Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Cheonan, 31151, Korea.
Department of Integrated Biomedical Science, Soonchunhyang University, Cheonan, 31151, Korea.
Biol Direct. 2023 Jun 15;18(1):32. doi: 10.1186/s13062-023-00388-4.
Adipose tissue, an organ critical for systemic energy homeostasis, is influenced by type 2 immunity in its development and function. The type 2 cytokine interleukin (IL)-4 induces the proliferation of bipotential adipocyte precursors (APs) in white fat tissue and primes these cells for differentiation into beige adipocytes, which are specialized for thermogenesis. However, the underlying mechanisms have not yet been comprehensively examined. Here, we identified six microRNA (miRNA) genes upregulated upon IL-4 stimulation in APs, miR-322, miR-503, miR-351, miR-542, miR-450a, and miR-450b; these are encoded in the H19X locus of the genome. Their expression is positively regulated by the transcription factor Klf4, whose expression also increases upon IL-4 stimulation. These miRNAs shared a large set of target genes, of which 381 genes were downregulated in mRNA expression upon IL-4 stimulation and enriched in Wnt signaling pathways. Two genes with downregulated expression, Ccnd1 and Fzd6, were repressed by H19X-encoded miRNAs. Additionally, the Wnt signaling activator LiCl downregulated the expression of this group of miRNAs in APs, indicating that Wnt signaling-related genes and these miRNAs form a double-negative feedback regulatory loop. This miRNA/Wnt feedback regulation modulated the elevated proliferation of APs induced by IL-4 stimulation and contributed to priming them for beige adipocyte differentiation. Moreover, the aberrant expression of these miRNAs attenuates the differentiation of APs into beige adipocytes. Collectively, our results suggest that H19X-encoded miRNAs facilitate the transition of APs from proliferation to differentiation in the IL-4-mediated regulation.
脂肪组织是维持全身能量稳态的关键器官,其发育和功能受 2 型免疫的影响。2 型细胞因子白细胞介素(IL)-4 可诱导白色脂肪组织中双潜能脂肪细胞前体(AP)的增殖,并使这些细胞向米色脂肪细胞分化,米色脂肪细胞专门进行产热。然而,其潜在的机制尚未被全面研究。在这里,我们鉴定了 6 个在 IL-4 刺激的 AP 中上调的 microRNA(miRNA)基因,即 miR-322、miR-503、miR-351、miR-542、miR-450a 和 miR-450b;这些 miRNA 编码在基因组的 H19X 基因座上。它们的表达受到转录因子 Klf4 的正向调控,而 Klf4 的表达也会在 IL-4 刺激后增加。这些 miRNA 共享一大组靶基因,其中 381 个基因在 IL-4 刺激后 mRNA 表达下调,并在 Wnt 信号通路中富集。两个下调表达的基因,Ccnd1 和 Fzd6,受到 H19X 编码的 miRNA 的抑制。此外,Wnt 信号激活剂 LiCl 在 AP 中下调了这组 miRNA 的表达,表明 Wnt 信号相关基因和这些 miRNA 形成了一个双负反馈调节环路。这种 miRNA/Wnt 反馈调节调节了 IL-4 刺激诱导的 AP 增殖的增加,并有助于为其米色脂肪细胞分化做好准备。此外,这些 miRNA 的异常表达会削弱 AP 向米色脂肪细胞的分化。总之,我们的研究结果表明,H19X 编码的 miRNA 促进了 AP 从增殖向 IL-4 介导的调节中的分化。
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