A Systematic Analysis on mRNA and MicroRNA Expression in Runting and Stunting Chickens

Runting and stunting syndrome (RSS), which is characterized by lower body weight, widely occurs in broilers. Some RSS chickens simply exhibit slow growth without pathological changes. An increasing number of studies indicate that broiler strains differ in susceptibility to infectious diseases, most likely due to their genetic differences. The objective of this study was to detect the differentially expressed miRNAs and mRNAs in RSS and normal chickens. By integrating miRNA with mRNA expression profiling, potential molecular mechanisms involved in RSS could be further explored. Twenty-two known miRNAs and 1,159 genes were differentially expressed in RSS chickens compared with normal chickens (P < 0.05). qPCR validation results displayed similar patterns. The differentially expressed genes were primarily involved in energy metabolism pathways. The antisense transcripts were extensively expressed in chicken liver albeit with reduced abundance. Dual-luciferase reporter assay indicated that gga-miR-30b/c directly target CARS through binding to its 3'UTR. The miR-30b/c: CARS regulation mainly occurred in liver. In thigh muscle and the hypothalamus, miR-30b/c are expressed at higher levels in RSS chickens compared with normal chickens from 2 to 6 w of age, and notably significant differences are observed at 4 w of age.