Short-term LPS-modulated DCs inoculation interferes with CIA progression when loaded with CII.

The region in promoters that specifies the transcription machinery is called the core promoter, displaying core promoter elements (CPE) necessary for establishment of a preinitiation complex and the initiation of transcription. A classical CPE is the TATA box. In fission yeast, Schizosaccharomyces pombe, a new CPE, called HomolD box, was discovered. Collectively, 141 ribosomal protein genes encoding the full set of 79 different ribosomal proteins and more than 60 other housekeeping genes display a HomolD box in the core promoter. Here, we show that transcription directed by the HomolD box requires the RNA polymerase II machinery, including the general transcription factors. Most intriguingly, however, we identify, by DNA affinity purification, Rrn7 as the protein binding to the HomolD box. Rrn7 is an evolutionary conserved member of the RNA polymerase I machinery involved in transcription initiation of core ribosomal DNA promoters. ChIP shows that Rrn7 cross-links to a ribosomal protein gene promoter containing the HomolD box but not to a promoter containing a TATA box. Taken together, our results suggest that Rrn7 is an excellent candidate to be involved in the coordination of ribosomal DNA and ribosomal gene transcription during ribosome synthesis and, therefore, offer a new perspective to study conservation and evolvability of regulatory networks in eukaryotes.Ribosome biogenesis in eukaryotes is a highly coordinated process involving three different RNA polymerases. RNA polymerase III (RNAPIII) 3 synthesizes the small 5 S RNA. RNAPI synthesizes the large rRNA precursor. Transcription at ribosomal RNA core promoters is initiated by the TATA binding protein (TBP) and TBP-associated factors (TAF 1 s) forming a preinitiation complex (PIC). In human cells, this complex is called SL1 and contains TBP and the TAF 1 s TAF 1 110, TAF 1 63, TAF I 48, and TAF I 41. The TAF 1 equivalents in fission and budding yeast are called Rrn6, Rrn7, and Rrn11, respectively, and are found with TBP in a complex called core factor (1, 2). The minor subunits of SL1 have no equivalents in yeast. RNAPII, finally, transcribes the ribosomal protein-encoding genes (3). RNAPII-dependent transcription also requires a PIC. In a TATA box containing core promoters, the first step in the formation of the PIC is the binding of TBP to the TATA box. TBP binds to the TATA box complexed with TFIID (TAF 11 s) followed by the other GTFs TFIIB, TFIIF, TFIIE, and TFIIH, respectively, to complete PIC formation for the recruitment of pol II (4 -6). However, it is also discussed that a preassembled holoenzyme including pol II, TBP, and the GTFs are targeted with the help of the mediator complex onto the DNA in the core promoter region for PIC formation (7,8).The 141 ribosomal protein genes of fission yeast encoding the full set of 79 ribosomal proteins are TATA-less promoters. Instead, they all contain the highly conserved sequence CAGT-CACA or its inverted form, TGTGACTG, within 100 bp upstream of the ATG start codon. This sequence was termed the HomolD bo...

The transcription of protein-coding genes is carried out by RNA polymerase II (RNAPII) and six general transcription factors (GTFs), called TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH. Together, this collection of proteins constitutes the basal transcription machinery, which recognizes the core promoter elements (CPEs) and participates in the basal transcription of RNAPII-transcribed genes. The GTFs and RNAPII are assembled on the CPEs to form a transcription preinitiation complex [1,2].Transcriptional activation also requires two other groups of multiprotein complexes, called activators and coactivators. Activators stimulate transcription by interacting with both the basal transcription machinery and gene-specific regulatory DNA sequences that reside upstream of the core promoters of RNAPII-transcribed genes. Coactivators enhance transcription by stimulating transcription initiation, facilitating promoter escape by RNAPII and interacting with gene-specific activator proteins [3]. The main coactivators required in in vitro transcription systems are the TFIID complex and the Mediator complex. TFIID contains the TATA-binding protein (TBP), which recognizes the TATA-box promoter sequence, and TBP-associated factors (TAFs), which recognize the CPEs. Mediator has been shown to be required for transcription in vivo and for optimal levels of both basal and activated transcription in vitro in nuclear extracts from human cells [4] The positive cofactor 4 (PC4) protein has an important role in transcriptional activation, which has been proposed to be mediated by transcription factor IIA (TFIIA) and TATA-binding protein-associated factors. To test this hypothesis, we cloned the Schizosaccharomyces pombe PC4 gene and analysed the role of the PC4 protein in the stimulation of basal transcription driven by TATA-containing and TATA-less promoters. Sc. pombe PC4 was able to stimulate basal transcription from several TATA-containing promoters and from the Initiator sequences of the highly transcribed Sc. pombe nmt1 gene. Moreover, it was demonstrated that Sc. pombe PC4 stimulates formation of the transcription preinitiation complex. Activation of transcription by PC4 was dependent on the Mediator complex and TFIIA, but was independent of TATA-binding protein-associated factor. PC4 binds to double-stranded and single-stranded DNA and interacts with TATA-binding protein, TFIIB, TFIIA, Mediator, TFIIH and the transcriptional activator protein VP16.Abbreviations Ad-MLP, adenovirus major late promoter; CK2, casein kinase 2; CPE, core promoter element; DCE, downstream core element; DPE, downstream promoter element; EMSA, electrophoretic mobility shift assay; GTFs, general transcription factors; PC4, positive cofactor 4; RNAPII, RNA polymerase II; TAFs, TBP-associated factors; TBP, TATA-binding protein; TF, transcription factor.

No abstract

Los pesticidas son sustancias quimicas usadas con fl'ecuencia en las zonas agr[colas de nuestro pais. Es un hecho bien establecido que estas sustancias pueden ser dafiinas para Ia salud no solo del trabajador agricola sino tambien para su descendencia. Su objetivo es estudiar Ia asociaci6n entre abortos espontaneos y Ia ocupaci6n agricola de Ia madre. Se efectu6 wz estudio descriptivo, recopilando las fichas clfnicas de aquellas pacientes que presentaron aborto espontaneo registrados en ellibro de procedimientos de Ia maternidad del Hospital San Francisco de L/ay-Llay entre enero del 2002 y diciembre del 2003. Se calcula Ia tasa de incidencia de aborto espontaneo comparando/a con las z'dtimas cifl'as nacionales disponibles, y el porcentaje de ocupaci6n agricola de Ia madre en relaci6n con Ia poblaci6n femenina ocupada de 15 m1os o mas de Ia misma (irea geografica segzln Censo de/2002. Se realiz61a prueba Z para comparacir5n de proporciones, e intervalos de confianza para !a raz6n entre las densidades de incidencia. La tasa de incidencia de aborto espontaneo fzw 81,02 casos/1.000 RNV versus 9,5 casos/1.000 RNV en Chile 1996, otorgando una raz6n de incidencia de 8,5 veces (JC = 6, 72-10,65). El porcentaje de ocupaci6n agricola es mayor que Ia poblaci6n femenina ocupada de 15 anos o mas de Ia rnisma area geograflca. (p < 0,0001). El riesgo de presentar aborto e.spontcineo en Llay-Llay y Catemu es mayor que el resto del pais. La ocupaci6n agricola estci relacionada con un mayor riesgo de aborto espontaneo, probablernente debida a Ia exposici6n a pesticidas.Pa/abras clave: A borto espontaneo, pesticidas, exposicic5n ocupacional.