The biarylpyrazole compound AM251 alters mitochondrial physiology via proteolytic degradation of ERRα.
The orphan nuclear receptor estrogen-related receptor alpha (ERRα) directs the transcription of nuclear genes involved in energy homeostasis control and the regulation of mitochondrial mass and function. A crucial role for controlling ERRα-mediated target gene expression has been ascribed to the biarylpyrazole compound 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-1-piperidinyl-1H-pyrazole-3-carboxamide (AM251) through direct binding to and destabilization of ERRα protein. Here, we provide evidence that structurally related AM251 analogs also have negative impacts on ERRα protein levels in a cell-type-dependent manner while having no deleterious actions on ERRγ. We show that these off-target cellular effects of AM251 are mediated by proteasomal degradation of nuclear ERRα. Cell treatment with the nuclear export inhibitor leptomycin B did not prevent AM251-induced destabilization of ERRα protein, whereas proteasome inhibition with MG132 stabilized and maintained its DNA-binding function, indicative of ERRα being a target of nuclear proteasomal complexes. NativePAGE analysis revealed that ERRα formed a ∼220-kDa multiprotein nuclear complex that was devoid of ERRγ and the coregulator peroxisome proliferator-activated receptor γ coactivator-1. AM251 induced SUMO-2,3 incorporation in ERRα in conjunction with increased protein kinase C activity, whose activation by phorbol ester also promoted ERRα protein loss. Down-regulation of ERRα by AM251 or small interfering RNA led to increased mitochondria biogenesis while negatively impacting mitochondrial membrane potential. These results reveal a novel molecular mechanism by which AM251 and related compounds alter mitochondrial physiology through destabilization of ERRα.
Laboratory of Clinical Investigation, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Boulevard, Suite 100, Baltimore, Maryland 21224, USA.
Susan M
SM
Krzysik-Walker
Isabel
I
González-Mariscal
Morten
M
Scheibye-Knudsen
Fred E
FE
Indig
Michel
M
Bernier
D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004734:Energy Metabolism; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism; D046912:Multiprotein Complexes / Q000378:metabolism; D010766:Phosphorylation; D010880:Piperidines / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D055550:Protein Stability; D011720:Pyrazoles / Q000494:pharmacology*; D011960:Receptors, Estrogen / Q000378:metabolism*; D058207:Sumoylation; D014463:Ultrasonography; D000097983:ERRalpha Estrogen-Related Receptor
D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D010880:Piperidines; D046988:Proteasome Endopeptidase Complex; D011720:Pyrazoles; D011960:Receptors, Estrogen; D000097983:ERRalpha Estrogen-Related Receptor; C103505:AM 251