UV-dependent alternative splicing uncouples p53 activity and PIG3 gene function through rapid proteolytic degradation.
The p53-inducible gene 3 (PIG3) is a transcriptional target of the tumor suppressor protein p53 and is thought to play a role in apoptosis. In this report, we identify a novel alternatively spliced product from the PIG3 gene that we call PIG3AS (PIG3 alternative splice). PIG3AS results from alternative pre-mRNA splicing that skips exon 4 of the five exons included in the PIG3 transcript. The resulting protein product shares its first 206 amino acids with PIG3 but has a unique 42-amino acid C terminus. In unstressed cells and after most DNA damage conditions that induce transcription from the PIG3 gene, production of the PIG3 transcript dominates. However, in response to UV light, pre-mRNA splicing shifts dramatically in favor of PIG3AS. Unlike the PIG3 protein, the PIG3AS protein is rapidly degraded with a short half-life and is stabilized by proteasome inhibition. Our results illustrate the first example of an endogenous, UV-inducible, alternative splicing event and that control of the splicing machinery is involved in the cellular DNA damage response. They also suggest that rapid proteolytic degradation represents a cellular mechanism for uncoupling p53 activity from PIG3 gene activation that is independent of promoter selectivity.
Nicholls
Chris D
CD
Cancer Biology Research Group, Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
Shields
Michael A
MA
Lee
Patrick W K
PW
Robbins
Stephen M
SM
Beattie
Tara L
TL
D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D004249:DNA Damage; D018076:DNA, Complementary / Q000378:metabolism; D003720:Densitometry; D005091:Exons; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014466:Ultraviolet Rays
D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; C411296:TP53I3 protein, human; D016159:Tumor Suppressor Protein p53