Willoughby Lee F, Manent Jan, Allan Kirsten, Lee Han, Portela Marta, Wiede Florian, Warr Coral, Meng Tzu-Ching, Tiganis Tony, Richardson Helena E
Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia.
FEBS J. 2017 Jul;284(14):2231-2250. doi: 10.1111/febs.14118. Epub 2017 Jun 30.
Tyrosine phosphorylation-dependent signalling is coordinated by the opposing actions of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). There is a growing list of adaptor proteins that interact with PTPs and facilitate the dephosphorylation of substrates. The extent to which any given adaptor confers selectivity for any given substrate in vivo remains unclear. Here we have taken advantage of Drosophila melanogaster as a model organism to explore the influence of the SH3/SH2 adaptor protein Dock on the abilities of the membrane (PTP61Fm)- and nuclear (PTP61Fn)-targeted variants of PTP61F (the Drosophila othologue of the mammalian enzymes PTP1B and TCPTP respectively) to repress PTK signalling pathways in vivo. PTP61Fn effectively repressed the eye overgrowth associated with activation of the epidermal growth factor receptor (EGFR), PTK, or the expression of the platelet-derived growth factor/vascular endothelial growth factor receptor (PVR) or insulin receptor (InR) PTKs. PTP61Fn repressed EGFR and PVR-induced mitogen-activated protein kinase signalling and attenuated PVR-induced STAT92E signalling. By contrast, PTP61Fm effectively repressed EGFR- and PVR-, but not InR-induced tissue overgrowth. Importantly, coexpression of Dock with PTP61F allowed for the efficient repression of the InR-induced eye overgrowth, but did not enhance the PTP61Fm-mediated inhibition of EGFR and PVR-induced signalling. Instead, Dock expression increased, and PTP61Fm coexpression further exacerbated the PVR-induced eye overgrowth. These results demonstrate that Dock selectively enhances the PTP61Fm-mediated attenuation of InR signalling and underscores the specificity of PTPs and the importance of adaptor proteins in regulating PTP function in vivo.
酪氨酸磷酸化依赖性信号传导由蛋白酪氨酸激酶（PTK）和蛋白酪氨酸磷酸酶（PTP）的相反作用协调。与PTP相互作用并促进底物去磷酸化的衔接蛋白的数量日益增加。在体内，任何给定的衔接蛋白对任何给定底物的选择性程度仍不清楚。在这里，我们利用黑腹果蝇作为模式生物，来探究SH3/SH2衔接蛋白Dock对PTP61F的膜靶向变体（PTP61Fm）和核靶向变体（PTP61Fn）（分别是哺乳动物酶PTP1B和TCPTP的果蝇同源物）在体内抑制PTK信号通路能力的影响。PTP61Fn有效抑制了与表皮生长因子受体（EGFR）、PTK激活相关的眼睛过度生长，或血小板衍生生长因子/血管内皮生长因子受体（PVR）或胰岛素受体（InR）PTK的表达。PTP61Fn抑制了EGFR和PVR诱导的丝裂原活化蛋白激酶信号传导，并减弱了PVR诱导的STAT92E信号传导。相比之下，PTP61Fm有效抑制了EGFR和PVR诱导的，但不是InR诱导的组织过度生长。重要的是，Dock与PTP61F共表达能够有效抑制InR诱导的眼睛过度生长，但并没有增强PTP61Fm介导的对EGFR和PVR诱导信号传导的抑制作用。相反，Dock的表达增加，并且PTP61Fm共表达进一步加剧了PVR诱导的眼睛过度生长。这些结果表明，Dock选择性地增强了PTP61Fm介导的InR信号传导的减弱，并强调了PTP的特异性以及衔接蛋白在体内调节PTP功能中的重要性。
