Abstract
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.
Highlights
Promotes their proliferation through its carbohydratebinding ability.[3,8] In addition, Gal-1 is a critical factor in the function of mouse mesenchymal stromal cell-mediated tumor
Gal-1 (10 ng/ml) significantly induced the motility of human adipose-derived mesenchymal stem cells (AD-MSCs) (32% increase compared with the control; Po0.01), the effect of Gal-1 in AD-MSC motility was lower than in UCB-MSCs (125% increase compared with the control; Po0.01) (Supplementary Data 1)
Our data demonstrate that Gal-1 stimulated motility that was mediated by downregulation of smad2/3-dependent COL-3/-5, and upregulation of NF-kB-dependent FN/LM-5 expression via c-Src/Cav-1 and protein kinase C (PKC) in human UCB-MSCs
Summary
Promotes their proliferation through its carbohydratebinding ability.[3,8] In addition, Gal-1 is a critical factor in the function of mouse mesenchymal stromal cell-mediated tumor. Recent studies clearly implicate the functional relevance of Gal-1 and extracellular matrix (ECM) proteins in mediating wound healing, motility, and adhesion.[10] Interestingly, alterations in ECM protein expression play a contrasting role in stem cell function. Human UCB-MSCs derived from cord blood after birth have self-renewal capacity and can differentiate into multiple cell types.[19] human UCB-MSCs might be regarded as a versatile biological system, and their use has led to major advances in cell therapy and regeneration strategies in bone regeneration and spinal cord injury.[20,21] Gal-1 and ECM proteins have relevance to stabilize stem cell transplantation, regulate motility, and control differentiation.[22,23,24] several clinical studies have detailed stem cell transplantation and/or therapeutic methods using Gal-1 and ECM proteins,[23,24] serious problems such as degeneration of scaffold protein, destruction of stem cell constituents, and alterations in stem cell functions may arise during transplantation and cell therapy.[25] A prerequisite for effective clinical application is selecting high-quality input materials, as well as understanding the regulatory mechanisms mediating various processes such as motility. We examined the involvement of ECM proteins in Gal-1-induced human UCB-MSC motility and its related signal pathways
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