Senescence of human skin-derived precursors regulated by Akt-FOXO3-p27KIP1/p15INK4b signaling

Abstract

Multipotent skin-derived precursors (SKPs) are dermal stem cells with the capacity to reconstitute the dermis and other tissues, such as muscles and the nervous system. Thus, the easily available human SKPs (hSKPs) hold great promises in regenerative medicine. However, long-term expansion is difficult for hSKPs in vitro. We previously demonstrated that hSKPs senesced quickly under routine culture conditions. To identify the underlying mechanisms so as to find an effective way to expand hSKPs, time-dependent microarray analysis of gene expression in hSKPs during in vitro culture was performed. We found that the senescence of hSKPs had a unique gene expression pattern that differs from reported typical senescence. Subsequent investigation ruled out the role of DNA damage and classical p53 and p16 INK4a signaling in hSKP senescence. Examination of cyclin-dependent kinase inhibitors revealed the involvement of p15 INK4b and p27 KIP1 . Further exploration about upstream signals indicated the contribution of Akt hypo-activity and FOXO3 to hSKP senescence. Forced activation of Akt and knockdown of FOXO3, p15 INK4b and p27 KIP1 effectively inhibited hSKP senescence and promoted hSKP proliferation. The unique senescent phenotype of human dermal stem cells and the role of Akt-FOXO3-p27 KIP1 /p15 INK4b signaling in regulating hSKP senescence provide novel insights into the senescence and self-renewal regulation of adult stem cells. The present study also points out a way to propagate hSKPs in vitro so as to fulfill their promises in regenerative medicine.

Targeting CXCR1 on breast cancer stem cells: signaling pathways and clinical application modelling

“…Since it has been recently described an involvement of the PI3K-Akt-FOXO3-p27 pathway [ 16 ] in cellular senescence, in order to better understand the differences in cell cycle phases induced by the different treatments, this pathway was further investigated (Figure 5 ). In agreement with the synergistic effect of R + P in inducing a G2/M arrest of cell cycle, it appeared that the combined treatment was able to induce cell senescence by decreasing PI3K-Akt activation paralleled by a decrease of the cytosolic p-FOXO3A (inactive) and by an increase of p27, thus suggesting that cells blocked in G2/M by the two drugs may undergo to senescence.…”

Spatiotemporal Expression of p63 in Mouse Epidermal Commitment

“…qPCR was conducted using GoTaq ® qPCR Master Mix (SYBR Green) (Promega) on a Roche LightCycler480 system (Roche Applied Science, Indianapolis, IN, USA) as previously described [ 37 , 38 ]. Primers used in these experiments are listed in Table S2 .…”

Multipotentiality of skin‐derived precursors: application to the regeneration of skin and other tissues

“…The PI3K‐Akt pathway seems to be implicated in the maintenance of SKPs in vitro regulating both the senescence and the self‐renewal of SKPs . More recently, Liu and collaborators performed a transcriptomic study to determine the modulation of specific genes underlying SKPs senescence. The most important change in gene expression occurred when SKPs were showed a high level of SA‐β‐galactosidase activity and hence considered as senescent.…”

“…Moreover, senescent SKPs exhibit a low level of double strand breaks (highlighted by the detection of gamma‐H2AX, a specifically phosphorylated form of H2A histone family member X) and a low expression of p53, suggesting that SKP senescence is not linked to DNA damage and p53 signalling. Researchers’ investigation revealed that Akt‐FOXO3‐p27 KIP1 /p15 INK4b signalling has a role in the senescence of SKPs . Recently, a beneficial effect of SKPs on their resistance to UVB‐induced apoptosis or damage was demonstrated .…”