Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, Center of Excellence for Cardiovascular and Metabolic Research, The Sahlgrenska Academy at the University of Gothenburg, SE-413 45 Gothenburg, Sweden.
Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, Center of Excellence for Cardiovascular and Metabolic Research, The Sahlgrenska Academy at the University of Gothenburg, SE-413 45 Gothenburg, Sweden.
J Biol Chem. 2014 Mar 7;289(10):6899-6907. doi: 10.1074/jbc.M113.511964. Epub 2014 Jan 22.
WNT1-inducible-signaling pathway protein 2 (WISP2) is primarily expressed in mesenchymal stem cells, fibroblasts, and adipogenic precursor cells. It is both a secreted and cytosolic protein, the latter regulating precursor cell adipogenic commitment and PPARγ induction by BMP4. To examine the effect of the secreted protein, we expressed a full-length and a truncated, non-secreted WISP2 in NIH3T3 fibroblasts. Secreted, but not truncated WISP2 activated the canonical WNT pathway with increased β-catenin levels, its nuclear targeting phosphorylation, and LRP5/6 phosphorylation. It also inhibited Pparg activation and the effect of secreted WISP2 was reversed by the WNT antagonist DICKKOPF-1. Differentiated 3T3-L1 adipose cells were also target cells where extracellular WISP2 activated the canonical WNT pathway, inhibited Pparg and associated adipose genes and, similar to WNT3a, promoted partial dedifferentiation of the cells and the induction of a myofibroblast phenotype with activation of markers of fibrosis. Thus, WISP2 exerts dual actions in mesenchymal precursor cells; secreted WISP2 activates canonical WNT and maintains the cells in an undifferentiated state, whereas cytosolic WISP2 regulates adipogenic commitment.
WNT1 诱导信号通路蛋白 2(WISP2)主要表达于间充质干细胞、成纤维细胞和脂肪生成前体细胞。它既是一种分泌蛋白,也是一种胞质蛋白,后者通过 BMP4 调节前体细胞向脂肪生成的定向和 PPARγ 的诱导。为了研究分泌蛋白的作用,我们在 NIH3T3 成纤维细胞中表达全长和截短的、非分泌型 WISP2。分泌型而非截短型的 WISP2 通过增加β-连环蛋白水平、其核靶向磷酸化和 LRP5/6 磷酸化来激活经典 WNT 途径。它还抑制了 Pparg 的激活,而 WNT 拮抗剂 DICKKOPF-1 可以逆转分泌型 WISP2 的作用。分化的 3T3-L1 脂肪细胞也是靶细胞,其中细胞外 WISP2 激活经典 WNT 途径,抑制 Pparg 和相关脂肪基因,并且与 WNT3a 相似,促进细胞的部分去分化,并诱导成纤维细胞表型,同时激活纤维化标志物。因此,WISP2 在间充质前体细胞中发挥双重作用;分泌型 WISP2 激活经典 WNT 并使细胞保持未分化状态,而胞质型 WISP2 则调节脂肪生成的定向。