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XB-ART-46464
J Biol Chem October 5, 2012; 287 (41): 34167-78.

Precise regulation of porcupine activity is required for physiological Wnt signaling.

Proffitt KD , Virshup DM .


Abstract
Gradients of diverse Wnt proteins regulate development, renewal, and differentiation. Porcupine (PORCN) is a membrane-bound O-acyltransferase that is required for post-translational modification of all Wnts to enable their transport, secretion, and activity. Mutations in PORCN are associated with focal dermal hypoplasia (FDH), whereas gene deletion causes embryonic lethality in mice. To study the protein in more detail, zinc finger nucleases were used to edit the PORCN genomic locus, establishing two HT1080 fibrosarcoma clones null for PORCN activity that facilitate the study of PORCN structure and function. We establish that PORCN is a key non-redundant node for the regulation of global Wnt signaling because PORCN null cells are completely incapable of autocrine Wnt signaling. The strength of Wnt signaling is exquisitely sensitive to PORCN expression, with a dynamic range of at least 3 orders of magnitude, suggesting that PORCN activity is a key modulator of all Wnt ligand activity. Consistent with this, we find that multiple FDH-associated mutants have only subtle alterations in enzyme activity yet are associated with a severe FDH phenotype. These studies support an essential regulatory role of PORCN in shaping Wnt signaling gradients.

PubMed ID: 22888000
PMC ID: PMC3464525
Article link: J Biol Chem


Species referenced: Xenopus laevis
Genes referenced: actb actl6a adh5 axin2 ctnnb1 dvl2 gusb pla2g4a porcn wnt1 wnt10b wnt2 wnt3 wnt3a wnt4 wnt6 wnt7a wnt7b wnt9a wnt9b


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References [+] :
Barker, Tissue-resident adult stem cell populations of rapidly self-renewing organs. 2010, Pubmed