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J Cell Biol. 2019 May 10. pii: jcb.201807068. doi: 10.1083/jcb.201807068. [Epub ahead of print]

Rhes travels from cell to cell and transports Huntington disease protein via TNT-like protrusion.

Author information

1
Department of Neuroscience, The Scripps Research Institute, Jupiter, FL.
2
Department of Neuroscience, The Scripps Research Institute, Jupiter, FL ssubrama@scripps.edu.

Abstract

Tunneling nanotubes (TNT) are thin, membranous, tunnel-like cell-to-cell connections, but the mechanisms underlying their biogenesis or functional role remains obscure. Here, we report, Rhes, a brain-enriched GTPase/SUMO E3-like protein, induces the biogenesis of TNT-like cellular protrusions, "Rhes tunnels," through which Rhes moves from cell to cell and transports Huntington disease (HD) protein, the poly-Q expanded mutant Huntingtin (mHTT). The formation of TNT-like Rhes tunnels requires the Rhes's serine 33, C-terminal CAAX, and a SUMO E3-like domain. Electron microscopy analysis revealed that TNT-like Rhes tunnels appear continuous, cell-cell connections, and <200 nm in diameter. Live-cell imaging shows that Rhes tunnels establish contact with the neighboring cell and deliver Rhes-positive cargoes, which travel across the plasma membrane of the neighboring cell before entering it. The Rhes tunnels carry Rab5a/Lyso 20-positive vesicles and transport mHTT, but not normal HTT, mTOR, or wtTau proteins. SUMOylation-defective mHTT, Rhes C263S (cannot SUMOylate mHTT), or CRISPR/Cas9-mediated depletion of three isoforms of SUMO diminishes Rhes-mediated mHTT transport. Thus, Rhes promotes the biogenesis of TNT-like cellular protrusions and facilitates the cell-cell transport of mHTT involving SUMO-mediated mechanisms.

PMID:
31076452
DOI:
10.1083/jcb.201807068

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