ABSTRACT

1. The Tibetan chicken, which is an indigenous breed living on the Tibetan Plateau, exhibits hypoxic adaptations to its high-altitude environment. However, the molecular mechanism behind this hypoxic adaptation is still unclear. This study aimed to investigate differentially expressed miRNAs involved in hypoxic adaptation through high-throughput RNA sequencing.

2. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to verify the differentially expressed miRNAs and their target genes in chicken embryonic heart tissues and fibroblasts. Luciferase reporter assays were performed to confirm the relationship between miRNAs and target genes.

3. The study identified 37 differentially expressed miRNAs in Tibetan chicken embryonic heart tissues, including 20 up- and 17 down-regulated miRNAs, compared to those found in lowland chickens. Differentially expressed miRNAs were mainly involved in biological processes, such as cell cycle arrest, toll-like receptor signalling pathways, and I-kappa B kinase/NF-kappa B signalling. The data showed that gga-miR-34 c-5p was significantly upregulated in Tibetan chicken tissues and hypoxic fibroblasts, while EHHADH, a target gene of gga-miR-34 c-5p, was downregulated. Moreover, gga-miR-34 c-5p dramatically decreased the luciferase activity of the wild EHHADH, whereas no effect on the mutational EHHADH was found.

4. This study identified miRNA expression profiles in the Tibetan chicken and suggested that miR-34 c-5p acts as a novel miRNA associated with hypoxic adaptation. This facilitates the understanding of molecular mechanisms that underlie long-term exposure to hypoxia.

摘要

1.藏鸡是一种生活在青藏高原上的土著品种，对高海拔环境表现出低氧适应性。但是，这种低氧适应背后的分子机制仍不清楚。这项研究旨在研究通过高通量RNA测序参与低氧适应的差异表达miRNA。

2.定量逆转录聚合酶链反应（qRT-PCR）用于验证鸡胚胎心脏组织和成纤维细胞中差异表达的miRNA及其靶基因。进行荧光素酶报告基因测定以证实miRNA与靶基因之间的关系。

3.研究发现，与低地鸡相比，藏族鸡胚胎心脏组织中有37种差异表达的miRNA，包括20种上调的miRNA和17种下调的miRNA。差异表达的miRNA主要参与生物学过程，例如细胞周期停滞，toll​​样受体信号通路和I-κB激酶/NF-κB信号传导。数据显示，藏鸡组织和低氧成纤维细胞中gga-miR-34 c-5p显着上调，而gga-miR-34 c-5p的靶基因EHHADH被下调。此外，gga-miR-34 c-5p大大降低了野生EHHADH的荧光素酶活性，而未发现对突变EHHADH的影响。

4.这项研究鉴定了藏鸡中的miRNA表达谱，并暗示miR-34 c-5p可作为一种与低氧适应相关的新型miRNA。这有助于了解长期暴露于低氧环境的分子机制。