FGF-7 modulates ureteric bud growth and nephron number in the developing kidney

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 547-554 ◽  
Author(s):  
J. Qiao ◽  
R. Uzzo ◽  
T. Obara-Ishihara ◽  
L. Degenstein ◽  
E. Fuchs ◽  
...  
Keyword(s):  
Expression Patterns ◽  
Body Volume ◽  
Metanephric Mesenchyme ◽  
Nephron Number ◽  
Wild Type ◽  
Ureteric Bud ◽  
Kidney Size ◽  
Bud Growth ◽  
Collecting System

The importance of proportioning kidney size to body volume was established by clinical studies which demonstrated that in-born defecits of nephron number predispose the kidney to disease. As the kidney develops, the expanding ureteric bud or renal collecting system induces surrounding metanephric mesenchyme to proliferate and differentiate into nephrons. Thus, it is likely that nephron number is related to ureteric bud growth. The expression patterns of mRNAs encoding Fibroblast Growth Factor-7 (FGF-7) and its high affinity receptor suggested that FGF-7 signaling may play a role in regulating ureteric bud growth. To test this hypothesis we examined kidneys from FGF-7-null and wild-type mice. Results of these studies demonstrate that the developing ureteric bud and mature collecting system of FGF-7-null kidneys is markedly smaller than wild type. Furthermore, morphometric analyses indicate that mature FGF-7-null kidneys have 30+/−6% fewer nephrons than wild-type kidneys. In vitro experiments demonstrate that elevated levels of FGF-7 augment ureteric bud growth and increase the number of nephrons that form in rodent metanephric kidney organ cultures. Collectively, these results demonstrate that FGF-7 levels modulate the extent of ureteric bud growth during development and the number of nephrons that eventually form in the kidney.

Evolution of gene expression patterns in a model of branching morphogenesis

1999 ◽  
Vol 277 (4) ◽  
pp. F650-F663 ◽  
Author(s):  
Anna Pavlova ◽  
Robert O. Stuart ◽  
Martin Pohl ◽  
Sanjay K. Nigam
Keyword(s):  
Gene Expression ◽  
Differential Expression ◽  
Expression Patterns ◽  
Branching Morphogenesis ◽  
Computational Method ◽  
Metanephric Mesenchyme ◽  
Ureteric Bud ◽  
Cdna Arrays ◽  
Apoptotic Genes ◽  
Collecting System

Branching morphogenesis of the ureteric bud in response to unknown signals from the metanephric mesenchyme gives rise to the urinary collecting system and, via inductive signals from the ureteric bud, to recruitment of nephrons from undifferentiated mesenchyme. An established cell culture model for this process employs cells of ureteric bud origin (UB) cultured in extracellular matrix and stimulated with conditioned media (BSN-CM) from a metanephric mesenchymal cell line (H. Sakurai, E. J. Barros, T. Tsukamoto, J. Barasch, and S. K. Nigam. Proc. Natl. Acad. Sci. USA 94: 6279–6284, 1997.). In the presence of BSN-CM, the UB cells form branching tubular structures reminiscent of the branching ureteric bud. The pattern of gene regulation in this model of branching morphogenesis of the kidney collecting system was investigated using high-density cDNA arrays. Software and analytical methods were developed for the quantification and clustering of genes. With the use of a computational method termed “vector analysis,” genes were clustered according to the direction and magnitude of differential expression in n-dimensional log-space. Changes in gene expression in response to the BSN-CM consisted primarily of differential expression of transcription factors with previously described roles in morphogenesis, downregulation of pro-apoptotic genes accompanied by upregulation of anti-apoptotic genes, and upregulation of a small group of secreted products including growth factors, cytokines, and extracellular proteinases. Changes in expression are discussed in the context of a general model for epithelial branching morphogenesis. In addition, the cDNA arrays were used to survey expression of epithelial markers and secreted factors in UB and BSN cells, confirming the largely epithelial character of the former and largely mesenchymal character of the later. Specific morphologies (cellular processes, branching multicellular cords, etc.) were shown to correlate with the expression of different, but overlapping, genomic subsets, suggesting differences in morphogenetic mechanisms at these various steps in the evolution of branching tubules.

