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Mitochondrial Protease ClpP is a Target for the Anticancer Compounds ONC201 and Related Analogues.

ABSTRACT: ONC201 is a first-in-class imipridone molecule currently in clinical trials for the treatment of multiple cancers. Despite enormous clinical potential, the mechanism of action is controversial. To investigate the mechanism of ONC201 and identify compounds with improved potency, we tested a series of novel ONC201 analogues (TR compounds) for effects on cell viability and stress responses in breast and other cancer models. The TR compounds were found to be ?50-100 times more potent at inhibiting cell proliferation and inducing the integrated stress response protein ATF4 than ONC201. Using immobilized TR compounds, we identified the human mitochondrial caseinolytic protease P (ClpP) as a specific binding protein by mass spectrometry. Affinity chromatography/drug competition assays showed that the TR compounds bound ClpP with ?10-fold higher affinity compared to ONC201. Importantly, we found that the peptidase activity of recombinant ClpP was strongly activated by ONC201 and the TR compounds in a dose- and time-dependent manner with the TR compounds displaying a ?10-100 fold increase in potency over ONC201. Finally, siRNA knockdown of ClpP in SUM159 cells reduced the response to ONC201 and the TR compounds, including induction of CHOP, loss of the mitochondrial proteins (TFAM, TUFM), and the cytostatic effects of these compounds. Thus, we report that ClpP directly binds ONC201 and the related TR compounds and is an important biological target for this class of molecules. Moreover, these studies provide, for the first time, a biochemical basis for the difference in efficacy between ONC201 and the TR compounds.

SUBMITTER: Graves PR

PROVIDER: S-EPMC6528275 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Mitochondrial Protease ClpP is a Target for the Anticancer Compounds ONC201 and Related Analogues.

Graves Paul R PR Aponte-Collazo Lucas J LJ Fennell Emily M J EMJ Graves Adam C AC Hale Andrew E AE Dicheva Nedyalka N Herring Laura E LE Gilbert Thomas S K TSK East Michael P MP McDonald Ian M IM Lockett Matthew R MR Ashamalla Hani H Moorman Nathaniel J NJ Karanewsky Donald S DS Iwanowicz Edwin J EJ Holmuhamedov Ekhson E Graves Lee M LM

ACS chemical biology 20190501 5

ONC201 is a first-in-class imipridone molecule currently in clinical trials for the treatment of multiple cancers. Despite enormous clinical potential, the mechanism of action is controversial. To investigate the mechanism of ONC201 and identify compounds with improved potency, we tested a series of novel ONC201 analogues (TR compounds) for effects on cell viability and stress responses in breast and other cancer models. The TR compounds were found to be ∼50-100 times more potent at inhibiting c ...[more]

PMID: 31021596

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Project description:The peptidase ClpP is conserved from bacteria to human. In the mitochondrial matrix, it multimerizes and forms a macromolecular proteasome-like cylinder. Because of its known relevance for the mitochondrial unfolded protein response during cell stress, we characterized two ClpP knock-out mouse founder lines and documented similar phenotypes. Ubiquitously, ClpP absence led to accumulation of its interactor protein ClpX without transcript upregulation. Interestingly, most wild-type tissues with substantial ClpP amounts had no detectable ClpX. This inverse correlation suggests that ClpX levels and degradation are regulated by ClpP. The expectation of similar protein levels, in view of a reported association of heptameric ClpP rings with hexameric ClpX rings, was confirmed only in testis of wild-type animals. Germline tissue was exceptional also in its vulnerability to ClpP deletion, with both founder lines showing complete infertility for males and females. Otherwise, ubiquitous mitochondrial dysfunction was apparent from severe growth retardation and reduced spontaneous motor activity of the animals, and from a pronounced decrease in pre-/postnatal survival. Spermatogenesis was found aborted at the spermatid stage, acrosomes and axonemes were not formed. Overall, tissue-specific roles of ClpP were evident by this massive effect for germ cells, mild bioenergetic deficits in muscle and liver tissues, and excellent compensation in brain. ClpX was previously reported to chaperone unfolded proteins and also DNA condensation in mitochondria, so it is likely that this pathway is particularly susceptible in germ cells. In conclusion, our study indicates that the role of ClpP in quality control is indispensable during development for cells with rapid changes of mitochondrial numbers, and is relevant during aging for growth and survival of the organism. Factorial design comparing ClpP knock-out mice with wild type littermates in five different tissues (brain, testis, liver, skeletal and heart muscle)

