Laminin α2-Mediated Podocyte Damage Is a Dominant Driver of Glomerular Disease in Alport Mice
- Glomerular Diseases: Podocyte Biology - II
November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1403 Podocyte Biology
- Cosgrove, Dominic E., Boys Town National Research Hospital, Omaha, Nebraska, United States
- Madison, Jacob D., Boys Town National Research Hospital, Omaha, Nebraska, United States
- Meehan, Daniel T., Boys Town National Research Hospital, Omaha, Nebraska, United States
Earlier work showed that the progressive accumulation of laminin α2 in the GBM activates focal adhesion kinase and NF-kappa B, resulting in elevated expression of pro-inflammatory cytokines and metalloproteinases. The receptor(s) for laminin α2 were never identified, nor the functional consequences of activation of the laminin α2 receptors on podocytes.
Cultured podocytes were overlayed with recombinant laminin 211 (or not) then transfected with either scrambled SiRNA or SiRNA specific for α-dystroglycan (DAG) and RNA analyzed by RNA-seq. Cell signaling characterization was done using the Full Moon Biosystems (Sunnyvale, CA) “cell signaling phospho Ab array”. This platform has 312 antibodies representing the most common cell signaling pathways. We performed this analysis on podocytes transfected with scrambled Si RNA +/- and either α-dystroglycan or integrin α7 knockdown in podocytes treated (or not) with laminin 211.
SiRNA studies show the genes that are most abundant and up regulated by laminin 211 that are normalized by DAG knockdown. This list includes profibrotic genes such as Acta2, Scube3, and TGF-Beta3, as well as genes that up-regulate ECM expression (Ccn2, which encodes CTGF) and Col4A1. KEGG analysis of this data implies important roles for laminin α2-mediated α-dystroglycan receptor activation in cell adhesion and cell migration. Full Moon cell signaling array studies demonstrate that laminin 211-mediated α-dystroglycan and α7β1 integrin signal by both shared and unique signaling pathways and are thus both functioning in laminin 211-mediated signaling in cultured podocytes. Both receptors showed significant activation of PI3K/AKT, Apoptosis, Cell cycle, Jak Stat, NFkappaB, p53, Ras and VEGF signaling pathways. mTor signaling was primarily influenced by integrin α7β1, and the TGF-beta signaling cascade was primarily activated by α-dystroglycan. Thus, the two receptors function both independently and more commonly through co-receptor signaling.
Laminin α2-mediated activation of integrin α7β1 and α-dystroglycan receptors is a major contributor to podocyte damage and glomerular disease progression in Alport mice.
- Other NIH Support