Sonic Hedgehog mediator Gli2 regulates bladder mesenchymal patterning.
OBJECTIVE
Congenital bladder anomalies are a major challenge to pediatric urologists. Understanding the mechanism of bladder development is crucial for advancing patient treatment. Current evidence suggests that Shh (R&D Systems) is an epithelial signal regulating bladder development, although the mechanism of the regulation is still unclear. We examined the regulation of bladder mesenchymal development.


METHODS
Mutation analysis, immunohistochemistry, immunoblot, in situ hybridization, and primary cell culture and transfection were performed. The mesenchyma proximal to the epithelium was defined as the inner zone and that distal to the epithelium was defined as the outer zone.


RESULTS
We found that the Shh transcriptional factor Gli2 and the Shh target gene Bmp4 (R&D Systems) were expressed in the inner mesenchymal zone of the bladder, where active cell proliferation was observed. In Gli2(-/-) bladder primary mesenchymal cell cultures transfection with adenoviruses expressing DeltaNGli2, a constitutionally active form of Gli2, up-regulated Bmp4 expression and promoted cell proliferation. In the outer mesenchymal zone, where Gli2 and Bmp4 expression was not detectable, smooth muscle alpha-actin was expressed. In Gli2(-/-) embryo bladders Bmp4 expression in the inner zone was lost and ectopic smooth muscle was detected in the inner mesenchymal zone. Exogenous Bmp4 (10 ng/ml) in primary smooth muscle cell culture repressed smooth muscle differentiation and repression was partially rescued by the Bmp4 antagonist Noggin (R&D Systems) (300 ng/ml).


CONCLUSIONS
Our data suggests that the Shh transcriptional factor Gli2 regulates radial patterning of the bladder mesenchyma.
Cheng
Wei
W
Division of Paediatric Surgery, Department of Paediatrics, Monash University, Melbourne, Australia. wei.cheng3@gmail.com
Yeung
Chung-Kwong
CK
Ng
Yuen-Keng
YK
Zhang
Jian-Rong
JR
Hui
Chi-Chung
CC
Kim
Peter C W
PC
D000704:Analysis of Variance; D000818:Animals; D049109:Cell Proliferation; D004195:Disease Models, Animal; D005260:Female; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins / Q000235:genetics* / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D051741:Kruppel-Like Transcription Factors / Q000235:genetics* / Q000378:metabolism; D008648:Mesoderm / Q000196:embryology / Q000473:pathology*; D051379:Mice; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011270:Pregnancy, Animal; D011336:Probability; D012313:RNA / Q000032:analysis; D051381:Rats; D012680:Sensitivity and Specificity; D014162:Transfection; D001743:Urinary Bladder / Q000196:embryology* / Q000473:pathology*; D000075746:Zinc Finger Protein Gli2
C000618551:Gli2 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; C509239:SHH protein, human; D000075746:Zinc Finger Protein Gli2; D012313:RNA