Project description:Both α-Synuclein (αSyn) accumulation and mitochondrial dysfunction have been implicated in the pathology of Parkinson's disease (PD). Although studies suggest that αSyn and its missense mutant, A53T, preferentially accumulate in the mitochondria, the mechanisms by which αSyn and mitochondrial proteins regulate each other to trigger mitochondrial and neuronal toxicity are poorly understood. ATP-dependent Clp protease (ClpP), a mitochondrial matrix protease, plays an important role in regulating mitochondrial protein turnover and bioenergetics activity. Here, we show that the protein level of ClpP is selectively decreased in αSyn-expressing cell culture and neurons derived from iPS cells of PD patient carrying αSyn A53T mutant, and in dopaminergic (DA) neurons of αSyn A53T mice and PD patient postmortem brains. Deficiency in ClpP induces an overload of mitochondrial misfolded/unfolded proteins, suppresses mitochondrial respiratory activity, increases mitochondrial oxidative damage and causes cell death. Overexpression of ClpP reduces αSyn-induced mitochondrial oxidative stress through enhancing the level of Superoxide Dismutase-2 (SOD2), and suppresses the accumulation of αSyn S129 phosphorylation and promotes neuronal morphology in neurons derived from PD patient iPS cells carrying αSyn A53T mutant. Moreover, we find that αSyn WT and A53T mutant interact with ClpP and suppress its peptidase activity. The binding of αSyn to ClpP further promotes a distribution of ClpP from soluble to insoluble cellular fraction in vitro and in vivo, leading to reduced solubility of ClpP. Compensating for the loss of ClpP in the substantia nigra of αSyn A53T mice by viral expression of ClpP suppresses mitochondrial oxidative damage, and reduces αSyn pathology and behavioral deficits of mice. Our findings provide novel insights into the mechanism underlying αSyn-induced neuronal pathology, and they suggest that ClpP might be a useful therapeutic target for PD and other synucleinopathies.

Project description:ATP-dependent Clp protease (ClpP) is a core unit of a major bacterial protease complex employing as a new attractive drug target for that isolates, which are resistant to antibiotics. Mycobacterium tuberculosis, a gram-positive bacterium, is one of the major causes of hospital acquired infections. ClpP in Mycobacterium tuberculosis is usually tightly regulated and strictly requires a member of the family of Clp-ATPase and often further accessory proteins for proteolytic activation. Inhibition of ClpP eliminates these safeguards and start proteolytic degradation. Such uncontrolled proteolysis leads to inhibition of bacterial cell division and eventually cell death. In order to inhibit Clp protease, at first three dimensional structure model of ClpP in Mycobacterium tuberculosis was determined by comparative homology modeling program MODELLER based on crystal structure of the proteolytic component of the caseinolytic Clp protease (ClpP) from E. coli as a template protein and has 55%sequence identity with ClpP protein. The computed model's energy was minimized and validated using PROCHECK to obtain a stable model structure and is submitted in Protein Model Database (PMDB-ID: PM0075741). Stable model was further used for virtual screening against marine derived bioactive compound database through molecular docking studies using AutoDock 3.05. The docked complexes were validated and enumerated based on the AutoDock Scoring function to pick out the best marine inhibitors based on docked Energy. Thus from the entire 186 Marine compounds which were Docked, we got best 5 of them with optimal docked Energy (Ara-A: -14.31 kcal/mol, Dysinosin C: - 14.90kcal/mol, Nagelamide A: -20.49 kcal/mol, Strobilin: -8.02 kcal/mol, Manoalide: -8.81 kcal/mol). Further the five best-docked complexes were analyzed through Python Molecular Viewer software for their interaction studies. Thus from the Complex scoring and binding ability its deciphered that these Marine compounds could be promising inhibitors for ClpP as Drug target yet pharmacological studies have to confirm it.

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Mitochondrial Protease ClpP is a Target for the Anticancer Compounds ONC201 and Related Analogues.

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Mitochondrial Protease ClpP is a Target for the Anticancer Compounds ONC201 and Related Analogues.

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