RESUMO
SR protein ASF/SF2 is a general pre-mRNA splicing factor as well as a regulator of alternative splicing. Data presented here show that ASF/SF2 is efficiently recruited to sites in the nucleus where adenovirus genes are transcribed and the resulting pre-mRNAs are processed. At the intermediate stages of a productive infection, ASF/SF2 colocalizes with small nuclear ribonucleoprotein particles (snRNPs), splicing factors in ring-like structures surrounding viral replication centres and, at late stages of the infection, in enlarged speckles. Results presented here demonstrate that ASF/SF2 requires only one of the two RNA-recognition motifs (RRMs) present in the protein for its efficient recruitment to the ring-like structures, where viral pre-mRNAs are transcribed and processed, and that the arginine/serine-rich (RS) domain in ASF/SF2 is both redundant and insufficient for the translocation of the protein to active viral RNA polymerase II genes in adenovirus-infected cells.
Assuntos
Adenoviridae/genética , Regulação Viral da Expressão Gênica/genética , Proteínas Nucleares/genética , Splicing de RNA/genética , RNA Mensageiro/genética , Transcrição Gênica , Células HeLa , Humanos , RNA Viral/genética , Proteínas de Ligação a RNA , Ribonucleoproteínas Nucleares Pequenas/genética , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Fatores de Processamento de Serina-ArgininaRESUMO
Profilin is one of the major components controlling actin polymerization. Here, profilin I was located in fibroblasts and HeLa cells by the use of two different sets of affinity-purified antibodies. Both antibody preparations labeled nuclei in a speckle-like pattern and displayed extensive colocalization with small nuclear ribonucleoprotein particle (snRNP)-core proteins and p80 coilin-containing Cajal bodies. Treatment with actinomycin D led to largely similar reorganizations of snRNPs and profilin, while profilin and Cajal bodies separated under these conditions. One of the profilin antibodies interfered with pre-mRNA splicing in vitro, further indicating a role for profilin during pre-mRNA processing.
Assuntos
Corpos Enovelados/metabolismo , Proteínas Contráteis , Proteínas dos Microfilamentos/metabolismo , Splicing de RNA/fisiologia , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Animais , Anticorpos/imunologia , Anticorpos/metabolismo , Núcleo Celular/metabolismo , Células Cultivadas , Fibroblastos/citologia , Fibroblastos/metabolismo , Células HeLa , Humanos , Imuno-Histoquímica , Profilinas , Isoformas de Proteínas/metabolismoRESUMO
Herpes simplex virus (HSV) immediate-early protein ICP27 is a multifunctional regulator of viral and cellular gene expression. It has previously been shown that ICP27 directly or indirectly modulates several posttranscriptional processes, such as pre-mRNA splicing and polyadenylation. We show here that pre-mRNA splicing is inhibited in nuclear extracts prepared from cells in which ICP27 has been transiently expressed. Our results show that splicing inhibition in ICP27 extracts is manifested at early stages of the splicing process. Furthermore, our results suggest that an enzymatic activity in ICP27-containing extracts causes the splicing inhibition.
