Molecular cloning of htra2-beta-1 and htra2-beta-2, two human homologs of tra-2 generated by alternative splicing
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1Max-Planck Institute for Psychiatry, Planegg, Germany.
Abstract:
A yeast two-hybrid screen was performed to find new factors involved in pre-mRNA splicing. Using SC35 as a bait, we isolated a human cDNA bearing high homology to the Drosophila transformer-2 (TRA-2) protein. This cDNA was named htra2-beta1. htra2-beta1 is a nuclear protein that colocalizes with SC35 in a speckled pattern. It interacts with several SR proteins tested in yeast. A second form named htra2-beta2 is generated by alternative splicing. This isoform gives rise to a truncated protein without an SR domain. Both isoforms are evenly distributed throughout adult rat tissue. The ratio of these two isoforms changes after stimulation of primary human T-cell and primary rat spleen cell cultures, indicating that alternative splicing is involved in regulation of htra2-beta activity.
Insights
Researchers identified a human protein, htra2-beta1, involved in pre-mRNA splicing by interacting with SR proteins. Its alternative splicing produces a second form, htra2-beta2, with altered activity in cell cultures.
Area of Science:
- Molecular Biology
- Gene Regulation
- RNA Splicing
Background:
- Pre-mRNA splicing is a critical process in gene expression.
- Identifying novel factors involved in splicing regulation is essential for understanding cellular function.
Purpose of the Study:
- To discover new factors participating in pre-mRNA splicing.
- To characterize the function and regulation of a newly identified splicing factor.
Main Methods:
- Yeast two-hybrid screening using SC35 as bait.
- Co-localization studies with SC35.
- Interaction assays with SR proteins.
- Analysis of alternative splicing in cell cultures.
Main Results:
- A human cDNA, htra2-beta1, homologous to Drosophila TRA-2, was isolated.
- htr2-beta1 is a nuclear protein that co-localizes with SC35 and interacts with SR proteins.
- Alternative splicing generates htra2-beta2, lacking an SR domain; its ratio changes upon cell stimulation.
Conclusions:
- htr2-beta1 is a novel human splicing factor interacting with SR proteins.
- Alternative splicing of htra2-beta regulates its activity, suggesting a role in cellular response.