Abstract: FR-PO245

Nrip2 Is Required for Endocytosis of Lrp6 and Wnt/β-Catenin Signaling Transduction in Zebrafish Pronephric Tubule

Session Information

Category: Cell Biology

  • 202 Apoptosis, Proliferation, Autophagy, Cell Senescence, Cell Transformation

Authors

  • Hou, Qing, Jinling Hospital, Nanjing, China
  • Wang, Ling, National Clinical Research Center of Kidney Disease, Jinling Hospital, Nanjing, China
  • Le, Wei-bo, Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
  • Zeng, Cai-hong, Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
  • Qin, Wei-song, National Clinical Research Center of Kidney Diseases,Jinling Hospital,Nanjing University School of Medicine, Nanjing, China
  • Chen, Zhao-hong, Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
  • Liu, Zhi-Hong, National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing China, Nanjing, China
Background

Low-Density Lipoprotein Receptor-Related Protein 6 (LRP6) functions as a co-receptor for Wnt/β-catenin signaling and as a ligand receptor for endocytosis, which is implicated in pathogenesis of renal damage and transduction of Wnt/β-catenin signaling.

Methods

Here, we identified a nuclear receptor interacting protein 2 (nrip2) as being required for endocytosis of lrp6 in zebrafish. In zebrafish, nrip2 is dynamically and specifically localized in pronephric tubule.

Results

From 24 to 72hpf, nrip2 is dynamically expressed in distal tubule, proximal straight tubule and proximal convoluted tubule, which is examined by in situ hybridization. Global knockout of nrip2 in zebrafish by CRISPR/Cas9 genome editing approach leads to impaired low-molecular fluorescent dextran uptake in proximal tubule comparing with normal control, which is also companied by reduced amount of endocytic apparatus and cilia by Transmission Electron Microscope imaging, and decreased expression of EEA1, an early endosome antigen 1, by Immunoelectron Microscorpe. Interestingly, loss of nrip2 resulted in reduction of lrp6 expression, not lrp2a (megalin). Nrip2 knockdown in Tg(Tcf/Lef-mimiP:dGFP), expressing GFP under the control of β-catenin/TCF responsive elements, resulted in decreased GFP expression. Meanwhile, overexression of nrip2 in HK-2 cells activated total β-catenin and active β-catenin, which means nrip2 is required for activation of Wnt/β-catenin signaling.

Conclusion

Above all, we found that nrip2 is required for endocytosis of lrp6 and transduction of Wnt/β-catenin signaling. Next, we will investigate and demonstrate that Wnt/β-catenin signaling is activated by nrip2 through lrp6.