Gastrin inhibits cholangiocyte growth in bile duct–ligated rats by interaction with cholecystokinin-B/gastrin receptors via D -myo-inositol 1,4,5-triphosphate–, Ca2+-, and protein kinase C α–dependent mechanisms

Authors

  • Alessandra Caligiuri,

    1. Departments of Internal Medicine, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    Search for more papers by this author
  • Gene LeSage,

    1. Departments of Internal Medicine, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    Search for more papers by this author
  • Leonardo Baiocchi,

    1. Departments of Medical Physiology, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    Search for more papers by this author
  • Noriatsu Kanno,

    1. Departments of Medical Physiology, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    Search for more papers by this author
  • Usha Chowdury,

    1. Departments of Medical Physiology, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    Search for more papers by this author
  • Jo Lynne Phinizy,

    1. Departments of Division of Research and Education, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    Search for more papers by this author
  • Shannon Glaser,

    1. Departments of Division of Research and Education, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    Search for more papers by this author
  • Gianfranco Alpini Ph.D.,

    Corresponding author
    1. Departments of Internal Medicine, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    2. Departments of Medical Physiology, Scott & White Hospital and The Texas A&M University System Health Science Center, College of Medicine
    3. Central Texas Veterans Health Care System, Temple, TX
    • Assistant Professor, Internal Medicine and Medical Physiology, Texas A&M University Health Science Center, College of Medicine and Central Texas Veterans Health Care System, 1901 South 1st Street, Bldg. 147, Temple, TX, 76504.fax: 254-771-5725 or 254-742-7184.
    Search for more papers by this author
  • Antonio Benedetti,

    1. Department of Gastroenterology, University of Ancona, Ancona, Italy
    Search for more papers by this author
  • Luca Marucci,

    1. Department of Gastroenterology, University of Ancona, Ancona, Italy
    Search for more papers by this author
  • Domenico Alvaro,

    1. Division of Gastroenterology, University of Rome, “La Sapienza”, Rome, Italy
    Search for more papers by this author
  • Emanuela Papa

    1. Division of Gastroenterology, University of Rome, “La Sapienza”, Rome, Italy
    Search for more papers by this author

Abstract

We studied the role of gastrin in regulating cholangiocyte proliferation induced by bile duct ligation (BDL). In purified cholangiocytes, we evaluated (1) for the presence of cholecystokinin-B (CCK-B)/gastrin receptors, (2) the effect of gastrin on d -myo-Inositol 1,4,5-triphosphate (IP3) levels, and (3) the effect of gastrin on DNA synthesis and adenosine 3′, 5′-monophosphate (cAMP) levels in the absence or presence of CCK-A (L-364,718) and CCK-B/gastrin (L-365,260) receptor inhibitors, 1,2-bis(2-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid tetrakis(acetxymethyl ester) (BAPTA/AM; an intracellular Ca2+ chelator), and 2 protein kinase C (PKC) inhibitors, 1-(5-Isoquinolinylsulfonyl)-2-methylpiperazine (H7) and staurosporin. To evaluate if gastrin effects on cholangiocyte proliferation are mediated by the isoform PKCα, we evaluated (1) for the presence of PKCα in cholangiocytes and (2) the effect of gastrin on the PKCα protein expression in a triton-soluble (containing cytoplasm + membrane) and a triton-insoluble (containing cytoskeleton) fraction. To evaluate the effects of gastrin in vivo, immediately following BDL, gastrin or bovine serum albumin (BSA) was infused by minipumps for 7 days to rats and we measured cholangiocyte growth and cAMP levels. We found CCK-B/gastrin receptors on cholangiocytes. Gastrin increased IP3 levels. Gastrin inhibited DNA synthesis and cAMP synthesis in cholangiocytes. Gastrin effects on cholangiocyte functions were blocked by L-365,260, BAPTA/AM, H7, and staurosporin but not by L-364,718. Gastrin induced translocation of PKCα from cholangiocyte cytoskeleton to membrane. In vivo, gastrin decreased cholangiocyte growth and cAMP synthesis compared with controls. We concluded that gastrin inhibits cholangiocyte growth in BDL rats by interacting with CCK-B/gastrin receptors through a signal transduction pathway involving IP3, Ca2+, and PKCα.

Ancillary