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IL-7 Induces an Epitope Masking of<i>γ</i>c Protein in IL-7 Receptor Signaling Complex
Goh, Tae Sik,Jo, Yuna,Lee, Byunghyuk,Kim, Geona,Hwang, Hyunju,Ko, Eunhee,Kang, Seung Wan,Oh, Sae-Ock,Baek, Sun-Yong,Yoon, Sik,Lee, Jung Sub,Hong, Changwan Hindawi Limited 2017 Mediators of inflammation Vol.2017 No.-
<P>IL-7 signaling via IL-7R<I>α</I>and common<I>γ</I>-chain (<I>γ</I>c) is necessary for the development and homeostasis of T cells. Although the delicate mechanism in which IL-7R<I>α</I>downregulation allows the homeostasis of T cell with limited IL-7 has been well known, the exact mechanism behind the interaction between IL-7R<I>α</I>and<I>γ</I>c in the absence or presence of IL-7 remains unclear. Additionally, we are still uncertain as to how only IL-7R<I>α</I>is separately downregulated by the binding of IL-7 from the IL-7R<I>α</I>/<I>γ</I>c complex. We demonstrate here that 4G3, TUGm2, and 3E12 epitope masking of<I>γ</I>c protein are induced in the presence of IL-7, indicating that the epitope alteration is induced by IL-7 binding to the preassembled receptor core. Moreover, the epitope masking of<I>γ</I>c protein is inversely correlated with the expression of IL-7R<I>α</I>upon IL-7 binding, implying that the structural alteration of<I>γ</I>c might be involved in the regulation of IL-7R<I>α</I>expression. The conformational change in<I>γ</I>c upon IL-7 binding may contribute not only to forming the functional IL-7 signaling complex but also to optimally regulating the expression of IL-7R<I>α</I>.</P>
Cho Eunji,Lee Sang Eun,Lee Unghwi,Goh Yuna,Jeong Seonyoung,Choi Junyoung,Jeong Won-Ki,Chang Sunghoe 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-
nArgBP2, a candidate gene for intellectual disability, is a postsynaptic protein critical for dendritic spine development and morphogenesis, and its knockdown (KD) in developing neurons severely impairs spine-bearing excitatory synapse formation. Surprisingly, nArgBP2 KD in mature neurons did not cause morphological defects in the existing spines at rest, raising questions of how it functions in mature neurons. We found that unlike its inaction at rest, nArgBP2 KD completely inhibited the enlargement of dendritic spines during chemically induced long-term potentiation (cLTP) in mature neurons. We further found that nArgBP2 forms condensates in dendritic spines and that these condensates are dispersed by cLTP, which spatiotemporally coincides with spine head enlargement. Condensates with CaMKII phosphorylation-deficient mutant or CaMKII inhibition are neither dispersed nor accompanied by spine enlargement during cLTP. We found that nArgBP2 condensates in spines exhibited liquid-like properties, and in heterologous and in vitro expression systems, nArgBP2 undergoes liquid-liquid phase separation via multivalent intermolecular interactions between SH3 domains and proline-rich domains. It also forms coacervates with CaMKIIα, which is rapidly dissembled by calcium/CaMKIIα-dependent phosphorylation. We further showed that the interaction between nArgBP2 and WAVE1 competes with nArgBP2 phase separation and that blocking the nArgBP2-WAVE1 interaction prevents spine enlargement during cLTP. Together, our results suggest that nArgBP2 at rest is confined to the condensates but is released by CaMKIIα-mediated phosphorylation during synaptic plasticity, which regulates its timely interaction with WAVE1 to induce spine head enlargement in mature neurons.