NCBI Summary:
This gene belongs to the evolutionarily conserved porcupine (Porc) gene family. Genes of the Porc family encode endoplasmic reticulum proteins with multiple transmembrane domains. Porcupine proteins are involved in the processing of Wnt (wingless and int homologue) proteins. Multiple alternatively spliced transcript variants encoding distinct isoforms have been observed. [provided by RefSeq, Jul 2008]
General function
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Cellular localization
Other Membrane
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Ovarian function
Early embryo development
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Expression regulated by
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Ovarian localization
Oocyte
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Porcn-dependent Wnt signaling is not required prior to mouse gastrulation. Biechele S et al. In mice and humans the X-chromosomal porcupine homolog (Porcn) gene is required for the acylation and secretion of all 19 Wnt ligands and thus represents a bottleneck for all Wnt signaling. We have generated a mouse line carrying a floxed allele for Porcn and used zygotic, oocyte-specific and visceral endoderm-specific deletions to investigate embryonic and extra-embryonic requirements for Wnt ligand secretion. We show that there is no requirement for Porcn-dependent secretion of Wnt ligands during preimplantation development of the mouse embryo. Porcn-dependent Wnts are first required for the initiation of gastrulation, where Porcn function is required in the epiblast but not the visceral endoderm. Heterozygous female embryos, which are mutant in both trophoblast and visceral endoderm due to imprinted X chromosome inactivation, complete gastrulation but display chorio-allantoic fusion defects similar to Wnt7b mutants. Our studies highlight the importance of Wnt3 and Wnt7b for embryonic and placental development but suggest that endogenous Porcn-dependent Wnt secretion does not play an essential role in either implantation or blastocyst lineage specification.