The protozoan parasite Trichomonas vaginalis (Tv) causes trichomoniasis, the most common non-viral sexually transmitted infection in the world. Although Tv has been linked to significant health complications, only two closely related 5-nitroimidazole drugs are approved for its treatment. The emergence of resistance to these drugs and lack of alternative treatment options poses an increasing threat to public health, making development of novel anti-Trichomonas compounds an urgent need. The proteasome, a critical enzyme complex found in all eukaryotes has three catalytic subunits, β1, β2, and β5 and has been validated as a drug target to treat trichomoniasis. With the goal of developing tools to study the Tv proteasome, we isolated the enzyme complex and identified inhibitors that preferentially inactivate either one or two of the three catalytic subunits. Using a mass spectrometry-based peptide digestion assay, these inhibitors were used to define the substrate preferences of the β1, β2 and β5 subunits. Subsequently, three model fluorogenic substrates were designed, each specific for one of the catalytic subunits. This novel substrate profiling methodology will allow for individual subunit characterization of other proteasomes of interest. Using the new substrates, we screened a library of 284 peptide epoxyketone inhibitors against Tv and determined the subunits targeted by the most active compounds. The data show that inhibition of the Tv β5 subunit alone is toxic to the parasite. Taken together, the optimized proteasome subunit substrates will be instrumental for understanding the molecular determinants of proteasome specificity and for accelerating drug development against trichomoniasis.

• Klíčová slova
• drug discovery, drug screening, parasite, protease inhibitor, proteasome, substrate specificity, trichomonas,
• MeSH
• inhibitory proteasomu farmakologie   chemie   MeSH
• katalytická doména * MeSH
• proteasomový endopeptidasový komplex * metabolismus   chemie   MeSH
• protozoální proteiny chemie   metabolismus   antagonisté a inhibitory   genetika   MeSH
• substrátová specifita MeSH
• Trichomonas vaginalis * enzymologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• inhibitory proteasomu MeSH
• proteasomový endopeptidasový komplex * MeSH
• protozoální proteiny MeSH

Here, we present remarkable epoxyketone-based proteasome inhibitors with low nanomolar in vitro potency for blood-stage Plasmodium falciparum and low cytotoxicity for human cells. Our best compound has more than 2,000-fold greater selectivity for erythrocytic-stage P. falciparum over HepG2 and H460 cells, which is largely driven by the accommodation of the parasite proteasome for a D-amino acid in the P3 position and the preference for a difluorobenzyl group in the P1 position. We isolated the proteasome from P. falciparum cell extracts and determined that the best compound is 171-fold more potent at inhibiting the β5 subunit of P. falciparum proteasome when compared to the same subunit of the human constitutive proteasome. These compounds also significantly reduce parasitemia in a P. berghei mouse infection model and prolong survival of animals by an average of 6 days. The current epoxyketone inhibitors are ideal starting compounds for orally bioavailable anti-malarial drugs.

• Klíčová slova
• epoxyketone, inhibition, malaria, plasmodium, proteasome,
• MeSH
• antimalarika * farmakologie   MeSH
• inhibitory proteasomu chemie   MeSH
• lidé MeSH
• myši MeSH
• Plasmodium falciparum MeSH
• Plasmodium * MeSH
• proteasomový endopeptidasový komplex chemie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antimalarika * MeSH
• inhibitory proteasomu MeSH
• proteasomový endopeptidasový komplex MeSH

Wedelolactone is a multi-target natural plant coumestan exhibiting cytotoxicity towards cancer cells. Although several molecular targets of wedelolactone have been recognized, the molecular mechanism of its cytotoxicity has not yet been elucidated. In this study, we show that wedelolactone acts as an inhibitor of chymotrypsin-like, trypsin-like, and caspase-like activities of proteasome in breast cancer cells. The proteasome inhibitory effect of wedelolactone was documented by (i) reduced cleavage of fluorogenic proteasome substrates; (ii) accumulation of polyubiquitinated proteins and proteins with rapid turnover in tumor cells; and (iii) molecular docking of wedelolactone into the active sites of proteasome catalytic subunits. Inhibition of proteasome by wedelolactone was independent on its ability to induce reactive oxygen species production by redox cycling with copper ions, suggesting that wedelolactone acts as copper-independent proteasome inhibitor. We conclude that the cytotoxicity of wedelolactone to breast cancer cells is partially mediated by targeting proteasomal protein degradation pathway. Understanding the structural basis for inhibitory mode of wedelolactone might help to open up new avenues for design of novel compounds efficiently inhibiting cancer cells.

