An in vivo reporter of BMP signaling in organogenesis reveals targets in the developing kidney.
BACKGROUND
Bone morphogenetic proteins (BMPs) regulate essential processes during organogenesis, and a functional understanding of these secreted proteins depends on identification of their target cells. In this study, we generate a transgenic reporter for organogenesis studies that we use to define BMP pathway activation in the developing kidney.


RESULTS
Mouse strains reporting on BMP pathway activation were generated by transgenically expressing beta-galactosidase under the control of BMP responsive elements from Id1. Reporter expression corresponds well with immunoassays for pathway activation in all organs studied, validating the model. Using these reporters we have generated a detailed map of cellular targets of BMP signaling in the developing kidney. We find that SMAD dependent BMP signaling is active in collecting duct trunks, but not tips. Furthermore, glomerular endothelial cells, and proximal nephron tubules from the renal vesicle stage onward show pathway activation. Surprisingly, little activation is detected in the nephrogenic zone of the kidney, and in organ culture BMP treatment fails to activate SMAD dependent BMP signaling in nephron progenitor cells. In contrast, signaling is efficiently induced in collecting duct tips.


CONCLUSIONS
Transgenic reporters driven by control elements from BMP responsive genes such as Id1 offer significant advantages in sensitivity and consistency over immunostaining for studies of BMP pathway activation. They also provide opportunities for analysis of BMP signaling in organ and primary cell cultures subjected to experimental manipulation. Using such a reporter, we made the surprising finding that SMAD dependent BMP signaling is inactive in nephron progenitors, and that these cells are refractory to activation by applied growth factors. Furthermore, we find that the BMP pathway is not normally active in collecting duct tips, but that it can be ectopically activated by BMP treatment, offering a possible explanation for the inhibitory effects of BMP treatment on collecting duct growth and branching.
Blank
Ulrika
U
Department of Molecular Medicine, Maine Medical Center Research Institute, 81 Research Drive, Scarborough, ME 04074, USA. Blanku@mmc.org
Seto
Marianne L
ML
Adams
Derek C
DC
Wojchowski
Don M
DM
Karolak
Michele J
MJ
Oxburgh
Leif
L
D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000502:physiology*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D018390:Gene Targeting; D017930:Genes, Reporter / Q000502:physiology*; D007668:Kidney / Q000196:embryology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D008822:Mice, Transgenic; D038081:Organogenesis / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D051898:Smad1 Protein / Q000096:biosynthesis / Q000235:genetics; D051902:Smad5 Protein / Q000096:biosynthesis / Q000235:genetics; D051904:Smad8 Protein / Q000096:biosynthesis / Q000235:genetics; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
D019485:Bone Morphogenetic Proteins; D051898:Smad1 Protein; D051902:Smad5 Protein; D051904:Smad8 Protein; D001616:beta-Galactosidase
Nature. 2006 Nov 23;444(7118):499-502
17086198
Gene Expr Patterns. 2007 Feb;7(4):491-500
