18S,5.8S,and 28S ribosomal RNAs(rRNAs)are cotranscribed as a pre-ribosomal RNA(pre-rRNA)from the rDNA by RNA polymerase I whose activity is vigorous during the S-phase,leading to a conflict with rDNA replication.This ...18S,5.8S,and 28S ribosomal RNAs(rRNAs)are cotranscribed as a pre-ribosomal RNA(pre-rRNA)from the rDNA by RNA polymerase I whose activity is vigorous during the S-phase,leading to a conflict with rDNA replication.This conflict is resolved partly by replication-fork-barrier(RFB)-sites sequences located downstream of the rDNA and RFB-binding proteins such as Ttf1.However,how Ttf1 is displaced from RFB-sites to allow replication fork progression remains elusive.Here,we reported that loss-of-function of Bms1l,a nucleolar GTPase,upregulates rDNA transcription,causes replication-fork stall,and arrests cell cycle at the S-to-G2 transition;however,the G1-to-S transition is constitutively active characterized by persisting DNA synthesis.Concomitantly,ubf,tif-IA,and taf1b marking rDNA transcription,Chk2,Rad51,and p53 marking DNA-damage response,and Rpa2,PCNA,Fen1,and Ttf1 marking replication fork stall are all highly elevated in bms1l mutants.We found that Bms1 interacts with Ttf1 in addition to Rc1l.Finally,we identified RFB-sites for zebrafish Ttf1 through chromatin immunoprecipitation sequencing and showed that Bms1 disassociates the Ttf1–RFB complex with its GTPase activity.We propose that Bms1 functions to balance rDNA transcription and replication at the S-phase through interaction with Rcl1 and Ttf1,respectively.TTF1 and Bms1 together might impose an S-phase checkpoint at the rDNA loci.展开更多
During ribosome biogenesis,the small subunit(SSU)processome is responsible for 40S assembly.The BMS1/RCL1 complex is a core component of the SSU processome that plays an important role in 18S rRNA processing and matur...During ribosome biogenesis,the small subunit(SSU)processome is responsible for 40S assembly.The BMS1/RCL1 complex is a core component of the SSU processome that plays an important role in 18S rRNA processing and maturation.Genetic studies using zebrafish mutants indicate that both Bms1-like(Bms1l)and Rcl1 are essential for digestive organ development.In spite of vital functions of this complex,the mutual dependence of these two nucleolar proteins for the stability and function remains elusive.In this study,we identified an RCL1-interacting domain in BMS1,which is conserved in zebrafish and humans.Moreover,both the protein stability and nucleolar entry of RCL1 depend on its interaction with BMS1,otherwise RCL1 degraded through the ubiquitination-proteasome pathway.Functional studies revealed that overexpression of RCL1 in BMS1-knockdown cells can partially rescue the defects in 18S rRNA processing and cell proliferation,and hepatocyte-specific overexpression of Rcl1 can resume zebrafish liver development in the bms1l substitution mutant bms1l^(sq163/sq163)but not in the knockout mutant bms1l^(zju1/zju1),which is attributed to the nucleolar entry of Rcl1 in the former mutant.Our data demonstrate that BMS1 and RCL1 interaction is essential for not only pre-rRNA processing but also the communication between ribosome biogenesis and cell cycle regulation.展开更多
We used Drosophila melanogaster as an experimental model to express mouse and pig BM88/CEND1(cell cycle exit and neuronal differentiation 1) in order to investigate its potential functional effects on Drosophila neuro...We used Drosophila melanogaster as an experimental model to express mouse and pig BM88/CEND1(cell cycle exit and neuronal differentiation 1) in order to investigate its potential functional effects on Drosophila neurogenesis. BM88/CEND1 is a neuron-specific protein whose function is implicated in triggering cells to exit from the cell cycle and differentiate towards a neuronal phenotype. Transgenic flies expressing either mouse or pig BM88/CEND1 in the nervous system had severe neuronal phenotypes with variable expressivity at various stages of embryonic development. In early embryonic stage 10,BM88/CEND1 expression led to an increase in the neuralspecific antigenicity of neuroectoderm at the expense of precursor cells [neuroblasts(Nbs) and ganglion mother cells(GMCs)] including the defective formation and differentiation of the MP2 precursors, whereas at later stages(12–15), protein accumulation induced gross morphological defects primarily in the CNS accompanied by a reduction of Nb and GMC markers. Furthermore, the neuronal precursor cells of embryos expressing BM88/CEND1 failed to carry out proper cell-cycle progression as revealed by the disorganized expression patterns of specific cell-cycle markers. BM88/CEND1 accumulation in the Drosophila eye affected normal eye disc development by disrupting the ommatidia. Finally, we demonstrated that expression of BM88/CEND1 modified/reduced the levels of activated MAP kinase indicating a functional effect of BM88/CEND1 on the MAPK signaling pathway. Our findings suggest that the expression of mammalian BM88/CEND1 in Drosophila exerts specific functional effects associated with neuronal precursor cell formation during embryonic neurogenesis and proper eye disc development.This study also validates the use of Drosophila as a powerful model system in which to investigate gene function and the underlying molecular mechanisms.展开更多
