Τίτλος:
Hypertonic conditions trigger transient plasmolysis, growth arrest and blockage of transporter endocytosis in Aspergillus nidulans and Saccharomyces cerevisiae
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
By using Aspergillus nidulans strains expressing functional GFP-tagged transporters under hypertonic conditions, we noticed the rapid appearance of cortical, relatively static, fluorescent patches (0.52.3 μm). These patches do not correspond to transporter microdomains as they co-localize with other plasma membrane-associated molecules, such as the pleckstrin homology (PH) domain and the SsoA t-Snare, or the lipophilic markers FM4-64 and filipin. In addition, they do not show characteristics of lipid rafts, MCCs or other membrane microdomains. Deconvoluted microscopic images showed that fluorescent patches correspond to plasma membrane invaginations. Transporters remain fully active during this phenomenon of localized plasmolysis. Plasmolysis was however associated with reduced growth rate and a dramatic blockage in transporter and FM4-64 endocytosis. These phenomena are transient and rapidly reversible upon wash-out of hypertonic media. Based on the observation that block in endocytosis by hypertonic treatment altered dramatically the cellular localization of tropomyosin (GFP-TpmA), although it did not affect the cortical appearance of upstream (SlaB-GFP) or downstream (AbpA-mRFP) endocytic components, we conclude that hypertonicity modifies actin dynamics and thus acts indirectly on endocytosis. This was further supported by the effect of latrunculin B, an actin depolymerization agent, on endocytosis. We show that the phenomena observed in A. nidulans also occur in Saccharomyces cerevisiae, suggesting that they constitute basic homeostatic responses of ascomycetes to hypertonic shock. Finally, our work shows that hypertonic treatments can be used as physiological tools to study the endocytic down-regulation of transporters in A. nidulans, as non-conditional genetic blocks affecting endocytic internalization are lethal or severely debilitating. © 2011 Informa UK, Ltd.
Συγγραφείς:
Bitsikas, V.
Karachaliou, M.
Gournas, C.
Diallinas, G.
Περιοδικό:
Molecular Membrane Biology
Λέξεις-κλειδιά:
carrier protein; cycloheximide; green fluorescent protein; hypertonic solution; latrunculin B; pleckstrin; protein uapa; SNARE protein; tropomyosin; unclassified drug; xanthine, actin polymerization; article; Aspergillus nidulans; cell cycle arrest; cell membrane; cell membrane transport; cellular distribution; controlled study; endocytosis; fungal spore germination; lipid raft; multivesicular body; nonhuman; plasmolysis; priority journal; protein domain; protein localization; Saccharomyces cerevisiae, Aspergillus nidulans; Down-Regulation; Endocytosis; Hypertonic Solutions; Membrane Microdomains; Membrane Transport Proteins; Saccharomyces cerevisiae, Ascomycota; Emericella nidulans; Fungi; Saccharomyces cerevisiae
DOI:
10.3109/09687688.2010.510484
