GABA induces the differentiation of small into large cholangiocytes by activation of Ca2+/CaMK I-dependent adenylyl cyclase 8§

Authors

  • Romina Mancinelli,

    1. Department of Anatomical, Histological, Forensic Medicine and Orthopedics Sciences, University “Sapienza”, Rome, Italy
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  • Antonio Franchitto,

    1. Department of Anatomical, Histological, Forensic Medicine and Orthopedics Sciences, University “Sapienza”, Rome, Italy
    2. Eleonora Lorillard Spencer Cenci Foundation, Rome, Italy
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  • Shannon Glaser,

    1. Department of Research, Central Texas Veterans Health Care System, Texas A&M Health Science Center, Temple, TX
    2. Scott & White Digestive Disease Research Center, Texas A&M Health Science Center, Temple, TX
    3. Division of Gastroenterology, Department of Medicine College of Medicine, and Texas A&M Health Science Center, Temple, TX
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  • Fanyin Meng,

    1. Department of Research, Central Texas Veterans Health Care System, Texas A&M Health Science Center, Temple, TX
    2. Scott & White Digestive Disease Research Center, Texas A&M Health Science Center, Temple, TX
    3. Division of Gastroenterology, Department of Medicine College of Medicine, and Texas A&M Health Science Center, Temple, TX
    4. Division of Research and Education, Scott & White Digestive Diseases Research Center, Texas A&M Health Science Center, Temple, TX
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  • Paolo Onori,

    1. Experimental Medicine, University of L'Aquila, L'Aquila, Italy
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  • Sharon DeMorrow,

    1. Scott & White Digestive Disease Research Center, Texas A&M Health Science Center, Temple, TX
    2. Division of Gastroenterology, Department of Medicine College of Medicine, and Texas A&M Health Science Center, Temple, TX
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  • Heather Francis,

    1. Department of Research, Central Texas Veterans Health Care System, Texas A&M Health Science Center, Temple, TX
    2. Scott & White Digestive Disease Research Center, Texas A&M Health Science Center, Temple, TX
    3. Division of Gastroenterology, Department of Medicine College of Medicine, and Texas A&M Health Science Center, Temple, TX
    4. Division of Research and Education, Scott & White Digestive Diseases Research Center, Texas A&M Health Science Center, Temple, TX
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  • Julie Venter,

    1. Division of Gastroenterology, Department of Medicine College of Medicine, and Texas A&M Health Science Center, Temple, TX
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  • Guido Carpino,

    1. Department of Health Science, IUSM University of Rome, Italy
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  • Kimberley Baker,

    1. Department of Research, Central Texas Veterans Health Care System, Texas A&M Health Science Center, Temple, TX
    2. Scott & White Digestive Disease Research Center, Texas A&M Health Science Center, Temple, TX
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  • Yuyan Han,

    1. Division of Gastroenterology, Department of Medicine College of Medicine, and Texas A&M Health Science Center, Temple, TX
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  • Yoshiyuki Ueno,

    1. Department Gastroenterology, Yamagata University Faculty of Medicine, Yamagata, Japan
    2. CREST, Yamagata, Japan
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  • Eugenio Gaudio,

    1. Department of Anatomical, Histological, Forensic Medicine and Orthopedics Sciences, University “Sapienza”, Rome, Italy
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    • *E.G. and G.A. share the senior authorship.

  • Gianfranco Alpini

    Corresponding author
    1. Department of Research, Central Texas Veterans Health Care System, Texas A&M Health Science Center, Temple, TX
    2. Scott & White Digestive Disease Research Center, Texas A&M Health Science Center, Temple, TX
    3. Division of Gastroenterology, Department of Medicine College of Medicine, and Texas A&M Health Science Center, Temple, TX
    • Ph.D., Scott & White Digestive Diseases Research Center, Central Texas Veterans Health Care System, Texas A & M Health Science Center College of Medicine, Olin E. Teague Medical Center, 1901 South 1st Street, Building 205, 1R60, Temple, TX 76504===

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    • *E.G. and G.A. share the senior authorship.

    • fax: 254-743-0378


  • Potential conflict of interest: Nothing to report.

  • This work was supported partly by the Dr. Nicholas C. Hightower Centennial Chair of Gastroenterology from Scott & White, the VA Research Scholar Award, a VA Merit Award, the National Institutes of Health (grant nos.: DK062975 and DK76898; to G.A.), and by University funds (to P.O.) and PRIN 2007 and Federate Athenaeum funds from University of Rome “La Sapienza” (to E.G.).

Abstract

Large, but not small, cholangiocytes (1) secrete bicarbonate by interaction with secretin receptors (SRs) through activation of cystic fibrosis transmembrane regulator (CFTR), Cl/HCO3 (apex) anion exchanger 2 (Cl/HCO3 AE2), and adenylyl cyclase (AC)8 (proteins regulating large biliary functions) and (2) proliferate in response to bile duct ligation (BDL) by activation of cyclic adenosine monophosphate (cAMP) signaling. Small, mitotically dormant cholangiocytes are activated during damage of large cholangiocytes by activation of D-myo-inositol 1,4,5-trisphosphate/Ca2+/calmodulin-dependent protein kinase (CaMK) I. gamma-Aminobutyric acid (GABA) affects cell functions by modulation of Ca2+-dependent signaling and AC. We hypothesized that GABA induces the differentiation of small into large cholangiocytes by the activation of Ca2+/CaMK I-dependent AC8. In vivo, BDL mice were treated with GABA in the absence or presence of 1,2-bis-(o-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid, tetraacetoxymethyl ester (BAPTA/AM) or N-(6-aminohexyl)-5-chloro-1-naphtalenesulfonamide (W7) before evaluating apoptosis and intrahepatic bile ductal mass (IBDM) of small and large cholangiocytes. In vitro, control- or CaMK I-silenced small cholangiocytes were treated with GABA for 3 days before evaluating apoptosis, proliferation, ultrastructural features, and the expression of CFTR, Cl/HCO3 AE2, AC8, and secretin-stimulated cAMP levels. In vivo administration of GABA induces the apoptosis of large, but not small, cholangiocytes and decreases large IBDM, but increased de novo small IBDM. GABA stimulation of small IBDM was blocked by BAPTA/AM and W7. Subsequent to GABA in vitro treatment, small cholangiocytes de novo proliferate and acquire ultrastructural and functional phenotypes of large cholangiocytes and respond to secretin. GABA-induced changes were prevented by BAPTA/AM, W7, and stable knockdown of the CaMK I gene. Conclusion: GABA damages large, but not small, cholangiocytes that differentiate into large cholangiocytes. The differentiation of small into large cholangiocytes may be important in the replenishment of the biliary epithelium during damage of large, senescent cholangiocytes. (HEPATOLOGY 2013;)

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