1] Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Science, Seoul National University, Seoul, Korea [2] BK21 PLUS Creative Veterinary Research Center, Seoul National University, Seoul, Korea.
Cell Death Dis. 2014 Feb 6;5(2):e1049. doi: 10.1038/cddis.2014.3.
Galectin-1 (Gal-1) belongs to a family of endogenous lectins with conserved carbohydrate recognition domains binding β-galactosidase sugars and plays a vital role in regulating stem cell functions including determination of cell fate. However, our understanding of the functional roles of Gal-1 in human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) is still fragmentary and incomplete. Gal-1 significantly increased motility after a 24-h incubation, and this effect was inhibited by β-lactose. We analyzed 17 extracellular matrix (ECM) genes in UCB-MSCs. Gal-1 decreased the expression of collagen genes COL3A1 (COL-3) and COL5A1 (COL-5) but increased the expression of fibronectin (FN) and laminin 5 (LM-5), that were reversed by β-lactose. Gal-1 increased protein kinase C (PKC), c-Src, and caveolin-1 (Cav-1) phosphorylation that was attenuated by β-lactose and the Src inhibitor PP2. In addition, pretreatment with the lipid raft disruptor Mβ-CD and the PKC inhibitors inhibited Gal-1-induced UCB-MSC motility. In addition, Gal-1 reduced smad2/3 phosphorylation and induced nuclear factor (NF)-κB phosphorylation. Pretreatment with Mβ-CD attenuated Gal-1-reduced smad2/3 phosphorylation, COL-3, and COL-5 expression but did not affect NF-κB phosphorylation, FN, or LM-5 expression. In contrast, PKC inhibitors only attenuated NF-κB phosphorylation, FN, and LM-5 expression. Reconstructing Gal-1-induced genetic changes by replacing it with siRNA specific for COL-3 or COL-5, or treatment of the cells with FN and LM-5 proteins, increased motility and its related proteins such as focal adhesion kinase, Akt, Erk, integrins, and matrix metalloproteinase-2. A combined treatment with COL-3/COL-5 siRNA or FN/LM-5 compared with that of single treatments was synergistic. However, a single Gal-1 treatment maximally stimulated motility and related protein phosphorylation/expression. These results demonstrate that Gal-1 stimulated human UCB-MSC motility by decreasing COL-3/COL-5 expression and increasing FN/LM-5 expression through a PKC-dependent NF-κB and c-Src/Cav-1-dependent smad2/3 pathway that was critical for governing the activation of FAK, Akt, Erk, integrins, and MMP2.
半乳糖凝集素 1（Gal-1）属于内源性凝集素家族，具有保守的碳水化合物识别结构域，能与β-半乳糖苷酶结合，在调节包括细胞命运决定在内的干细胞功能方面发挥着重要作用。然而，我们对半乳糖凝集素 1 在人脐血间充质干细胞（UCB-MSCs）中的功能作用的了解仍然是零碎和不完整的。Gal-1 在孵育 24 小时后显著增加了运动性，而这一作用可被β-乳糖所抑制。我们分析了 UCB-MSCs 中的 17 种细胞外基质（ECM）基因。Gal-1 降低了胶原蛋白基因 COL3A1（COL-3）和 COL5A1（COL-5）的表达，但增加了纤维连接蛋白（FN）和层粘连蛋白 5（LM-5）的表达，而这些作用可被β-乳糖所逆转。Gal-1 增加了蛋白激酶 C（PKC）、c-Src 和小窝蛋白-1（Cav-1）的磷酸化，而这一作用可被β-乳糖和 Src 抑制剂 PP2 所抑制。此外，用脂筏破坏剂 Mβ-CD 和 PKC 抑制剂预处理会抑制 Gal-1 诱导的 UCB-MSC 运动性。此外，Gal-1 降低了 smad2/3 的磷酸化并诱导了核因子（NF）-κB 的磷酸化。用 Mβ-CD 预处理会减弱 Gal-1 诱导的 smad2/3 磷酸化、COL-3 和 COL-5 的表达，但不影响 NF-κB 的磷酸化、FN 或 LM-5 的表达。相反，PKC 抑制剂仅减弱了 NF-κB 的磷酸化、FN 和 LM-5 的表达。用 COL-3/COL-5 的特异性 siRNA 替换 Gal-1 或用 FN 和 LM-5 蛋白处理细胞，会重建 Gal-1 诱导的基因变化，从而增加运动性及其相关蛋白，如黏着斑激酶、Akt、Erk、整合素和基质金属蛋白酶-2。与单一处理相比，用 COL-3/COL-5 siRNA 或 FN/LM-5 联合处理具有协同作用。然而，单一 Gal-1 处理最大限度地刺激了运动性和相关蛋白的磷酸化/表达。这些结果表明，Gal-1 通过降低 COL-3/COL-5 的表达和增加 FN/LM-5 的表达，通过 PKC 依赖性 NF-κB 和 c-Src/Cav-1 依赖性 smad2/3 通路刺激人 UCB-MSC 的运动性，该通路对调控黏着斑激酶、Akt、Erk、整合素和 MMP2 的激活至关重要。
