Abstract 13417: IGF-1 Enhances Expression of iPS Cell Reprogramming Factors and Telomerase activities in Human Dermal Fibroblasts: A potential Role for IGF-1 in Induction of Pluripotent Stem Cells and Antisenescence
Background: Reprogramming somatic cells into induced pluropotent stem cells (iPS) using transcription factors (Oct4, Sox2, Klf4 and c-myc) offers a novel approach for regenerative medicine. However, the iPS cell generation has several obstacles, including the poor efficiency of iPS reprogramming and frequent re-entry of iPS cells into the stage of senescence during passage. Insulin-like growth factor (IGF-1) and its downstream phosphoinositide 3-kinase (PI3K) signaling pathway may maintain the proliferative potential of stem cells. This study was to test the effects of IGF-1 on iPS cell generation and senescence.
Methods and Results: Human dermal fibroblasts were transduced with reprogramming factors (Oct4, Sox2, Klf4 and c-myc) using a lentiviral vectors. Quantitative real-time PCR was performed to assess expression of Oct4 and Nanog. IGF-1 treatment (10 ng/ml) significantly increased Oct4 (3.6 ± 0.5 fold, p<0.02) and Nanog (2.9 ± 0.4 fold, p<0.02) mRNA levels in the transduced cells. GAPDH mRNA was not affected by IGF-1 treatment. A stem cell protein array showed that IGF-1 increased Nanog, Oct4 and Sox2 protein levels. Moreover, the telomerase activity, a marker of cell antisenescence, was increased by IGF-1 (IGF-1 vs. control = 14.8 ± 0.6 vs 5.8 ± 0.5 arbitrary units, p<0.05) assessed using the TRAPeze Telomerase Detection Assay. IGF-1 also decreased expression of the senescence marker p53 mRNA by real-time PCR, and p53 protein levels by Western blot. IGF-1 treatment also increased alkaline phosphatase activity, a marker for pluripotency. In addition, the effects of IGF-1 on iPS generation and cell senescence were attenuated by IGF-1 receptor neutralizing antibodies and PI3 kinase inhibitor LY294002, but not by mitogen-activated protein/ERK kinase inhibitor PD98059.
Conclusion: IGF-1 may enhance expression of programming factors and telomerase activities in human dermal fibroblasts transduced into iPS cells, while inhibiting expression of the senescence-inducing protein p53. The effects of IGF-1 may be mediated by the PI3 kinase/Akt pathway. Our data demonstrate that the novel biological effects of IGF-1 on iPS generation, and may allow development of an enhanced therapeutic option by employing iPS for treating cardiovascular diseases.
- Stem/progenitor cells
- Growth factors
- Cardiovascular disease prevention
- Heart failure
- Signal transduction
- © 2010 by American Heart Association, Inc.