The classic mode of G protein-coupled receptor (GPCR)-mediated transactivation of the receptor tyrosine kinase epidermal growth factor receptor (EGFR) transactivation occurs via matrix metalloprotease (MMP)-mediated cleavage of plasma membrane-anchored EGFR ligands. Herein, we show that the Gαs-activating GPCR ligands vasoactive intestinal peptide (VIP) and prostaglandin E2 (PGE2 ) transactivate EGFR through increased cell-surface delivery of the EGFR ligand transforming growth factor-α (TGFα) in polarizing madin-darby canine kidney (MDCK) and Caco-2 cells. This is achieved by PKA-mediated phosphorylation of naked cuticle homolog 2 (NKD2), previously shown to bind TGFα and direct delivery of TGFα-containing vesicles to the basolateral surface of polarized epithelial cells. VIP and PGE2 rapidly activate protein kinase A (PKA) that then phosphorylates NKD2 at Ser-223, a process that is facilitated by the molecular scaffold A-kinase anchoring protein 12 (AKAP12). This phosphorylation stabilized NKD2, ensuring efficient cell-surface delivery of TGFα and increased EGFR activation. Thus, GPCR-triggered, PKA/AKAP12/NKD2-regulated targeting of TGFα to the cell surface represents a new mode of EGFR transactivation that occurs proximal to ligand cleavage by MMPs.

中文翻译：

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蛋白激酶A介导的裸皮表皮同源物2的磷酸化刺激表皮生长因子受体反式激活的转化生长因子α的细胞表面传递。

G蛋白偶联受体（GPCR）介导的酪氨酸激酶表皮生长因子受体（EGFR）活化的经典模式是通过基质金属蛋白酶（MMP）介导的质膜锚定EGFR配体的裂解而发生的。在这里，我们显示激活Gαs的GPCR配体血管活性肠肽（VIP）和前列腺素E2（PGE2）通过增加在极化马丹-达比犬肾中的EGFR配体转化生长因子-α（TGFα）的细胞表面传递而激活EGFR。 （MDCK）和Caco-2细胞。这是通过PKA介导的裸露角质层同源物2（NKD2）的磷酸化来实现的，NKD2先前已显示出可与TGFα结合并将含TGFα的囊泡直接递送至极化上皮细胞的基底外侧表面。VIP和PGE2快速激活蛋白激酶A（PKA），然后在Ser-223处磷酸化NKD2，该过程由分子支架A激酶锚定蛋白12（AKAP12）促进。这种磷酸化稳定了NKD2，确保了TGFα的有效细胞表面递送和增强的EGFR激活。因此，由GPCR触发的PKA / AKAP12 / NKD2调节的TGFα靶向细胞表面代表了一种新的EGFR转激活模式，该模式发生在MMP配体切割的近端。