MYC is downregulated by a mitochondrial checkpoint mechanism
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Xiaonan Zhang1, Arjan Mofers2, Per Hydbring1, Maria Hägg Olofsson1, Jing Guo3,4, Stig Linder1,2 and Padraig D'Arcy2
1Cancer Center Karolinska, Department of Oncology and Pathology, Karolinska Institute, SE-171 76 Stockholm, Sweden
2Department of Medical and Health Sciences, Linköping University, SE-581 83 Linköping, Sweden
3Department of Medical Biochemistry and Biophysics (MBB), Karolinska Institute, SE-171 77 Stockholm, Sweden
4Cardiovascular and Metabolic Disorders Program, Duke-NUS (National University of Singapore) Medical School, 16957 Singapore, Singapore
Stig Linder, email: Stig.Linder@liu.se
Padraig D’Arcy, email: Padraig.Darcy@liu.se
Keywords: mitochondria, MYC, CRD-BP, let-7/miR-34a, cancer
Received: July 15, 2017 Accepted: August 25, 2017 Published: October 06, 2017
The MYC proto-oncogene serves as a rheostat coupling mitogenic signaling with the activation of genes regulating growth, metabolism and mitochondrial biogenesis. Here we describe a novel link between mitochondria and MYC levels. Perturbation of mitochondrial function using a number of conventional and novel inhibitors resulted in the decreased expression of MYC mRNA. This decrease in MYC mRNA occurred concomitantly with an increase in the levels of tumor-suppressive miRNAs such as members of the let-7 family and miR-34a-5p. Knockdown of let-7 family or miR-34a-5p could partially restore MYC levels following mitochondria damage. We also identified let-7-dependent downregulation of the MYC mRNA chaperone, CRD-BP (coding region determinant-binding protein) as an additional control following mitochondria damage. Our data demonstrates the existence of a homeostasis mechanism whereby mitochondrial function controls MYC expression.
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