AIM To provide evidence regarding the postoperative treatment of patients with T4 b N1-3 M0/Tx N3 b M0 gastric cancer, for which guidelines have not been established. METHODS Patients who had undergone curative resect...AIM To provide evidence regarding the postoperative treatment of patients with T4 b N1-3 M0/Tx N3 b M0 gastric cancer, for which guidelines have not been established. METHODS Patients who had undergone curative resection between 1996 and 2014 with a pathological stage of T4 b N1-3 M0/Tx N3 b M0 for gastric cancer were retrospectively analyzed; staging was based on the 7 th edition of the American Joint Committee on Cancer staging system. The clinicopathological characteristics, administration of adjuvant chemotherapy, and patterns of recurrence were studied. Univariate and multivariate analyses of prognostic factors were conducted. The chemotherapeutic agents mainly included fluorouropyrimidine, platinum and taxanes, used as monotherapy, doublet, or triplet regimens. Patterns of first recurrence were categorized as locoregional recurrence, peritoneal dissemination, or distant metastasis.RESULTS The 5-year overall survival(OS) of the whole group(n = 176) was 16.8%, and the median OS was 25.7 mo(95%CI: 20.9-30.5). Lymphovascular invasion and a node positive rate(NPR) ≥ 0.8 were associated with a poor prognosis(P = 0.01 and P = 0.048, respectively). One hundred forty-seven(83.5%) of the 176 patients eventually experienced recurrence; the most common pattern of the first recurrence was distant metastasis. The prognosis was best for patients with locoregional recurrence and worst for those with peritoneal dissemination. Twelve(6.8%) of the 176 patients did not receive adjuvant chemotherapy, while 164(93.2%) patients received adjuvant chemotherapy. Combined chemotherapy, including doublet and triplet regimens, was associated with a better prognosis than monotherapy, with no significant difference in 5-year OS(17.5% vs 0%, P = 0.613). The triplet regimen showed no significant survival benefit compared with the doublet regimen for 5-year OS(18.5% vs 17.4%, P = 0.661). Thirty-nine(22.1%) patients received adjuvant chemotherapy for longer than six months; the median OS in patients who received adjuvant chemotherapy for longer than six months was 40.2 mo(95%CI: 30.6-48.2), significantly longer than the 21.6 mo(95%CI: 19.1-24.0) in patients who received adjuvant chemotherapy for less than six months(P = 0.001).CONCLUSION Patients with T4 b N1-3 M0/Tx N3 b M0 gastric cancer showed a poor prognosis and a high risk of distant metastasis. Adjuvant chemotherapy for longer than six months improved outcomes for them.展开更多
基金by the National Key R&D Program of China(2018YFA0800501)the National Natural Science Foundation of China(31771596 and 32000565).
文摘18S,5.8S,and 28S ribosomal RNAs(rRNAs)are cotranscribed as a pre-ribosomal RNA(pre-rRNA)from the rDNA by RNA polymerase I whose activity is vigorous during the S-phase,leading to a conflict with rDNA replication.This conflict is resolved partly by replication-fork-barrier(RFB)-sites sequences located downstream of the rDNA and RFB-binding proteins such as Ttf1.However,how Ttf1 is displaced from RFB-sites to allow replication fork progression remains elusive.Here,we reported that loss-of-function of Bms1l,a nucleolar GTPase,upregulates rDNA transcription,causes replication-fork stall,and arrests cell cycle at the S-to-G2 transition;however,the G1-to-S transition is constitutively active characterized by persisting DNA synthesis.Concomitantly,ubf,tif-IA,and taf1b marking rDNA transcription,Chk2,Rad51,and p53 marking DNA-damage response,and Rpa2,PCNA,Fen1,and Ttf1 marking replication fork stall are all highly elevated in bms1l mutants.We found that Bms1 interacts with Ttf1 in addition to Rc1l.Finally,we identified RFB-sites for zebrafish Ttf1 through chromatin immunoprecipitation sequencing and showed that Bms1 disassociates the Ttf1–RFB complex with its GTPase activity.We propose that Bms1 functions to balance rDNA transcription and replication at the S-phase through interaction with Rcl1 and Ttf1,respectively.TTF1 and Bms1 together might impose an S-phase checkpoint at the rDNA loci.
