C‐Myc Indirectly Controls ATP 13 A 2 Levels via HIF ‐1α Activation

ABSTRACT c‐Myc is an essential transcription factor controlling an extensive range of intracellular processes, and the abnormal activity of c‐Myc is associated with many different complex diseases, such as different types of cancer and neurodegenerative diseases. Understanding the regulatory functions of c‐Myc has been challenging due to its intricate and multifaceted roles in cellular processes. The ATP13A2 ( PARK9 ) gene encodes the ATP13A2 protein, which has important roles in lysosomal functions and metal ion transport. The association of ATP13A2 with Kufor‐Rakeb Syndrome (KRS), as well as its role in Parkinson's disease, highlights its significance in maintaining cellular homeostasis. While our previous study indicated that c‐Myc might play a role in the regulation of the ATP13A2 gene and its mutation linked to KRS, very little is known about the transcriptional regulation of the ATP13A2 gene. In this study, we identified potential c‐Myc transcription factor binding sites on the ATP13A2 promoter and showed in vivo c‐Myc binding using ChIP assay. qPCR and luciferase analyses revealed that the ATP13A2 transcription level was decreased upon 36 h of c‐Myc overexpression. In contrast, western blot analysis revealed an increased ATP13A2 protein level under the same conditions. We further analyzed this discrepancy in a time‐dependent manner, and results indicated that after c‐Myc overexpression, ATP13A2 expression was markedly upregulated for the first 24 h, but this impact gradually decreased, returning to baseline levels by 72 h. Both HIF1α and p53 exhibited transient upregulation followed by a time‐dependent decrease, suggesting that the initial increase in ATP13A2 may be regulated by c‐Myc‐driven HIF1α stabilization, which was supported by the elevated ATP13A2 expression and HIF1α stabilization by CoCl 2 treatment. Prussian blue analysis indicated corresponding changes in intracellular iron accumulation with the temporal alterations in ATP13A2 expression. Our findings indicate that c‐Myc indirectly causes an increased ATP13A2 expression by increasing HIF1α accumulation. image