Intermediate filaments attenuate stimulation-dependent mobility of endosomes/lysosomes in astrocytes.
Intermediate filament (IF) proteins upregulation is a hallmark of astrocyte activation and reactive gliosis, but its pathophysiological implications remain incompletely understood. A recently reported association between IFs and directional mobility of peptidergic vesicles allows us to hypothesize that IFs affect vesicle dynamics and exocytosis-mediated astrocyte communication with neighboring cells. Here, we ask whether the trafficking of recycling vesicles (i.e., those fused to and then retrieved from the plasma membrane) and endosomes/lysosomes depends on IFs. Recycling vesicles were labeled by antibodies against vesicle glutamate transporter 1 (VGLUT1) and atrial natriuretic peptide (ANP), respectively, and by lysotracker, which labels endosomes/lysosomes. Quantitative fluorescence microscopy was used to monitor the mobility of labeled vesicles in astrocytes, derived from either wild-type (WT) mice or mice deficient in glial fibrillary acidic protein and vimentin (GFAP(-/-)Vim(-/-)), the latter lacking astrocyte IFs. Stimulation with ionomycin or ATP enhanced the mobility of VGLUT1-positive vesicles and reduced the mobility of ANP-positive vesicles in WT astrocytes. In GFAP(-/-)Vim(-/-) astrocytes, both vesicle types responded to stimulation, but the relative increase in mobility of VGLUT1-positive vesicles was more prominent compared with nonstimulated cells, whereas the stimulation-dependent attenuation of ANP-positive vesicles mobility was reduced compared with nonstimulated cells. The mobility of endosomes/lysosomes decreased following stimulation in WT astrocytes. However, in GFAP(-/-)Vim(-/-) astrocytes, a small increase in the mobility of endosomes/lysosomes was observed. These findings show that astrocyte IFs differentially affect the stimulation-dependent mobility of vesicles. We propose that upregulation of IFs in pathologic states may alter the function of astrocytes by deregulating vesicle trafficking.
Potokar
Maja
M
Celica Biomedical Center, Ljubljana, Slovenia.
Stenovec
Matjaz
M
Gabrijel
Mateja
M
Li
Lizhen
L
Kreft
Marko
M
Grilc
Sonja
S
Pekny
Milos
M
Zorec
Robert
R
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology*; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002491:Central Nervous System Agents / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology; D011992:Endosomes / Q000187:drug effects / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein; D007382:Intermediate Filaments / Q000187:drug effects / Q000502:physiology*; D015759:Ionomycin / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009038:Motion; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism; D014746:Vimentin / Q000235:genetics / Q000378:metabolism
D002491:Central Nervous System Agents; D005904:Glial Fibrillary Acidic Protein; D009419:Nerve Tissue Proteins; C493465:Slc17a7 protein, mouse; D050598:Vesicular Glutamate Transport Protein 1; D014746:Vimentin; C528900:glial fibrillary astrocytic protein, mouse; D015759:Ionomycin; D009320:Atrial Natriuretic Factor; D000255:Adenosine Triphosphate