Home About us Contact
|
Home About us Contact | ||
|
|
||
Nucleolar Protein (nucleolar + protein)
Selected AbstractsCANu1, a novel nucleolar protein, accumulated on centromere in response to DNA damageGENES TO CELLS, Issue 8 2008Choong-Ryoul Sihn Single nucleotide polymorphism is known to be an ideal marker to detect human diseases. We isolated a novel human gene, to be called as CANu1, by the large-scale genome-wide association analysis to screen specific Single nucleotide polymorphisms in colon cancer. It is mapped to chromosome 14q11.2 and its transcript contains a 948-nt open reading frame encoding a protein of 315 aa. Here, we observed that green fluorescence protein (GFP)-fused CANu1 protein was localized to nucleoli and the C-termini of CANu1 protein were essential for its localization. Moreover, the silencing of the CANu1 gene by siRNA caused ribosomal stress leading to G1 cell cycle arrest, the induction of p53 protein, and the translocation of B23 protein. In addition, CANu1 protein was translocated from nucleolus to nuclear foci in response to UV damage. Interestingly, the mobility of a GFP-CANu1 protein in the UV damaged cells was two times faster than non-irradiated cells. Taken together, we report that a novel nucleolar protein, CANu1, is essential to maintain ribosomal structure and responsive upon UV damage. [source] Fatty acid acylation regulates trafficking of the unusual Plasmodium falciparum calpain to the nucleolusMOLECULAR MICROBIOLOGY, Issue 1 2009Ilaria Russo Summary The Plasmodium falciparum genome encodes a single calpain. By generating P. falciparum clones expressing C-terminally tagged calpain, we localized this protein to the nucleolus. Pf_calpain possesses an unusual and long N-terminal domain in which we identified three subregions that are highly conserved among Plasmodium species. Two have putative targeting signals: a myristoylation motif and a nuclear localization sequence. We assessed their functionality. Our data show that the nuclear localization sequence is an active nuclear import motif that contains an embedded signal conferring nucleolar localization on various chimeras. The N-terminus is myristoylated at Gly2 and palmitoylated at Cys3 and Cys22. Palmitoylation status has an important role in dictating P. falciparum calpain localization. The targeting signals function in mammalian cells as well as in the parasite. P. falciparum calpain is a unique nucleolar protein with an interesting mechanism of targeting. [source] Interaction of the plant glycine-rich RNA-binding protein MA16 with a novel nucleolar DEAD box RNA helicase protein from Zea maysTHE PLANT JOURNAL, Issue 6 2004Elisenda Gendra Summary The maize RNA-binding MA16 protein is a developmentally and environmentally regulated nucleolar protein that interacts with RNAs through complex association with several proteins. By using yeast two-hybrid screening, we identified a DEAD box RNA helicase protein from Zea mays that interacted with MA16, which we named Z. maysDEAD box RNA helicase 1 (ZmDRH1). The sequence of ZmDRH1 includes the eight RNA helicase motifs and two glycine-rich regions with arginine,glycine-rich (RGG) boxes at the amino (N)- and carboxy (C)-termini of the protein. Both MA16 and ZmDRH1 were located in the nucleus and nucleolus, and analysis of the sequence determinants for their cellular localization revealed that the region containing the RGG motifs in both proteins was necessary for nuclear/nucleolar localization The two domains of MA16, the RNA recognition motif (RRM) and the RGG, were tested for molecular interaction with ZmDRH1. MA16 specifically interacted with ZmDRH1 through the RRM domain. A number of plant proteins and vertebrate p68/p72 RNA helicases showed evolutionary proximity to ZmDRH1. In addition, like p68, ZmDRH1 was able to interact with fibrillarin. Our data suggest that MA16, fibrillarin, and ZmDRH1 may be part of a ribonucleoprotein complex involved in ribosomal RNA (rRNA) metabolism. [source] The role of RNA polymerase I transcription and embryonic genome activation in nucleolar development in bovine preimplantation embryosMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 7 2008O. Svarcova Abstract The aim of the present study was to investigate the role of RNA polymerase I (RPI) transcription in nucleolar development during major transcriptional activation (MTA) in cattle. Late eight-cell embryos were cultured in the absence (control group) or presence of actinomycin D (AD) (RPI inhibition, AD 0.2 µg/ml; total transcriptional inhibition, AD 2.0 µg/ml). Late four-cell embryos were cultured to late eight-cell stage in 0.2 µg/ml AD (MTA prevention, ADLT (long-term total transcriptional inhibition group). Embryos were processed for autoradiography, transmission electron microscopy, fluorescent in situ hybridization (ribosomal RNA, rRNA), silver staining (nucleolar proteins), and immunofluorescence (RPI). Control embryos displayed extranucleolar and nucleolar transcription, functional nucleoli, and distinct RPI localization. Nuclei (97%) showed large rRNA clusters, in 94.1% co-localized with nucleolar proteins deposits. In AD 0.2 group, only extranucleolar transcription was detected. Segregated dense-fibrillar and granular components, but no fibrillar centers, were observed. RPI was dispersed. Nuclei (55%) presented rRNA clusters, in 38.8% co-localized with silver-stained deposits. AD 2.0 and ADLT groups displayed no transcription and disintegrating nucleolar precursors. AD 2.0 (34%) and 14% (ADLT) of nuclei presented clusters of maternally inherited rRNA. In AD 2.0 group, RPI was dispersed, but 17.2% of nuclei showed colocalization of rRNA with nucleolar proteins. In ADLT group, RPI was lacking and clustering of nucleolar proteins was hampered. In conclusion, rDNA transcription is not required for targeting of rRNA processing proteins, rRNA is maternally inherited and target to rDNA independent of transcription, and de novo transcription is required for proper nucleologenesis in cattle. Mol. Reprod. Dev. 75: 1095,1103, 2008. © 2008 Wiley-Liss, Inc. [source] | ||||||||||