Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway.
Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway.
Front Endocrinol (Lausanne). 2024 May 24;15:1395750. doi: 10.3389/fendo.2024.1395750. eCollection 2024.
The beneficial effect of thermogenic adipocytes in maintaining body weight and protecting against metabolic disorders has raised interest in understanding the regulatory mechanisms defining white and beige adipocyte identity. Although alternative splicing has been shown to propagate adipose browning signals in mice, this has yet to be thoroughly investigated in human adipocytes.
We performed parallel white and beige adipogenic differentiation using primary adipose stem cells from 6 unrelated healthy subjects and assessed differential gene and isoform expression in mature adipocytes by RNA sequencing.
We find 777 exon junctions with robust differential usage between white and beige adipocytes in all 6 subjects, mapping to 562 genes. Importantly, only 10% of these differentially spliced genes are also differentially expressed, indicating that alternative splicing constitutes an additional layer of gene expression regulation during beige adipocyte differentiation. Functional classification of alternative isoforms points to a gain of function for key thermogenic transcription factors such as and , and enzymes such as , or . We find that a large majority of the splice variants arise from differential TSS usage, with beige-specific TSSs being enriched for PPARγ and MED1 binding compared to white-specific TSSs. Finally, we validate beige specific isoform expression at the protein level for two thermogenic regulators, PPARγ and PEMT.
These results suggest that differential isoform expression through alternative TSS usage is an important regulatory mechanism for human adipocyte thermogenic specification.
产热脂肪细胞在维持体重和预防代谢紊乱方面的有益作用引起了人们对理解定义白色和米色脂肪细胞特征的调节机制的兴趣。尽管已经表明在小鼠中，选择性剪接传播脂肪棕色信号，但尚未在人类脂肪细胞中进行彻底研究。
我们使用来自 6 个无关健康个体的原代脂肪干细胞进行平行的白色和米色脂肪生成分化，并通过 RNA 测序评估成熟脂肪细胞中的差异基因和异构体表达。
我们在所有 6 个个体的白色和米色脂肪细胞中发现了 777 个exon 接头，它们具有很强的差异使用，映射到 562 个基因。重要的是，这些差异剪接基因中只有 10%的基因也表现出差异表达，这表明选择性剪接是米色脂肪细胞分化过程中基因表达调控的另一个层次。替代异构体的功能分类指向关键的产热转录因子（如 和 ）和酶（如 或 ）的功能获得。我们发现，大多数剪接变体来自于 TSS 使用的差异，与白色特异性 TSS 相比，米色特异性 TSS 富含 PPARγ 和 MED1 结合。最后，我们在两个产热调节剂 PPARγ 和 PEMT 的蛋白质水平上验证了米色特异性异构体的表达。
这些结果表明，通过选择性 TSS 使用的差异异构体表达是人类脂肪细胞产热特化的重要调节机制。