基金This work was supported by grants fromthe National Natural Science Foundation of China(31771596 and 32000565)。
文摘During ribosome biogenesis,the small subunit(SSU)processome is responsible for 40S assembly.The BMS1/RCL1 complex is a core component of the SSU processome that plays an important role in 18S rRNA processing and maturation.Genetic studies using zebrafish mutants indicate that both Bms1-like(Bms1l)and Rcl1 are essential for digestive organ development.In spite of vital functions of this complex,the mutual dependence of these two nucleolar proteins for the stability and function remains elusive.In this study,we identified an RCL1-interacting domain in BMS1,which is conserved in zebrafish and humans.Moreover,both the protein stability and nucleolar entry of RCL1 depend on its interaction with BMS1,otherwise RCL1 degraded through the ubiquitination-proteasome pathway.Functional studies revealed that overexpression of RCL1 in BMS1-knockdown cells can partially rescue the defects in 18S rRNA processing and cell proliferation,and hepatocyte-specific overexpression of Rcl1 can resume zebrafish liver development in the bms1l substitution mutant bms1l^(sq163/sq163)but not in the knockout mutant bms1l^(zju1/zju1),which is attributed to the nucleolar entry of Rcl1 in the former mutant.Our data demonstrate that BMS1 and RCL1 interaction is essential for not only pre-rRNA processing but also the communication between ribosome biogenesis and cell cycle regulation.
基金supported by the General Secretariat of Research and Technology-EPAN (Competitiveness and Entepreneurship) Program
文摘We used Drosophila melanogaster as an experimental model to express mouse and pig BM88/CEND1(cell cycle exit and neuronal differentiation 1) in order to investigate its potential functional effects on Drosophila neurogenesis. BM88/CEND1 is a neuron-specific protein whose function is implicated in triggering cells to exit from the cell cycle and differentiate towards a neuronal phenotype. Transgenic flies expressing either mouse or pig BM88/CEND1 in the nervous system had severe neuronal phenotypes with variable expressivity at various stages of embryonic development. In early embryonic stage 10,BM88/CEND1 expression led to an increase in the neuralspecific antigenicity of neuroectoderm at the expense of precursor cells [neuroblasts(Nbs) and ganglion mother cells(GMCs)] including the defective formation and differentiation of the MP2 precursors, whereas at later stages(12–15), protein accumulation induced gross morphological defects primarily in the CNS accompanied by a reduction of Nb and GMC markers. Furthermore, the neuronal precursor cells of embryos expressing BM88/CEND1 failed to carry out proper cell-cycle progression as revealed by the disorganized expression patterns of specific cell-cycle markers. BM88/CEND1 accumulation in the Drosophila eye affected normal eye disc development by disrupting the ommatidia. Finally, we demonstrated that expression of BM88/CEND1 modified/reduced the levels of activated MAP kinase indicating a functional effect of BM88/CEND1 on the MAPK signaling pathway. Our findings suggest that the expression of mammalian BM88/CEND1 in Drosophila exerts specific functional effects associated with neuronal precursor cell formation during embryonic neurogenesis and proper eye disc development.This study also validates the use of Drosophila as a powerful model system in which to investigate gene function and the underlying molecular mechanisms.
文摘AIM To provide evidence regarding the postoperative treatment of patients with T4 b N1-3 M0/Tx N3 b M0 gastric cancer, for which guidelines have not been established. METHODS Patients who had undergone curative resection between 1996 and 2014 with a pathological stage of T4 b N1-3 M0/Tx N3 b M0 for gastric cancer were retrospectively analyzed; staging was based on the 7 th edition of the American Joint Committee on Cancer staging system. The clinicopathological characteristics, administration of adjuvant chemotherapy, and patterns of recurrence were studied. Univariate and multivariate analyses of prognostic factors were conducted. The chemotherapeutic agents mainly included fluorouropyrimidine, platinum and taxanes, used as monotherapy, doublet, or triplet regimens. Patterns of first recurrence were categorized as locoregional recurrence, peritoneal dissemination, or distant metastasis.RESULTS The 5-year overall survival(OS) of the whole group(n = 176) was 16.8%, and the median OS was 25.7 mo(95%CI: 20.9-30.5). Lymphovascular invasion and a node positive rate(NPR) ≥ 0.8 were associated with a poor prognosis(P = 0.01 and P = 0.048, respectively). One hundred forty-seven(83.5%) of the 176 patients eventually experienced recurrence; the most common pattern of the first recurrence was distant metastasis. The prognosis was best for patients with locoregional recurrence and worst for those with peritoneal dissemination. Twelve(6.8%) of the 176 patients did not receive adjuvant chemotherapy, while 164(93.2%) patients received adjuvant chemotherapy. Combined chemotherapy, including doublet and triplet regimens, was associated with a better prognosis than monotherapy, with no significant difference in 5-year OS(17.5% vs 0%, P = 0.613). The triplet regimen showed no significant survival benefit compared with the doublet regimen for 5-year OS(18.5% vs 17.4%, P = 0.661). Thirty-nine(22.1%) patients received adjuvant chemotherapy for longer than six months; the median OS in patients who received adjuvant chemotherapy for longer than six months was 40.2 mo(95%CI: 30.6-48.2), significantly longer than the 21.6 mo(95%CI: 19.1-24.0) in patients who received adjuvant chemotherapy for less than six months(P = 0.001).CONCLUSION Patients with T4 b N1-3 M0/Tx N3 b M0 gastric cancer showed a poor prognosis and a high risk of distant metastasis. Adjuvant chemotherapy for longer than six months improved outcomes for them.
