Distinct effects of ANGPT2 on gene expression of glomerular podocytes and mesangial cells.

Glomerular diseases are the leading cause of chronic kidney diseases with the pathomechanisms largely unclear. ANGPT2 is known to regulate endothelial cell homeostasis through TEK/Tie2 and its dysregulation causes endothelial damage. Here, we found that ANGPT2 is upregulated in glomerular diseases and wondered whether it also acts on the other two glomerular cell types, podocytes and mesangial cells. We treated podocytes and mesangial cells in culture with ANGPT2 but didn't find changes in morphology and survival. RNA-seq analysis revealed that gene expression was altered in both podocytes and mesangial cells and that the differentially expressed genes in the two cell types were fundamentally different and enriched in distinct cellular processes and pathways according to GO and KEGG analyses. Mechanistically, the Ingenuity Pathway Analysis (IPA) analysis revealed that ERK and AKT were the most connected nodes in the networks of the regulated genes of both podocytes and mesangial cells, suggesting that ANGPT2 affected ERK and AKT in both cell types. Interestingly, immunoblotting showed that phosphorylated ERK and AKT were both increased in podocytes while decreased in mesangial cells by ANGPT2. We found that mesangial cells, but not podocytes, expressed TEK and ANGPT1, suggesting that ANGPT2 could antagonize ANGPT1-TEK-ERK axis in mesangial cells similarly to endothelial cells. We searched databases and found that integrin alpha(v) (ITGAV) is an ANGPT2 interacting protein and expressed in podocytes, suggesting that ITGAV mediates ANGPT2 effect on podocytes. In conclusion, increased ANGPT2 may be involved in glomerular injury by affecting podocytes and mesangial cells in addition to endothelial cells. The complexity of the effect of ANGPT2 in glomeruli may apply to other factors.