Conditioned medium from a rat ureteric bud cell line in combination with bFGF induces complete differentiation of isolated metanephric mesenchyme

Development ◽  
1996 ◽  
Vol 122 (12) ◽  
pp. 4159-4167 ◽  
Author(s):  
I.D. Karavanova ◽  
L.F. Dove ◽  
J.H. Resau ◽  
A.O. Perantoni
Keyword(s):  
Cell Line ◽  
Conditioned Medium ◽  
Culture System ◽  
Expression Patterns ◽  
Blot Hybridization ◽  
Northern Blot Hybridization ◽  
Metanephric Mesenchyme ◽  
Ureteric Bud ◽  
Nephron Differentiation

Differentiation of metanephric mesenchyme is triggered by an inductive signal(s) from the epithelial ureteric bud. As a result of this induction, most of the metanephric mesenchyme converts into epithelium of a nephron. We have developed and characterized an explant culture system, in which metanephric mesenchyme can grow and completely differentiate in vitro in the absence of an inductive tissue. When separated 13 dpc rat metanephric mesenchymes were cultured in serum-free conditioned medium from a rat ureteric bud cell line (RUB1) in the presence of bFGF and TGFalpha, they were induced to differentiate into nephron epithelia and glomeruli-like structures. The nephric type of differentiation was confirmed by both morphological and molecular criteria and paralleled the developmental changes of nephron differentiation in vivo. Expression patterns of brush-border antigen as well as molecular markers of kidney differentiation Wt1, Lim1, Hgf and c-met, c-ret, Shh, Wnt4, Wnt7b, and Wnt11 were analyzed in explants by whole mount and tissue section in situ hybridization following 1–9 days in culture. The expression of secreted patterning molecules Bmp7 and Wnt7b, but not Shh or Wnt11, were demonstrated by RT-PCR and northern blot hybridization with RNA from the RUB1 cells. Our culture system lends itself to examining the relevance of these and other signaling molecules required for nephron differentiation.

The metanephric blastema differentiates into collecting system and nephron epithelia in vitro

Development ◽  
1995 ◽  
Vol 121 (10) ◽  
pp. 3207-3214 ◽  
Author(s):  
J. Qiao ◽  
D. Cohen ◽  
D. Herzlinger
Keyword(s):  
Cell Fate ◽  
Mesenchymal Cells ◽  
Lacz Gene ◽  
Metanephric Mesenchyme ◽  
Ureteric Bud ◽  
Ureteric Buds ◽  
Collecting System ◽  
Metanephric Blastema

The kidney forms from two tissue populations derived from intermediate mesoderm, the ureteric bud and metanephric mesenchyme. It is currently accepted that metanephric mesenchyme is committed to differentiating into nephrons while the ureteric bud is restricted to forming the renal collecting system. To test this hypothesis, we transferred lacZ into pure metanephric mesenchyme isolated from gestation day 13 rat embryos. The fate of tagged mesenchymal cells and their progeny was characterized after co-culture with isolated ureteric buds. When induced to differentiate by the native inducer of kidney morphogenesis, lineage-tagged mesenchymal cells exhibit the potential to differentiate into collecting system epithelia, in addition to nephrons. The fate of cells deriving from isolated ureteric buds was also examined and results of these lacZ gene transfer experiments indicate that the majority of ureteric bud cells differentiate into the renal collecting system. These cell fate studies combined with in situ morphological observations raise the possibility that collecting system morphogenesis in vivo occurs by growth of the ureteric bud and recruitment of mesenchymal cells from the metanephric blastema. Thus, metanephric mesenchyme may be a pluripotent renal stem population.

Dominant effects of RET receptor misexpression and ligand-independent RET signaling on ureteric bud development

Development ◽  
1999 ◽  
Vol 126 (7) ◽  
pp. 1375-1386 ◽  
Author(s):  
S. Srinivas ◽  
Z. Wu ◽  
C.M. Chen ◽  
V. D'Agati ◽  
F. Costantini
Keyword(s):  
Kidney Development ◽  
Collecting Duct ◽  
Target Cells ◽  
Metanephric Mesenchyme ◽  
Ureteric Bud ◽  
Independent Form ◽  
Normal Expression ◽  
Bud Growth

