Abstract
The growth hormone receptor (GHR) gene is correlated with many phenotypic and physiological alternations in chicken, such as shorter shanks, lower body weight and muscle mass loss. However, the role of the GHR gene in mitochondrial function remains unknown in poultry. In this study, we assessed the function of mitochondria in sex-linked dwarf (SLD) chicken skeletal muscle and interfered with the expression of GHR in DF-1 cells to investigate the role of the GHR gene in chicken mitochondrial function both in vivo and in vitro. We found that the expression of key regulators of mitochondrial biogenesis and mitochondrial DNA (mtDNA)-encoded oxidative phosphorylation (OXPHOS) genes were downregulated and accompanied by reduced enzymatic activity of OXPHOS complexes in SLD chicken skeletal muscle and GHR knockdown cells. Then, we assessed mitochondrial function by measuring mitochondrial membrane potential (ΔΨm), mitochondrial swelling, reactive oxygen species (ROS) production, malondialdehyde (MDA) levels, ATP levels and the mitochondrial respiratory control ratio (RCR), and found that mitochondrial function was impaired in SLD chicken skeletal muscle and GHR knockdown cells. In addition, we also studied the morphology and structure of mitochondria in GHR knockdown cells by transmission electron microscopy (TEM) and MitoTracker staining. We found that knockdown of GHR could reduce mitochondrial number and alter mitochondrial structure in DF-1 cells. Above all, we demonstrated for the first time that the GHR gene is essential for chicken mitochondrial function in vivo and in vitro.
Highlights
Mitochondria are dynamic organelles with a crucial role in cellular energy homeostasis and metabolism, with the generation of adenosine triphosphate (ATP) through the respiratory chain (RC) being one of their main functions [1]
The relative mRNA levels of the Growth hormone (GH) gene were not significantly different, for growth hormone receptor (GHR) and insulin-like growth factor 1 (IGF1), were significantly downregulated in sex-linked dwarf (SLD) chicken skeletal muscle compared with normal chicken skeletal muscle, indicating the low level of GH binding activity in SLD chicken skeletal muscle (Figure 1A)
In order to investigate the role of GHR in mitochondrial biogenesis in vivo, we assessed the relative mRNA expression of the genes involved in the PGC1α–nuclear respiratory factor-1 (NRF1)–TFAM signaling pathway using quantitative real-time PCR (qRT-PCR)
Summary
Mitochondria are dynamic organelles with a crucial role in cellular energy homeostasis and metabolism, with the generation of adenosine triphosphate (ATP) through the respiratory chain (RC) being one of their main functions [1]. Mitochondrial biogenesis is essential for its function, which is mainly regulated by nuclear genes through the PGC1α–NRF1–TFAM signaling pathway [4]. Previous studies have reported that insulin-like growth factor 1 (IGF1) signaling can regulate mitochondrial biogenesis markers in the steroidogenic cells of prepubertal testis [10], and is essential for mitochondrial biogenesis in cancer cells [11]. These findings suggest that the GHR gene plays a pivotal role in mammalian mitochondrial function both in vivo and in vitro. We demonstrate for the first time that GHR is essential for chicken mitochondrial function both in vivo and in vitro
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