Temporal and contextual orchestration of cardiac fate by WNT-BMP synergy and threshold.
Cardiomyogenic development proceeds with a cascade of intricate signalling events that operate in a temporo-spatial fashion to specify cardiac cell fate during early embryogenesis. In fact, conflicting reports exist regarding the role of Wnt/β-catenin signalling during cardiomyogenesis. Here, we describe a dose-dependent and temporal effect of Wnt/β-catenin signalling on in vitro cardiomyogenesis using embryonic stem cells (ESCs) as a model system. We could demonstrate that canonical Wnt activation during early stage of differentiation either through ligand or by GSK3β inhibition helped in maintaining Oct4 and Nanog expressions, and in parallel, it promoted mesoderm and endoderm inductions. In contrast, it led to attenuation in cardiomyogenesis that was reversed by moderate concentration of DKK1, but not soluble Fz8. However, higher DKK1 could also block cardiomyogenesis, suggesting thereby governance of a particular signalling threshold underlying this developmental event. Interestingly, Wnt signalling activation at early stage modulated BMP4 expression in a stage-specific manner. Wnt activation, synchronized with BMP4 and brachyury up-regulation at early stage, correlated well with mesoderm induction. Conversely, Wnt activation led to BMP4 and Wnt5a down-regulation at late stage culminating in cardiomyogenic attenuation. Our findings suggested the existence of precise regulatory machinery with context-dependent role of Wnt for fine tuning mesoderm induction and its derivatives, through establishment of Wnt gradient during ESCs' differentiation. Moreover, contrary to mere activation/inhibition, a specific threshold of Wnt and BMP and their synergy seemed necessary for providing the guiding cues in orchestrating mesoderm induction and subsequent cardiomyogenesis.
National Centre for Cell Science, Ganeshkhind, Pune, Maharashtra, India.
Mahesh K
MK
Verma
Nibedita
N
Lenka
D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D055415:Bone Morphogenetic Protein 4 / Q000276:immunology / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D004707:Endoderm / Q000166:cytology / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D018398:Homeodomain Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D011485:Protein Binding; D015398:Signal Transduction / Q000187:drug effects; D051820:TCF Transcription Factors / Q000378:metabolism; D013997:Time Factors; D051153:Wnt Proteins / Q000378:metabolism*; D000071818:Wnt-5a Protein; D051176:beta Catenin / Q000378:metabolism
D000906:Antibodies; D055415:Bone Morphogenetic Protein 4; D018398:Homeodomain Proteins; D008164:Luminescent Proteins; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; D051820:TCF Transcription Factors; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; C438615:Wnt5a protein, mouse; D051176:beta Catenin; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3