Protein kinase Calpha (PKCalpha) acts upstream of PKCtheta to activate IkappaB kinase and NF-kappaB in T lymphocytes.
Protein kinase Calpha (PKCalpha) acts upstream of PKCtheta to activate IkappaB kinase and NF-kappaB in T lymphocytes.
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蛋白激酶 Calpha (PKCalpha) 在 PKCtheta 上游发挥作用，激活 T 淋巴细胞中的 IkappaB 激酶和 NF-kappaB。
DOI：
10.1128/mcb.23.19.7068-7081.2003
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发表时间：
2003
影响因子：
5.3
通讯作者：
Paya,CarlosV
中科院分区：
文献类型：
--
作者：
Trushin,SergeyA;Pennington,KevinN;Carmona,EvaM;Asin,Susana;Savoy,DorisN;Billadeau,DanielD;Paya,CarlosV
NF-κB 是一种普遍存在的转录因子，是调节免疫反应和炎症的关键。 T 细胞受体 (TCR) 交联导致 NF-κB 激活，这是一种 IκB 激酶 (IKK) 依赖性过程。然而，TCR 激活后调节 IKK 活性的上游激酶仍有待充分表征。在此，我们利用遗传分析、药理学抑制和 RNA 干扰 (RNAi) 证明，在 CD3/CD28 交联触发 T 细胞激活后，IKK 复合物的激活需要传统蛋白激酶 C (PKC) 亚型 PKCα，而不是 PKCβ1。我们发现，在 Ca2+ 流入的情况下，具有催化活性的 PKCαA25E 会诱导 IKK 活性和 NF-κB 依赖性转录；在第 246 和 248 位的两个天冬氨酸突变后，该酶被废除，这是 Ca2+ 与 PKCα 结合和细胞膜募集所必需的。动力学研究表明，TCR/CD28 交联后 IKK 激活的早期阶段（1 至 5 分钟）是 PKCα 依赖性的，IKK 激活的后期阶段（5 至 25 分钟）是 PKCθ 依赖性的。 PKCαA25E 对 IKK 和 NF-κB 依赖性转录的激活会被 PKCθ 抑制剂 rottlerin 或激酶失活形式的 PKCθ 的表达所消除。综上所述，我们的结果表明 PKCα 在 PKCθ 的上游发挥作用，在 TCR 激活后激活 T 淋巴细胞中的 IKK 复合物和 NF-κB。
NF-κB is an ubiquitous transcription factor that is a key in the regulation of the immune response and inflammation. T-cell receptor (TCR) cross-linking leads to NF-κB activation, an IκB kinase (IKK)-dependent process. However, the upstream kinases that regulate IKK activity following TCR activation remain to be fully characterized. Herein, we demonstrate using genetic analysis, pharmacological inhibition, and RNA interference (RNAi) that the conventional protein kinase C (PKC) isoform PKCα, but not PKCβ1, is required for the activation of the IKK complex following T-cell activation triggered by CD3/CD28 cross-linking. We find that in the presence of Ca2+influx, the catalytically active PKCαA25E induces IKK activity and NF-κB-dependent transcription; which is abrogated following the mutations of two aspartates at positions 246 and 248, which are required for Ca2+binding to PKCα and cell membrane recruitment. Kinetic studies reveal that an early phase (1 to 5 min) of IKK activation following TCR/CD28 cross-linking is PKCα dependent and that a later phase (5 to 25 min) of IKK activation is PKCθ dependent. Activation of IKK- and NF-κB-dependent transcription by PKCαA25E is abrogated by the PKCθ inhibitor rottlerin or the expression of the kinase-inactive form of PKCθ. Taken together, our results suggest that PKCα acts upstream of PKCθ to activate the IKK complex and NF-κB in T lymphocytes following TCR activation.