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.