Hostname: page-component-7c8c6479df-5xszh Total loading time: 0 Render date: 2024-03-29T05:40:51.067Z Has data issue: false hasContentIssue false

Differential alternative splicing activity of isoforms of polypyrimidine tract binding protein (PTB)

Published online by Cambridge University Press:  29 June 2001

MATTHEW C. WOLLERTON
Affiliation:
Department of Biochemistry, 80 Tennis Court Road, Old Addenbrookes Site, University of Cambridge, Cambridge CB2 1GA, United Kingdom
CLARE GOODING
Affiliation:
Department of Biochemistry, 80 Tennis Court Road, Old Addenbrookes Site, University of Cambridge, Cambridge CB2 1GA, United Kingdom
FIONA ROBINSON
Affiliation:
Department of Biochemistry, 80 Tennis Court Road, Old Addenbrookes Site, University of Cambridge, Cambridge CB2 1GA, United Kingdom
EMMA C. BROWN
Affiliation:
Department of Biochemistry, 80 Tennis Court Road, Old Addenbrookes Site, University of Cambridge, Cambridge CB2 1GA, United Kingdom
RICHARD J. JACKSON
Affiliation:
Department of Biochemistry, 80 Tennis Court Road, Old Addenbrookes Site, University of Cambridge, Cambridge CB2 1GA, United Kingdom
CHRISTOPHER W.J. SMITH
Affiliation:
Department of Biochemistry, 80 Tennis Court Road, Old Addenbrookes Site, University of Cambridge, Cambridge CB2 1GA, United Kingdom
Get access

Abstract

Polypyrimidine tract binding protein (PTB) is an RNA-binding protein that regulates splicing by repressing specific splicing events. It also has roles in 3′-end processing, internal initiation of translation, and RNA localization. PTB exists in three alternatively spliced isoforms, PTB1, PTB2, and PTB4, which differ by the insertion of 19 or 26 amino acids, respectively, between the second and third RNA recognition motif domains. Here we show that the PTB isoforms have distinct activities upon α-tropomyosin (TM) alternative splicing. PTB1 reduced the repression of TM exon 3 in transfected smooth muscle cells, whereas PTB4 enhanced TM exon 3 skipping in vivo and in vitro. PTB2 had an intermediate effect. The PTB4 > PTB2 > PTB1 repressive hierarchy was observed in all in vivo and in vitro assays with TM, but the isoforms were equally active in inducing skipping of α-actinin exons and showed the opposite hierarchy of activity when tested for activation of IRES-driven translation. These findings establish that the ratio of PTB isoforms could form part of a cellular code that in turn controls the splicing of various other pre-mRNAs.

Type
Research Article
Copyright
2001 RNA Society

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)