title: Ectopic expression of gastrokine 1 in gastric cancer cells up-regulates tight and adherens junction proteins network.
abstract: Gastrokine 1 (GKN1) is a stomach-specific protein important in the replenishment of the surface lumen epithelial cell layer and in maintaining mucosal integrity. A role in cell proliferation and differentiation has also been hypothesized. Despite these findings, the function(s) as well as the cellular localization of GKN1 in the cellular machinery are currently not clarified. The investigation of subcellular localization of GKN1 in gastric cancer cells can provide insights into its potential cellular roles. Subcellular fractions of gastric cancer cells (AGS) transfected with full-length GKN1 (flGKN1) or incubated with recombinant GKN1 (rGKN1) lacking the first 20 amino acids at N-terminal were analyzed by Western blot and confocal microscopy and compared with those from normal gastric tissue. Wild type GKN1 (wtGKN1) and flGKN1 were revealed in the cytoplasm and in the membrane fractions of gastric cells, whereas rGKN1 was revealed in the cytoplasmic fractions, but a high amount was detected in the membrane pellet of the AGS lysate. The cellular distribution of GKN1 was also confirmed by confocal microscopy. The purified protein was also used to highlight its possible association with actin through confocal microscopy, pelleting assay, and size-exclusion chromatography. GKN1 co-localizes with actin in normal gastric tissue, but no direct interaction was observed between the two proteins in vitro. Most likely, GKN1 indirectly participates in actin stabilization since its overexpression in gastric cancer cells strongly increases the expression of tight and adherens junction proteins.
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Emilia
authors.initials: E
authors.lastname: Rippa
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Filomena
authors.initials: F
authors.lastname: Altieri
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Chiara Stella
authors.initials: CS
authors.lastname: Di Stadio
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Miselli
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Lamberti
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy; CNR, Institute of Experimental Endocrinology and Oncology G. Salvatore, Naples, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Federico
authors.affiliation: Department of Anesthesia, Surgical and Emergency Sciences, Second University of Naples, Naples, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Quagliariello
authors.affiliation: Department of Anesthesia, Surgical and Emergency Sciences, Second University of Naples, Naples, Italy.
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Papale
authors.affiliation: Department of Medicine and Health Science, University of Molise, Isernia, Italy.
authors.forename: Germano
authors.initials: G
authors.lastname: Guerra
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy; CEINGE, Advanced Biotechnology Scarl, Naples, Italy. Electronic address: arcari@unina.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Arcari
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000502:physiology; D000066630:Ectopic Gene Expression; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D036361:Peptide Hormones / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism*; D019108:Tight Junctions / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C477000:GKN1 protein, human; D036361:Peptide Hormones
keywords: Actin; Cellular localization; Confocal microscopy; Gastric cancer; Gastrokine 1