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A WT1 co-regulator controls podocyte phenotype by shuttling between adhesion structures and nucleus
Manakan B Srichai1, Martha Konieczkowski, Aparna Padiyar
1Departments of Medicine and Physiology and Biophysics, School of Medicine, Case Western Reserve University and Rammelkamp Center for Research and Education, MetroHealth System Campus, Cleveland, Ohio 44109-1998, USA.
The Journal of Biological Chemistry
|January 23, 2004
Summary
WTIP, a novel WT1-interacting protein, is crucial for kidney podocyte function and may link slit diaphragm assembly to nuclear gene regulation, especially after injury.
Area of Science:
- Nephrology
- Molecular Biology
- Cell Biology
Background:
- Glomerular podocyte differentiation is vital for kidney filtration barrier integrity.
- WT1 (Wilms tumor 1) is a key transcription factor regulating podocyte differentiation.
- Familial focal segmental glomerulosclerosis is linked to chromosome 19q13.1, suggesting involvement of novel genes in this region.
Purpose of the Study:
- To identify and characterize novel proteins interacting with WT1.
- To investigate the role of WT1-interacting protein (WTIP) in podocyte biology and kidney function.
- To explore the potential link between WTIP, WT1, and kidney disease pathogenesis.
Main Methods:
- Yeast two-hybrid assays to identify protein interactions.
- Domain analysis and protein localization studies (in situ hybridization, co-immunoprecipitation).
- Functional assays including transcriptional activation inhibition and leptomycin B treatment.
Main Results:
- A novel WT1-interacting protein, WTIP, was identified and mapped to chromosome 19q13.1.
- WTIP shares structural similarity with zyxin subfamily LIM domain proteins and is developmentally regulated in kidney podocytes.
- WTIP interacts with WT1, influences WT1-dependent transcription, and localizes to podocyte actin spots and cell-cell junctions, translocating to the nucleus upon injury.
Conclusions:
- WTIP is a novel WT1-interacting protein critical for podocyte function.
- WTIP may serve as a molecular link between the slit diaphragm, actin cytoskeleton, and nuclear gene expression.
- WTIP's nuclear shuttling after podocyte injury suggests a role in modulating gene expression in response to damage.