During kidney development, factors from the metanephric mesenchyme induce the growth and repeated branching of the ureteric bud, which gives rise to the collecting duct system and also induces nephrogenesis. One signaling pathway known to be required for this process includes the receptor tyrosine kinase RET and co-receptor GFR(α)-1, which are expressed in the ureteric bud, and the secreted ligand GDNF produced in the mesenchyme. To examine the role of RET signaling in ureteric bud morphogenesis, we produced transgenic mice in which the pattern of RET expression was altered, or in which a ligand-independent form of RET kinase was expressed. The Hoxb7 promoter was used to express RET throughout the ureteric bud branches, in contrast to its normal expression only at the bud tips. This caused a variable inhibition of ureteric bud growth and branching reminiscent of, but less severe than, the RET knockout phenotype. Manipulation of the level of GDNF, in vitro or in vivo, suggested that this defect was due to insufficient rather than excessive RET signaling. We propose that RET receptors expressed ectopically on ureteric bud trunk cells sequester GDNF, reducing its availability to the normal target cells at the bud tips. When crossed to RET knockout mice, the Hoxb7/RET transgene, which encoded the RET9 isoform, supported normal kidney development in some RET−/− animals, indicating that the other major isoform, RET51, is not required in this organ. Expression of a Hoxb7/RET-PTC2 transgene, encoding a ligand-independent form of RET kinase, caused the development of abnormal nodules, outside the kidney or at its periphery, containing branched epithelial tubules apparently formed by deregulated growth of the ureteric bud. This suggests that RET signaling is not only necessary but is sufficient to induce ureteric bud growth, and that the orderly, centripetal growth of the bud tips is controlled by the spatially and temporally regulated expression of GDNF and RET.

Proteoglycans are required for maintenance of Wnt-11 expression in the ureter tips

Development ◽  
1996 ◽  
Vol 122 (11) ◽  
pp. 3627-3637 ◽  
Author(s):  
A. Kispert ◽  
S. Vainio ◽  
L. Shen ◽  
D.H. Rowitch ◽  
A.P. McMahon
Keyword(s):  
Collecting Duct ◽  
Expression Patterns ◽  
Branching Morphogenesis ◽  
Proteoglycan Synthesis ◽  
Metanephric Mesenchyme ◽  
Ureteric Bud ◽  
Metanephric Kidney ◽  
Specific Factors ◽  
Collecting Duct Epithelium ◽  
Metanephric Blastema

Development of the metanephric kidney requires the concerted interaction of two tissues, the epithelium of the ureteric duct and the metanephric mesenchyme. Signals from the ureter induce the metanephric mesenchyme to condense and proliferate around the ureter tip, reciprocal signals from the mesenchyme induce the ureter tip to grow and to branch. Wnt genes encode secreted glycoproteins, which are candidate mediators of these signaling events. We have identified three Wnt genes with specific, non-overlapping expression patterns in the metanephric kidney, Wnt-4, Wnt-7b and Wnt-11. Wnt-4 is expressed in the condensing mesenchyme and the comma- and S-shaped bodies. Wnt-7b is expressed in the collecting duct epithelium from 13.5 days post coitum onward. Wnt-1l is first expressed in the nephric duct adjacent to the metanephric blastema prior to the outgrowth of the ureteric bud. Wnt-l1 expression in Danforth's short-tail mice suggests that signaling from the mesenchyme may regulate Wnt-ll activation. During metanephric development, Wnt-11 expression is confined to the tips of the branching ureter. Maintenance of this expression is independent of Wnt-4 signaling and mature mesenchymal elements in the kidney. Moreover, Wnt-ll expression is maintained in recombinants between ureter and lung mesenchyme suggesting that branching morphogenesis and maintenance of Wnt-ll expression are independent of metanephric mesenchyme-specific factors. Interference with proteoglycan synthesis leads to loss of Wnt-ll expression in the ureter tip. We suggest that Wnt-11 acts as an autocrine factor within the ureter epithelium and that its expression is regulated at least in part by proteoglycans.

scholarly journals Genetic Dissection of Cadherin Function during Nephrogenesis

2002 ◽  
Vol 22 (5) ◽  
pp. 1474-1487 ◽  
Author(s):  
Ulf Dahl ◽  
Anders Sjödin ◽  
Lionel Larue ◽  
Glenn L. Radice ◽  
Stefan Cajander ◽  
...  
Keyword(s):  
Kidney Development ◽  
Morphological Changes ◽  
Genetic Dissection ◽  
Metanephric Mesenchyme ◽  
Ureteric Bud ◽  
Metanephric Kidney ◽  
The Individual ◽  
Deficient Mice

