Downregulation of APE1/Ref-1 is involved in the senescence of mesenchymal stem cells.
The senescence of human mesenchymal stem cells (hMSCs) causes disruption of tissue and organ maintenance, and is thus an obstacle to stem cell-based therapies for disease. Although some researchers have studied changes in the characteristics of hMSCs (decreases in differentiation ability and self-renewal), comparing young and old ages, the mechanisms of stem cell senescence have not yet been defined. In this study, we developed a growth curve for human bone marrow derived MSCs (hBMSCs) which changes into a hyperbolic state after passage number 7. Senescence associated beta-galactosidase (SA beta-gal) staining of hBMSCs showed 10% in passage 9 and 45% in passage 11. We detected an increase in endogenous superoxide levels during senescence that correlated with senescence markers (SA beta-gal, hyperbolic growth curve). Interestingly, even though endogenous superoxide increased in a replicative senescence model, the expression of APE1/Ref-1, which is sensitive to intracellular redox state, decreased. These effects were confirmed in a stress-induced senescence model by exogenous treatment with H(2)O(2). This change is related to the p53 activity that negatively regulates APE1/Ref-1. p21 expression levels, which represent p53 activity, were transiently increased in passage 9, meaning that they correlated with the expression of APE1/Ref-1. Overexpression of APE1/Ref-1 suppressed superoxide production and decreased SA beta-gal in hBMSCs. In conclusion, intracellular superoxide accumulation appears to be the main cause of the senescence of hBMSCs, and overexpression of APE1/Ref-1 can rescue cells from the senescence phenotype. Maintaining characteristics of hBMSCs by regulating intracellular reactive oxygen species production can contribute to tissue regeneration and to improved cell therapy.
Heo
Jun-Young
JY
Department of Biochemistry, College of Medicine, Chungnam National University, Teajeon, South Korea.
Jing
Kaipeng
K
Song
Kyoung-Sub
KS
Seo
Kang-Sik
KS
Park
Ji-Hoon
JH
Kim
Jong-Seok
JS
Jung
Yeon-Joo
YJ
Hur
Gang-Min
GM
Jo
Deog-Yeon
DY
Kweon
Gi-Ryang
GR
Yoon
Wan-Hee
WH
Lim
Kyu
K
Hwang
Byung-Doo
BD
Jeon
Byeong Hwa
BH
Park
Jong-Il
JI
D015153:Blotting, Western; D002460:Cell Line; D016922:Cellular Senescence / Q000502:physiology*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000096:biosynthesis*; D015536:Down-Regulation; D005434:Flow Cytometry; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D018613:Microscopy, Confocal; D018384:Oxidative Stress / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism
D013481:Superoxides; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase