Amazing stuff!
"Scientists ... have discovered hundreds of proteins that are constantly transported throughout the healthy brain in small membrane-enclosed sacs, revealing a new form of communication between brain cells. ...
The proteins identified included many with known functions in the brain, including the tau and synuclein seen moving between cells in Alzheimer’s disease.
“This is a confirmation that in the healthy brain, tau and synuclein—and their movement around the brain—is normal,” ... “But with Alzheimer’s disease it’s a toxic form of the protein that is transported between neurons.” ..."From the abstract:
"Intercellular transfer of toxic proteins between neurons is thought to contribute to neurodegenerative disease, but whether direct interneuronal protein transfer occurs in the healthy brain is not clear. To assess the prevalence and identity of transferred proteins and the cellular specificity of transfer, we biotinylated retinal ganglion cell proteins in vivo and examined biotinylated proteins transported through the rodent visual circuit using microscopy, biochemistry, and mass spectrometry. Electron microscopy demonstrated preferential transfer of biotinylated proteins from retinogeniculate inputs to excitatory lateral geniculate nucleus (LGN) neurons compared with GABAergic neurons. An unbiased mass spectrometry-based screen identified ∼200 transneuronally transported proteins (TNTPs) isolated from the visual cortex. The majority of TNTPs are present in neuronal exosomes, and virally expressed TNTPs, including tau and β-synuclein, were detected in isolated exosomes and postsynaptic neurons. Our data demonstrate transfer of diverse endogenous proteins between neurons in the healthy intact brain and suggest that TNTP transport may be mediated by exosomes."
Proteomic screen reveals diverse protein transport between connected neurons in the visual system (open access)
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