Ca2+ regulation of dynamin-independent endocytosis in cortical astrocytes.
Astrocytes release ATP and glutamate through vesicular exocytosis to mediate neuron-glial interactions. In contrast to exocytosis, the endocytic pathways in astroglial cells are poorly understood. Here, we identify a constitutive endocytic pathway in cultured astrocytes that is dependent on neither clathrin nor dynamin. This dynamin-independent endocytic pathway is regulated by Rab5, an early endosome protein. The endocytosed vesicles show fast transition from early endosomes to late endosomes and lysosomes within a few minutes. Interestingly, this clathrin- and dynamin-independent endocytosis in astrocytes is potently regulated by intracellular Ca(2+). ATP and glutamate greatly enhance the dynamin-independent endocytosis through elevating the intracellular Ca(2+). In addition, amyloid-beta peptide (A beta) also enhances the dynamin-independent endocytosis by inducing Ca(2+) transients in astrocytes. These results demonstrate a novel endocytic pathway in glial cells that is dynamin independent but tightly regulated by intracellular Ca(2+). The regulation by ATP, glutamate, and A beta suggests an important role of the dynamin-independent endocytosis in both physiological and pathological conditions.
Jiang
Min
M
Department of Biology, Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Chen
Gong
G
D000255:Adenosine Triphosphate / Q000494:pharmacology; D016229:Amyloid beta-Peptides / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D002966:Clathrin / Q000378:metabolism; D034281:Dynamins / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects*; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D018698:Glutamic Acid / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D010957:Plasmids; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014162:Transfection; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
D016229:Amyloid beta-Peptides; D002966:Clathrin; D049452:Green Fluorescent Proteins; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D020696:rab5 GTP-Binding Proteins; D034281:Dynamins; D002118:Calcium