Silencing of RB1 but not of RB2/P130 induces cellular senescence and impairs the differentiation potential of human mesenchymal stem cells.
Stem cell senescence is considered deleterious because it may impair tissue renewal and function. On the other hand, senescence may arrest the uncontrolled growth of transformed stem cells and protect organisms from cancer. This double function of senescence is strictly linked to the activity of genes that the control cell cycle such as the retinoblastoma proteins RB1, RB2/P130, and P107. We took advantage of the RNA interference technique to analyze the role of these proteins in the biology of mesenchymal stem cells (MSC). Cells lacking RB1 were prone to DNA damage. They showed elevated levels of p53 and p21(cip1) and increased regulation of RB2/P130 and P107 expression. These cells gradually adopted a senescent phenotype with impairment of self-renewal properties. No significant modification of cell growth was observed as it occurs in other cell types or systems. In cells with silenced RB2/P130, we detected a reduction of DNA damage along with a higher proliferation rate, an increase in clonogenic ability, and the diminution of apoptosis and senescence. Cells with silenced RB2/P130 were cultivated for extended periods of time without adopting a transformed phenotype. Of note, acute lowering of P107 did not induce relevant changes in the in vitro behavior of MSC. We also analyzed cell commitment and the osteo-chondro-adipogenic differentiation process of clones derived by MSC cultures. In all clones obtained from cells with silenced retinoblastoma genes, we observed a reduction in the ability to differentiate compared with the control clones. In summary, our data show evidence that the silencing of the expression of RB1 or RB2/P130 is not compensated by other gene family members, and this profoundly affects MSC functions.
Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Naples, Italy.
Nicola
N
Alessio
Wolfgang
W
Bohn
Verena
V
Rauchberger
Flavio
F
Rizzolio
Marilena
M
Cipollaro
Michael
M
Rosemann
Martin
M
Irmler
Johannes
J
Beckers
Antonio
A
Giordano
Umberto
U
Galderisi
D017209:Apoptosis; D002453:Cell Cycle; D002454:Cell Differentiation; D002478:Cells, Cultured; D016922:Cellular Senescence; D004249:DNA Damage; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism*; D034622:RNA Interference; D016160:Retinoblastoma Protein / Q000235:genetics* / Q000378:metabolism; D050717:Retinoblastoma-Like Protein p130 / Q000235:genetics* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
C493837:RBL2 protein, human; D016160:Retinoblastoma Protein; D050717:Retinoblastoma-Like Protein p130; D016159:Tumor Suppressor Protein p53