Wilhelm bernhard workshop on the cell nucleus

Yuan L.. et al.: J. Cell Biol. 142:331-339, 1998

POSTERS

TRANSCRIPTION AND SPLICING IN THE TESTIS OF MICE FED ON A GENETICALLY MODIFIED-SOYBEAN DIET

Cisterna B.¹, Vecchio L.¹, Manuali E.², Malatesta M.³, Biggiogera M. <sup>1

1</sup>Dipartimento di Biologia Animale, Laboratorio di Biologia Cellulare, University of Pavia, ²Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Perugia, and ³Istituto di Istologia ed Analisi di Laboratorio, University of Urbino “Carlo Bo”, Italy
We have focused our attention on some features of the transcription/splicing mechanism in the testis from mice fed on genetically modified (GM) soybean and sacrified after 1, 2, 5 and 8 months. Our data show a decrease in anti-RNA Polimerase II, in SC35 splicing factor and Sm labelling both in somatic cells (Sertoli cells) and in spermatogonia, spermatocytes and spermatids, after 1, 2 and 5 mounths on this diet. We have also observed an increase/accumulation of perichromatin granules (PG), containing mRNA, in the nucleus of Sertoli cells. Moreover, these cells display a significant decrease of nuclear pore. As for the morphology, in Sertoli cells (GM+), perichromatinic fibrils (PF) are numerous, nucleoli are more reticulated and larger, signal of high transcriptional activity. Moreover, many vescicles, probably correlated to SER are present in the cytoplasm. At 8 months, there is a resumption of transcription accompained by an increase in labelling for anti-RNA Pol II and anti-hnRNP. Considering that the increase of PG in GM-fed animals is probably due to a decrease of the nuclear pore density, some hypotheses can be proposed to explain this phenomenon, taking into account the fact that such an RNA accumulation seems to be transient.

actin is involved in the initiation of transcription by RNA polymerase II

Fuchsova B. ¹, Mavrommatis E.¹, Philimonenko V.V.³, Goodrich J.A.⁴, Hope T.J.², Lessard, J.L⁵, Hozak P.³ and de Lanerolle P.¹

Departments of ¹Physiology and Biophysics and ²Microbiology and Immunology, University of Illinois at Chicago, USA; ³Cell Ultrastructure and Molecular Biology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic; ⁴Chemistry and Biochemistry, University of Colorado at Boulder, and ⁵Children's Hospital Research Foundation, Cincinnati, USA
Actin is an abundant protein in the cell nucleus and a number of studies have pointed to its role in transcription. We have demonstrated that  actin is present in RNA polymerase II (Pol II) preinitiation complexes (PIC) assembled on immobilized DNA template and co purifies with Pol II fraction from HeLa cell nuclei. In addition, we have shown that it co localizes with Pol II at EM level. Antibodies to  actin inhibit transcription by Pol II in vitro and when microinjected into the nuclei of living cells. To further characterize the role of  actin in PIC formation we studied its association with TATA-binding protein (TBP). Immunofluorescence studies showed that  actin co localizes with TBP in the nucleolus of HeLa cells but there was no significant overlap in the nucleoplasm. Introduction of new transcription sites by virus infection caused redistribution of  actin and TBP to the sites of intense transcription labeled by BrUTP incorporation. Moreover,  actin co localizes with the accumulations of TBP in the nucleus of adenovirus infected cells. The co localization of TBP and  actin was further confirmed at EM level. Taken together, these data suggest that  actin is involved in the initiation of transcription powered by Pol II.