Department of Urology and Prostate Disease Center, University of Florida College of Medicine, Gainesville, FL 32610, USA.
Biochem J. 2013 Jun 15;452(3):411-21. doi: 10.1042/BJ20121004.
AGAP2 [Arf (ADP-ribosylation factor) GAP (GTPase-activating protein) with GTP-binding-protein-like, ankyrin repeat and PH (pleckstrin homology) domains] is a multidomain Arf GAP that was shown to promote the fast recycling of transferrin receptors. In the present study we tested the hypothesis that AGAP2 regulates the trafficking of β2-adrenergic receptors. We found that AGAP2 formed a complex with β-arrestin1 and β-arrestin2, proteins that are known to regulate β2-adrenergic receptor signalling and trafficking. AGAP2 co-localized with β-arrestin2 on the plasma membrane, and knockdown of AGAP2 expression reduced plasma membrane association of β-arrestin2 upon β2-adrenergic receptor activation. AGAP2 also co-localized with internalized β2-adrenergic receptors on endosomes, and overexpression of AGAP2 slowed accumulation of β2-adrenergic receptor in the perinuclear recycling endosomes. In contrast, knockdown of AGAP2 expression prevented the recycling of the β2-adrenergic receptor back to the plasma membrane. In addition, AGAP2 formed a complex with endogenous ERK (extracellular-signal-regulated kinase) and overexpression of AGAP2 potentiated ERK phosphorylation induced by β2-adrenergic receptors. Taken together, these results support the hypothesis that AGAP2 plays a role in the signalling and recycling of β2-adrenergic receptors.
AGAP2（Arf（ADP-ribosylation factor）GAP（GTPase-activating protein）与 GTP 结合蛋白样、锚蛋白重复和 PH（pleckstrin homology）结构域）是一种多结构域的 Arf GAP，它被证明可以促进转铁蛋白受体的快速回收。在本研究中，我们检验了以下假设：AGAP2 调节β2-肾上腺素能受体的运输。我们发现，AGAP2 与β-arrestin1 和 β-arrestin2 形成复合物，β-arrestin1 和 β-arrestin2 是已知调节β2-肾上腺素能受体信号和运输的蛋白质。AGAP2 与β-arrestin2 在质膜上共定位，并且 AGAP2 表达的敲低减少了β2-肾上腺素能受体激活时β-arrestin2 在质膜上的结合。AGAP2 还与内吞的β2-肾上腺素能受体在内体上共定位，并且 AGAP2 的过表达减缓了β2-肾上腺素能受体在核周再循环内体中的积累。相比之下，AGAP2 表达的敲低阻止了β2-肾上腺素能受体返回到质膜的循环。此外，AGAP2 与内源性 ERK（细胞外信号调节激酶）形成复合物，并且 AGAP2 的过表达增强了β2-肾上腺素能受体诱导的 ERK 磷酸化。总之，这些结果支持 AGAP2 在β2-肾上腺素能受体的信号和回收中发挥作用的假设。
