Regulation of hepatic glutamine metabolism by miR-122

•miR-122, the most abundant liver specific microRNA and a potent tumor suppressor, regulates glutamine metabolism.•SIRM analysis showed enhanced glutaminolysis and impeded gluconeogenesis in the livers of miR-122 KO mice.•Gls, a key enzyme involved in glutaminolysis and a miR-122 target is upregulated in miR-122 KO livers.•Ectopic miR-122 expression suppressed glutaminolysis but enhanced gluconeogenesis in a glutamine dependent HCC cell line.•Expression of MIR-122 negatively correlated with that of GLS in human primary HCCs.