LncCRHR1 acts as a competing endogenous RNA to regulate FGF19 expression by sponging miR-302d in bovine mastitis

As the first dual-purpose (dairy and beef) breed developed in China, Xinjiang Brown cattle are highly resistant to disease and tolerant of roughage. The identification of genes regulating resistance to mastitis is a novel means of enhancing the breeding of Xinjiang Brown cattle. In previous studies, the lncCRHR1-miR-302d-FGF19 axis was identified as a competing endogenous RNA (ceRNA) network in Xinjiang Brown cattle. Based on that, functional studies were conducted at the cellular level. Nuclear and cytoplasmic localization revealed that lncCRHR1 is expressed primarily in the cytoplasm, suggesting that it may function as part of a ceRNA mechanism in bovine mammary epithelial cells. Overexpression of lncCRHR1 promoted proliferation of bovine mammary alveolar cells (MAC-T) and inflammatory cytokine release while inhibiting apoptosis, while downregulation had the reverse effect. Dual-luciferase reporter assays confirmed lncCRHR1 targets miR-302d, with miR-302d observed to inhibit both proliferation and inflammatory cytokine secretion while promoting apoptosis. Additionally, a targeting relationship was observed between miR-302d and FGF19 , with FGF19 promoting proliferation and cytokine secretion and inhibiting apoptosis. LncCRHR1 bound competitively to miR-302d and FGF19 , thereby participating in the inflammatory response, proliferation, and apoptosis in MAC-T cells. This study provides a potential target for molecular breeding aimed at combating bovine mastitis. • ● LncCRHR1 acts as a cytoplasmic ceRNA to sponge miR-302d in bovine mammary epithelial cells • ● The lncCRHR1/miR-302d/FGF19 axis regulates cell proliferation, inflammation, and apoptosis in mastitis • ● Targeting this ceRNA network presents a novel molecular strategy for breeding mastitis-resistant cattle