BMP-2 and OP-1 exert direct and opposite effects on renal branching morphogenesis.
The bone morphogenetic proteins, BMP-2 and OP-1, are candidates for growth factors that control renal branching morphogenesis. We examined their effects in embryonic kidney explants and in the mIMCD-3 cell model of collecting duct morphogenesis (mIMCD-3 cells are derived from the terminal inner medullary collecting duct of the SV40 mouse). Osteogenic protein-1 (OP-1), at a dose of 0.25 nM, increased explant growth by 30% (P = 0.001). In contrast, 100-fold greater concentrations of OP-1 (28 nM) decreased explant growth by 10% (P < 0.001). BMP-2 was entirely inhibitory (maximum inhibition of 7% at 5 nM, P < 0.0004). In an in vitro model for branching morphogenesis utilizing the kidney epithelial cell line, mIMCD-3, low doses of OP-1 (< 0.5 nM) increased the number of tubular structures formed by 28 +/- 5% (P = 0.01), whereas concentrations > 0.5 nM decreased that number by 22 +/- 8% (P = 0.02). All concentrations of BMP-2 (0.05-10 nM) were inhibitory (maximum inhibition at 10 nM of 88 +/- 3%, P < 0.0001). Stimulatory doses of OP-1 increased tubular length (P = 0.003) and the number of branch points/structure (3.2-fold increase, P = 0.0005) compared with BMP-2. To determine the molecular basis for these effects, we demonstrated that BMP-2 is bound to mIMCD-3 cells by the type I serine/threonine kinase receptor, ALK-3, and that OP-1 bound to an approximately 80-kDa protein using ligand-receptor affinity assays. To demonstrate that OP-1 can exert both stimulatory and inhibitory effects within a developing kidney, embryonic explants were treated with agarose beads saturated with 2 microM OP-1. OP-1 decreased the number of ureteric bud/collecting duct branches adjacent to the beads by 58 +/- 1% (P < 0.0001). In contrast, the number of branches in tissue distal to the OP-1 beads was enhanced, suggesting a stimulatory effect at lower doses of OP-1. We conclude that OP-1 and BMP-2 directly control branching morphogenesis and that the effects of OP-1 are dependent on its local concentration within developing kidney tissue.
Piscione
T D
TD
Division of Nephrology, Hospital for Sick Children, Toronto, Ontario, Canada.
Yager
T D
TD
Gupta
I R
IR
Grinfeld
B
B
Pei
Y
Y
Attisano
L
L
Wrana
J L
JL
Rosenblum
N D
ND
D029404:Activin Receptors; D030201:Activin Receptors, Type I; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D052006:Bone Morphogenetic Protein Receptors, Type II; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004622:Embryo, Mammalian; D005865:Gestational Age; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000196:embryology*; D007679:Kidney Medulla / Q000166:cytology / Q000187:drug effects; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects; D051379:Mice; D008822:Mice, Transgenic; D009024:Morphogenesis / Q000187:drug effects; D009924:Organ Culture Techniques; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D017978:Receptors, Growth Factor / Q000096:biosynthesis; D018125:Receptors, Transforming Growth Factor beta / Q000096:biosynthesis; D013539:Simian virus 40 / Q000235:genetics; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000494:pharmacology
C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D012333:RNA, Messenger; D017978:Receptors, Growth Factor; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D029404:Activin Receptors; D030201:Activin Receptors, Type I; C498219:Bmpr2 protein, mouse; D052006:Bone Morphogenetic Protein Receptors, Type II