TY - JOUR
T1 - Redundant intronic repressors function to inhibit fibroblast growth factor receptor-1 α-exon recognition in glioblastoma cells
AU - Jin, Wei
AU - Huang, Eileen S.C.
AU - Bi, Weiqi
AU - Cote, Gilbert J.
PY - 1999/9/24
Y1 - 1999/9/24
N2 - The human fibroblast growth factor receptor-1 primary transcript is alternatively processed to produce receptor forms that vary in their affinity for fibroblast growth factor. The inclusion of a single exon (α) in normal brain glial cells produces a low affinity form of the receptor. Recognition of the α-exon is dysregulated during neoplastic transformation of glial cells to produce a high affinity receptor form. In this study, we have identified a second intronic repressor of RNA splicing located approximately 250 nucleotides upstream of the α-exon. Deletion or mutation of this sequence resulted in a significant increase in exon recognition in glioblastoma cells. This intronic repressor was found to share significant sequence homology with an intronic repressor element located downstream of the α-exon. The two repressor elements are functionally redundant in that they are capable of inhibiting α-exon recognition when positioned upstream or downstream of the exon. Finally, the elements were found to mediate enhanced exclusion of an unrelated exon, but only the repressors were placed flanking the exon. However, under these conditions, the cell-specific exon exclusion was no longer maintained. These results suggest that although the α-exon inclusion is actively repressed in glioblastomas, the absence of trans-activators appears to be key to the production of the high affinity form of fibroblast growth factor receptor-1 in glioblastomas.
AB - The human fibroblast growth factor receptor-1 primary transcript is alternatively processed to produce receptor forms that vary in their affinity for fibroblast growth factor. The inclusion of a single exon (α) in normal brain glial cells produces a low affinity form of the receptor. Recognition of the α-exon is dysregulated during neoplastic transformation of glial cells to produce a high affinity receptor form. In this study, we have identified a second intronic repressor of RNA splicing located approximately 250 nucleotides upstream of the α-exon. Deletion or mutation of this sequence resulted in a significant increase in exon recognition in glioblastoma cells. This intronic repressor was found to share significant sequence homology with an intronic repressor element located downstream of the α-exon. The two repressor elements are functionally redundant in that they are capable of inhibiting α-exon recognition when positioned upstream or downstream of the exon. Finally, the elements were found to mediate enhanced exclusion of an unrelated exon, but only the repressors were placed flanking the exon. However, under these conditions, the cell-specific exon exclusion was no longer maintained. These results suggest that although the α-exon inclusion is actively repressed in glioblastomas, the absence of trans-activators appears to be key to the production of the high affinity form of fibroblast growth factor receptor-1 in glioblastomas.
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U2 - 10.1074/jbc.274.39.28035
DO - 10.1074/jbc.274.39.28035
M3 - Article
C2 - 10488155
AN - SCOPUS:0033600792
SN - 0021-9258
VL - 274
SP - 28035
EP - 28041
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 39
ER -