ABSTRACT The distinct expression of R-cadherin in the induced aggregating metanephric mesenchyme suggests that it may regulate the mesenchymal-epithelial transition during kidney development. To address whether R-cadherin is required for kidney ontogeny, R-cadherin-deficient mice were generated. These mice appeared to be healthy and were fertile, demonstrating that R-cadherin is not essential for embryogenesis. The only kidney phenotype of adult mutant animals was the appearance of dilated proximal tubules, which was associated with an accumulation of large intracellular vacuoles. Morphological analysis of nephrogenesis in R-cadherin −/− mice in vivo and in vitro revealed defects in the development of both ureteric bud-derived cells and metanephric mesenchyme-derived cells. First, the morphology and organization of the proximal parts of the ureteric bud epithelium were altered. Interestingly, these morphological changes correlated with an increased rate of apoptosis and were further supported by perturbed branching and patterning of the ureteric bud epithelium during in vitro differentiation. Second, during in vitro studies of mesenchymal-epithelial conversion, significantly fewer epithelial structures developed from R-cadherin −/− kidneys than from wild-type kidneys. These data suggest that R-cadherin is functionally involved in the differentiation of both mesenchymal and epithelial components during metanephric kidney development. Finally, to investigate whether the redundant expression of other classic cadherins expressed in the kidney could explain the rather mild kidney defects in R-cadherin-deficient mice, we intercrossed R-cadherin −/− mice with cadherin-6−/− , P-cadherin −/−, and N-cadherin +/− mice. Surprisingly, however, in none of the compound knockout strains was kidney development affected to a greater extent than within the individual cadherin knockout strains.

Regulation of BMP7 expression during kidney development

Development ◽  
1998 ◽  
Vol 125 (17) ◽  
pp. 3473-3482 ◽  
Author(s):  
R.E. Godin ◽  
N.T. Takaesu ◽  
E.J. Robertson ◽  
A.T. Dudley
Keyword(s):  
Wnt Signaling ◽  
Kidney Development ◽  
Tooth Development ◽  
Expression Patterns ◽  
Wnt Signaling Pathway ◽  
Sodium Chlorate ◽  
Bmp Signaling ◽  
Proteoglycan Synthesis ◽  
Metanephric Mesenchyme ◽  
Ureteric Bud

Members of the Bone Morphogenetic Protein (BMP) family exhibit overlapping and dynamic expression patterns throughout embryogenesis. However, little is known about the upstream regulators of these important signaling molecules. There is some evidence that BMP signaling may be autoregulative as demonstrated for BMP4 during tooth development. Analysis of BMP7 expression during kidney development, in conjunction with studies analyzing the effect of recombinant BMP7 on isolated kidney mesenchyme, suggest that a similar mechanism may operate for BMP7. We have generated a beta-gal-expressing reporter allele at the BMP7 locus to closely monitor expression of BMP7 during embryonic kidney development. In contrast to other studies, our analysis of BMP7/lacZ homozygous mutant embryos, shows that BMP7 expression is not subject to autoregulation in any tissue. In addition, we have used this reporter allele to analyze the expression of BMP7 in response to several known survival factors (EGF, bFGF) and inducers of metanephric mesenchyme, including the ureteric bud, spinal cord and LiCl. These studies show that treatment of isolated mesenchyme with EGF or bFGF allows survival of the mesenchyme but neither factor is sufficient to maintain BMP7 expression in this population of cells. Rather, BMP7 expression in the mesenchyme is contingent on an inductive signal. Thus, the reporter allele provides a convenient marker for the induced mesenchyme. Interestingly LiCl has been shown to activate the Wnt signaling pathway, suggesting that BMP7 expression in the mesenchyme is regulated by a Wnt signal. Treatment of whole kidneys with sodium chlorate to disrupt proteoglycan synthesis results in the loss of BMP7 expression in the mesenchyme whereas expression in the epithelial components of the kidney are unaffected. Heterologous recombinations of ureteric bud with either limb or lung mesenchyme demonstrate that expression of BMP7 is maintained in this epithelial structure. Taken together, these data indicate that BMP7 expression in the epithelial components of the kidney is not dependent on cell-cell or cell-ECM interactions with the metanephric mesenchyme. By contrast, BMP7 expression in the metanephric mesenchyme is dependent on proteoglycans and possibly Wnt signaling.

