Abstracts are provided in the language submitted.

Glomerular diseases are characterised by a disruption of glomerular permselectivity, often due to damage to glomerular epithelial cells (GECs) or podocytes, which are highly differentiated cells in the glomerular capillary wall. Mechanisms underlying podocyte damage converge on disruption of the cytoskeleton. The Ste20-like kinase SLK is a serine/threonine kinase, which may regulate cytoskeletal structure. Genetic deletion of SLK in mouse podocytes leads to glomerular damage. Previous studies have shown that SLK facilitates assembly and activation of focal adhesion complexes in fibroblasts and that SLK phosphorylates paxillin, a multi-domain adapter protein. The present study aims to identify pathways by which SLK regulates cytoskeletal structure in podocytes, focusing on focal adhesion components paxillin and vinculin. Primary cultured GECs were established from mice with a floxed SLK allele. Cre recombinase was transduced into GECs to delete SLK. Expression and localization of paxillin and vinculin in focal adhesion complexes in knockout and control GECs was evaluated using immunoblotting and immunofluorescence microscopy. Compared to SLK-replete (control) GECs, deletion of SLK reduced the number of paxillin and vinculin particles, as well as the paxillin area. Addition of the podocyte toxin adriamycin decreased both vinculin and paxillin particles, as well as vinculin area in the control cells. Deletion of SLK did not change paxillin and vinculin colocalization or total expression. These results suggest that deletion of SLK in GECs or treatment of GECs with adriamycin may lead to greater focal adhesion complex instability or turnover due to subcellular redistribution of paxillin and vinculin. (246 words)

Craig Bryan