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XB-ART-55997
Dev Biol September 1, 2019; 453 (1): 48-55.

PTK7 proteolytic fragment proteins function during early Xenopus development.

Lichtig H , Cohen Y , Bin-Nun N , Golubkov V , Frank D .


Abstract
Protein Tyrosine Kinase 7 (PTK7) is as a critical regulator of canonical and non-canonical Wnt-signaling during embryonic development and cancer cell formation. Disrupting PTK7 activity perturbs vertebrate nervous system development, and also promotes human cancer formation. Observations in different model systems suggest a complex cross-talk between PTK7 protein and Wnt signaling. During Xenopus laevis nervous system development, we previously showed that PTK7 protein positively regulates canonical Wnt signaling by maintaining optimal LRP6 protein levels, but PTK7 also acts in concert with LRP6 protein to repress non-canonical Wnt activity. PTK7 is a transmembrane protein, but studies in cancer cells showed that PTK7 undergoes "shedding" by metalloproteases to different proteolytic fragments. Some PTK7 proteolytic fragments are oncogenic, being localized to alternative cytoplasmic and nuclear cell compartments. In this study we examined the biological activity of two proteolytic carboxyl-terminal PTK7 proteolytic fragments, cPTK7 622-1070 and cPTK7 726-1070 during early Xenopus nervous system development. We found that these smaller PTK7 proteolytic fragments have similar activity to full-length PTK7 protein to promote canonical Wnt-signaling via regulation of LRP6 protein levels. In addition to cancer systems, this study shows in vivo proof that these smaller PTK7 proteolytic fragments can recapitulate full-length PTK7 protein activity in diverse systems, such as vertebrate nervous system development.

PubMed ID: 31125531
Article link: Dev Biol

Genes referenced: acss2.2 egr2 gbx2.2 hesx1 hoxb3 hoxd1 lrp6 mtnr1a myc nodal3.1 odc1 ptk7 sia1 sox2 tub
Morpholinos: ptk7 MO4 ptk7 MO5


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