Abstract: SA-PO209

Flotillin-2 Is Required to Recruit Slit Diaphragm Protein into Rafts and Mediates Podocyte Injury and Proteinuric Glomerular Disease

Session Information

  • Glomerular: Cell Biology
    November 04, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Glomerular

  • 1003 Glomerular: Cell Biology

Authors

  • Zhang, Li, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China
  • Zhang, Hong, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China
  • Shi, Wei, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China
  • Liang, Xinling, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China
Background

Podocytes are critical in the maintenance of the normal glomerular filtration barrier and is believed to be the target of numerous glomerular diseases leading to proteinuria. Lipid microdomains in podocytes play important roles in the normal cell morphology and glomerular barrier function.Raft proteins are thought to mediate diverse cellular processes. Flotillin-2/reggie-1(Flot-2) is a ubiquitously expressed and highly conserved raft protein. However, the biologic function in podocyte and proteinuric glomerular disease remains unknown.

Results

Here,we identify and describe the functional role of Flot-2 as a novel podocyte-protein of the kidney glomerulus. Our novel studies demonstrate that flot2 expression is significantly reduced in glomerular podocytes of subjects with proteinuric glomerular diseases, and is also markedly reduced in response to podocyte injury induced by Lipopolysaccharide (LPS)/Adriamycin (ADR) in vitro and in vivo.We further find by immunoelectron microscopy that flot2 localizes to the insertion site of the slit diaphragm (SD) of podocytes. Reduced flot2 expression in vitro and in vivo using small interfering RNA and podocyte- specific flot2 knockout causes cytoskeleton disruptions and fails to recruit podocin, nephrin and CD2AP into rafts. Podocyte-specific flot2-deletion develops worse albuminuria, podocyte injury and glomerular pathology in LPS or ADR-induced nephropathy mice. Conversely, overexpression of flot2 in vitro and in vivo podocytes attenuates cytoskeleton disruptions and inhibits the reduction of SD-associated protein podocin, nephrin and CD2AP in lipid rafts. Meanwhile, podocyte injury, albuminuria and pathologic aberrance are prevented in podocyte-specific flot2 overexpression of transgenic mice when challenged with LPS or ADR. Mechanistically, we show that Flot2 and podocin directly interacts with each other via their SPFH domain. Further studies reveal that Krüppel-like factor 15(KLF15) directly bound to the flot2 promoter region, and regulate the expression of flot2 protein.

Conclusion

Thus, our results first indicate that flot-2 is required to recruit slit diaphragm protein into rafts and mediates podocyte injury and proteinuric glomerular disease. Maintaining necessary flot2 would be one potent way to prevent proteinuria kidney diseases.

Funding

  • Government Support - Non-U.S.