State University of Campinas, Department of Clinical Medicine, Division of Rheumatology, Laboratory of Molecular Biology of Cartilage, SP, Brazil.
Clinics (Sao Paulo). 2012;67(1):35-40. doi: 10.6061/clinics/2012(01)06.
Hypoxia-inducible factor 1 alpha regulates genes related to cellular survival under hypoxia. This factor is present in osteroarthritic chondrocytes, and cytokines, such as interleukin-1 beta, participate in the pathogenesis of osteoarthritis, thereby increasing the activities of proteolytic enzymes, such as matrix metalloproteinases, and accelerating cartilage destruction. We hypothesize that Hypoxia Inducible Factor-1 alpha (HIF-1α) can regulate cytokines (catabolic action) and/or growth factors (anabolic action) in osteoarthritis. The purpose of this study was to investigate the modulation of HIF-1α in human osteoarthritic chondrocytes by interleukin-1 beta (IL-1β) and insulin-like growth factors I (IGF-I) and II (IGF-II) and to determine the involvement of the phosphatidylinositol-3-kinase (PI-3K) pathway in this process.
Human osteroarthritic chondrocytes were stimulated with IL-1β, IGF-I and IGF-II and LY294002, a specific inhibitor of PI-3K. Nuclear protein levels and gene expression were analyzed by western blot and quantitative reverse transcription-polymerase chain reaction analyses, respectively.
HIF-1α expression was upregulated by IL-1β at the protein level but not at the gene level. IGF-I treatment resulted in increases in both the protein and mRNA levels of HIF-1α , whereas IGF-II had no effect on its expression. However, all of these stimuli exploited the PI-3K pathway.
IL-1β upregulated the levels of HIF-1α protein post-transcriptionally, whereas IGF-I increased HIF-1α at the transcript level. In contrast, IGF-II did not affect the protein or gene expression levels of HIF-1α . Furthermore, all of the tested stimuli exploited the PI-3K pathway to some degree. Based on these findings, we are able to suggest that Hypoxia inducible Factor-1 exhibits protective activity in chondrocytes during osteoarthritis.
缺氧诱导因子 1α 调节缺氧条件下细胞存活相关基因。该因子存在于骨关节炎软骨细胞中，细胞因子（如白细胞介素-1β）参与骨关节炎的发病机制，从而增加蛋白水解酶（如基质金属蛋白酶）的活性，加速软骨破坏。我们假设缺氧诱导因子-1α（HIF-1α）可以调节骨关节炎中的细胞因子（分解代谢作用）和/或生长因子（合成代谢作用）。本研究旨在探讨白细胞介素-1β（IL-1β）和胰岛素样生长因子 I（IGF-I）和 II（IGF-II）对人骨关节炎软骨细胞中 HIF-1α 的调节作用，并确定该过程中磷脂酰肌醇-3-激酶（PI-3K）途径的参与。
用白细胞介素-1β（IL-1β）、胰岛素样生长因子 I（IGF-I）和 II（IGF-II）和 LY294002（PI-3K 的特异性抑制剂）刺激人骨关节炎软骨细胞。通过 Western blot 和定量逆转录聚合酶链反应分析分别分析核蛋白水平和基因表达。
IL-1β在蛋白水平而非基因水平上调 HIF-1α 的表达。IGF-I 处理导致 HIF-1α 的蛋白和 mRNA 水平均增加，而 IGF-II 对其表达没有影响。然而，所有这些刺激都利用了 PI-3K 途径。
IL-1β在后转录水平上调 HIF-1α 蛋白水平，而 IGF-I 则在转录水平增加 HIF-1α。相反，IGF-II 对 HIF-1α 的蛋白或基因表达水平没有影响。此外，所有测试的刺激都在某种程度上利用了 PI-3K 途径。基于这些发现，我们可以假设缺氧诱导因子-1 在骨关节炎软骨细胞中具有保护活性。
