Glomerular transcriptome changes associated with lipopolysaccharide-induced proteinuria

Background: Global gene expression patterns have recently been characterized in normal glomeruli, but gene expression changes that accompany glomerular disease remain poorly characterized.

Method: Here, we mapped global glomerular gene expression profile changes occurring in conjunction with lipopolysaccharide (LPS)-induced proteinuria in mice.

Results: We observed dramatic transcriptional reprogramming in glomeruli in response to LPS, representing some 20% of all genes and about 45% of the genes that are normally highly expressed in glomeruli. Bioinformatic analysis revealed significant changes in transcripts encoding proteins involved in the regulation of adherence junctions, actin cytoskeleton and survival in podocytes. In the LPS-treated mice, we observed dysregulation of genes expressed in glomerular endothelial and mesangial cells and in podocytes, there was also a significant decrease in podocyte number. Moreover, collagen alpha1, alpha2 (IV) and laminin 10 (laminin alpha 5 beta 1 gamma 1), which are expressed in immature glomeruli, were upregulated in the glomeruli of LPS-treated mice, suggesting remodeling of the glomerular basement membrane and activation of mesangial cells. By superimposing the LPS-induced changes onto GlomNet, a protein-protein interaction network was predicted for podocyte proteins affected by LPS.

Conclusions: The detected changes in glomerular gene expression and their involvement in protein interaction networks provide putative markers for early and transient glomerular injury and proteinuria.