title: Hypoxia-dependent mRNA expression pattern of splicing factor YT521 and its impact on oncological important target gene expression.
abstract: The ubiquitously expressed splicing factor YT521 (YTHDC1) is characterized by alternatively spliced isoforms with regulatory impact on cancer-associated gene expression. Our recent findings account for the prognostic significance of YT521 in endometrial cancer. In this study, we investigated the hypoxia-dependency of YT521 expression as well as its differential isoform activities on oncological important target genes. YT521's potential regulatory influence on splicing was investigated by a minigene assay for the specific target gene CD44. Functional splicing analysis was performed by YT521 knock-down or overexpression, respectively. In addition, YT521 expression was determined under hypoxia. The two protein-generating YT521 mRNA isoforms 1 and 2 caused a comparable, specific induction of CD44v alternative splicing (P < 0.01). In a number of oncological target genes, YT521 upregulation significantly altered BRCA2 expression pattern, while YT521 knock-down created a significant regulatory impact on PGR expression, respectively. Hypoxia induced a specific switch towards the processing of two non-protein-coding mRNA variants, of which one is described for the first time in this study. The presented study underlines the comparable regulatory potential of both YT521 isoforms 1 and 2, on the investigated target genes in vivo and in vitro. Hypoxia induces a specific switch in YT521 expression pattern towards the two non-protein coding mRNA variants, the already characterized isoform 3 and the newly discovered exon 8-skipping isoform. The altered YT521 alternative splicing is functionally coupled with nonsense-mediated decay and can be interpreted as regulated unproductive splicing and transcription with consecutive impact on the processing of specific cancer-associated genes, such as BRCA2 and PGR.
authors.affiliation: Gynecological Hospital, University Medical Center Freiburg, Freiburg, Germany; German Cancer Research Center, Heidelberg, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Hirschfeld
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Markus
authors.initials: M
authors.lastname: Jaeger
authors.forename: Stefan
authors.initials: S
authors.lastname: Stamm
authors.forename: Thalia
authors.initials: T
authors.lastname: Erbes
authors.forename: Sebastian
authors.initials: S
authors.lastname: Mayer
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Tong
authors.forename: Elmar
authors.initials: E
authors.lastname: Stickeler
mesh_terms: D017398:Alternative Splicing; D024682:BRCA2 Protein / Q000096:biosynthesis; D015687:Cell Hypoxia / Q000235:genetics; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000096:biosynthesis; D061986:MCF-7 Cells; D009369:Neoplasms / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics*; D009687:Nuclear Proteins / Q000096:biosynthesis; D020033:Protein Isoforms / Q000235:genetics; D034622:RNA Interference; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics*
chemical_list: D024682:BRCA2 Protein; C551750:BRCA2 protein, human; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D047908:Intracellular Signaling Peptides and Proteins; C439067:MRFAP1 protein, human; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C490769:YTHDC1 protein, human
keywords: BRCA2; YT521; cancer; hypoxia; splicing