DNA mismatch repair （MMR） processes the chemically induced mispairs following treatment with clinically important nucleoside analogs such as 6-thioguanine （6-TG） and 5-fluorouracil （5-FU）. MMR processing of thes...DNA mismatch repair （MMR） processes the chemically induced mispairs following treatment with clinically important nucleoside analogs such as 6-thioguanine （6-TG） and 5-fluorouracil （5-FU）. MMR processing of these drugs has been implicated in activation of a prolonged G2/M cell cycle arrest for repair and later induction of apoptosis and/or autophagy for irreparable DNA damage. In this study, we investigated the role of Bcl2 and adenovirus EIB Nineteen-kilodalton Interacting Protein （BNIP3） in the activation of autophagy, and the temporal relationship between a G2/M cell cycle arrest and the activation of BNIP3-mediated autophagy following MMR processing of 6-TG and 5-FU. We found that BNIP3 protein levels are upregulated in a MLHI （MMR＋）-dependent manner following 6-TG and 5-FU treatment. Subsequent small-interfering RNA （siRNA）-mediated BNIP3 knockdown abrogates 6-TG- induced autophagy. We also found that p53 knockdown or inhibition of mTOR activity by rapamycin cotreatment impairs 6-TG- and 5-FU-induced upregulation of BNIP3 protein levels and autophagy. Furthermore, suppression of Checkpoint kinase 1 （Chkl） expression with a subsequent reduction in 6-TG-induced G2/M cell cycle arrest by Chkl siRNA promotes the extent of 6-TG-induced autophagy. These findings suggest that BNIP3 mediates 6-TG- and 5-FU-induced autophagy in a p53- and mTOR-dependent manner. Additionally, the duration of Chkl-activated G2/ M cell cycle arrest determines the level of autophagy following MMR processing of these nucleoside analogs.展开更多
DNA mismatch repair （MMR） is one of the biological pathways, which plays a critical role in DNA home- ostasis, primarily by repairing base-pair mismatches and insertion/deletion loops that occur during DNA replicati...DNA mismatch repair （MMR） is one of the biological pathways, which plays a critical role in DNA home- ostasis, primarily by repairing base-pair mismatches and insertion/deletion loops that occur during DNA replication. MMR also takes part in other metabolic pathways and regulates cell cycle arrest. Defects in MMR are associated with genomic instability, predisposition to certain types of cancers and resistance to certain therapeutic drugs. Moreover, genetic and epigenetic alterations in the MMR system demonstrate a significant relationship with human fertility and related treatments, which helps us to understand the etiology and susceptibility of human infertility. Alterations in the MMR system may also influence the health of offspring conceived by assisted reproductive technology in humans. However, further studies are needed to explore the specific mechanisms by which the MMR system may affect human infertility. This review addresses the physiological mechanisms of the MMR system and associations between altera- tions of the MMR system and human fertility and related treatments, and potential effects on the next generation.展开更多
文摘DNA mismatch repair （MMR） processes the chemically induced mispairs following treatment with clinically important nucleoside analogs such as 6-thioguanine （6-TG） and 5-fluorouracil （5-FU）. MMR processing of these drugs has been implicated in activation of a prolonged G2/M cell cycle arrest for repair and later induction of apoptosis and/or autophagy for irreparable DNA damage. In this study, we investigated the role of Bcl2 and adenovirus EIB Nineteen-kilodalton Interacting Protein （BNIP3） in the activation of autophagy, and the temporal relationship between a G2/M cell cycle arrest and the activation of BNIP3-mediated autophagy following MMR processing of 6-TG and 5-FU. We found that BNIP3 protein levels are upregulated in a MLHI （MMR＋）-dependent manner following 6-TG and 5-FU treatment. Subsequent small-interfering RNA （siRNA）-mediated BNIP3 knockdown abrogates 6-TG- induced autophagy. We also found that p53 knockdown or inhibition of mTOR activity by rapamycin cotreatment impairs 6-TG- and 5-FU-induced upregulation of BNIP3 protein levels and autophagy. Furthermore, suppression of Checkpoint kinase 1 （Chkl） expression with a subsequent reduction in 6-TG-induced G2/M cell cycle arrest by Chkl siRNA promotes the extent of 6-TG-induced autophagy. These findings suggest that BNIP3 mediates 6-TG- and 5-FU-induced autophagy in a p53- and mTOR-dependent manner. Additionally, the duration of Chkl-activated G2/ M cell cycle arrest determines the level of autophagy following MMR processing of these nucleoside analogs.
基金Project supported by the National Basic Research Programs (973) of China(Nos.2012CB944901 and 2014CB943302)the National Natural Science Foundation of China(Nos.81200475,81370760,and 81571500)the Zhejiang Provincial Natural Science Foundation of China(No.LZ13H040001)
文摘DNA mismatch repair （MMR） is one of the biological pathways, which plays a critical role in DNA home- ostasis, primarily by repairing base-pair mismatches and insertion/deletion loops that occur during DNA replication. MMR also takes part in other metabolic pathways and regulates cell cycle arrest. Defects in MMR are associated with genomic instability, predisposition to certain types of cancers and resistance to certain therapeutic drugs. Moreover, genetic and epigenetic alterations in the MMR system demonstrate a significant relationship with human fertility and related treatments, which helps us to understand the etiology and susceptibility of human infertility. Alterations in the MMR system may also influence the health of offspring conceived by assisted reproductive technology in humans. However, further studies are needed to explore the specific mechanisms by which the MMR system may affect human infertility. This review addresses the physiological mechanisms of the MMR system and associations between altera- tions of the MMR system and human fertility and related treatments, and potential effects on the next generation.
