The hepatocellular carcinoma suppressor 1 （HCCS1） gene was identified by both positional cloning from a predominant region of loss of heterozygosity （17p 13.3） in liver cancer and by functional screening for genes...The hepatocellular carcinoma suppressor 1 （HCCS1） gene was identified by both positional cloning from a predominant region of loss of heterozygosity （17p 13.3） in liver cancer and by functional screening for genes affecting cell proliferation in large-scale transfection assays. Its overexpression results in inhibition of cell proliferation in cell culture and tumor growth in nude mice. To understand its transcription regulation, the promoter architecture has been dissected in detail. The major start of transcription was mapped by primer extension to a C residue, 177 nucleotides upstream of the ATG codon. By assessing the promoter activity of a set of linker-scanning mutants of the minimal promoter （-60 to ＋148 region） in a transient transfection assay, we found that the ＋1 to ＋ 40 region is critical to HCCS1 gene transcription, containing binding sites for transcription factors NF-kB （-21 to ＋7 and ＋40 to ＋26）, p53 （＋29 to ＋9） and ETS （＋4 to ＋20 and ＋23 to ＋39）. Biochemical and molecular analyses revealed that the ETS transcription factors ETS-2 and Elf-1 bind to the two ETS sites in situ and contribute significantly to the transcriptionally active state of the HCCS1 gene, while NF-kB, p53 and two other members of the ETS family （ETS-1 and NERF2） appear to play little role. Our observations provide insight into the mechanistic aspects of HCCS1 transcription regulation.展开更多
The effects of cooled external exhaust gas recirculation （EGR） on the combustion and emission performance of diesel fuel homogeneous charge compression ignition （HCCI） are studied. Homogeneous mixture is formed by...The effects of cooled external exhaust gas recirculation （EGR） on the combustion and emission performance of diesel fuel homogeneous charge compression ignition （HCCI） are studied. Homogeneous mixture is formed by injecting fuel in-cylinder in the negative valve overlap （NVO） period. So, the HCCI combustion which has low NOx and smoke emission is achieved. Cooled external EGR can delay the start of combustion effectively, which is very useful for high cetane fuel （diesel） HCCI, because these fuels can easily self-ignition, which makes the start of combustion more early. External EGR can avoid the knock combustion of HCCI at high load which means that the EGR can expand the high load limit. HCCI maintains low smoke emission at various EGR rate and various load compared with conventional diesel engine because there is no fuel-rich area in cylinder.展开更多
基金grants to Jing De Zhu from the Shanghai Science Foundation （04DZ14006 , 05DZ19318） the National Science Foundation （30450001, 30570850 , 10574134） the National Research Program for Basic Research of China （2004CB518804 , 2002CB713700）.
文摘The hepatocellular carcinoma suppressor 1 （HCCS1） gene was identified by both positional cloning from a predominant region of loss of heterozygosity （17p 13.3） in liver cancer and by functional screening for genes affecting cell proliferation in large-scale transfection assays. Its overexpression results in inhibition of cell proliferation in cell culture and tumor growth in nude mice. To understand its transcription regulation, the promoter architecture has been dissected in detail. The major start of transcription was mapped by primer extension to a C residue, 177 nucleotides upstream of the ATG codon. By assessing the promoter activity of a set of linker-scanning mutants of the minimal promoter （-60 to ＋148 region） in a transient transfection assay, we found that the ＋1 to ＋ 40 region is critical to HCCS1 gene transcription, containing binding sites for transcription factors NF-kB （-21 to ＋7 and ＋40 to ＋26）, p53 （＋29 to ＋9） and ETS （＋4 to ＋20 and ＋23 to ＋39）. Biochemical and molecular analyses revealed that the ETS transcription factors ETS-2 and Elf-1 bind to the two ETS sites in situ and contribute significantly to the transcriptionally active state of the HCCS1 gene, while NF-kB, p53 and two other members of the ETS family （ETS-1 and NERF2） appear to play little role. Our observations provide insight into the mechanistic aspects of HCCS1 transcription regulation.
基金This project is supported by National Basic Research Program of China (973Program, No. 2001CB209205)National Natural Science Foundation ofChina (No. 50406016)
文摘The effects of cooled external exhaust gas recirculation （EGR） on the combustion and emission performance of diesel fuel homogeneous charge compression ignition （HCCI） are studied. Homogeneous mixture is formed by injecting fuel in-cylinder in the negative valve overlap （NVO） period. So, the HCCI combustion which has low NOx and smoke emission is achieved. Cooled external EGR can delay the start of combustion effectively, which is very useful for high cetane fuel （diesel） HCCI, because these fuels can easily self-ignition, which makes the start of combustion more early. External EGR can avoid the knock combustion of HCCI at high load which means that the EGR can expand the high load limit. HCCI maintains low smoke emission at various EGR rate and various load compared with conventional diesel engine because there is no fuel-rich area in cylinder.
