Basal and antigen-induced exposure of the proline-rich sequence in CD3ε.
Basal and antigen-induced exposure of the proline-rich sequence in CD3ε.
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DOI：
10.4049/jimmunol.1003225
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发表时间：
2011-02-15
期刊：
影响因子：
--
通讯作者：
Gil D
中科院分区：
文献类型：
--
作者：
de la Cruz J;Kruger T;Parks CA;Silge RL;van Oers NS;Luescher IF;Schrum AG;Gil D
CD3ε 胞质尾部含有保守的富含脯氨酸序列 (PRS)，可影响 TCR-CD3 表达和信号转导。尽管 PRS 可以结合胞质接头 Nck 的 SH3.1 结构域，但 PRS 是否可组成性地用于 Nck 结合，或者代表一个通过 TCR-CD3 接合 (CD3Δc) 时的构象变化而暴露的神秘基序，目前尚未解决。此外，顺式作用 CD3ε 富含碱性氨基酸的延伸段 (BRS) 及其独特的磷酸肌醇结合能力可能在多大程度上影响 PRS 可及性尚不清楚。在这项研究中，我们发现新鲜收获的原代胸腺细胞表达低至中等基础水平的 Nck 可接触的 PRS（“开放 CD3”），尽管大多数 TCR-CD3 复合物无法被 Nck 接触（“封闭 CD3”）。 Ag 体内呈递诱导了 open-CD3，占 MHC+ 小鼠胸腺细胞中基础水平的一半。使用抗 CD3 抗体或肽-MHC 配体进行额外刺激，进一步将开放 CD3 升高至基础水平以上，这与抗原结合诱导最大 PRS 暴露的模型一致。我们还发现，APC 诱导的开放 CD3 构象比配体占据的时间更长，从而标记了已参与的受体。最后，CD3ε BRS-磷酸肌醇相互作用在采用初始闭合 CD3 构象或通过 Ab 刺激诱导开放 CD3 方面均不起作用。因此，开放 CD3 的基础水平被 TCR-CD3 接合后更高的诱导水平所取代，涉及 CD3Δc 和 CD3ε PRS 对 Nck 的延长可及性。
The CD3ε cytoplasmic tail contains a conserved proline-rich sequence (PRS) that influences TCR–CD3 expression and signaling. Although the PRS can bind the SH3.1 domain of the cytosolic adapter Nck, whether the PRS is constitutively available for Nck binding or instead represents a cryptic motif that is exposed via conformational change upon TCR–CD3 engagement (CD3Δc) is currently unresolved. Furthermore, the extent to which a cis-acting CD3ε basic amino acid-rich stretch (BRS), with its unique phosphoinositide-binding capability, might impact PRS accessibility is not clear. In this study, we found that freshly harvested primary thymocytes expressed low to moderate basal levels of Nck-accessible PRS (“open-CD3”), although most TCR–CD3 complexes were inaccessible to Nck (“closed-CD3”). Ag presentation in vivo induced open-CD3, accounting for half of the basal level found in thymocytes from MHC+ mice. Additional stimulation with either anti-CD3 Abs or peptide–MHC ligands further elevated open-CD3 above basal levels, consistent with a model wherein antigenic engagement induces maximum PRS exposure. We also found that the open-CD3 conformation induced by APCs outlasted the time of ligand occupancy, marking receptors that had been engaged. Finally, CD3ε BRS–phosphoinositide interactions played no role in either adoption of the initial closed-CD3 conformation or induction of open-CD3 by Ab stimulation. Thus, a basal level of open-CD3 is succeeded by a higher, induced level upon TCR–CD3 engagement, involving CD3Δc and prolonged accessibility of the CD3ε PRS to Nck.
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影响因子：
64.5
作者：
Kuhns MS;Davis MM
通讯作者：
Davis MM
影响因子：
32.4
作者：
Minguet, Susana;Swamy, Mahima;Schamel, Wolfgang W. A.
通讯作者：
Schamel, Wolfgang W. A.
影响因子：
32.4
作者：
LUESCHER, IF;ANJUERE, F;ROMERO, P
通讯作者：
ROMERO, P
影响因子：
4.4
作者：
Gil, Diana;Schrum, Adam G.;Palmer, Ed
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Palmer, Ed
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7.5
作者：
Harder, T;Simons, K
通讯作者：
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