Objective To study the exact function of human gene 5 transactivated by pre-S1 protein of hepatitis B virus(PS1TP5)by investigating the gene expression of PS1TP5 in yeast cells. Methods Reverse transcription-polymerase chain reaction(RT-PCR)was performed to amplify the gene of PS1TP5 using the mRNA of HepG2 cells as template and the gene was cloned into pGEM-T vector.The gene of PS1TP5 was cut from pGEM-T-PS1TP5 vector and cloned into yeast expressive plasmid pGBKT7,then pGBKT7-PS1TP5 was transformed into yeast cell AH109.The yeast protein was isolated and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and Western hybridization.Results PS1TP5 gene was successfully amplified and identified by DNA sequencing.The digested fragment was cloned into pGBKT7 vector and transformed into yeast cell AH109.The results of SDS-PAGE and Western assay showed that the relative molecular weight of the expressed product was about 36 950,and PS1TP5 protein existed in yeast cells.Conclusion The findings suggest that PS1TP5 can be successfully expressed in yeast cell.

BACKGROUNDThe hepatitis B virus (HBV) genome includes S, C, P and X regions. The S region is divided into four subregions of pre-pre-S, pre-S1, pre-S2 and S. PS1TP5 (human gene 5 transactivated by pre-S1 protein of HBV) is a novel target gene transactivated by the pre-S1 protein that has been screened with a suppression subtractive hybridization technique in our laboratory (GenBank accession: AY427953). In order to investigate the biological function of the PS1TP5 protein, we performed a yeast two-hybrid system 3 to screen proteins from a human leukocyte cDNA library interacting with the PS1TP5 protein.

METHODSThe reverse transcription polymerase chain reaction (RT-PCR) was performed to amplify the gene of PS1TP5 from the mRNA of HepG2 cells and the gene was then cloned into the pGEM-T vector. After being sequenced and analyzed with Vector NTI 9.1 and NCBI BLAST software, the target gene of PS1TP5 was cut from the pGEM-T vector and cloned into a yeast expression plasmid pGBKT7, then "bait" plasmid pGBKT7-PS1TP5 was transformed into the yeast strain AH109. The yeast protein was isolated and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting hybridization. After expression of the pGBKT7-PS1TP5 fusion protein in the AH109 yeast strain was accomplished, a yeast two-hybrid screening was performed by mating AH109 with Y187 containing a leukocyte cDNA library plasmid. The mated yeast was plated on quadruple dropout medium and assayed for alpha-gal activity. The interaction between the PS1TP5 protein and the proteins obtained from positive colonies was further confirmed by repeating the yeast two-hybrid screen. After extracting and sequencing of plasmids from blue colonies we carried out a bioinformatic analysis.

RESULTSForty true positive colonies were selected and sequenced, full length sequences were obtained and we searched for homologous DNA sequences from GenBank. Among the 40 positive colonies, 23 coding genes with known functions were obtained, including Homo sapien leukocyte adhesion protein p150, 95, interleukin 2 receptor gamma chain, PALM2-AKAP2 protein (PALM2-AKAP2), eukaryotic translation initiation factor 4A, beta-2-microglobin, solute carrier family 9 (sodium/hydrogen exchanger), calreticulin, asialoglycoprotein receptor 1 (ASGR1), MHC class II lymphocyte antigen, cytochrome c oxidase subunit 1, lymphocyte antigen 86 (LY86) and lymphocyte cytosolic protein 1. One novel gene with unknown function was found and named as PS1TP5BP1. After being electronically spliced, it was deposited in GenBank (accession number: DQ471327).

CONCLUSIONSGenes of proteins interacting with PS1TP5 were successfully screened from leukocyte cDNA library. These results suggested that PS1TP5 was closely correlated with immunoregulation, carbohydrate metabolism, signal transduction, the formation of hepatic fibrosis and initiation and development of tumors and also brought some new clues for further studying the biological functions of the pre-S1 protein.

Amino Acid Sequence ; Base Sequence ; DNA, Complementary ; chemistry ; Gene Library ; Hepatitis B Surface Antigens ; genetics ; physiology ; Humans ; Leukocytes ; metabolism ; Molecular Sequence Data ; Plasmids ; Protein Interaction Mapping ; Protein Precursors ; genetics ; physiology ; Recombinant Fusion Proteins ; biosynthesis ; Transcriptional Activation ; Two-Hybrid System Techniques ; Yeasts ; genetics

Objective: To explore the factors influencing the sexual function of the male patients with obstructive sleep apnea (OSA). METHODS: Using Arizona Sexual Experience Scale (ASEX) and Epworth Sleepiness Scale (ESS), we conducted a questionnaire investigation among 81 male patients with OSA aged 40.5 ± 8.6 years and 35 healthy volunteers aged 38.8 ± 10 years. According to the sex drive (SD) score in ASEX, we divided the OSA patients into an SD reduction group (SD score = 4, n = 32) and a non-SD reduction group (SD score <4, n = 49), compared the clinical data and polysomnographic (PSG) indexes, and analyzed the factors influencing SD by evaluating the association of the PSG indexes with the SD score. RESULTS: The OSA patients scored significantly higher than the healthy controls in ESS (8 ± 5 vs 5 ± 4, P <0.05) and ASEX (15 ± 4 vs 10 ± 2, P <0.05), and so did the patients of the SD reduction group than those of the non-SD reduction group in ESS (9 ± 5 vs 6 ± 5, P <0.05) and saturation impair time below 90% (SIT90) (41.01 ± 26.95 vs 21.87 ± 19.03, P <0.05). Multivariate regression analysis revealed that the SD score was significantly correlated with age (β = 0.25, P <0.001) and SIT90 (β = 0.4, P <0.001) in the OSA patients. CONCLUSIONS OSA affects various aspects of the sexual function, particularly SD, of the patient. The duration of hypoxia and age of the patient are independent risk factors for SD reduction, which can be considered as a main clinical symptom of OSA.
Adult ; Age Factors ; Case-Control Studies ; Humans ; Hypoxia ; complications ; Libido ; physiology ; Male ; Risk Factors ; Sleep Apnea, Obstructive ; complications ; Surveys and Questionnaires ; Time Factors