bims-cytox1 Biomed News
on Cytochrome oxidase subunit 1
Issue of 2024–03–03
two papers selected by
Gavin McStay, Liverpool John Moores University
  1. Optic atrophy 1 mediates muscle differentiation by promoting a metabolic switch via the supercomplex assembly factor SCAF1.
  2. HIF1A transcriptional regulation of COX4I2 impacts angiogenesis in pheochromocytoma.
  1. iScience. 2024 Mar 15. 27(3): 109164
    Optic atrophy 1 mediates muscle differentiation by promoting a metabolic switch via the supercomplex assembly factor SCAF1.
    Matthew Triolo, Nicole Baker, Soniya Agarwal, Nikita Larionov, Tina Podinić, Mireille Khacho.
      Myogenic differentiation is integral for the regeneration of skeletal muscle following tissue damage. Though high-energy post-mitotic muscle relies predominantly on mitochondrial respiration, the importance of mitochondrial remodeling in enabling muscle differentiation and the players involved are not fully known. Here we show that the mitochondrial fusion protein OPA1 is essential for muscle differentiation. Our study demonstrates that OPA1 loss or inhibition, through genetic and pharmacological means, abolishes in vivo muscle regeneration and in vitro myotube formation. We show that both the inhibition and genetic deletion of OPA1 prevent the early onset metabolic switch required to drive myoblast differentiation. In addition, we observe an OPA1-dependent upregulation of the supercomplex assembly factor, SCAF1, at the onset of differentiation. Importantly, preventing the upregulation of SCAF1, through OPA1 loss or siRNA-mediated SCAF1 knockdown, impairs metabolic reprogramming and muscle differentiation. These findings reveal the integral role of OPA1 and mitochondrial reprogramming at the onset of myogenic differentiation.
    Keywords:  Molecular biology; Physiology
    DOI:  https://doi.org/10.1016/j.isci.2024.109164
  2. Biochem Biophys Res Commun. 2024 Feb 06. pii: S0006-291X(24)00174-8. [Epub ahead of print]704 149638
    HIF1A transcriptional regulation of COX4I2 impacts angiogenesis in pheochromocytoma.
    Xiuci Li, Ran Zhuo, Yongxin Mao, Chen Fang, Jun Dai, Lei Ye, Chenghe Wang, Fukang Sun.
       BACKGROUND: Pheochromocytoma (PCC) is a rare neuroendocrine tumor. Angiogenesis is primary contributing factor for tumorigenesis. Cytochrome c oxidase 4I2 (COX4I2) has been confirmed to take part in the progression of cancer. Hypoxia-inducible factor 1A (HIF1A) is the main regulatory factor for the steady-state response of hypoxia, involved in metabolism and angiogenesis. In this study, we intended to explore the functions of COX4I2 in PCC and the effect mechanism between HIF1A and COX4I2.
    MATERIALS AND METHODS: The RNA-sequencing and immunohistochemistry tested COX4I2 expression in highly vascular PCC. Small interfering RNA (siRNA) was used to reduce the mRNA expression of COX4I2, and a small molecule inhibitor was utilized to reduce the protein expression of HIF1A. Culturing cells in 1% O2environment was performed to activate HIF1A. Western blot was applied to quantify the expression of target genes at the protein levels. The supernatant from PCC cells and fibroblasts acted as the conditioned medium. We conducted the tube formation and transwell assays in human vascular endothelial cells (HUVECs) to determine angiogenesis, the binding of COX4I2 promoter and HIF1A was evaluated by the dual luciferase reporter assay.
    RESULTS: COX4I2 had been rigorously shown to be overexpressed in highly vascular PCC. Knockdown of COX4I2 in PCC cells (MPC) did not significantly impact angiogenesis, while knockdown of COX4I2 in fibroblast (3T3) notably inhibited angiogenesis. RNA sequencing suggested that the expression of 11 vascular markers, such as CD34 and angiogenesis associated pathways in 3T3, decreased with knockdown of COX4I2. HIF1A had been shown to enhance the mRNA expression of COX4I2 through transcriptional regulation. Activation and inhibition of HIF1A resulted in upregulation and downregulation of COX4I2, respectively. The HIF1A inhibitor demonstrated a reduction in angiogenesis.
    CONCLUSION: COX4I2 is overexpressed in highly vascular PCC and contributes to angiogenesis in fibroblasts. Mechanistically, HIF1A transcriptional regulation enhances COX4I2 and its effects on angiogenesis in PCC. COX4I2 might serve as a vascular marker and represent a potential target for vascular therapy.
    Keywords:  Angiogenesis; COX4I2; Fibroblast; HIF1A; Pheochromocytoma
    DOI:  https://doi.org/10.1016/j.bbrc.2024.149638
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