Change search
ReferencesLink to record
Permanent link

Direct link
Hrp59, an hnRNP M-like protein in Chironomus and Drosophila, binds to exonic splicing enhancers in a subset of pre-mRNAs
Stockholm University, Faculty of Science, Department of Molecular Biology and Functional Genomics.
2004 (English)In: Journal of Cell Biology, ISSN 0021-9525, Vol. 168, no 7, 1031-1025 p.Article in journal (Refereed) Published
Abstract [en]

Here, we study an insect hnRNP M protein, referred to as Hrp59. Hrp59 is relatively abundant, has a modular domain organization containing three RNA-binding domains, is dynamically recruited to transcribed genes, and binds to premRNA cotranscriptionally. Using the Balbiani ring system of Chironomus, we show that Hrp59 accompanies the mRNA from the gene to the nuclear envelope, and is released from the mRNA at the nuclear pore. The association of Hrp59 with transcribed genes is not proportional to the amount of synthesized RNA, and in vivo Hrp59 binds preferentially to a subset of mRNAs, including its own mRNA. By coimmunoprecipitation of Hrp59-RNA complexes and microarray hybridization against Drosophila whole-genome arrays, we identify the preferred mRNA targets of Hrp59 in vivo and show that Hrp59 is required for the expression of these target mRNAs. We also show that Hrp59 binds preferentially to exonic splicing enhancers and our results provide new insights into the role of hnRNP M in splicing regulation.

Place, publisher, year, edition, pages
2004. Vol. 168, no 7, 1031-1025 p.
URN: urn:nbn:se:su:diva-23272DOI: 10.1083/jcb.200407173OAI: diva2:191080
Part of urn:nbn:se:su:diva-218Available from: 2004-08-30 Created: 2004-08-30 Last updated: 2010-01-29Bibliographically approved
In thesis
1. Isolation and functional characterization of Hrp65-binding proteins in Chironomus tentans
Open this publication in new window or tab >>Isolation and functional characterization of Hrp65-binding proteins in Chironomus tentans
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

It is well-established that the organization of nuclear components influences gene expression processes, yet little is known about the mechanisms that contribute to the spatial co-ordination of nuclear activities. The salivary gland cells of Chironomus tentans provide a suitable model system for studying gene expression in situ, as they allow for direct visualization of the synthesis, processing and export of a specific protein-coding transcript, the Balbiani ring (BR) pre-mRNA, in a nuclear environment in which chromatin and non-chromatin structures can easily be distinguished. The RNAbinding protein Hrp65 has been identified in this model system as a protein associated with non-chromatin nucleoplasmic fibers, referred to as connecting fibers (CFs). The CFs associate with BR RNP particles in the nucleoplasm, suggesting that Hrp65 is involved in mRNA biogenesis at the post-transcriptional level. However, the function of Hrp65 is not known, nor is the function or the composition of CFs. In the work described in this thesis, we have identified by yeast two-hybrid screening and characterized different proteins that bind to Hrp65. These proteins include a novel hnRNP protein in C. tentans named Hrp59, various isoforms of Hrp65, the splicing- and mRNA export factor HEL/UAP56, and a RING-domain protein of unknown function. Immuno-electron microscopy experiments showed that Hrp59 and HEL are present in CFs, and in larger structures in the nucleoplasm of C. tentans salivary gland cells.

Hrp59 is a C. tentans homologue of human hnRNP M, and it associates cotranscriptionally with a subset of pre-mRNAs, including its own transcript, in a manner that does not depend quantitatively on the amount of synthesized RNA. Hrp59 accompanies the BR pre-mRNA from the gene to the nuclear envelope, and is released from the BR mRNA at the nuclear pore complex. We have identified the preferred RNA targets of Hrp59 in Drosophila cells, and we have shown that Hrp59 binds preferentially to exonic splicing enhancer sequences.

Hrp65 self-associates through an evolutionarily conserved domain that can also mediate heterodimerization of Hrp65 homologues. Different isoforms of Hrp65 interact with each other in all possible combinations, and Hrp65 can oligomerize into complexes of at least six molecules. The interaction between different Hrp65 isoforms is crucial for their intracellular localization, and we have discovered a mechanism by which Hrp65-2 is imported into the nucleus through binding to Hrp65-1.

Hrp65 binds to HEL/UAP56 in C. tentans cells. We have analyzed the distribution of the two proteins on polytene chromosomes and in the nucleoplasm of salivary gland cells, and our results suggest that Hrp65 and HEL become associated during posttranscriptional gene expression events. HEL binds to the BR pre-mRNP cotranscriptionally, and incorporation of HEL into the pre-mRNP does not depend on the location of introns along the BR pre-mRNA. HEL accompanies the BR mRNP to the nuclear pore and is released from the BR mRNP during translocation into the cytoplasm.

Place, publisher, year, edition, pages
Stockholm: Institutionen för molekylärbiologi och funktionsgenomik, 2004. 80 p.
gene expression, RNA-binding proteins, mRNA biogenesis, nuclear structure
National Category
Biochemistry and Molecular Biology
urn:nbn:se:su:diva-218 (URN)91-7265-921-1 (ISBN)
Public defence
2004-09-20, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 8 C, Stockholm, 09:15
Available from: 2004-08-30 Created: 2004-08-30Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text
By organisation
Department of Molecular Biology and Functional Genomics
In the same journal
Journal of Cell Biology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 19 hits
ReferencesLink to record
Permanent link

Direct link