Cross-talk between bone morphogenetic protein and transforming growth factor-beta signaling is essential for exendin-4-induced insulin-positive differentiation of AR42J cells.
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.
Yew
Kok-Hooi
KH
Department of Surgery Research, The Children's Mercy Hospital, Kansas City, Missouri 64108, USA.
Hembree
Mark
M
Prasadan
Krishna
K
Preuett
Barry
B
McFall
Christopher
C
Benjes
Christina
C
Crowley
Amanda
A
Sharp
Susan
S
Tulachan
Sidhartha
S
Mehta
Sheilendra
S
Tei
Eri
E
Gittes
George
G
D000818:Animals; D052160:Benzothiazoles; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D003959:Diamines; D004305:Dose-Response Relationship, Drug; D000077270:Exenatide; D005934:Glucagon / Q000378:metabolism; D052216:Glucagon-Like Peptide 1; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans; D008024:Ligands; D009930:Organic Chemicals / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D020033:Protein Isoforms; D011498:Protein Precursors / Q000378:metabolism; D011804:Quinolines; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051785:Smad Proteins; D051898:Smad1 Protein; D051902:Smad5 Protein; D051904:Smad8 Protein; D015534:Trans-Activators / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D014688:Venoms / Q000378:metabolism*
D052160:Benzothiazoles; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D003959:Diamines; D007328:Insulin; D008024:Ligands; D009930:Organic Chemicals; D010446:Peptide Fragments; D010455:Peptides; D010750:Phosphoproteins; D020033:Protein Isoforms; D011498:Protein Precursors; D011804:Quinolines; D012333:RNA, Messenger; D051785:Smad Proteins; D051898:Smad1 Protein; C497400:Smad1 protein, rat; D051902:Smad5 Protein; C497799:Smad5 protein, rat; D051904:Smad8 Protein; C109462:Smad9 protein, rat; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D014688:Venoms; C098022:SYBR Green I; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D000077270:Exenatide