Rescue of secretion of rare-disease-associated misfolded mutant glycoproteins in UGGT1 knock-out mammalian cells.
Gabor Tax, Kevin P Guay, Ludovica Pantalone, Martina Ceci, Tatiana Soldà, Charlie J Hitchman, Johan C Hill, Snežana Vasiljević, Andrea Lia, Carlos P Modenutti, Kees R Straatman, Angelo Santino, Maurizio Molinari, Nicole Zitzmann, Daniel N Hebert, Pietro Roversi, Marco Trerotola
Author Information
Gabor Tax: Leicester Institute of Chemical and Structural Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester, England, UK. ORCID
Kevin P Guay: Department of Biochemistry and Molecular Biology, and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, USA.
Ludovica Pantalone: Department of Medical, Oral and Biotechnological Sciences, "G. d'Annunzio" University of Chieti-Pescara, Pescara, Italy. ORCID
Martina Ceci: Department of Medical, Oral and Biotechnological Sciences, "G. d'Annunzio" University of Chieti-Pescara, Pescara, Italy. ORCID
Tatiana Soldà: Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera Italiana (USI), Bellinzona, Switzerland.
Charlie J Hitchman: Leicester Institute of Chemical and Structural Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester, England, UK. ORCID
Johan C Hill: Institute of Glycobiology, Department of Biochemistry, University of Oxford, Oxford, UK. ORCID
Snežana Vasiljević: Institute of Glycobiology, Department of Biochemistry, University of Oxford, Oxford, UK.
Andrea Lia: Leicester Institute of Chemical and Structural Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester, England, UK. ORCID
Carlos P Modenutti: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (FCEyN-UBA) e Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN) CONICET, Pabellón 2 de Ciudad Universitaria, Ciudad de Buenos Aires, Argentina. ORCID
Kees R Straatman: Core Biotechnology Services, University of Leicester, Leicester, England, UK. ORCID
Angelo Santino: Institute of Sciences of Food Production, ISPA-CNR Unit of Lecce, Lecce, Italy. ORCID
Maurizio Molinari: Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera Italiana (USI), Bellinzona, Switzerland. ORCID
Nicole Zitzmann: Institute of Glycobiology, Department of Biochemistry, University of Oxford, Oxford, UK. ORCID
Daniel N Hebert: Department of Biochemistry and Molecular Biology, and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, USA. ORCID
Pietro Roversi: Leicester Institute of Chemical and Structural Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester, England, UK. ORCID
Marco Trerotola: Department of Medical, Oral and Biotechnological Sciences, "G. d'Annunzio" University of Chieti-Pescara, Pescara, Italy. ORCID
Endoplasmic reticulum (ER) retention of misfolded glycoproteins is mediated by the ER-localized eukaryotic glycoprotein secretion checkpoint, UDP-glucose glycoprotein glucosyl-transferase (UGGT). The enzyme recognizes a misfolded glycoprotein and flags it for ER retention by re-glucosylating one of its N-linked glycans. In the background of a congenital mutation in a secreted glycoprotein gene, UGGT-mediated ER retention can cause rare disease, even if the mutant glycoprotein retains activity ("responsive mutant"). Using confocal laser scanning microscopy, we investigated here the subcellular localization of the human Trop-2-Q118E, E227K and L186P mutants, which cause gelatinous drop-like corneal dystrophy (GDLD). Compared with the wild-type Trop-2, which is correctly localized at the plasma membrane, these Trop-2 mutants are retained in the ER. We studied fluorescent chimeras of the Trop-2 Q118E, E227K and L186P mutants in mammalian cells harboring CRISPR/Cas9-mediated inhibition of the UGGT1 and/or UGGT2 genes. The membrane localization of the Trop-2 Q118E, E227K and L186P mutants was successfully rescued in UGGT1 cells. UGGT1 also efficiently reglucosylated Trop-2-Q118E-EYFP in cellula. The study supports the hypothesis that UGGT1 modulation would constitute a novel therapeutic strategy for the treatment of pathological conditions associated to misfolded membrane glycoproteins (whenever the mutation impairs but does not abrogate function), and it encourages the testing of modulators of ER glycoprotein folding quality control as broad-spectrum rescue-of-secretion drugs in rare diseases caused by responsive secreted glycoprotein mutants.
