Gastroenterology
Volume 137, Issue 2 , Pages 607-617.e4, August 2009

Synaptic Scaffolding Molecule Binds to and Regulates Vasoactive Intestinal Polypeptide Type-1 Receptor in Epithelial Cells

  • Heon Yung Gee

      Affiliations

    • Department of Pharmacology and Brain Korea 21 Project for Medical Science, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
    • ,
  • Young Woong Kim

      Affiliations

    • Department of Pharmacology and Brain Korea 21 Project for Medical Science, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
    • ,
  • Min Jae Jo

      Affiliations

    • Department of Pharmacology and Brain Korea 21 Project for Medical Science, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
    • ,
  • Wan Namkung

      Affiliations

    • Department of Pharmacology and Brain Korea 21 Project for Medical Science, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
    • ,
  • Joo Young Kim

      Affiliations

    • Department of Pharmacology and Brain Korea 21 Project for Medical Science, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
    • ,
  • Hyun Woo Park

      Affiliations

    • Department of Pharmacology and Brain Korea 21 Project for Medical Science, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
    • ,
  • Kyung Sik Kim

      Affiliations

    • Department of Surgery, Yonsei University College of Medicine, Seoul, Korea
    • ,
  • Hoguen Kim

      Affiliations

    • Department of Pathology, Yonsei University College of Medicine, Seoul, Korea
    • ,
  • Akemichi Baba

      Affiliations

    • Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
    • ,
  • Jinhee Yang

      Affiliations

    • Creative Research Initiative Center for Synaptogenesis and Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Korea
    • ,
  • Eunjoon Kim

      Affiliations

    • Creative Research Initiative Center for Synaptogenesis and Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Korea
    • ,
  • Kyung Hwan Kim

      Affiliations

    • Department of Pharmacology and Brain Korea 21 Project for Medical Science, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
    • Corresponding Author InformationReprint requests Address requests for reprints to: Min Goo Lee, MD, Department of Pharmacology, Yonsei University College of Medicine, 134 Sinchon-Dong, Seoul 120-752, Korea. fax: (82) 2 313 1894 or Kyung Hwan Kim, MD, Department of Pharmacology, Yonsei University College of Medicine, 134 Sinchon-Dong, Seoul 120-752, Korea
    • ,
  • Min Goo Lee

      Affiliations

    • Department of Pharmacology and Brain Korea 21 Project for Medical Science, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea
    • Corresponding Author InformationReprint requests Address requests for reprints to: Min Goo Lee, MD, Department of Pharmacology, Yonsei University College of Medicine, 134 Sinchon-Dong, Seoul 120-752, Korea. fax: (82) 2 313 1894 or Kyung Hwan Kim, MD, Department of Pharmacology, Yonsei University College of Medicine, 134 Sinchon-Dong, Seoul 120-752, Korea

Received 21 July 2008; accepted 29 January 2009. published online 04 February 2009.

Background & Aims

Vasoactive intestinal polypeptide (VIP) is a principal regulator of fluid and electrolyte secretion in the gastrointestinal system. The VIP type-1 receptor (VPAC1), a class II G-protein-coupled receptor, contains a putative C-terminal PDZ-binding motif. A yeast 2-hybrid screen indicated that the C-terminus of VPAC1 bound to the PDZ domain of synaptic scaffolding molecule (S-SCAM, also known as membrane-associated guanylate kinase inverted-2 [MAGI-2]). We analyzed the association between S-SCAM and VPAC1.

Methods

The biochemical properties and physiologic significance of the interaction between VPAC1 and S-SCAM were examined in heterologous expression systems, T84 colonic epithelial cells, and human pancreas and colon tissues using an integrated molecular and physiologic approach.

Results

The physical interaction between VPAC1 and S-SCAM was confirmed by immunoprecipitation in HEK 293 mammalian cells and human pancreatic and colonic tissues. Immunocytochemical analysis indicated that S-SCAM recruited VPAC1 to the junctional area near the apical end of the lateral membrane in T84 cells. Several lines of evidence revealed that S-SCAM inhibits VPAC1 activation. Overexpression of S-SCAM inhibited VPAC1-mediated cAMP production and agonist-induced VPAC1 internalization in HEK 293 and HeLa cells. In addition, S-SCAM decreased the VPAC1-mediated current through the cystic fibrosis transmembrane conductance regulator in Xenopus oocytes, especially at low concentrations of VIP. Importantly, loss of S-SCAM increased VIP-induced short-circuit currents in T84 monolayers, which endogenously express VPAC1 and S-SCAM.

Conclusions

S-SCAM/MAGI-2 interacts with and regulates VPAC1 intracellular localization in epithelial cells and inhibits VPAC1 agonist-induced activation and internalization.

Abbreviations used in this paper: CFTR, cystic fibrosis transmembrane conductance regulator, GPCR, G-protein-coupled receptor, GRK, G-protein-coupled receptor kinase, Isc, short circuit current, MAGI-2, membrane-associated guanylate kinase inverted-2, MAGUK, membrane-associated guanylate kinase, PDZ, PSD-95/Dlg/ZO-1, SH3, Src homology-3, S-SCAM, synaptic scaffolding molecule, VIP, vasoactive intestinal polypeptide, VPAC1, VIP type-1 receptor, YFP, yellow fluorescent protein

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 H.Y.G. and Y.W.K. contributed equally to this work.

 Conflicts of interest The authors disclose no conflicts.

 Funding Supported by grants KRF-2005-015-E00067 from the Korea Research Foundation and R11-2007-040-01001-0 and R01-2007-000-20710-0 from the Korea Science and Engineering Foundation, Ministry of Education, Science and Technology, Korea.

PII: S0016-5085(09)00169-3

doi:10.1053/j.gastro.2009.01.065

Gastroenterology
Volume 137, Issue 2 , Pages 607-617.e4, August 2009

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