PTEN/AKT/mTOR pathway involvement in autophagy, mediated by miR-99a-3p and energy metabolism in ammonia-exposed chicken bursal lymphocytes

Abstract

Emission of atmospheric ammonia (NH3) is an environmental challenge because of its harmful effects on humans and animals including birds. Among all organisms, NH3 is highly sensitive to birds. Autophagy plays a critical role in Bursa of fabricius (BF)-mediated immune responses against various hazardous substances. Therefore, we designed our work to demonstrate whether NH3 can induce autophagy in broiler chicken BF. In this study, the downregulated levels of mammalian target of rapamycin and light chain-3 (LC-Ⅰ), as well as the upregulated levels of phosphate and tensin homology (PTEN), protein kinase B (AKT), autophagy related-5, light chain-3 (LC3-Ⅱ), Becline-1, and Dynein, were found. Our results of transmission electron microscopy displayed signs of autophagosomes/autophagic lysosomes, and immunofluorescence assay displayed that NH3 exposure reduced the relative amount of CD8+ B-lymphocyte in chicken BF. Exposure of NH3 led to energy metabolism disturbance by decreasing mRNA levels of glucose metabolism factors aconitase-2, hexokinase-1, hexokinase-2, lactate dehydrogenase-A, lactate dehydrogenase-B, pyruvate kinase, phosphofructokinase and succinate dehydrogenase complex unit-B, and adenosine triphosphates (ATPase) activities (Na+/K+ ATPase, Ca2+ ATPase, Mg2+ ATPase, and Ca/Mg2+ ATPase). Moreover, phosphate and tensin homology was found as target gene of microRNA-99a-3p which confirmed that high concentration of NH3 caused autophagy in chicken BF. In summary, these findings suggested that ammonia induced autophagy via miR-99a-3p, the reduction of ATPase activity, and the alteration of autophagy-related factors, and energy metabolism mediation in BF. Our findings provide information to assess the harmful effects of NH3 on chicken and clues for human health pathophysiology.

Keywords

• NH3
• autophagy
• ATPase
• miR-99a-3p
• PTEN/AKT/mTOR signaling pathway