title: Profilin is associated with transcriptionally active genes.
abstract: We have raised antibodies against the profilin of Chironomus tentans to study the location of profilin relative to chromatin and to active genes in salivary gland polytene chromosomes. We show that a fraction of profilin is located in the nucleus, where profilin is highly concentrated in the nucleoplasm and at the nuclear periphery. Moreover, profilin is associated with multiple bands in the polytene chromosomes. By staining salivary glands with propidium iodide, we show that profilin does not co-localize with dense chromatin. Profilin associates instead with protein-coding genes that are transcriptionally active, as revealed by co-localization with hnRNP and snRNP proteins. We have performed experiments of transcription inhibition with actinomycin D and we show that the association of profilin with the chromosomes requires ongoing transcription. However, the interaction of profilin with the gene loci does not depend on RNA. Our results are compatible with profilin regulating actin polymerization in the cell nucleus. However, the association of actin with the polytene chromosomes of C. tentans is sensitive to RNase, whereas the association of profilin is not, and we propose therefore that the chromosomal location of profilin is independent of actin.
authors.affiliation: Department of Molecular Biology & Functional Genomics, Stockholm University, Stockholm, Sweden.
authors.forename: Emilia
authors.initials: E
authors.lastname: Söderberg
authors.forename: Viktoria
authors.initials: V
authors.lastname: Hessle
authors.forename: Anne
authors.initials: A
authors.lastname: von Euler
authors.forename: Neus
authors.initials: N
authors.lastname: Visa
mesh_terms: D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002467:Cell Nucleus / Q000378:metabolism; D002683:Chironomidae / Q000254:growth & development / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004331:Drosophila melanogaster / Q000378:metabolism; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000032:analysis / Q000378:metabolism; D006801:Humans; D007814:Larva / Q000378:metabolism; D008969:Molecular Sequence Data; D059007:Polytene Chromosomes / Q000378:metabolism; D051304:Profilins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000032:analysis / Q000378:metabolism; D012469:Salivary Glands / Q000378:metabolism; D016415:Sequence Alignment; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D000199:Actins; D000906:Antibodies; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D051304:Profilins; D012333:RNA, Messenger; D017411:Ribonucleoproteins, Small Nuclear; D003609:Dactinomycin