Human GBP1 Is Involved in the Repair of Damaged Phagosomes/Endolysosomes

Abstract

Mouse guanylate-binding proteins (mGBPs) are recruited to various invasive pathogens, thereby conferring cell-autonomous immunity against these pathogens. However, whether and how human GBPs (hGBPs) target M. tuberculosis (Mtb) and L. monocytogenes (Lm) remains unclear. Here, we describe hGBPs association with intracellular Mtb and Lm, which was dependent on the ability of bacteria to induce disruption of phagosomal membranes. hGBP1 formed puncta structures which were recruited to ruptured endolysosomes. Furthermore, both GTP-binding and isoprenylation of hGBP1 were required for its puncta formation. hGBP1 was required for the recovery of endolysosomal integrity. In vitro lipid-binding assays demonstrated direct binding of hGBP1 to PI4P. Upon endolysosomal damage, hGBP1 was targeted to PI4P and PI(3,4)P2-positive endolysosomes in cells. Finally, live-cell imaging demonstrated that hGBP1 was recruited to damaged endolysosomes, and consequently mediated endolysosomal repair. In summary, we uncover a novel interferon-inducible mechanism in which hGBP1 contributes to the repair of damaged phagosomes/endolysosomes.

Guanylate-binding protein 1 acts as a pro-viral factor for the life cycle of hepatitis C virus

“…Thus, the access of GBP1 to the MW must be mediated by a different mechanism. Recent studies indicate a direct binding of GBP1 to phosphatidylinositol-4-phosphate (PI4P) upon endolysosomal damage [ 61 ]. In HCV infected cells, PI4P accumulates in the MW to enrich the ER-derived membranes in cholesterol by an OSBP-mediated PI4P-cholesterol exchange [ 62 ].…”