Chicken GLUT4 function via enhancing mitochondrial oxidative phosphorylation and inhibiting ribosome pathway in skeletal muscle satellite cells.

Glucose Transporter 4 (GLUT4) is a crucial protein facilitating glucose uptake and metabolism across cell membranes in mammals. However, information on GLUT4 in birds has historically been limited. In this study, we investigated the dynamic expression profile of chicken GLUT4 using real-time quantitative PCR (RT-qPCR) and examined its potential effects and mechanisms via GLUT4 overexpression and RNA sequencing (RNA-seq) in chicken primary skeletal muscle satellite cells (CP-SMSCs). Our results demonstrated that chicken GLUT4 is differentially expressed across tissues, with predominant expression in skeletal muscles, and across developmental stages of CP-SMSCs, with notable upregulation during the phases of cell proliferation and early differentiation. Notably, 0.1 μM insulin for 60 min significantly elevated the expression of GLUT4 in CP-SMSCs (P < 0.05). GLUT4 overexpression in CP-SMSCs promoted cell proliferation, as evidenced by Cell Counting Kit-8 (CCK-8) (P < 0.05) and 5-Ethynyl-2'-Deoxyuridine (EDU) assays (P < 0.05), and enhanced glucose consumption following 0.1 μM insulin treatment (P < 0.05). However, it inhibited glucose consumption 12 h after the addition of 5 g/L glucose (P < 0.05). After overexpressing GLUT4, we identified 302 differentially expressed genes (DEGs) in CP-SMSCs, with 134 upregulated and 168 downregulated. These DEGs are primarily enriched in pathways such as oxidative phosphorylation, ribosome, cardiac muscle contraction, ATP metabolic processes, and mitochondrial protein complexes. Specifically, in the enriched oxidative phosphorylation pathway, the upregulated DEGs (12) encode mitochondrial proteins, while the downregulated DEGs (6) are nuclear genome-derived. The ribosomal pathway is predominantly inhibited, accompanying with the downregulation of the translocase of outer mitochondrial membrane 7 (TOMM7)/translocase of inner mitochondrial membrane 8 (TIMM8A) complex responsible for mitochondrial protein transport, and a reduction in 28S (LOC121106978) and 18S (LOC112533601) ribosomal rRNAs. In conclusion, chicken GLUT4 is dynamically modulated during development and acts as an insulin responder that significantly regulates cellular glucose uptake and cell proliferation. This regulation occurs mainly through enhancing the mitochondrial oxidative phosphorylation and inhibiting ribosomal pathway.