Department of Dermatology, Aarhus Sygehus, Aarhus University Hospital, P.P. Oerumsgade 11, Aarhus C DK-8000, Denmark.
Br J Dermatol. 2013 Feb;168(2):302-10. doi: 10.1111/bjd.12049.
The JAK (Janus kinase)/STAT (signal transducer and activator of transcription) signalling pathway is known to play an important role in many cellular processes including inflammation. The activation of STAT1 is dependent on tyrosine 701 and serine 727 phosphorylation, which leads to the formation of the STAT dimer and modulation of STAT1 activity, respectively.
To determine STAT1 expression and activation in psoriatic skin.
Biopsies were collected from patients with psoriasis. mRNA expression was evaluated by quantitative polymerase chain reaction, whereas the protein and phosphorylation level of STAT1 were evaluated by Western blotting. STAT1 localization was determined by immunofluorescence analysis and STAT1-induced transcriptional activity was analysed in cultured human keratinocytes using a reporter assay.
The expression of STAT1 was demonstrated to be significantly increased at both mRNA and protein level in lesional psoriatic skin. In addition, the phosphorylation level of STAT1(Tyr701) and STAT1(Ser727) was significantly increased in lesional compared with nonlesional psoriatic skin. Luciferase assays showed a significant induction of the STAT1-induced transcriptional activity when cultured human keratinocytes were stimulated with either interferon (IFN)-α or IFN-γ. STAT1(Ser727) phosphorylation induced by IFN-α, IFN-γ or ultraviolet B was mediated by a protein kinase C (PKC)-δ- and p38 mitogen-activated protein kinase-dependent mechanism in human keratinocytes, whereas IFN-α-induced STAT1(Tyr701) phosphorylation was mediated by a PKC-δ-dependent mechanism.
This study demonstrates for the first time that the phosphorylation level of STAT1(Tyr701) and STAT1(Ser727) is increased in lesional psoriatic skin. In addition, specific signalling pathways leading to this phosphorylation have been identified. Together, our data indicate an important role of STAT1 in the pathogenesis of psoriasis.
JAK（Janus 激酶）/STAT（信号转导和转录激活因子）信号通路在许多细胞过程中发挥着重要作用，包括炎症。STAT1 的激活依赖于酪氨酸 701 和丝氨酸 727 的磷酸化，分别导致 STAT 二聚体的形成和 STAT1 活性的调节。
确定银屑病皮肤中 STAT1 的表达和激活。
从银屑病患者中采集活检组织。通过定量聚合酶链反应评估 mRNA 表达，通过 Western 印迹评估 STAT1 的蛋白和磷酸化水平。通过免疫荧光分析确定 STAT1 的定位，并通过报告基因分析在培养的人角质形成细胞中分析 STAT1 诱导的转录活性。
在病变银屑病皮肤中，STAT1 的表达在 mRNA 和蛋白水平均显著增加。此外，与非病变银屑病皮肤相比，STAT1（Tyr701）和 STAT1（Ser727）的磷酸化水平显著增加。荧光素酶测定显示，当用干扰素（IFN）-α或 IFN-γ刺激培养的人角质形成细胞时，STAT1 诱导的转录活性显著诱导。IFN-α、IFN-γ 或紫外线 B 诱导的 STAT1（Ser727）磷酸化在人角质形成细胞中通过蛋白激酶 C（PKC）-δ和 p38 丝裂原激活蛋白激酶依赖性机制介导，而 IFN-α 诱导的 STAT1（Tyr701）磷酸化通过 PKC-δ 依赖性机制介导。
本研究首次证明，在病变银屑病皮肤中 STAT1（Tyr701）和 STAT1（Ser727）的磷酸化水平增加。此外，已经确定了导致这种磷酸化的特定信号通路。总之，我们的数据表明 STAT1 在银屑病的发病机制中起着重要作用。
