Objective  To screen and analyze differentially expressed proteins and their biological significance in the liver of mice exposed to light at night.

  Methods  Totally 16 healthy male C57BL/6J mice were randomly divided into an experimental group (n = 8) exposed to light 24 hours a day continuously for 10 days and a control group (n = 8) with lighting 12 hours a day also for 10 consecutive days. Tandem mass tag (TMT) technology was applied to detect differentially expressed proteins in liver tissues of the mice. The differential protein expressions were analyzed using Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analysis.

  Results  A total of 383 differentially expressed proteins were identified, of which 215 were expressed at an up-regulated level and 168 proteins were expressed at a down-regulated level. GO enrichment analysis and KEGG signaling pathway analysis revealed that the differentially expressed proteins were mainly distributed in the cytoplasm, and their major molecular functions were protein binding, mainly involved in protein and lipid biological metabolic processes, and their pathways involved in signaling pathways of oxidative phosphorylation, tumor necrosis factor (TNF), and retinoic acid-inducible gene-I (RIG-I)-like receptor. Protein molecules such as mitochondrial cytochrome C oxidase subunit 3 (MT-CO3), mitochondrial Fo complex subunit F2 (ATP5J2), Itchy E3 ubiquitin protein ligase (ITCH), nuclear factor kappa B p65 subunit (NF-κB p65), and inhibitor of nuclear factor Kappa-B kinase subunit Beta (IKBKB) may play a key role.

  Conclusion  In terms of differentially expressed proteins and their functions in liver tissue, light exposure at night may lead to obesity and cancer in mice.