Sclerostin-erbB-3 interactions: modulation of erbB-3 activity by sclerostin.
To gain insights into the mechanism of action of sclerostin, a protein that regulates bone mass, we performed yeast two-hybrid analyses using human SOST (sclerostin) cDNA cloned into pGBKT7 DNA-binding domain vector as a bait, and a normalized, high-complexity, universal cDNA library in a GAL4 activating domain vector. We identified an interaction between sclerostin and the carboxyl-terminal portion of the receptor tyrosine-protein kinase erbB-3. To determine the biological relevance of this interaction, we treated MC3T3-E1 mouse osteoblast cells transfected with either a SOST expression plasmid or a control vector, with recombinant heregulin/neuregulin. Phospho-p44/42 (Thr202/Tyr204) MAPK was assessed in heregulin/neuregulin treated cells. We observed an increase in phospho-p44/42 (Thr202/Tyr204) MAPK concentrations in SOST transfected cells but not in cells transfected with a control vector, thus demonstrating a modulatory effect of sclerostin on heregulin/neuregulin signaling in osteoblasts. The data demonstrate that sclerostin functions in part, by modulating the activity of erbB-3.
Nephrology and Hypertension Research, Department of Internal Medicine, MS 1-120, Mayo Clinic, 200 1st St., Southwest, Rochester, MN 55905, USA.
Theodore A
TA
Craig
Rajiv
R
Kumar
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D015723:Gene Library; D005819:Genetic Markers / Q000235:genetics; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010006:Osteoblasts / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D048868:Adaptor Proteins, Signal Transducing; D019485:Bone Morphogenetic Proteins; D005819:Genetic Markers; C422903:SOST protein, human; D020893:Receptor, ErbB-3