Regulation of alternative splicing of alpha-actinin transcript by Bruno-like proteins.
BACKGROUND
The Bruno-like or CELF proteins, such as mammalian CUGBP1 and Etr-3, Xenopus EDEN-BP, and Drosophila Bruno (Bru), are regulators of gene expression at the post-transcriptional level, and contain three RNA-recognition motifs (RRMs). It has been shown that mammalian CUGBP1 and Etr-3 regulate alternative splicing of cardiac troponin T pre-mRNA via binding to CUG-triplet repeats.


RESULTS
Using in vitro selection and UV-crosslinking experiments, we found that zebrafish Bruno-like proteins bound to repeat elements of uridine and purine (termed UREs). It is known that non-muscle (NM) and smooth muscle (SM) exons of the rat alpha-actinin gene are used in a mutually exclusive manner. Transfection experiments in mammalian cells showed that zebrafish Brul and Etr-3 induced the muscle-specific splicing of rat alpha-actinin pre-mRNA via binding to the URE at the branch point upstream of the NM exon. In contrast, zebrafish Etr-1 promoted skipping of both the NM and SM exons in a manner which was not dependent on URE-binding.


CONCLUSIONS
Our results showed that Bruno-like proteins bind to UREs and regulate the alternative splicing of alpha-actinin pre-mRNA. Members of the Bruno family play multiple roles in splicing regulation.
Suzuki
Hitoshi
H
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0101, Japan.
Jin
Yui
Y
Otani
Hifumi
H
Yasuda
Kunio
K
Inoue
Kunio
K
D000185:Actinin / Q000235:genetics*; D017398:Alternative Splicing; D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D000067879:CELF1 Protein; D018900:Dinucleotide Repeats / Q000235:genetics; D051959:ELAV Proteins; D000067778:ELAV-Like Protein 3; D005786:Gene Expression Regulation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015027:Zebrafish; D029961:Zebrafish Proteins
D000067879:CELF1 Protein; C412365:CELF1 protein, zebrafish; D051959:ELAV Proteins; D000067778:ELAV-Like Protein 3; C490262:Elavl3 protein, rat; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D029961:Zebrafish Proteins; C088635:elavl3 protein, zebrafish; D000185:Actinin