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Transcriptional Profiling of the Megabladder Mouse - A Unique Model of Bladder Dysmorphogenesis

ABSTRACT: Recent studies in our lab have identified a mutant mouse model of obstructive nephropathy designated mgb for megabladder. Homozygotic mgb mice (mgb-/-) develop lower urinary tract obstruction in utero due to a lack of bladder smooth muscle differentiation. This defect is the result of a random transgene insertion into chromosome 16 followed by a translocation of this fragment into chromosome 11. In an effort to identify potential gene targets affected in mgb mice, we performed transcriptional profiling on embryonic day 15 (E15) mgb-/- bladders using both a Chromosome 11/16 Custom GeneChip Array and the Affymetrix Mouse Genome 430 2.0 GeneChip. This analysis identified no definitive mis-expressed gene targets on chromosome 11. In contrast, mgb-/- mice significantly over-expressed a cluster of gene products located on the translocated fragment of chromosome 16 including urotensin II-related peptide (Urp), which was shown to be preferentially over-expressed in developing mgb-/- bladders. Immunohistochemical studies indicated that the spatial distribution of Urp was altered in mgb-/- bladders, while biochemical studies suggested a potential role for Urp in modifying smooth muscle cell phenotype in vitro. Pathway analysis of mgb microarray data showed dysregulation of at least 60 gene products associated with the differentiation of smooth muscle. In conclusion, the results of this study indicate that the molecular pathways controlling normal smooth muscle development are severely altered in mgb-/- bladders, and provide the first evidence that Urp may play a critical role in bladder smooth muscle development. Keywords: mgb mutant bladders

ORGANISM(S): Mus musculus

PROVIDER: GSE8715 | GEO | 2007/08/09

SECONDARY ACCESSION(S): PRJNA101957

REPOSITORIES: GEO

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Project description:Recent studies in our lab have identified a mutant mouse model of obstructive nephropathy designated mgb for megabladder. Homozygotic mgb mice (mgb-/-) develop lower urinary tract obstruction in utero due to a lack of bladder smooth muscle differentiation. This defect is the result of a random transgene insertion into chromosome 16 followed by a translocation of this fragment into chromosome 11. In an effort to identify potential gene targets affected in mgb mice, we performed transcriptional profiling on embryonic day 15 (E15) mgb-/- bladders using both a Chromosome 11/16 Custom GeneChip Array and the Affymetrix Mouse Genome 430 2.0 GeneChip. This analysis identified no definitive mis-expressed gene targets on chromosome 11. In contrast, mgb-/- mice significantly over-expressed a cluster of gene products located on the translocated fragment of chromosome 16 including urotensin II-related peptide (Urp), which was shown to be preferentially over-expressed in developing mgb-/- bladders. Immunohistochemical studies indicated that the spatial distribution of Urp was altered in mgb-/- bladders, while biochemical studies suggested a potential role for Urp in modifying smooth muscle cell phenotype in vitro. Pathway analysis of mgb microarray data showed dysregulation of at least 60 gene products associated with the differentiation of smooth muscle. In conclusion, the results of this study indicate that the molecular pathways controlling normal smooth muscle development are severely altered in mgb-/- bladders, and provide the first evidence that Urp may play a critical role in bladder smooth muscle development. Keywords: mgb mutant bladders Gene expression profiling was performed on two separate study groups. First, total cellular RNA was isolated from wildtype (n=2; 1 female/1 male), mgb+/- (n=2; 1 female/1 male), and mgb-/- (n=2; 1 female/1 male) E15 whole embryos. Second, total cellular RNA was isolated from the bladders of E15 wildtype (n=7; 3 female/4 male), mgb+/- mice (n=7; 3 female/4 male), and mgb-/- mice (n=11; 7 females/4 males).

Project description:Smooth muscle cells (SMCs) are important in a number of physiological systems and organs, including the cardiovascular system. The hallmark property of differentiated SMCs is the ability to contract, but contractile SMCs themselves show a range of phenotypes allowing prolonged tonic contraction in vascular smooth muscle or rapid phasic contraction in tissues such as bladder. Another distinctive characteristic, in contrast with terminally differentiated striated muscle cells, is that SMCs exhibit phenotypic plasticity. Vascular SMCs are able to modulate their phenotype along a continuum between a contractile phenotype, characteristic of healthy blood vessels, and a more proliferative âsyntheticâ phenotype, so-named for the enhanced synthesis and secretion of extracellular matrix components. Synthetic phenotype cells are found in a number of pathological situations such as atherosclerosis and arterial injury. We used mouse exon-junction (MJAY) arrays to gain insights into both the global contribution of alternative splicing events in re-shaping the transcriptome of dedifferentiating mouse aorta and bladder SMCs, and into the underlying regulatory mechanisms of the alternative splicing program. Affymetrix splice junction arrays (MJAY) were used to profile changes in both alternative splicing and transcript levels during the phenotypic modulation of smooth muscle cells when placed in culture. RNA extracted from intact aorta and bladder smooth muscle tissue was used for differentiated samples. For dedifferentiated, proliferative samples smooth muscle cells were enzymatically dispersed and grown in tissue culture for a week. Triplicate RNA samples were prepared from smooth muscle tissue of mouse aorta and bladder (differentiated) and from smooth muscle cells from each tissue cultured for 7 days (proliferative). The samples allowed comparison of alternative splicing (and other transcriptome) changes between differentiated and proliferative smooth muscle cell samples from two distinct types of smooth muscle cell, as well as allowing direct comparison of aorta (tonic smooth muscle) and bladder (phasic smooth muscle).

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Transcriptional Profiling of the Megabladder Mouse - A Unique Model of Bladder Dysmorphogenesis

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