Leptin receptor JAK2/STAT3 signaling modulates expression of Frizzled receptors in articular chondrocytes.
Leptin receptor JAK2/STAT3 signaling modulates expression of Frizzled receptors in articular chondrocytes.
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DOI：
10.1016/j.joca.2010.09.006
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发表时间：
2010-12
影响因子：
7
通讯作者：
Roessler, B. J.
中科院分区：
文献类型：
--
作者：
Ohba, S.;Lanigan, T. M.;Roessler, B. J.
分化的关节软骨细胞表达瘦素受体（LRb）的功能亚型;然而，这些细胞中的瘦素-LRb信号传导却知之甚少。我们假设，瘦素-LRb信号在关节软骨细胞的功能，以调节经典的Wnt信号事件，通过改变卷曲受体的表达。将人软骨细胞系和原代关节软骨细胞在含有血清的生长培养基中生长24小时，然后在处理前将培养基更换为含有1% Nutridoma-SP的DMEM以获得血清缺乏的环境24小时。治疗包括重组人瘦素（10-100 nM）、重组人IL-6（0.3-3 nM）或重组人促红细胞生成素（10 mU/ml）。处理后30分钟至48小时收获细胞，并使用免疫印迹或荧光素酶测定分析全细胞裂解物。用瘦素处理细胞导致JAK 2的激活和随后LRb上特定酪氨酸残基的磷酸化，随后Frizzled-1（Fzd 1）和Frizzled-7（Fzd 7）的表达呈剂量和时间依赖性增加。瘦素介导的Fzd 1和Fzd 7表达的增加被蛋白质合成抑制剂放线菌酮或JAK 2抑制剂AG 490预处理阻断。使用一系列的混合促红细胞生成素胞外结构域瘦素胞内结构域受体（ELR）的细胞质尾中的特定酪氨酸残基的突变的实验表明，Fzd 1和Fzd 7的表达的增加依赖于LRb介导的磷酸化的STAT 3，但不是ERK 1/2或STAT 5。在Wnt-3a刺激之前对软骨细胞进行瘦素预处理导致经典Wnt信号传导的幅度增加。这些实验表明，瘦素-LRb信号在关节软骨细胞调节典型的Wnt信号受体的表达，并表明，这些途径之间的直接串扰是重要的，在确定软骨细胞的稳态。
Differentiated articular chondrocytes express a functional isoform of the leptin receptor (LRb); however, leptin-LRb signaling in these cells is poorly understood. We hypothesized that leptin-LRb signaling in articular chondrocytes functions to modulate canonical Wnt signaling events by altering the expression of Frizzled receptors. Human chondrocyte cell lines and primary articular chondrocytes were grown in serum containing growth media for 24 hrs, followed by a media change to DMEM containing 1% Nutridoma-SP to obtain a serum-deficient environment for 24 hours before treatment. Treatments included recombinant human leptin (10–100 nM), recombinant human IL-6 (0.3-3 nM), or recombinant human erythropoietin (10 mU/ml). Cells were harvested 30 min to 48 hrs after treatment and whole cell lysates were analyzed using immunoblots or luciferase assays. Treatment of cells with leptin resulted in activation of JAK2 and subsequent phosphorylation of specific tyrosine residues on LRb, followed by dose- and time-dependent increases in the expression of Frizzled-1 (Fzd1) and Frizzled-7 (Fzd7). Leptin-mediated increases in the expression of Fzd1 and Fzd7 were blocked by pre-treatment with the protein synthesis inhibitor cycloheximide or the JAK2 inhibitor AG490. Experiments using a series of hybrid erythropoietin extracellular domain-leptin intracellular domain receptors (ELR) harboring mutations of specific tyrosine residues in the cytoplasmic tail showed that increases in the expression of Fzd1 and Fzd7 were dependent on LRb-mediated phosphorylation of STAT3, but not ERK1/2 or STAT5. Leptin pre-treatment of chondrocytes prior to Wnt-3a stimulation resulted in an increased magnitude of canonical Wnt signaling. These experiments show that leptin-LRb signaling in articular chondrocytes modulates expression of canonical Wnt signaling receptors and suggests that direct cross-talk between these pathways is important in determining chondrocyte homeostasis.
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影响因子：
16.2
作者：
Dhillon, H;Zigman, JM;Lowelll, BB
通讯作者：
Lowelll, BB
影响因子：
5
作者：
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通讯作者：
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作者：
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作者：
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作者：
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