Differential expression and co-expression gene network analyses reveal molecular mechanisms and candidate biomarkers involved in breast muscle myopathies in chicken

Abstract

The broiler industry is facing an increasing prevalence of breast myopathies, such as white striping (WS) and wooden breast (WB), and the precise aetiology of these occurrences remains poorly understood. To progress our understanding of the structural changes and molecular pathways involved in these myopathies, a transcriptomic analysis was performed using an 8 × 60 K Agilent chicken microarray and histological study. The study used pectoralis major muscles from three groups: slow-growing animals (n = 8), fast-growing animals visually free from defects (n = 8), or severely affected by both WS and WB (n = 8). In addition, a weighted correlation network analysis was performed to investigate the relationship between modules of co-expressed genes and histological traits. Functional analysis suggested that selection for fast growing and breast meat yield has progressively led to conditions favouring metabolic shifts towards alternative catabolic pathways to produce energy, leading to an adaptive response to oxidative stress and the first signs of inflammatory, regeneration and fibrosis processes. All these processes are intensified in muscles affected by severe myopathies, in which new mechanisms related to cellular defences and remodelling seem also activated. Furthermore, our study opens new perspectives for myopathy diagnosis by highlighting fine histological phenotypes and genes whose expression was strongly correlated with defects.

Enhanced cytokine expression and upregulation of inflammatory signaling pathways in broiler chickens affected by wooden breast myopathy

“…Therefore, the abnormal expressions of these cytokines implied the imbalance of Th1/Th2 ratio in WB affected birds, which could further lead to immune disorder and aggravate the progress of inflammatory response. Our findings are consistent with a previous report, which demonstrated that a large number of differentially expressed genes are involved in the regulation of inflammatory cytokines secretion and the activation of the immune system cascade in muscle of birds severely affected by white striping and WB 28 . Despite of the pro‐inflammatory roles of cytokines in myositis muscle, they also play diverse functions during muscle repair and remodeling.…”

Molecular Phenotyping of White Striping and Wooden Breast Myopathies in Chicken

“…The muscles used in the present study are issued of a trial already described in Pampouille et al (2019) . Briefly, PM muscles were sampled on 42-day-old chickens originating from two chicken lines: an experimental slow-growing (SG) line showing no lesions related to WS and WB defects ( n = 8) and a commercial fast-growing (FG) one, in which both WS and WB defects were observed at different degrees ( n = 32).…”

“…Total RNA was extracted from 100 mg of PM muscle with a commercial kit (RNA Now, Ozyme, Saint-Cyr-l’École, France) as described previously ( Pampouille et al, 2019 ). Reverse transcription was done with 10 micrograms of RNA using SuperScript II reverse transcriptase (Invitrogen, Montigny-le-Bretonneux, France), random primers (Promega, Charbonnières-les-Bains, France), and RNAse Out (Invitrogen, Montigny-le-Bretonneux, France) according to manufacturer recommendations.…”

“…There is also strong evidence of muscle cell regeneration associated with increased expression of several myogenic regulatory factors ( Clark and Velleman, 2016 ). High-throughput metabolomic or transcriptomic approaches have also revealed a great number of dysregulated molecular pathways involved in the response to oxidative stress, altered glucose utilization and lipid metabolism, muscle degeneration and repair, inflammatory responses, and extracellular matrix (ECM) remodeling ( Abasht et al, 2016 , 2019 ; Kuttappan et al, 2017 ; Papah et al, 2018 ; Pampouille et al, 2019 ). In addition, the WB condition was recently associated with muscle weakness ( Norring et al, 2018 ).…”

Integrated environmental and genomic analysis reveals the drivers of local adaptation in African indigenous chickens

“…The dAAF pattern is mostly homogeneous across these genes, but a few intronic SNPs from HBE1 show the largest dAAF ( Figure 7G). These genes are overexpressed in broilers with severe myopathic breast muscles, possibly as a response to insufficient oxygen and oxidative stress (44). Accordingly, their expression may be adaptive in scavenging chickens in response to oxidative stress from food conversion in high SoilOrgC agro-ecology.…”