WNT-11 SIGNALLING, ITS ROLE IN CARDIOGENESIS AND IDENTIFICATION OF WNT/â-CATENIN PATHWAY TARGET GENES, ACTA UNIVERSITATIS OULUENSIS D Medica 1047
|Kustantaja:||Oulun yliopisto|| |
|Sijainti:||Print Tietotalo|| |
|Tekijät:||RAILO ANTTI|| |
Wnt genes encode secreted signalling molecules that control embryonic development including organogenesis, while dysregulated Wnt signalling is connected to many diseases such as cancer. Specifically, Wnts control a number of cellular processes such as proliferation, adhesion, differentiation and aging. Many Wnt proteins activate the canonical â-catenin signalling pathway that regulates transcription of a still poorly characterized set of target genes. Wnts also transduce their signaling in cells via â-catenin-independent “non-canonical” pathways, which are not well understood. In this study, Wnt-11 signalling mechanisms in a mammalian model cell line and roles of Wnt-11 in heart development were analyzed in detail. In addition the aim was to identify new Wnt target genes by direct chromatin immunoprecipitation and Affymetrix GeneChip assays in the model cells exposed to Wnt-3a.
Our studies reveal that Wnt-11 signalling coordinates the activity of key cell signalling pathways, namely the canonical Wnt/â-catenin, the JNK/AP-1, the NF-êB and PI3K/Akt pathways in the CHO cells. Analysis of the Wnt-11-deficient embryos revealed a crucial role in heart organogenesis. Wnt-11 signalling coordinates cell interactions during assembly of the myocardial wall and Wnt-11 localizes the expression of N-cadherin and â-catenin to specific cellular domains in the embryonic ventricular cardiomyocytes. Collectively these studies reveal that the mammalian Wnt-11 behaves as a non-canonical Wnt and that it is a critical factor in the coordination of heart development. Specifically, it controls components of the cell adhesion machinery. Analysis of the Wnt target genes revealed a highly context-dependent profile in the Wnt-regulated genes. Several new putative target genes were discovered. Out of the candidate Wnt target genes, Disabled-2 was identified as a potential new direct target for Wnt signalling.