Regulation of scute function by extramacrochaete in vitro and in vivo

Development ◽  
1994 ◽  
Vol 120 (12) ◽  
pp. 3595-3603 ◽  
Author(s):  
C.V. Cabrera ◽  
M.C. Alonso ◽  
H. Huikeshoven
Keyword(s):  
Expression Patterns ◽  
Transcription Activation ◽  
Loss Of Function ◽  
Wild Type ◽  
Helix Loop Helix ◽  
In The Wild ◽  
Yeast Assay ◽  
Number Of Cells

The pattern of adult sensilla in Drosophila is established by the dosage-sensitive interaction of two antagonistic groups of genes. Sensilla development is promoted by members of the achaete-scute complex and the daughterless gene whereas it is suppressed by whereas extramacrochaete (emc) and hairy. All these genes encode helix-loop-helix proteins. The products of the achaete-scute complex and daughterless interact to form heterodimers able to activate transcription. In this report, we show that (1) extra-macrochaete forms heterodimers with the achaete, scute, lethal of scute and daughterless products; (2) extramacrochaete inhibits DNA-binding of Achaete, Scute and Lethal of Scute/Daughterless heterodimers and Daughterless homodimers and (3) extramacrochaete inhibits transcription activation by heterodimers in a yeast assay system. In addition, we have studied the expression patterns of scute in wild-type and extramacrochaete mutant imaginal discs. Expression of scute RNA during imaginal development occurs in groups of cells, but high levels of protein accumulate in the nuclei of only a subset of the RNA-expressing cells. The pattern is dynamic and results in a small number of protein-containing cells that correspond to sensillum precursors. extramacrochaete loss-of-function alleles develop extra sensilla and correspondingly display a larger number of cells with scute protein. These cells appear to arise from those that in the wild type already express scute RNA; hence, extramacrochaete is a repressor of scute function whose action may take place post-transcriptionally.

scholarly journals Characterization of the Mycobacterium tuberculosis Sigma Factor SigM by Assessment of Virulence and Identification of SigM-Dependent Genes

2006 ◽  
Vol 75 (1) ◽  
pp. 452-461 ◽  
Author(s):  
Nisheeth Agarwal ◽  
Samuel C. Woolwine ◽  
Sandeep Tyagi ◽  
William R. Bishai
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mouse Model ◽  
Consensus Sequence ◽  
Expression Patterns ◽  
Wild Type ◽  
Time To Death ◽  
Small Set ◽  
Genomic Microarray

ABSTRACT Alternate sigma factors have been implicated in the survival of mycobacteria in response to specific stresses. To characterize the role of SigM in Mycobacterium tuberculosis, a sigM deletion mutant was generated by allelic exchange in the virulent CDC1551 strain. Comparing the wild-type and ΔsigM strains by complete genomic microarray, we observed a low level of baseline expression of sigM in wild-type M. tuberculosis and no significant differences in the gene expression patterns between these two strains. Alternatively, a SigM-overexpressing M. tuberculosis strain was constructed and microarray profiling revealed SigM-dependent expression of a relatively small group of genes, which included four esat-6 homologues: esxE, esxF, esxT, and esxU. An assessment of SigM-dependent promoters from the microarray analysis revealed a putative consensus sequence for M. tuberculosis SigM of −35 GGAAC and −10 CGTCR. In vitro expression studies showed that M. tuberculosis sigM transcripts accumulate slightly in stationary phase and following heat shock. To understand the role of SigM in pathogenesis, the M. tuberculosis sigM deletion strain was compared with the isogenic wild-type strain and the complemented mutant strain for survival in murine macrophages and in the mouse model. The mutant was found to have similar abilities to survive in both the resting and activated J774A.1 macrophages. Mouse organ bacterial burdens indicated that the mutant proliferated and persisted at the same level as that of the wild-type and complemented strains in lung and spleen tissues. In time-to-death experiments in the mouse model, the ΔsigM mutant exhibited lethality times comparable to those observed for the wild-type and complemented strains. These data indicate that M. tuberculosis SigM governs the expression of a small set of genes, including four esat-6 homologues, and that the loss of sigM does not confer a detectable virulence defect in the macrophages and mouse models of infection.

Sign in / Sign up

Export Citation Format

Share Document