Involvement of β-PIX in Protamine Sulfate Induced Loss of Stress Fibers in Renal Podocytes

Abstract

Degree Project Thesis, Programme in Medicine. TITLE: Involvement of β-PIX in Protamine Sulfate Induced Loss of Stress Fibers in Renal Podocytes. ABSTRACT Dicle Özkan, Peter Mundel, MD & Lisa Buvall, PhD, Master Thesis in Medicine 2014, Department of Neuroscience & Physiology, Gothenburg University/Sahlgrenska Academy, Gothenburg, Sweden & Division of Nephrology at Massachusetts General Hospital & Harvard Medical School, Boston, USA Chronic kidney disease (CKD) is a major cost to the healthcare systems with poor treatment options causing low quality of life among patients. Most CKDs are caused by podocyte damage. Podocyte morphology and stability in the glomerular filtration barrier is controlled by Rho GTPases (RhoA, Rac1 and Cdc42). The Rac1 activating Guanine Nucleotide Exchange Factor (GEF) β-PIX seems to be involved in renal physiology and pathogenesis. Protamine sulfate (PS) has been shown to disrupt the glomerular filtration barrier by up regulating Rac1 and resulting in podocyte stress fiber loss. Here we aimed to investigate the involvement of β-PIX in PS induced stress fiber rearrangement. By using a lentiviral approach to knockdown β-PIX in immortalized mouse podocytes and treating them with PS (600ug/ml) for 1 h we could show that podocyte β-PIX knockdown prevented stress fiber loss when compared to PS treated Scr shRNA (control) infected podocytes, which lost their stress fibers. This data indicate that β-PIX is involved in PS induced podocyte stress fiber loss, probably due to its Rac1 activating properties and demonstrates the importance of β-PIX in renal pathogenesis. Key Words: Chronic kidney disease, glomerular filtration barrier, podocyte, Rho GTPases, β-pix, protamine sulfate