Proteomic Analysis of Gliosomes from Mouse Brain: Identification and Investigation of Glial Membrane Proteins

Astrocytes are being increasingly
recognized as crucial contributors
to neuronal function at synapses, axons, and somas. Reliable methods
that can provide insight into astrocyte proteins at the neuron–astrocyte
functional interface are highly desirable. Here, we conducted a mass
spectrometry analysis of Percoll gradient-isolated gliosomes, a viable
preparation of glial subcellular particles often used to study mechanisms
of astrocytic transmitter uptake and release and their regulation.
Gliosomes were compared with synaptosomes, a preparation containing
the neurotransmitter release machinery, and, accordingly, synaptosomes
were enriched for proteins involved in synaptic vesicle-mediated transport.
Interestingly, gliosome preparations were found to be enriched for
different classes of known astrocyte proteins, such as VAMP3 (involved
in astrocyte exocytosis), Ezrin (perisynaptic astrocyte cytoskeletal
protein), and Basigin (astrocyte membrane glycoprotein), as well as
for G-protein-mediated signaling proteins. Mass spectrometry data
are available via ProteomeXchange with the identifier PXD001375. Together,
these data provide the first detailed description of the gliosome
proteome and show that gliosomes can be a useful preparation to study
glial membrane proteins and associated processes.