Porosome in astrocytes.
Secretion is a universal cellular process occurring in bakers yeast, to the complex multicellular organisms, to humans beings. Neurotransmission, digestion, immune response or the release of hormones occur as a result of cell secretion. Secretory defects result in numerous diseases and hence a molecular understanding of the process is critical. Cell secretion involves the transport of vesicular products from within cells to the outside. Porosomes are permanent cup-shaped supramolecular structures at the cell plasma membrane, where secretory vesicles transiently dock and transiently fuse to release intravesicular contents to the outside. In the past decade, porosomes have been determined to be the universal secretory machinery in cells, present in the exocrine pancreas, endocrine and neuroendocrine cells, and in neurons. In this study, we report for the first time the presence of porosomes in rat brain astrocytes. Using atomic force microscopy on live astrocytes, cup-shaped porosomes measuring 10-15 nm are observed at the cell plasma membrane. Further studies using electron microscopy confirm the presence of porosomes in astrocytes. Analogous to neuronal porosomes, there is a central plug in the astrocyte porosome complex. Immunoisolation and reconstitution of the astrocyte porosome in lipid membrane, demonstrates a structure similar to what is observed in live cells. These studies demonstrate that in astrocytes, the secretory apparatus at the cell plasma membrane is similar to what is found in neurons.
Lee
Jin-Sook
JS
Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Cho
Won Jin
WJ
Jeftinija
Ksenija
K
Jeftinija
Srdija
S
Jena
Bhanu P
BP
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D005089:Exocytosis / Q000502:physiology*; D006801:Humans; D018625:Microscopy, Atomic Force; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D051381:Rats; D022142:Secretory Vesicles / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25 / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism
C498858:Snap23 protein, rat; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins