Laser Capture Microdissection-Microarray Analysis of Focal Segmental Glomerulosclerosis Glomeruli

Abstract

Focal segmental glomerulosclerosis (FSGS) is a major cause of end-stage renal disease. In this report we used laser capture microdissection to purify diseased glomeruli, and microarrays to provide universal gene expression profiles. The results provide a deeper understanding of the molecular mechanisms of the disease process and suggest novel therapeutic strategies. Consistent with earlier studies, molecular markers of the differentiated podocyte, including WT1, nephrin, and VEGF, were dramatically downregulated in the diseased glomerulus. We also observed multiple changes consistent with increased TGF-β signaling, including elevated expression of TGF-β₂, TGF-β₃, SMAD2, TGF-β₁ receptor, and thrombospondin. In addition, there was relatively low level expression of Csf1r, a marker of macrophages, but elevated expression of the chemokines CXCL1, CXCL2, CCL3, and CXCL14. We also observed strongly upregulated expression of Sox9, a transcription factor that can drive a genetic program of chondrogenesis and fibrosis. Further, the gene with the greatest fold increase in expression in the diseased glomerulus was osteopontin, which has been previously strongly implicated in kidney fibrosis in the unilateral ureteral obstruction mouse model. These results confirm old findings, and indicate the involvement of new genetic pathways in the cause and progression of FSGS.

Podocin Inactivation in Mature Kidneys Causes Focal Segmental Glomerulosclerosis and Nephrotic Syndrome

“…We used microarrays to reveal the perturbations in gene expression in isolated glomeruli at various time points after podocin inactivation and found a molecular signature unique from other, previously published models of FSGS, [43][44][45] thus, confirming the heterogeneity of FSGS depending on the mechanism by which podocyte injury is incurred. Intriguingly, we found that genes involved in cell-cycle regulation were the earliest genes to be transcriptionally activated in our model.…”

Renal macrophage migration and crystal phagocytosis via inflammatory-related gene expression during kidney stone formation and elimination in mice: Detection by association analysis of stone-related gene expression and microstructural observation

“…(19) Cxcl1 encodes chemokine (C-X-C motif) ligand 1 (CXCL1), known as growth-related oncogene 1 (GRO1), which could enhance the adhesion of monocytes to matrix protein, (20) and is involved in the atherogenic recruitment of monocytes. (21) At present, there is no evidence of a relationship between CXCL1 and kidney stone formation; on the other hand, simultaneous increased expression of CXCL1 and OPN in the transplanted kidney, (22) focal segmental glomerulosclerosis glomeruli, (23) and colon cancer (24) suggest that CXCL1 could play an important role with osteopontin in kidney stone formation or elimination. Increased expression of H2-Eb1 (encodes MHC class II) and Tgfb1 (encodes TGF-b1) could be associated with helper T-cell activation via antigen presentation.…”

Sox9 plays multiple roles in the lung epithelium during branching morphogenesis

“…In the heart, Sox9 is required for proper organization the valvular ECM proteins (60), whereas in the gonads, Sox9 regulates many ECM proteins as well as modifiers of the ECM such as matrix metalloproteinases (61,62). Sox9 also plays a role in fibrotic and sclerotic disorders in various tissues, in which Sox9 causes excessive and inappropriate ECM deposition by activating ECM proteins (63)(64)(65)(66)(67)(68). Furthermore, Sox9 plays a critical role during chondrogenesis (30), and ChiP analysis in chondrocytes has shown that Sox9 directly binds to loci of 18 different ECM genes, including Col2a1 (69).…”