Heterogeneous CRISPR/Cas9 Editing of HMOX1 Is Associated with Altered Heme–Biliverdin Metabolism and Basal Stress-Associated Transcriptional Programs in Chicken LMH Cells

Heme oxygenase-1 (HO-1), encoded by HMOX1, catalyzes the rate-limiting step of heme degradation and generates biliverdin, carbon monoxide, and ferrous iron, thereby linking heme turnover with redox regulation and stress-associated signaling. In birds, biliverdin is retained as a major heme-derived product, but the cellular consequences of HMOX1 perturbation remain insufficiently defined. Here, CRISPR/Cas9-mediated editing was used to generate a heterogeneous HMOX1-edited population in Chicken hepatocellular carcinoma-derived cells. The selected sgRNA reduced HO-1 protein abundance by approximately 47%, and no detectable cleavage was observed at the seven predicted high-risk off-target loci examined. Compared with vector-control cells, HMOX1-edited cells exhibited intracellular heme accumulation, reduced biliverdin levels, increased oxidation-sensitive fluorescence, and reduced CCK-8 absorbance values, indicating disruption of heme–biliverdin metabolic and redox homeostasis. RNA sequencing identified 2650 differentially expressed genes, including 951 upregulated and 1699 downregulated genes. Downregulated genes were mainly enriched in immune, cytokine, MAPK/stress, and extracellular signaling-associated pathways, whereas DNA replication and cell-cycle-related genes were increased. Enrichment-term association and STRING functional-association analyses further identified a coordinated module involving IL1B, JUN, NFKBIA, IRF1, TGFB1, IL10, CCL5, and PTGS2. Independent RT-qPCR analysis confirmed selected expression trends. These findings show that heterogeneous HMOX1 editing and reduced HO-1 abundance are associated with disruption of the avian heme–biliverdin metabolic axis and coordinated remodeling of basal immune, stress, extracellular signaling, and cell-cycle-associated transcriptional programs in Chicken hepatocellular carcinoma-derived cells.