• Klíčová slova
• breast cancer, copper, proteasome, reactive oxygen species, wedelolactone,
• MeSH
• inhibitory proteasomu chemie   farmakologie   toxicita   MeSH
• kumariny chemie   farmakologie   toxicita   MeSH
• lidé MeSH
• měď metabolismus   MeSH
• nádorové buněčné linie MeSH
• nádory prsu metabolismus   MeSH
• proteasomový endopeptidasový komplex chemie   metabolismus   MeSH
• proteolýza MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• simulace molekulového dockingu MeSH
• ubikvitinace MeSH
• vazba proteinů MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• inhibitory proteasomu MeSH
• kumariny MeSH
• měď MeSH
• proteasomový endopeptidasový komplex MeSH
• reaktivní formy kyslíku MeSH
• wedelolactone MeSH Prohlížeč

Inhibition of proteasome, a proteolytic complex responsible for the degradation of ubiquitinated proteins, has emerged as a powerful strategy for treatment of multiple myeloma (MM), a plasma cell malignancy. First-in-class agent, bortezomib, has demonstrated great positive therapeutic efficacy in MM, both in pre-clinical and in clinical studies. However, despite its high efficiency, a large proportion of patients do not achieve sufficient clinical response. Therefore, the development of a second-generation of proteasome inhibitors (PIs) with improved pharmacological properties was needed. Recently, several of these new agents have been introduced into clinics including carfilzomib, marizomib and ixazomib. Further, new orally administered second-generation PI oprozomib is being investigated. This review provides an overview of main mechanisms of action of PIs in MM, focusing on the ongoing development and progress of novel anti-proteasome therapeutics.

• Klíčová slova
• bortezomib, multiple myeloma, new-generation proteasome inhibitors,
• MeSH
• inhibitory proteasomu terapeutické užití   MeSH
• lidé MeSH
• mnohočetný myelom farmakoterapie   enzymologie   MeSH
• proteasomový endopeptidasový komplex chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• inhibitory proteasomu MeSH
• proteasomový endopeptidasový komplex MeSH

The idea of "repurposing" of existing drugs provides an effective way to develop and identify new therapies. Disulfiram (Antabuse), a drug commonly used for the treatment of alcoholism, shows promising anticancer activity in both preclinical and clinical studies. In the human body, disulfiram is rapidly converted to its reduced metabolite, diethyldithiocarbamate. If copper ions are available, a bis(diethyldithiocarbamate)-copper(II) complex is formed. Disulfiram's selective anticancer activity is attributed to the copper(II) complex's ability to inhibit the cellular proteasome. It is assumed that the complex inhibits the proteasome by a mechanism that is distinct to the clinically used drug bortezomib, targeting the 19S rather than the 20S proteasome. This difference could be explained by inhibition of the JAMM domain of the POH1 subunit within the lid of the 19S proteasome.

• MeSH
• antitumorózní látky chemie   farmakologie   terapeutické užití   MeSH
• bortezomib MeSH
• dithiokarb chemie   MeSH
• inhibitory proteasomu chemie   farmakologie   terapeutické užití   MeSH
• komplexní sloučeniny chemie   farmakologie   terapeutické užití   MeSH
• kyseliny boronové chemie   farmakologie   terapeutické užití   MeSH
• lidé MeSH
• měď chemie   MeSH
• nádorové buněčné linie MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• oxidační stres účinky léků   MeSH
• proteasomový endopeptidasový komplex chemie   metabolismus   MeSH
• pyraziny chemie   farmakologie   terapeutické užití   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antitumorózní látky MeSH
• bortezomib MeSH
• dithiokarb MeSH
• inhibitory proteasomu MeSH
• komplexní sloučeniny MeSH
• kyseliny boronové MeSH
• měď MeSH
• proteasomový endopeptidasový komplex MeSH
• pyraziny MeSH

β-Hydroxy-β-methylbutyrate (HMB) is a leucine metabolite that may have a positive effect in protein catabolic conditions. Therefore, we hypothesized that HMB treatment could attenuate the sepsis-induced protein catabolic state. The aims of our study were to elucidate the effect of HMB in healthy and septic animals and to evaluate the differences in the action of HMB in different muscle types. Intact and septic (5 mg endotoxin/kg i.p.) rats were administered with HMB (0.5 g/kg/day) or saline. After 24 h, extensor digitorum longus (EDL) and soleus (SOL) muscles were isolated and used for determination of total and myofibrillar proteolysis, protein synthesis, leucine oxidation, activity of cathepsins B and L, chymotrypsin-like activity, and expression of α-subunits of proteasome. Our results indicate that the catabolic state induced by the endotoxin treatment was caused both by increase in protein breakdown (due to activation of proteasome system) and by attenuation of protein synthesis. The EDL (muscle composed of white, fast-twitch fibers) was more susceptible to these changes than the SOL (muscle composed of red, slow-twitch fibers). The HMB treatment had no effect in healthy animals but counteracted the changes in septic animals. The action of HMB was mediated by attenuation of proteasome activity and protein breakdown, not by stimulation of protein synthesis. More pronounced effect of the HMB treatment on myofibrillar proteolysis was observed in the SOL.

• MeSH
• časové faktory MeSH
• kathepsin B chemie   MeSH
• kathepsin L chemie   MeSH
• kosterní svaly účinky léků   metabolismus   MeSH
• krysa rodu Rattus MeSH
• kyslík chemie   MeSH
• leucin chemie   MeSH
• lyzozomy metabolismus   MeSH
• potkani Wistar MeSH
• proteasomový endopeptidasový komplex chemie   MeSH
• sepse farmakoterapie   metabolismus   MeSH
• valeráty farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• beta-hydroxyisovaleric acid MeSH Prohlížeč
• kathepsin B MeSH
• kathepsin L MeSH
• kyslík MeSH
• leucin MeSH
• proteasomový endopeptidasový komplex MeSH
• valeráty MeSH