000090802:rab7 GTP-Binding Proteins
chemical_list: D018076:DNA, Complementary; D005656:Fungal Proteins; D000090802:rab7 GTP-Binding Proteins; D020558:GTP Phosphohydrolases; D020691:rab GTP-Binding Proteins