IGF-2 is necessary for retinoblastoma-mediated enhanced adaptation after small-bowel resection

J Gastrointest Surg. 2014 Nov;18(11):1887-93. doi: 10.1007/s11605-014-2586-1. Epub 2014 Jul 8.

Abstract

Previously, we have demonstrated that genetically disrupting retinoblastoma protein (Rb) expression in enterocytes results in taller villi, mimicking resection-induced adaption responses. Rb deficiency also results in elevated insulin-like growth factor-2 (IGF-2) expression in villus enterocytes. We propose that postoperative disruption of Rb results in enhanced adaptation which is driven by IGF-2. Inducible, intestine-specific Rb-null mice (iRbIKO) and wild-type (WT) littermates underwent a 50% proximal small-bowel resection (SBR) at 7-9 weeks of age. They were then given tamoxifen on postoperative days (PODs) 4-6 and harvested on POD 28. The experiment was then repeated on double knockouts of both IGF-2 and Rb (IGF-2 null/iRbIKO). iRbIKO mice demonstrated enhanced resection-induced adaptive villus growth after SBR and increased IGF-2 messenger RNA (mRNA) in ileal villus enterocytes compared to their WT littermates. In the IGF-2 null/iRbIKO double-knockout mice, there was no additional villus growth beyond what was expected of normal resection-induced adaptation. Adult mice in which Rb is inducibly deleted from the intestinal epithelium following SBR have augmented adaptive growth. IGF-2 expression is necessary for enhanced adaptation associated with acute intestinal Rb deficiency.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / genetics
  • Animals
  • Apoptosis
  • Blotting, Western
  • Cell Proliferation
  • Disease Models, Animal
  • Enterocytes / metabolism*
  • Immunohistochemistry
  • Insulin-Like Growth Factor II / metabolism*
  • Intestinal Mucosa / metabolism
  • Intestine, Small / pathology
  • Intestine, Small / surgery*
  • Linear Models
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • RNA, Messenger / analysis
  • Random Allocation
  • Real-Time Polymerase Chain Reaction
  • Retinoblastoma Protein / genetics
  • Retinoblastoma Protein / metabolism*
  • Tamoxifen / pharmacology
  • Tissue and Organ Harvesting

Substances

  • RNA, Messenger
  • Retinoblastoma Protein
  • Tamoxifen
  • Insulin-Like Growth Factor II