Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, 06006 Badajoz, Spain.
Biomolecules. 2024 Oct 12;14(10):1288. doi: 10.3390/biom14101288.
The 18-exon human gene codes for dual-activity triokinase and FMN cyclase (TKFC) in an ORF, spanning from exon 2 to exon 18. In addition to TKFC-coding transcripts (classified as type by their intron-17 splice), databases contain evidence for alternative transcripts, but none of them has been expressed, studied, and reported in the literature. A novel full-ORF transcript was cloned from brain cDNA and sequenced (accession no. DQ344550). It results from an alternative 3' splice-site in intron 17. The cloned cDNA contains an ORF also spanning from exon 2 to exon 18 of the gene but with a 56-nt insertion between exons 17 and 18 (classified as type). This insertion introduces an in-frame stop, and the resulting ORF codes for a shorter TKFC variant, which, after expression, is enzymatically inactive. intron-17 splicing was found to be differentially expressed in human tissues. In a multiple-tissue northern blot using oligonucleotide probes, the liver showed a strong expression of the -like splice of intron 17, and the heart preferentially expressed the -like splice. Through a comparison to global expression data from massive-expression studies of human tissues, it was inferred that the intestine preferentially expresses transcripts that contain neither of those splices. An analysis of transcript levels quantified by RNA-Seq in the GTEX database revealed an exception to this picture due to the occurrence of a non-coding short transcript with a -like splice. Altogether, the results support the occurrence of potentially relevant transcript variants of the gene, differentially expressed in human tissues. (This work is dedicated in memoriam to Professor Antonio Sillero, 1938-2024, for his lifelong mentoring and his pioneering work on triokinase).
人类 18 外显子基因在一个 ORF 中编码双活性三激酶和 FMN 环化酶 (TKFC)，从外显子 2 延伸到外显子 18。除了 TKFC 编码转录本（因其内含子 17 剪接而被归类为 类型），数据库中还包含替代 转录本的证据，但没有一个在文献中被表达、研究和报道。从脑 cDNA 中克隆并测序了一种新型全长 ORF 转录本（登录号 DQ344550）。它源自内含子 17 中的替代 3'剪接位点。克隆的 cDNA 包含一个 ORF，也从 基因的外显子 2 延伸到外显子 18，但在外显子 17 和外显子 18 之间有 56 个核苷酸的插入（归类为 类型）。该插入引入了一个框内终止，产生的 ORF 编码一个较短的 TKFC 变体，该变体在表达后无酶活性。内含子 17 剪接在人类组织中表现出差异表达。在使用寡核苷酸探针的多组织 northern blot 中，肝脏显示出强烈的内含子 17 样剪接表达，而心脏则优先表达 样剪接。通过与人类组织大规模表达研究的全球表达数据进行比较，可以推断出肠道优先表达既不含这些剪接体又不含这些剪接体的 转录本。对 GTEX 数据库中 RNA-Seq 定量分析转录本水平的分析显示，由于存在具有 样剪接的非编码短转录本，这种情况出现了例外。总的来说，这些结果支持 基因存在潜在相关的转录变体，在人类组织中差异表达。（这项工作是为了纪念 Antonio Sillero 教授（1938-2024 年）而进行的，他毕生指导并开创了三激酶的研究）。
