Contreras Esteban G, Gaete Marcia, Sánchez Natalia, Carrasco Héctor, Larraín Juan
Center for Aging and Regeneration, Center for Cell Regulation and Pathology, Faculty of Biological Sciences, P. Universidad Católica de Chile, Alameda 340, Santiago, Chile.
Development. 2009 Sep;136(17):2987-96. doi: 10.1242/dev.035501.
Tail regeneration in Xenopus tadpoles is a favorable model system to understand the molecular and cellular basis of tissue regeneration. Although turnover of the extracellular matrix (ECM) is a key event during tissue injury and repair, no functional studies to evaluate its role in appendage regeneration have been performed. Studying the role of Hyaluronan (HA), an ECM component, is particularly attractive because it can activate intracellular signaling cascades after tissue injury. Here we studied the function of HA and components of the HA pathway in Xenopus tadpole tail regeneration. We found that transcripts for components of this pathway, including Hyaluronan synthase2 (HAS2), Hyaluronidase2 and its receptors CD44 and RHAMM, were transiently upregulated in the regenerative bud after tail amputation. Concomitantly, an increase in HA levels was observed. Functional experiments using 4-methylumbelliferone, a specific HAS inhibitor that blocked the increase in HA levels after tail amputation, and transgenesis demonstrated that the HA pathway is required during the early phases of tail regeneration. Proper levels of HA are required to sustain proliferation of mesenchymal cells in the regenerative bud. Pharmacological and genetic inhibition of GSK3beta was sufficient to rescue proliferation and tail regeneration when HA synthesis was blocked, suggesting that GSK3beta is downstream of the HA pathway. We have demonstrated that HA is an early component of the regenerative pathway and is required for cell proliferation during the early phases of Xenopus tail regeneration. In addition, a crosstalk between HA and GSK3beta signaling during tail regeneration was demonstrated.
非洲爪蟾蝌蚪的尾巴再生是一个用于理解组织再生分子和细胞基础的良好模型系统。尽管细胞外基质(ECM)的更新是组织损伤和修复过程中的关键事件,但尚未进行评估其在附肢再生中作用的功能研究。研究透明质酸(HA)这一ECM成分的作用尤其具有吸引力,因为它在组织损伤后可激活细胞内信号级联反应。在此,我们研究了HA及其信号通路成分在非洲爪蟾蝌蚪尾巴再生中的功能。我们发现,该信号通路成分的转录本,包括透明质酸合酶2(HAS2)、透明质酸酶2及其受体CD44和RHAMM,在尾巴截肢后的再生芽中短暂上调。同时,观察到HA水平升高。使用4-甲基伞形酮(一种特异性HAS抑制剂,可阻断尾巴截肢后HA水平的升高)进行的功能实验以及转基因实验表明,HA信号通路在尾巴再生的早期阶段是必需的。需要适当水平的HA来维持再生芽中间充质细胞的增殖。当HA合成被阻断时,对GSK3β的药理和基因抑制足以挽救增殖和尾巴再生,这表明GSK3β在HA信号通路的下游。我们已经证明,HA是再生信号通路的早期成分,在非洲爪蟾尾巴再生的早期阶段是细胞增殖所必需的。此外,还证明了尾巴再生过程中HA与GSK3β信号之间存在相互作用。