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Multiorgan mRNA misexpression in murine autosomal recessive polycystic kidney disease
Vincent H Gattone1, Justin L Ricker, Chad M Trambaugh
1Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA. gattone@anatomy.iupui.edu
Background:
BALB/c mice homozygous for the cpk mutation develop a form of polycystic kidney disease (PKD) with multiorgan pathology similar to human autosomal recessive PKD. Messenger RNA expression in multiple affected organs was analyzed to determine if common gene cascades were misexpressed in the cystic kidney and extrarenal sites of disease. In cystic kidneys, misexpressed mRNAs were found in one of four general groups: proliferation/cell growth, apoptosis, differentiation or extracellular matrix.
Methods:
RNA was isolated from kidney, liver and pancreas of cystic and normal BALB/c-cpk mice. Using Northern blot hybridization and ribonuclease protection assays (RPA), the expression of several genes thought to be associated with PKD, namely c-myc, epidermal growth factor receptor (EGF-R) and PKD-1, were evaluated. RPAs were used to assess mRNA expression of cyclins and members of the bax/bcl-2 family. In addition, kidney, liver and pancreas were immunostained for c-Myc and PCNA.
Results:
Cystic kidney, liver and pancreas all exhibited similar patterns of mRNA misexpression of c-myc, EGF-R and PKD-1. In addition, a number of cell proliferation and apoptosis-related mRNAs also were elevated in cystic kidney and pancreas. Renal epithelial cells expressing proliferation-associated proteins [c-Myc and proliferating cell nuclear antigen (PCNA)] were nearly absent in normal kidney; however, cells of cystic and non-cystic renal tubules plus liver and pancreatic cyst exhibited an increased number of nuclei labeled with antibodies to these proteins.
Conclusions:
These data suggest that similar pathologic mechanisms (including the expression of c-myc, EGF-R, PKD-1, cyclin, and bax/bcl-2 family mRNAs) may be responsible for the development of cystic changes in kidney, liver and pancreas in murine autosomal recessive PKD. Treatments targeting these similarly misexpressed mRNAs may be efficacious in ameliorating the cystic pathology in the kidney as well as the other affected organs in ARPKD.
Insights
BALB/c mice with polycystic kidney disease (PKD) show misexpressed genes in kidneys, liver, and pancreas. These findings suggest common pathways in autosomal recessive PKD, offering targets for treatment.
Area of Science:
- Genetics and Molecular Biology
- Pathology
- Biochemistry
Background:
- BALB/c mice with cpk mutation exhibit polycystic kidney disease (PKD) and multiorgan pathology resembling human autosomal recessive PKD.
- Analysis of messenger RNA (mRNA) expression in affected organs aimed to identify common gene cascades involved in cystic kidney and extrarenal disease sites.
- Misexpressed mRNAs in cystic kidneys were categorized into proliferation/cell growth, apoptosis, differentiation, or extracellular matrix groups.
Purpose of the Study:
- To investigate common gene expression patterns in polycystic kidney disease (PKD) across multiple organs.
- To determine if similar molecular mechanisms underlie cystic changes in the kidney, liver, and pancreas of affected mice.
- To identify potential therapeutic targets by understanding shared gene misexpression in autosomal recessive PKD.
Main Methods:
- RNA isolation from kidney, liver, and pancreas of normal and cystic BALB/c-cpk mice.
- Northern blot hybridization and ribonuclease protection assays (RPA) to evaluate expression of c-myc, epidermal growth factor receptor (EGF-R), and PKD-1.
- RPAs for cyclins and bax/bcl-2 family members; immunostaining for c-Myc and proliferating cell nuclear antigen (PCNA).
Main Results:
- Similar mRNA misexpression patterns of c-myc, EGF-R, and PKD-1 were observed in cystic kidney, liver, and pancreas.
- Elevated cell proliferation and apoptosis-related mRNAs were found in cystic kidney and pancreas.
- Proliferation markers (c-Myc, PCNA) were increased in renal tubules, liver, and pancreatic cysts, but absent in normal kidney epithelium.
Conclusions:
- Pathologic mechanisms involving c-myc, EGF-R, PKD-1, cyclin, and bax/bcl-2 family mRNAs may drive cystic changes in kidney, liver, and pancreas in murine autosomal recessive PKD.
- These findings suggest shared molecular pathways contributing to multiorgan pathology in this PKD model.
- Targeting these misexpressed mRNAs could offer therapeutic strategies for ameliorating cystic pathology in multiple organs in autosomal recessive PKD.