title: Nutrient stress alters the glycosylation status of LGR5 resulting in reduced protein stability and membrane localisation in colorectal tumour cells: implications for targeting cancer stem cells.
abstract: BACKGROUND
  LGR5 is an important marker of intestinal stem cells and performs its vital functions at the cell membrane. Despite the importance of LGR5 to both normal and cancer stem cell biology, it is not known how microenvironmental stress affects the expression and subcellular distribution of the protein.
  
  
  METHODS
  Nutrient stress was induced through glucose starvation. Glycosylation status was assessed using endoglycosidase or tunicamycin treatment. Flow cytometry and confocal microscopy were used to assess subcellular distribution of LGR5.
  
  
  RESULTS
  Glucose deprivation altered the glycosylation status of LGR5 resulting in reduced protein stability and cell surface expression. Furthermore, inhibiting LGR5 glycosylation resulted in depleted surface expression and reduced localisation in the cis-Golgi network.
  
  
  CONCLUSIONS
  Nutrient stress within a tumour microenvironment has the capacity to alter LGR5 protein stability and membrane localisation through modulation of LGR5 glycosylation status. As LGR5 surface localisation is required for enhanced Wnt signalling, this is the first report to show a mechanism by which the microenvironment could affect LGR5 function.
authors.affiliation: Cancer Research UK Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Bristol BS8 1TD, UK.
authors.forename: R G
authors.initials: RG
authors.lastname: Morgan
authors.affiliation: School of Physiology and Pharmacology, Bristol BS8 1TD, UK.
authors.forename: E
authors.initials: E
authors.lastname: Molnár
authors.affiliation: Cancer Research UK Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Bristol BS8 1TD, UK.
authors.forename: R F
authors.initials: RF
authors.lastname: Jones
authors.affiliation: Cancer Research UK Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Bristol BS8 1TD, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Collard
authors.affiliation: Cell Biology Laboratories, School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Lane
authors.affiliation: Cancer Research UK Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Bristol BS8 1TD, UK.
authors.forename: A
authors.initials: A
authors.lastname: Greenhough
authors.affiliation: Cancer Research UK Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Bristol BS8 1TD, UK.
authors.forename: C
authors.initials: C
authors.lastname: Paraskeva
authors.affiliation: Cancer Research UK Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Bristol BS8 1TD, UK.
authors.forename: A C
authors.initials: AC
authors.lastname: Williams
mesh_terms: D000236:Adenoma / Q000235:genetics / Q000378:metabolism* / Q000628:therapy; D002462:Cell Membrane / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000628:therapy; D005502:Food; D005947:Glucose / Q000172:deficiency*; D006031:Glycosylation; D006801:Humans; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D055550:Protein Stability; D021381:Protein Transport; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000502:physiology*; D014407:Tumor Cells, Cultured; D059016:Tumor Microenvironment
chemical_list: C116884:LGR5 protein, human; D043562:Receptors, G-Protein-Coupled; D005947:Glucose