NOTES
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CONFLICTS OF INTEREST
No potential conflict of interest relevant to this article was reported.
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AUTHOR CONTRIBUTIONS
Conception or design: K.S.K., Y.S.C., Y.W.C.
Acquisition, analysis, or interpretation of data: K.S.K., Y.K.C., M.J.K., J.W.H., K.M., S.Y.J., S.K.K., Y.S.C., Y.W.C.
Drafting the work or revising: K.S.K., Y.K.C., M.J.K., Y.S.C., Y.W.C.
Final approval of the manuscript: K.S.K, Y.S.C., Y.W.C.
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FUNDING
This work was supported by a grant (Kyung-Soo Kim, 2016F2) from the Korean Diabetes Association and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2018R1C1B5042633).
Fig. 1The effect of umbilical cord-mesenchymal stem cell-conditioned medium (UC-MSC-CM) on glucose uptake in C2C12 myotubes. The results are expressed as the fold change of the mean±standard error (n≥3). 2-DG, 2-deoxy glucose. aP<0.05, vs. insulin-unstimulated group, bP<0.05, vs. insulin-stimulated group, cP<0.05, vs. insulin and palmitate treated group.
Fig. 2The effect of umbilical cord-mesenchymal stem cell-conditioned medium (UC-MSC-CM) on protein expression of glucose transporter type 4 (GLUT4). (A) Western blot. (B) Protein expression of membranous GLUT4. (C) Protein expression of cytosolic GLUT4. The results are expressed as the fold change of the mean±standard error (n≥3). aP<0.05, vs. insulin-stimulated group, bP<0.05, vs. insulin and palmitate treated group.
Fig. 3The effect of umbilical cord-mesenchymal stem cell-conditioned medium (UC-MSC-CM) on the insulin-signaling pathway. (A) Representative Western blots for figure B–E. (B, C) Protein expression of insulin receptor substrate 1 (IRS1) at Ser612 (B) and Ser307 (C). (D) Protein expression of phosphoinositide 3-kinase (PI3K). (E) Protein expression of phosphorylated protein kinase B (p-AKT). The results are expressed as the fold change of the mean±standard error (n≥3). aP<0.05, vs. insulin-stimulated group, bP<0.05, vs. insulin and palmitate treated group.
Fig. 4The effect of umbilical cord-mesenchymal stem cell-conditioned medium (UC-MSC-CM) on mitochondrial contents and functions. (A) Protein level of mitochondrial transcription factor A (mtTFA). (B) The relative level of mitochondrial DNA (mtDNA) copy number. (C) Protein level of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). (D) Mitochondrial reactive oxygen species (ROS). (E) Intracellular ROS. (F) Fatty acid oxidation. (G) Mitochondrial membrane potential. (H) Adenosine triphosphate (ATP) contents. (I) ATP synthesis. The results are expressed as the fold change of the mean±standard error (n≥3). CCCP, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. aP<0.05, vs. insulin-stimulated group, bP<0.05, vs. insulin and palmitate treated group.
Fig. 5Analysis of secreted factors in umbilical cord mesenchymal stem cell-conditioned medium. EDA-A2, ectodysplasin-A2; IGFBP, insulin-like growth factor binding protein; TIMP, tissfATCC, Manassas, VA, USA) and maintained in Dulbeccoue inhibitor of metalloproteinases; IL-6, interleukin-6; MIP2, macrophage inflammatory protein 2; SPARC, secreted protein acidic and rich in cysteine; GRO, growth related oncogene; MCP, monocyte chemoattractant protein; Dkk, Dickkopf-related protein; VEGF, vascular endothelial growth factor; GDF, growth differentiation factor; HGF, hepatocyte growth factor; MMP-1, matrix metalloproteinase-1; FGF, fibroblast growth factor; KGF, keratinocyte growth factor.