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Podocyte cell cycle regulation and proliferation in collapsing glomerulopathies
L Barisoni1, M Mokrzycki, L Sablay
1Department of Pathology, New York University, New York 10016, USA. barisoni@yahoo.com
Kidney International
|July 8, 2000
Summary
In collapsing glomerulopathies (CGs), podocyte proliferation occurs due to reduced levels of cell cycle inhibitors p27 and p57. This loss of inhibition drives cyclin A expression and podocyte cell cycle activation in these kidney diseases.
Area of Science:
- Nephrology
- Cell Biology
- Molecular Pathology
Background:
- Mature podocytes are terminally differentiated and typically growth-arrested.
- Under pathological conditions, podocyte mitosis can occur without cell division, except in collapsing glomerulopathies (CGs).
- CGs, including HIV-associated nephropathy (HIVAN) and idiopathic CG, are characterized by podocyte dedifferentiation and proliferation.
Purpose of the Study:
- To investigate the molecular mechanisms driving podocyte proliferation in CG.
- To analyze the expression of key cell cycle regulators and podocyte markers in HIVAN and idiopathic CG.
Main Methods:
- Analysis of proliferation marker Ki-67, cyclins (A, D1), cyclin-dependent kinase inhibitors (p27, p57), and synaptopodin.
- Comparison of eight HIVAN cases, two idiopathic CG cases, and normal kidney controls.
Main Results:
- Significant reduction or absence of p27, p57, and cyclin D1 in affected glomeruli.
- Expression of cyclin A and Ki-67 observed in a subset of glomeruli.
- Partial loss of synaptopodin and cyclin D1 in non-affected glomeruli.
Conclusions:
- Loss of p27 and p57 likely activates the podocyte cell cycle via cyclin A expression in CG.
- Reduced cyclin D1 suggests its role in cell cycle dysregulation in CG.
- Findings highlight podocyte plasticity and offer insights into CG pathogenesis.