Transcriptomic Characterization Reveals Mitochondrial Involvement in Nrf2/Keap1-Mediated Osteoclastogenesis

Although osteoclasts play crucial roles in the skeletal system, the mechanisms that underlie oxidative stress during osteoclastogenesis remain unclear. The transcription factor Nrf2 and its suppressor, Keap1, function as central mediators of oxidative stress. To further elucidate the function of Nrf2/Keap1-mediated oxidative stress regulation in osteoclastogenesis, DNA microarray analysis was conducted in this study using wild-type (WT), <i>Keap1</i> knockout (<i>Keap1</i> KO), and <i>Nrf2</i> knockout (<i>Nrf2</i> KO) osteoclasts. Principal component analysis showed that 403 genes, including <i>Nqo1</i>, <i>Il1f9</i>, and <i>Mmp12</i>, were upregulated in <i>Keap1</i> KO compared with WT osteoclasts, whereas 24 genes, including <i>Snhg6</i>, <i>Ccdc109b</i>, and <i>Wfdc17</i>, were upregulated in <i>Nrf2</i> KO compared with WT osteoclasts. Moreover, 683 genes, including <i>Car2</i>, <i>Calcr</i>, and <i>Pate4</i>, were upregulated in <i>Nrf2</i> KO cells compared to <i>Keap1</i> KO cells. Functional analysis by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis showed upregulated genes in <i>Nrf2</i> KO osteoclasts were mostly enriched in oxidative phosphorylation. Furthermore, GeneMANIA predicted the protein-protein interaction network of novel molecules such as Rufy4 from genes upregulated in <i>Nrf2</i> KO osteoclasts. Understanding the complex interactions between these molecules may pave the way for developing promising therapeutic strategies against bone metabolic diseases caused by increased osteoclast differentiation under oxidative stress.