Abstract
In recent years, the poultry industry has experienced an increased incidence of myopathies affecting breasts of fast-growing broilers, such as White Striping (WS) and Wooden Breast (WB) defects. To explore the molecular mechanisms and genes involved in WS and WB onset, we decided to perform a Weighted Gene Co-expression Network Analysis (WGCNA) using the gene expression profile and meat quality parameters of Pectoralis major muscles analysed in our previous study. Among the 212 modules identified by WGCNA, the red, darkred, midnightblue and paleturquoise4 modules were chosen for subsequent analysis. Functional analysis evidenced pathways involved in extracellular matrix (ECM) organization, collagen metabolism, cellular signaling and unfolded protein response. The hub gene analysis showed several genes coding for ECM components as the most interconnected nodes in the gene network (e.g. COL4A1, COL4A2, LAMA2, LAMA4, FBLN5 and FBN1). In this regard, this study suggests that alterations in ECM composition could somehow activate the cascade of biological reactions that result in the growth-related myopathies onset, and the involvement of Collagen IV alterations in activating the endoplasmic reticulum (ER) stress response may be hypothesized. Therefore, our findings provide further and innovative knowledge concerning the molecular mechanisms related to the breast abnormalities occurrence in modern broilers.
Highlights
In recent years, the poultry industry has experienced an increased incidence of myopathies affecting breasts of fast-growing broilers, such as White Striping (WS) and Wooden Breast (WB) defects
The 212 gene modules identified by Weighted Gene Co-expression Network Analysis (WGCNA) are shown by cluster dendrogram (Supplementary Figure S1), in which the branches correspond to modules and each leaf in the branch represents one probe
Considering their detrimental effect on the poultry industry, an improvement in the knowledge regarding the molecular pathways involved in the onset of these modern myopathies can be extremely important
Summary
The poultry industry has experienced an increased incidence of myopathies affecting breasts of fast-growing broilers, such as White Striping (WS) and Wooden Breast (WB) defects. Numerous studies have demonstrated that the incidence of emerging myopathies has a strong genetic determinism, as shown by the moderate (h2 = 0.34) to high (h2 = 0.65) hereditability values observed in high-yielding c hickens[7,8], suggesting that the prevalence of these growth-related abnormalities could be related to unfavorable correlated responses to broiler selection criteria adopted in modern b roilers[2,9] Within this context, transcriptomic and gene expression studies can be helpful to improve knowledge concerning myodegenerative defects. It has been speculated that hypoxia could be one of the possible major causative processes underlying the occurrence of these muscular disorders[2] According to this scenario, Hoving-Bolink et al.[14] and Soglia et al.[1] reported that the hypertrophy induced by the genetic selection carried out in fast-growing broiler led to a reduced capillary density, which may result in an impaired oxygen and nutrient supply to the muscle. The underlying causes of these breast abnormalities remain currently unclear
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