Expression of Novel Podocyte-Associated Proteins sult1b1 and ankrd25

Abstract

Background/Aims: Podocytes have a unique function in the renal ultrafiltration that is achieved by expressing proteins that are highly specific to podocytes. In this study, we identified two novel podocyte-associated proteins. Methods: The expression of sult1b1 and ankrd25 in mouse tissues was studied by RT-PCR. The protein expression was studied by generating polyclonal antibodies that were used in Western blotting and immunohistochemistry. Results: By RT-PCR we detected sult1b1 expression only in glomerular, liver and brain tissues. By immunohistochemistry, sult1b1 was detected in the kidney exclusively in the Golgi apparatus of the podocyte. No expression outside the glomerulus was observed in the kidney. The ankrd25 transcript was detected in most mouse tissues analyzed by RT-PCR. In the kidney, however, immunohistochemistry showed that this protein was expressed only by podocyte, mesangial, and smooth muscle cells. In podocytes, ankrd25 was localized to foot processes. Conclusions: Identification of these two novel glomerulus-associated proteins opens up possibilities to investigate their role in the renal filter physiology and diseases. We speculate that sult1b1 may be involved in the sulfonylation of podocyte protein podocalyxin, whereas ankrd25 may contribute to controlling actin dynamics in podocyte foot processes.

A role for genetic susceptibility in sporadic focal segmental glomerulosclerosis

“…Since WNK4 was present on both lists, a total of 5 genes were selected for analysis. Because the exact mouse ortholog for human KANK1 is unknown, because Kank2 is more highly expressed in mouse podocytes (49), and because Kank1 and Kank2 were recently identified as susceptibility genes for nephrotic syndrome, we targeted both Kank1 and Kank2. Multiple shRNAs were generated for the 6 candidate genes.…”

KANK deficiency leads to podocyte dysfunction and nephrotic syndrome

“…In addition, this variant was absent from >6,500 controls (from 13,000 control chromosomes) in . For KANK2, a previous study showed that Kank2 mRNA is enriched in glomeruli rather than tubules in the mouse kidney and that KANK2 partially colocalizes with synaptopodin, but not with endothelial marker CD31, in human adult kidney (12). KANK2 localized to podocyte cell bodies as well as nuclei in rat glomeruli ( Figure 2B and Supplemental Figure 2B).…”