Precise regulation of porcupine activity is required for physiological Wnt signaling.
Precise regulation of porcupine activity is required for physiological Wnt signaling.
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DOI：
10.1074/jbc.m112.381970
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发表时间：
2012-10-05
期刊：
影响因子：
--
通讯作者：
Virshup DM
中科院分区：
文献类型：
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作者：
Proffitt KD;Virshup DM
背景：Wnts控制发育和分化；它们的分泌可能受到调节。结果：所有 Wnt 活性都绝对需要 O-酰基转移酶 PORCN 的翻译后修饰，其丰度或活性在大动态范围内紧密调节信号传导。结论：PORCN 活性的细微变化会产生重大后果并导致人类局灶性真皮发育不全疾病。意义：PORCN 是所有 Wnt 信号传导的关键调节因子。不同 Wnt 蛋白的梯度调节发育、更新和分化。 Porcupine (PORCN) 是一种膜结合 O-酰基转移酶，是所有 Wnt 翻译后修饰所必需的，以实现其运输、分泌和活性。 PORCN 突变与局灶性真皮发育不全 (FDH) 相关，而基因缺失会导致小鼠胚胎死亡。为了更详细地研究该蛋白质，使用锌指核酸酶编辑 PORCN 基因组位点，建立了两个 PORCN 活性无效的 HT1080 纤维肉瘤克隆，以促进 PORCN 结构和功能的研究。我们确定 PORCN 是调节全局 Wnt 信号传导的关键非冗余节点，因为 PORCN 无效细胞完全不能自分泌 Wnt 信号传导。 Wnt 信号传导的强度对 PORCN 表达极其敏感，动态范围至少为 3 个数量级，表明 PORCN 活性是所有 Wnt 配体活性的关键调节剂。与此一致的是，我们发现多个 FDH 相关突变体仅在酶活性上发生细微变化，但却与严重的 FDH 表型相关。这些研究支持 PORCN 在塑造 Wnt 信号梯度中的重要调节作用。
Background: Wnts control development and differentiation; their secretion may be regulated. Results: All Wnt activity absolutely requires post-translational modification by the O-acyltransferase PORCN, whose abundance or activity modulates signaling tightly and over a large dynamic range. Conclusion: Subtle changes in PORCN activity have major consequences and cause the human disease focal dermal hypoplasia. Significance: PORCN is a key regulator of all Wnt signaling. 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.