Farstad-O'Halloran Kara, Sooda Anuradha, Iqbal Tooba, Wilton Steve, Aung-Htut May T
Personalised Medicine Centre, Health Futures Institute, Murdoch University, Murdoch, Perth, WA 6150, Australia.
Perron Institute for Neurological and Translational Science, The University of Western Australia, Nedlands, Perth, WA 6009, Australia.
Genes (Basel). 2025 Mar 31;16(4):412. doi: 10.3390/genes16040412.
Apolipoprotein C-III () plays a crucial role in triglyceride metabolism and is closely associated with cardiovascular disease risk. Elevated APOC3 levels contribute to higher plasma triglycerides and increased risk of atherosclerosis, making expression an attractive and logical therapeutic target.
While studying various transcript isoforms expressed in hepatoma cell lines (HepG2, Huh7) and healthy liver tissue using publicly available long-read RNA sequencing, we found three novel isoforms. These isoforms were validated through RT-PCR and Sanger sequencing.
All three novel isoforms are splicing variants of the MANE transcript, . Isoforms 1 and 2 exhibit splicing patterns similar to from exons 2-4; however, isoform 1 shares its exon 1 splicing pattern with , while isoform 2 features an extended exon 1 that includes exon 1a, the adjacent intronic region, and exon 1b. The third isoform closely resembles , but lacks exon 2, which contains the translation start codon. Remarkably, similar splicing patterns and transcript variants were observed in Caco-2 cells, a model of the small intestine, indicating that these isoforms are not liver-specific.
This study identifies three novel isoforms and highlights their expression in both hepatic and intestinal cell models. Further studies are needed to elucidate the functional roles of these novel isoforms and their contribution to the regulation of gene expression.
载脂蛋白C-III（APOC3）在甘油三酯代谢中起关键作用，与心血管疾病风险密切相关。APOC3水平升高会导致血浆甘油三酯升高和动脉粥样硬化风险增加，使得APOC3表达成为一个有吸引力且合理的治疗靶点。
在使用公开可得的长读长RNA测序研究肝癌细胞系（HepG2、Huh7）和健康肝脏组织中表达的各种APOC3转录本异构体时，我们发现了三种新的APOC3异构体。这些异构体通过逆转录聚合酶链反应（RT-PCR）和桑格测序进行了验证。
所有三种新异构体都是MANE转录本APOC3-001的剪接变体。异构体1和2表现出与外显子2 - 4的APOC3-001相似的剪接模式；然而，异构体1与APOC3-002共享其外显子1剪接模式，而异构体2具有延伸的外显子1，其包括外显子1a、相邻的内含子区域和外显子1b。第三种异构体与APOC3-001非常相似，但缺少包含翻译起始密码子的外显子2。值得注意的是，在小肠模型Caco-2细胞中观察到了类似的APOC3剪接模式和转录变体，表明这些异构体并非肝脏特异性的。
本研究鉴定出三种新的APOC3异构体，并突出了它们在肝脏和肠道细胞模型中的表达。需要进一步研究以阐明这些新异构体的功能作用及其对APOC3基因表达调控的贡献。
