Figure 4. STXBP4 functions in the actin cytoskeleton tension‐mediated Hippo pathway regulation by forming a complex with α‐catenin and a group of Hippo PY motif‐containing proteins. (This figure is related to Appendix Figs S6 and S7; Table EV7).

• A
  A summary map of cytoscape‐generated protein–protein interaction network for STXBP4, α‐catenin, and a group of Hippo pathway proteins.
• B
  STXBP4 forms a protein complex with α‐catenin and a group of Hippo pathway proteins.
• C
  STXBP4 promotes the association of α‐catenin with AMOT and LATS1. HEK293T cells were transfected with the indicated SFB‐tagged constructs and subjected to the pull‐down assay.
• D
  Loss of STXBP4 diminishes the association of α‐catenin with AMOT, LATS1, and YAP. HEK293A and STXBP4 KO cells were transfected with the SFB‐tagged α‐catenin construct and subjected to the pull‐down assay.
• E
  STXBP4 induces the co‐localization between α‐catenin and AMOT as well as LATS1 and YAP. HEK293A cells were transfected with the indicated constructs, and immunofluorescence was performed. Scale bar, 20 μm.
• F–H
  Identification of several STXBP4 missense mutations that disrupt its interaction with α‐catenin and AMOT. The missense mutations within the STXBP4 α‐catenin‐binding region and the 9‐amino acid sequence of the STXBP4 WW domain were indicated and annotated (F). The identified missense mutations, respectively, disrupted the STXBP4‐ α‐catenin (G) and STXBP4‐AMOT (H) complex formation.
• I
  Inhibition of actin cytoskeleton promotes the STXBP4‐associated protein complex formation. HEK293A and the STXBP4 KO cells were subjected to immunoprecipitation using pre‐immune serum and anti‐STXBP4 serum under the indicated treatments.
• J
  The missense mutations of STXBP4 (F) diminished the ability of STXBP4 to rescue YAP phosphorylation in the STXBP4 KO cells with low actin cytoskeleton tension. YAP phosphorylation was detected using phospho‐tag gel, where the YAP phosphorylation level was indicated.

Source data are available online for this figure.