TY - JOUR
T1 - SMC1 involvement in fragile site expression
AU - Musio, Antonio
AU - Montagna, Cristina
AU - Mariani, Tullio
AU - Tilenni, Manuela
AU - Focarelli, Maria Luisa
AU - Brait, Lorenzo
AU - Indino, Esterina
AU - Benedetti, Pier Alberto
AU - Chessa, Luciana
AU - Albertini, Alberto
AU - Reid, Thomas
AU - Vezzoni, Paolo
PY - 2005/2/15
Y1 - 2005/2/15
N2 - Common fragile sites have been involved in neoplastic transformation, although their molecular basis is still poorly understood. Here, we demonstrate that inhibition of the SMC1 by RNAi is sufficient to induce fragile site expression. By investigating normal, ATM- and ATR-deficient cell lines, we provide evidence that the contribution of SMC1 in preventing the collapse of stalled replication fork is an Atr-dependent pathway. Using a fluorescent antibody specific for γ-H2AX, we show that very rare discrete nuclear foci appear 1 and 2 h after exposure to aphidicolin and/or RNAi-SMC1, but became more numerous and distinct after longer treatment times. In this context, fragile sites might be viewed as an in vitro phenomenon originating from double-strand breaks formed because of a stalled DNA replication that lasted too long to be managed by physiological rescue acting through the Atr/Smc1 axis. We propose that in vivo, following an extreme replication block, rare cells could escape checkpoint mechanisms and enter mitosis with a defect in genome assembly, eventually leading to neoplastic transformation.
AB - Common fragile sites have been involved in neoplastic transformation, although their molecular basis is still poorly understood. Here, we demonstrate that inhibition of the SMC1 by RNAi is sufficient to induce fragile site expression. By investigating normal, ATM- and ATR-deficient cell lines, we provide evidence that the contribution of SMC1 in preventing the collapse of stalled replication fork is an Atr-dependent pathway. Using a fluorescent antibody specific for γ-H2AX, we show that very rare discrete nuclear foci appear 1 and 2 h after exposure to aphidicolin and/or RNAi-SMC1, but became more numerous and distinct after longer treatment times. In this context, fragile sites might be viewed as an in vitro phenomenon originating from double-strand breaks formed because of a stalled DNA replication that lasted too long to be managed by physiological rescue acting through the Atr/Smc1 axis. We propose that in vivo, following an extreme replication block, rare cells could escape checkpoint mechanisms and enter mitosis with a defect in genome assembly, eventually leading to neoplastic transformation.
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U2 - 10.1093/hmg/ddi049
DO - 10.1093/hmg/ddi049
M3 - Article
C2 - 15640246
AN - SCOPUS:14044258550
SN - 0964-6906
VL - 14
SP - 525
EP - 533
JO - Human molecular genetics
JF - Human molecular genetics
IS - 4
ER -