Cross-talk between bone morphogenetic protein and transforming growth factor-beta signaling is essential for exendin-4-induced insulin-positive differentiation of AR42J cells

J Biol Chem. 2005 Sep 16;280(37):32209-17. doi: 10.1074/jbc.M505465200. Epub 2005 Jul 14.

Abstract

A key goal of cellular engineering is to manipulate progenitor cells to become beta-cells, allowing cell replacement therapy to cure diabetes mellitus. As a paradigm for cell engineering, we have studied the molecular mechanisms by which AR42J cells become beta-cells. Bone morphogenetic proteins (BMPs), implicated in a myriad of developmental pathways, have not been well studied in insulin-positive differentiation. We found that the canonical intracellular mediators of BMP signaling, Smad-1 and Smad-8, were significantly elevated in AR42J cells undergoing insulin-positive differentiation in response to exendin-4 treatment, suggesting a role for BMP signaling in beta-cell formation. Similarly, endogenous BMP-2 ligand and ALK-1 receptor (activin receptor-like kinase-1; known to activate Smads 1 and 8) mRNAs were specifically up-regulated in exendin-4-treated AR42J cells. Surprisingly, Smad-1 and Smad-8 levels were suppressed by the addition of BMP-soluble receptor inhibition of BMP ligand binding to its receptor. Here, insulin-positive differentiation was also ablated. BMP-2 ligand antisense also strongly inhibited Smad-1 and Smad-8 expression, again with the abolition of insulin-positive differentiation. These results demonstrate a previously unrecognized key role for BMP signaling in mediating insulin-positive differentiation through the intracellular Smad signaling pathway. In short, BMP signaling may represent a novel downstream target of exendin-4 (glucagon-like peptide 1) signaling and potentially serve as an upstream regulator of transforming growth factor-beta isoform signaling to differentiate the acinar-like AR42J cells into insulin-secreting cells.

Publication types

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

MeSH terms

  • Animals
  • Benzothiazoles
  • Blotting, Western
  • Bone Morphogenetic Protein 2
  • Bone Morphogenetic Proteins / metabolism*
  • Cell Differentiation
  • DNA Primers / chemistry
  • DNA-Binding Proteins / metabolism
  • Diamines
  • Dose-Response Relationship, Drug
  • Exenatide
  • Glucagon / metabolism
  • Glucagon-Like Peptide 1
  • Insulin / metabolism*
  • Islets of Langerhans
  • Ligands
  • Organic Chemicals / pharmacology
  • Peptide Fragments / metabolism
  • Peptides / metabolism*
  • Phosphoproteins / metabolism
  • Polymerase Chain Reaction
  • Protein Binding
  • Protein Isoforms
  • Protein Precursors / metabolism
  • Quinolines
  • RNA, Messenger / metabolism
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction*
  • Smad Proteins
  • Smad1 Protein
  • Smad5 Protein
  • Smad8 Protein
  • Trans-Activators / metabolism
  • Transforming Growth Factor beta / metabolism*
  • Venoms / metabolism*

Substances

  • Benzothiazoles
  • Bmp2 protein, rat
  • Bone Morphogenetic Protein 2
  • Bone Morphogenetic Proteins
  • DNA Primers
  • DNA-Binding Proteins
  • Diamines
  • Insulin
  • Ligands
  • Organic Chemicals
  • Peptide Fragments
  • Peptides
  • Phosphoproteins
  • Protein Isoforms
  • Protein Precursors
  • Quinolines
  • RNA, Messenger
  • Smad Proteins
  • Smad1 Protein
  • Smad1 protein, rat
  • Smad5 Protein
  • Smad5 protein, rat
  • Smad8 Protein
  • Smad9 protein, rat
  • Trans-Activators
  • Transforming Growth Factor beta
  • Venoms
  • SYBR Green I
  • Glucagon-Like Peptide 1
  • Glucagon
  • Exenatide