A mutation-created novel intra-exonic pre-mRNA splice site causes constitutive activation of KIT in human gastrointestinal stromal tumors.
We report a new mechanism of aberrant pre-mRNA splicing resulting in constitutive activation of a mis-spliced oncoprotein (KIT) leading to malignancy (gastrointestinal stromal tumor) in contrast to loss of function of mis-spliced proteins resulting in diverse human diseases in the literature. The mechanisms of three consecutive molecular events, deletion of noncoding and coding regions encompassing the 3' authentic splice site, creation of a novel intra-exonic pre-mRNA 3' splice acceptor site leading to in-frame loss of 27 nucleotides (nine amino acids; Lys550-Lys558), and the mechanism of constitutive activation of the mis-spliced KIT are elucidated. Loss of a peptide in a critical location unleashed the protein from autoinhibition (as evidenced by three-dimensional structural analysis), causing KIT to become constitutively activated and resulting in the GIST phenotype. We also demonstrated that only one of the following two exonic splicing enhancers is sufficient for inclusion of the KIT exon 11 in vivo: AACCCATGT (nucleotides 2-10 from the 5' end, which are recognized by SC35, SRp55, and SF2/ASF) or GGTTGTTGAGG (nucleotides 27-37 from the 5' end, which are recognized by SC35 and SRp55), suggestive of exonic enhancer redundancy.
Chen
Lei L
LL
Department of Sarcoma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA. llchen@mdanderson.org
Sabripour
Mahyar
M
Wu
Elsie F
EF
Prieto
Victor G
VG
Fuller
Gregory N
GN
Frazier
Marsha L
ML
D017398:Alternative Splicing; D001483:Base Sequence; D004252:DNA Mutational Analysis; D005091:Exons; D016368:Frameshift Mutation; D005770:Gastrointestinal Neoplasms / Q000235:genetics* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008969:Molecular Sequence Data; D010641:Phenotype; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis* / Q000235:genetics*; D022821:RNA Splice Sites / Q000235:genetics*; D017154:Stromal Cells
D022821:RNA Splice Sites; D019009:Proto-Oncogene Proteins c-kit