ABSTRACT
Toxoplasma gondii GRA10 expressed as a GFP-GRA10 fusion protein in HeLa cells moved to the nucleoli within the nucleus rapidly and entirely. GRA10 was concentrated specifically in the dense fibrillar component of the nucleolus morphologically by the overlap of GFP-GRA10 transfection image with IFA images by monoclonal antibodies against GRA10 (Tg378), B23 (nucleophosmin) and C23 (nucleolin). The nucleolar translocalization of GRA10 was caused by a putative nucleolar localizing sequence (NoLS) of GRA10. Interaction of GRA10 with TATA-binding protein associated factor 1B (TAF1B) in the yeast two-hybrid technique was confirmed by GST pull-down assay and immunoprecipitation assay. GRA10 and TAF1B were also co-localized in the nucleolus after co-transfection. The nucleolar condensation of GRA10 was affected by actinomycin D. Expressed GFP-GRA10 was evenly distributed over the nucleoplasm and the nucleolar locations remained as hollows in the nucleoplasm under a low dose of actinomycin D. Nucleolar localizing and interacting of GRA10 with TAF1B suggested the participation of GRA10 in rRNA synthesis of host cells to favor the parasitism of T. gondii.
Subject(s)
Animals , Humans , Mice , Alpha-Amanitin/pharmacology , Antibodies, Monoclonal/analysis , Antibodies, Protozoan/analysis , Dactinomycin/pharmacology , Fluorescent Antibody Technique, Direct , Gene Expression/physiology , Green Fluorescent Proteins/genetics , HeLa Cells , Mice, Inbred BALB C , Nucleic Acid Synthesis Inhibitors/pharmacology , Nucleolus Organizer Region/drug effects , Pol1 Transcription Initiation Complex Proteins/metabolism , Protein Sorting Signals/physiology , Protozoan Proteins/biosynthesis , Recombinant Fusion Proteins/genetics , Toxoplasma/physiology , TransfectionABSTRACT
<p><b>UNLABELLED</b>From large-scale sequence of human fetal liver cDNA library, we have obtained a full-length cDNA from an EST after further sequencing. It has been demonstrated by the alignment comparison with data base available that it is a novel member of Ubc family and got the number from GeneBank: UBF-F1 AF 294842.</p><p><b>AIM AND METHODS</b>To demonstrate its authenticity, UBF was amplified from the total RNA of human fetal liver and HL-60 cell line using RT-PCR, and the PCR products were further sequenced and compared with the original UBF sequence. To evaluate the expression level and subcellular location of UBF in human multiple tissues, in situ hybridization was carried out on the frozen section of human fetal multiple tissues and HL-60 cell line with DIG-labeled UBF cDNA probes.</p><p><b>RESULTS</b>The experimental results of RT-PCR and sequencing showed that the sequence of RT-PCR products were the same as the original UBF. The experimental results of in situ hybridization showed that UBF was expressed widely by human multiple fetal tissues and the expression level were very high in HL-60 cells.</p><p><b>CONCLUSION</b>It is suggested that the special structure of UBF is authentic, and the expression profiling research of UBF shows that UBF is expressed widely by human multiple fetal tissues and the expression level is very high in HL-60 cells, implying that UBF plays the important function in the developing tissues and leukemia cells. It is also suggested that UBF may be functionally related with the nucleic-involving cellular activities based on the results of sub-cellular localizations.</p>