University of SaskatchewanHARVEST
  • Login
  • Submit Your Work
  • About
    • About HARVEST
    • Guidelines
    • Browse
      • All of HARVEST
      • Communities & Collections
      • By Issue Date
      • Authors
      • Titles
      • Subjects
      • This Collection
      • By Issue Date
      • Authors
      • Titles
      • Subjects
    • My Account
      • Login
      JavaScript is disabled for your browser. Some features of this site may not work without it.
      View Item 
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item

      NESFATIN-1 AND NESFATIN-1-LIKE PEPTIDE: NUCLEOBINDIN-1/2-ENCODED INSULINOTROPIC AND ENTEROTROPIC PEPTIDES

      Thumbnail
      View/Open
      RAMESH-THESIS.pdf (2.384Mb)
      Date
      2015-06-05
      Author
      Ramesh, Naresh
      Type
      Thesis
      Degree Level
      Masters
      Metadata
      Show full item record
      Abstract
      Nucleobindins are a class of secreted, multi-domain Ca2+ binding proteins that interact with nucleic acids. Two nucleobindins, nucleobindin-1 (NUCB1) and nucleobindin-2 (NUCB2) have been identified so far. In 2006, nesfatin-1, an 82 amino acid peptide encoded in NUCB2 was discovered. Nesfatin-1 is an anorexigenic and insulinotropic peptide found abundantly in hypothalamus, pancreas and stomach. Meal responsive insulin secretion is regulated by glucagon like peptide-1 (GLP-1), glucose dependent insulinotropic polypeptide (GIP), peptide YY (PYY) and cholecystokinin (CCK) secreted by intestinal mucosal cells. Since both nesfatin-1 and intestinal hormones modulate insulin secretion, nesfatin-1 could regulate intestinal hormones to elicit its insulinotropic action. Nucleobindin-1 primarily regulates Ca2+ homeostasis. Like NUCB2, NUCB1 is also present in the pancreas, stomach, intestine and pituitary. NUCB2 has a high similarity (62% in humans) to NUCB1. Both proteins also retain their prohormone convertase cleavage sites. However, no information exists on whether NUCB1 encodes bioactive peptides. The fact that NUCB1 is a secreted protein suggests an endocrine function for NUCB1 and/or its encoded peptide. This research hypothesizes that nesfatin-1 is enterotropic, and NUCB1 encodes an insulinotropic nesfatin-1-like peptide (NLP). Nesfatin-1 protein expression was found in STC-1 cells and it co-localized GLP-1, GIP, CCK and PYY in mouse enteroendocrine cells. Treatment of STC-1 cells with nesfatin-1 stimulated GLP-1, GIP, CCK mRNA expression and protein secretion, while opposite effects were found for PYY. In silico analysis of the NUCB1 amino acid sequence found a 77 amino acid NLP. Mouse pancreatic islets and MIN6 cells express NUCB1 mRNA and protein. NUCB1 was co-localized with insulin in mouse pancreatic islets. While treatment of cells with synthetic NLP increased preproinsulin mRNA expression and secretion, a scrambled peptide based on NLP was ineffective, indicating that the specific amino acid sequence is crucial for its insulinotropic action. Overall, the data presented supports the hypotheses. The studies reaffirm NUCB2 expression in intestine and provide the first set of evidence for nesfatin-1 regulation of enteric hormones. It also found a novel NUCB1 encoded insulinotropic NLP that could elicit other functions of nesfatin-1.
      Degree
      Master of Science (M.Sc.)
      Department
      Veterinary Biomedical Sciences
      Program
      Veterinary Biomedical Sciences
      Committee
      Unniappan, Suraj; Loewen, Matthew; Machin, Karen
      Copyright Date
      May 2015
      URI
      http://hdl.handle.net/10388/12640
      Subject
      Nucleobindins
      Nesfatin-1
      Nesfatin-1-Like Peptide
      Enteric Hormones
      Insulin
      Collections
      • Graduate Theses and Dissertations
      University of Saskatchewan

      University Library

      © University of Saskatchewan
      Contact Us | Disclaimer | Privacy