HNRNP-L Interacts with the Signal-Responsive Alternative Splicing Regulatory Element of CD45
| dc.contributor.advisor | Lynch, Kristen W. | en |
| dc.creator | Rothrock, Caryn Robin | en |
| dc.date.accessioned | 2010-07-12T18:42:28Z | |
| dc.date.available | 2010-07-12T18:42:28Z | |
| dc.date.issued | 2005-08-11 | |
| dc.description.abstract | Alternative splicing is emerging as a common mechanism for altering protein expression in response to extracellular cues. Of particular interest is how cell-signaling pathways modify mRNA isoform expression. The T cell tyrosine phosphatase CD45 provides a useful model system to explore the regulation of cell-signaling induced alternative splicing. CD45 has three variable exons that are differentially excluded in T cells upon antigen challenge or activation. An exonic splicing silencer element, named ESS1, is necessary for regulation of inclusion or exclusion of CD45 exon 4 in the mature mRNA. This sequence is also sufficient to confer T cell activation induced repression of a heterologous exon. ESS1 contains a sequence motif that is present in CD45 variable exons 5 and 6, as well as exons of other signal responsive genes. Point mutations in conserved nucleotides within this motif abolish T cell activation-induced skipping of CD45 variable exons 4, 5, and 6. Biochemical purification of RNA binding proteins from nuclear extract identifies a number of hnRNP family members that bind ESS1 RNA sequence in a specific manner. Mass spectrometry identifies three of these, including p65 as heterogeneous ribonucleoprotein L (hnRNP-L), p55 as Polypyrimidine Tract Binding Protein (PTB or hnRNP-I), and p40 as heterogeneous ribonucleoprotein E2 (hnRNP-E2). Recombinant hnRNP-L, PTB, and hnRNP-E2 bind specificity to wild type ESS1 RNA, as tested by mobility shift and UV crosslinking assays. Mutations in the ESS1 sequence, which prevent exon skipping in vivo, reduce recombinant hnRNP-L binding in vitro. Recombinant PTB and hnRNP-E2 do not appear to have reduced binding to mutant ESS1 sequence. HnRNP-L appears to be the main sequence-specific binding component of ESS1 RNA, and may be involved in repressing CD45 variable exon 4 in response to T cell activation. | en |
| dc.format.digitalOrigin | born digital | en |
| dc.format.medium | Electronic | en |
| dc.format.mimetype | application/pdf | en |
| dc.identifier.oclc | 61711234 | |
| dc.identifier.uri | https://hdl.handle.net/2152.5/642 | |
| dc.language.iso | en | en |
| dc.subject | RNA Isoforms | en |
| dc.subject | Antigens, CD45 | en |
| dc.subject | Alternative Splicing | en |
| dc.title | HNRNP-L Interacts with the Signal-Responsive Alternative Splicing Regulatory Element of CD45 | en |
| dc.type | Thesis | en |
| dc.type.genre | dissertation | en |
| dc.type.material | Text | en |
| thesis.date.available | 2005-08-11 | |
| thesis.degree.department | Graduate School of Biomedical Sciences | en |
| thesis.degree.discipline | Biological Chemistry | en |
| thesis.degree.grantor | UT Southwestern Medical Center | en |
| thesis.degree.level | Doctoral | en |
| thesis.degree.name | Doctor of Philosophy | en |