CXCL12基因通过在其前mRNA的3'末端的选择性剪接产生一系列转录变体。本研究探讨了这些替代转录本的生物学活性以及参与CXCL12转录和RNA剪接调控的机制。我们在编码保守的3'UTR的CXCL12αDNA区域中鉴定了一个“GA”插入突变。该变体转录物被命名为CXCL12-3\'GA+。该突变在健康的中国个体中以13.2%的频率发生。然而,其在健康白种人中的频率为22.6%，明显高于在中国观察到的。基因组分析表明，GA突变可能编码G-四链体结构，紧邻重要的富含AU的元件（ARE）簇，这些元件是3'UTR上mRNA稳定性的公认调节剂。使用编码CXCL12的3'UTR的分子构建体的实验表明,与WT等位基因相比,GA+等位基因可以显著增加基因表达。进一步的研究发现，WT等位基因与通过可变剪接导致外显子2缺失的225bp次要转录同种型（MTI）的产生有关。使用从WT/GA+基因型携带者的培养PBMC收集的样品的ARMS-PCR表明,与WT等位基因相比,GA+等位基因优先转录。总之,该研究表明，在CXCL12α的3'UTR编码区域中插入GA可能通过选择性mRNA剪接影响基因表达。这一发现为理解编码CXCL12基因3'UTR的序列中的多个元件如何调节其转录提供了基础，并可能导致有关涉及异常CXCL12α表达的疾病的见解。
The CXCL12 gene produces a series of transcript variants through alternative splicing at the 3\' end of its pre-mRNA. This study explores the biological activities of these alternative transcripts and the mechanisms involved in the regulation of CXCL12 transcription and RNA splicing. We identified a \"GA\" insertion mutation in the region of CXCL12α DNA encoding the conserved 3\'UTR. This variant transcript was named CXCL12-3\'GA+. The mutation occurred at a frequency of 13.2% in healthy Chinese individuals. However, its frequency in healthy Caucasians was 22.6%, significantly higher than what was observed in the Chinese. Genomic analysis indicated that the GA+ mutation likely encodes a G-quadruplex structure in close proximity to a cluster of important AU-rich elements (AREs) that are well-established regulators of mRNA stability at the 3\'UTR. Experiments using molecular constructs encoding the 3\'UTR of CXCL12 revealed that the GA+ allele can significantly increase gene expression compared to the WT allele. Further studies uncovered that the WT allele was associated with the production of a 225-bp minor transcript isoform (MTI) through alternative splicing resulting in the deletion of exon 2. ARMS-PCR using samples collected from cultured PBMCs of WT/GA+ genotype carriers indicated that the GA+ allele was preferentially transcribed compared to the WT allele. In summary, the study demonstrates that a GA insertion in the region encoding the 3\'UTR of CXCL12α may affect gene expression through alternative mRNA splicing. This finding provides a basis for understanding how multiple elements in the sequence encoding the 3\'UTR of the CXCL12 gene regulates its transcription and may lead to insights about diseases involving abnormal CXCL12α expression.
