Journal: The Journal of Biological Chemistry
Article Title: Follistatin-like 1 (FSTL1) interacts with Wnt ligands and Frizzled receptors to enhance Wnt/β-catenin signaling in obstructed kidneys in vivo
doi: 10.1016/j.jbc.2022.102010
Figure Lengend Snippet: FSTL1 interacts with canonical Wnt ligands. A , FSTL1 interacts with Wnt1. HEK293T cells were transfected with Wnt1 plasmid in the absence or the presence of FSTL1-HA plasmid. Cell lysates were immunoprecipitated with anti-FSTL1 to pull down Wnt1 ( left panel ). Reciprocal IP was performed ( right panel ). Western blotting was performed on whole lysates and precipitates as indicated. B , FSTL1 interacts with Wnt2 and Wnt3a. HEK293T cells were transfected with FATL1-HA in the absence or the presence of Wnt2-V5 or Wnt3a-V5 plasmid. Cell lysates were immunoprecipitated with IgG or anti-V5 antibody to pull down FSTL1 ( left panel ). Reciprocal IP was also performed ( right panel s ). C , FSTL1 interacts with Wnt8a, Wnt8b, Wnt9a, and Wnt10b. HEK293T cells were transfected with FSTL1-HA in the absence or the presence of V5-tagged Wnt8a, Wnt8b, Wnt9a, and Wnt10b plasmids. Cell lysates were immunoprecipitated with anti-V5, followed by Western blotting with anti-FSTL1 or anti-V5 antibody on the precipitates and lysates as indicated. D , interaction of FSTL1 and Wnt2 occurs in the extracellular space. HEK293T cells were transfected with Wnt2-V5 in the absence or the presence of FSTL1-HA plasmid. Cell culture medium was immunoprecipitated with anti-HA antibody, followed by Western blotting with anti-V5 or anti-HA antibody on the precipitates and medium as indicated. E and F , interaction of FSTL1 and Wnt3a ( E ) or Wnt10b ( F ) occurs in the extracellular space. HEK293T cells were transfected with FSTL1-HA in the absence or the presence of Wnt3a-V5 ( E ) or Wnt10b-V5 ( F ) plasmid. Cell culture medium was immunoprecipitated with anti-V5 antibody, followed by Western blotting with anti-V5 or anti-FSTL1 on the precipitates and medium as indicated. G , ALK3 does not interact with Wnt3a. HEK293T cells were transfected with Wnt3a-V5 in the absence or the presence of FSTL1-HA or ALK3-HA plasmid. Cell lysates were immunoprecipitated with anti-HA antibody, followed by Western blotting with anti-V5 or anti-HA antibody on the precipitates and lysates as indicated. H , FSTL1 interacts with Wnt1 and Wnt3a in the kidney. Lysates from mouse kidneys with UUO for 7 days were immunoprecipitated with a combination of anti-Wnt1 and anti-Wnt3a antibodies or normal IgG, and the precipitates and lysates were subjected to Western blotting as indicated. I , FSTL1 directly interacts with Wnt3a. Recombinant Wnt3a protein (1.5 μg) was incubated with and without recombinant FSTL1 protein (3 μg) in 300 μl Tris-buffered saline/0.1% Triton X-100 overnight at 4 °C. Input samples were collected, and remaining mixtures were incubated with anti-FSTL1 antibodies followed by Protein G agarose. Eluted proteins and inputs were analyzed by Western blotting as indicated. J , domain organization of full-length (FL) and mutant FSTL1 proteins. K , interactions of EC–VWC and EC domains of FSTL1 with Wnt3a. HEK293T cells were transfected with Wnt3a-V5 plasmid in the absence or the presence of FL, EC–VWC, or EC plasmid. Cell lysates were immunoprecipitated with anti-FSTL1. Western blotting was performed on whole lysates and precipitates as indicated. L , VWC but not FS domain of FSTL1 interacts with Wnt3a. HEK293T cells were transfected with Wnt3a-V5 plasmid in the absence or the presence of 3× FLAG-FS or 3× FLAG-VWC plasmid. Cell lysates were immunoprecipitated with anti-FLAG. Western blotting was performed on whole lysates and precipitates as indicated. EC, the extracellular calcium–binding domain; FS, the follistatin-like domain; FSTL1, follistatin-like 1; HA, hemagglutinin; HEK293T, human embryonic kidney 293T cell line; IgG, immunoglobulin G; IP, immunoprecipitation; UUO, unilateral ureteral obstruction; VWC, a domain with homology to von Willebrand factor type C domain.
Article Snippet: To determine whether there are direct interactions between FSTL1 and WNT3a, or between FZD4 and FSTL1, recombinant WNT3a (catalog no.: 315-20; PeproTech), FSTL1 (catalog no.:1738-FN; R&D Systems), and FZD4-Fc (catalog no.: 194-FZ; R&D Systems) proteins were added to Tris-buffered saline/0.1% Triton X-100 at indicated concentrations and incubated overnight at 4 °C.
Techniques: Transfection, Plasmid Preparation, Immunoprecipitation, Western Blot, Cell Culture, Recombinant, Incubation, Saline, Mutagenesis, Binding Assay