Small RNA sequencing reveals miRNAs important for hypoxic adaptation in the Tibetan chicken

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.

KEYWORDS:

• Tibetan chickens
• miRNAs
• miR-34c-5p
• EHHADH
• hypoxic adaptation

Ethics approval and consent to participate

The animal experiment in this study was approved via the animal care and ethical committee of Sichuan Animal Science Academy. All experimental procedures and animal care performed in the present study were approved according to the recommendations of Sichuan academy of animal science. All efforts were made to minimise suffering.

Disclosure statement

The authors declare that there is no conflict of interest regarding the publication of this paper.

Additional information

Funding

This work was supported by the Science Fund for Distinguished Young Scholars of Sichuan Province (No. 2019JDJQ0021); The National modern agricultural technology system construction of China (no.CARS-41-G04); The Province Key Technologies R & D Program of Livestock and Poultry Breeding Programs of Sichuan Province (No. 2016NYZ0043).