Crosstalk between Hippo and TGFβ: Subcellular Localization of YAP/TAZ/Smad Complexes.
The Hippo pathway plays a crucial role in growth control, proliferation and tumor suppression. Activity of the signaling pathway is associated with cell density sensing and tissue organization. Furthermore, the Hippo pathway helps to coordinate cellular processes through crosstalk with growth-factor-mediated signaling pathways such as TGFβ. Here we have examined the localization of interactions between proteins of the Hippo pathway (YAP/TAZ) and TGFβ (Smad2/3) signaling pathway by using in situ proximity ligation assays. We investigated the formation of protein complexes between YAP/TAZ and Smad2/3 and examined how these interactions were affected by TGFβ stimulation and cell density in HaCaT keratinocytes and in Smad4-deficient HT29 colon cancer cells. We demonstrate that TGFβ induces formation of YAP/TAZ-Smad2/3 complexes in HaCaT cells. Under sparse cell conditions, the complexes were detected to a higher degree and were predominantly located in the nucleus, while under dense culture conditions, the complexes were fewer and mainly located in the cytoplasm. Surprisingly, we could not detect any YAP/TAZ-Smad2/3 complexes in HT29 cells. To examine if Smad4 deficiency was responsible for the absence of interactions, we treated HaCaT cells with siRNA targeting Smad4. However, we could still observe complex formation in the siRNA-treated cells, suggesting that Smad4 is not essential for the YAP-Smad2/3 interaction. In conclusion, this study shows localized, density-dependent formation of YAP/TAZ-Smad2/3 complexes in HaCaT cells and provides evidence supporting a crosstalk between the Hippo and the TGFβ signaling pathways.
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, 751 85 Uppsala, Sweden.
Karin
K
Grannas
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, 751 85 Uppsala, Sweden.
Linda
L
Arngården
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, 751 85 Uppsala, Sweden.
Peter
P
Lönn
Department of Oncology-Pathology, Karolinska University Hospital, 171 76 Stockholm, Sweden.
Magdalena
M
Mazurkiewicz
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, 751 85 Uppsala, Sweden.
Andries
A
Blokzijl
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, 751 85 Uppsala, Sweden.
Agata
A
Zieba
Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, 751 85 Uppsala, Sweden. Electronic address: Ola.Soderberg@igp.uu.se.
Ola
O
Söderberg
D000217:Acyltransferases; D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis / Q000378:metabolism*; D045744:Cell Line, Tumor; D003106:Colon / Q000378:metabolism / Q000473:pathology; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D000090683:Hippo Signaling Pathway; D006801:Humans; D010750:Phosphoproteins / Q000032:analysis / Q000378:metabolism*; D060066:Protein Interaction Maps; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000378:metabolism*; D015398:Signal Transduction; D051896:Smad Proteins, Receptor-Regulated / Q000032:analysis / Q000378:metabolism*; D051899:Smad2 Protein / Q000032:analysis / Q000378:metabolism; D051900:Smad3 Protein / Q000032:analysis / Q000378:metabolism; D014157:Transcription Factors / Q000032:analysis / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000378:metabolism*; D000091102:YAP-Signaling Proteins
D048868:Adaptor Proteins, Signal Transducing; D010750:Phosphoproteins; C497782:SMAD2 protein, human; D051896:Smad Proteins, Receptor-Regulated; D051899:Smad2 Protein; D051900:Smad3 Protein; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D000091102:YAP-Signaling Proteins; C088374:YAP1 protein, human; D000217:Acyltransferases; C108675:TAFAZZIN protein, human; D017346:Protein Serine-Threonine Kinases
Hippo; Smad; TGFβ; in situ PLA; interaction