Transcriptome analysis of primary podocytes reveals novel calcium regulated regulatory networks

Struk T.; Nair V.; Eichinger F.; Kretzler M.; Wedlich-Söldner R.; Bayraktar S.; Pavenstädt H.

Abstract

Podocytes are pivotal in establishing the selective permeability of the glomerular filtration barrier. Recently, we showed that an increase of the intracellular calcium ion concentration [Ca2+] causes a rapid and transient actin reset (CaAR) measurable through live imaging microscopy using lifeact-mCherry as an actin dye in different cell types including the podocyte. This and other studies show the critical role [Ca2+] and the actin cytoskeleton play in podocyte homeostasis. To further investigate the role of [Ca2+] and the actin cytoskeleton in podocytes, we used a double fluorescent reporter mouse model to establish a primary podocyte culture system. We treated these podocytes temporarily with a Calcium Ionophore and facultatively with Latrunculin A, an inhibitor of actin polymerization. Unbiased genome wide transcriptional analysis identified a transcriptional response in podocytes to elevated [Ca2+] levels, affecting mRNA levels of PDGF-BB, RICTOR, and MIR17HG as mediators of Ca2+-signaling. Comparison of the ex vivo transcriptional response from the primary podocyte culture with glomerular transcripts across a wide spectrum of CKD disease confirmed co-regulation of transcript sets, establishing the disease relevance of the model system. Our findings demonstrate novel [Ca2+] regulated gene networks in podocytes deepening our understanding of podocyte biology and disease.