17129766
J Histochem Cytochem. 2007 Mar;55(3):275-85
17142805
Blood. 2007 Mar 1;109(5):1953-61
17068149
J Cell Sci. 2007 Mar 15;120(Pt 6):964-72
17311849
PLoS Genet. 2006 Dec;2(12):e216
17194222
Dev Biol. 2007 Nov 1;311(1):136-46
17869237
Dev Biol. 2007 Nov 15;311(2):679-90
17936743
Mol Cell Biol. 2008 Jan;28(1):248-57
17967875
Development. 2004 Sep;131(18):4593-605
15342483
J Cell Sci. 2004 Sep 15;117(Pt 20):4653-63
15331632
Nat Genet. 2004 Oct;36(10):1117-21
15378062
J Exp Zool. 1968 Feb;167(2):129-50
5692092
Development. 1989 Apr;105(4):707-14
2557196
Genes Dev. 1991 Aug;5(8):1333-44
1907940
Mech Dev. 1995 Mar;50(1):71-83
7605753
Genes Dev. 1995 Nov 15;9(22):2795-807
7590254
Genes Dev. 1995 Nov 15;9(22):2808-20
7590255
Science. 1996 May 3;272(5262):738-41
8614838
Development. 1996 Oct;122(10):2977-86
8898212
Dev Dyn. 1997 Mar;208(3):349-62
9056639
Genes Cells. 1996 Jan;1(1):59-72
9078367
Am J Physiol. 1997 Dec;273(6 Pt 2):F961-75
9435686
Mol Cell. 1998 Mar;1(4):611-7
9660945
Development. 1998 Sep;125(17):3473-82
9693150
J Biol Chem. 1998 Sep 4;273(36):22865-8
9722503
Annu Rev Biochem. 1998;67:753-91
9759503
Mech Dev. 1999 Feb;80(2):181-4
10072785
Development. 1999 Apr;126(8):1631-42
10079226
Development. 1999 Apr;126(8):1753-68
10079236
Genes Dev. 1999 Jun 15;13(12):1601-13
10385628
Development. 1999 Sep;126(18):4005-15
10457010
Development. 2005 Feb;132(3):529-39
15634693
Proc Natl Acad Sci U S A. 2005 Apr 5;102(14):5062-7
15781876
Dev Biol. 2005 May 15;281(2):210-26
15893974
Dev Biol. 2005 Oct 15;286(2):637-46
16154126
Dev Biol. 2006 Mar 1;291(1):67-82
16414041
Dev Dyn. 2008 Jan;237(1):132-44
18069689
Kidney Int. 2008 Jan;73(2):181-91
17943079
J Am Soc Nephrol. 2008 Jan;19(1):117-24
18178801
Genes Dev. 2008 Feb 15;22(4):543-57
18281466
J Am Soc Nephrol. 2008 Apr;19(4):685-94
18272846
Circ Res. 2008 Apr 25;102(8):914-22
18309101
Biol Reprod. 2008 Jun;78(6):994-1001
18322278
J Cell Biochem. 2008 Jun 1;104(3):942-52
18247340
Genesis. 2008 Jul;46(7):335-46
18615729
Dev Biol. 2002 Apr 1;244(1):44-65
11900458
Am J Respir Cell Mol Biol. 2002 Aug;27(2):160-9
12151307
Dev Biol. 2002 Sep 1;249(1):108-20
12217322
Kidney Int. 2003 Jan;63(1):365-76
12472805
Genome Res. 2003 Mar;13(3):476-84
12618378
EMBO J. 2003 May 15;22(10):2453-62
12743039
Cell. 2003 Oct 31;115(3):281-92
14636556
Dev Biol. 2004 Feb 15;266(2):285-98
14738877
Nat Genet. 2000 Feb;24(2):171-4
10655064
Cell. 2000 Jan 21;100(2):229-40
10660046
J Clin Invest. 2000 Apr;105(7):863-73
10749566
Development. 2000 Jul;127(13):2917-31
10851136
Dev Dyn. 2001 Feb;220(2):141-54
11169847
Exp Nephrol. 2001;9(6):372-9
11701996
J Biol Chem. 2002 Feb 15;277(7):4883-91
11729207
Mech Dev. 2002 Mar;112(1-2):207-11
11850197
Proc Natl Acad Sci U S A. 2002 Mar 5;99(5):2878-83
11854453
EMBO J. 2004 Feb 25;23(4):844-56
14963489
Am J Physiol Renal Physiol. 2004 Apr;286(4):F625-33
14656760
Science. 2004 Mar 12;303(5664):1684-6
15017003
J Biol Chem. 2004 Mar 26;279(13):12051-9
14718543
Development. 2004 May;131(9):2205-18
15073157
Oncogene. 2004 Jul 1;23(30):5242-51
15107829
Development. 2004 Aug;131(15):3501-12
15215210
Dev Biol. 2006 Jul 1;295(1):103-15
16630606
Development. 2006 Sep;133(17):3473-84
16887829
Development. 2006 Nov;133(22):4463-73
17035289