Replication stress (RS) is a major driver of genomic instability and tumorigenesis. Here, we investigated whether RS induced by the nucleotide analog fludarabine and specific kinase inhibitors [e.g. targeting checkpoint kinase 1 (Chk1) or ataxia telangiectasia and Rad3-related (ATR)] led to apoptosis or senescence in four cancer cell lines differing in TP53 mutation status and expression of lamin A/C (LA/C). RS resulted in uneven chromatin condensation in all cell types, as evidenced by the presence of metaphasic chromosomes with unrepaired DNA damage, as well as detection of less condensed chromatin in the same nucleus, frequent ultrafine anaphase bridges, and micronuclei. We observed that responses to these chromatin changes may be distinct in individual cell types, suggesting that expression of lamin A/C and lamin B1 (LB1) may play an important role in the transition of damaged cells to senescence. MCF7 mammary carcinoma cells harboring wild-type p53 (WT-p53) and LA/C responded to RS by transition to senescence with a significant reduction of lamin B receptor and LB1 proteins. In contrast, a lymphoid cancer cell line WSU-NHL (WT-p53) lacking LA/C and expressing low levels of LB1 died after several hours, while lines MEC-1 and SU-DHL-4, both with mutated p53, and SU-DHL-4 with mutations in LA/C, died at different rates by apoptosis. Our results show that, in addition to being influenced by p53 mutation status, the response to RS (apoptosis or senescence) may also be influenced by lamin A/C and LB1 status.
- MeSH
- apoptóza fyziologie MeSH
- lamin typ A metabolismus MeSH
- lidé MeSH
- MFC-7 buňky MeSH
- mutace MeSH
- nádorové buněčné linie MeSH
- nádorový supresorový protein p53 genetika MeSH
- replikace DNA fyziologie MeSH
- stárnutí buněk fyziologie MeSH
- vidarabin analogy a deriváty farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Nitric oxide (NO) produced by mammalian nitric oxide synthases (mNOSs) is an important mediator in a variety of physiological functions. Crystal structures of mNOSs have shown strong conservation of the active-site residue Val567 (numbering for rat neuronal NOS, nNOS). NOS-like proteins have been identified in several bacterial pathogens, and these display striking sequence identity to the oxygenase domain of mNOS (NOSoxy), with the exception of a Val to Ile mutation at the active site. Preliminary studies have highlighted the importance of this Val residue in NO-binding, substrate recognition, and oxidation in mNOSs. To further elucidate the role of this valine in substrate and substrate analogue recognition, we generated five Val567 mutants of the oxygenase domain of the neuronal NOS (nNOSoxy) and used UV-visible and EPR spectroscopy to investigate the effects of these mutations on the heme distal environment, the stability of the heme-FeII-CO complexes, and the binding of a series of substrate analogues. Our results are consistent with Val567 playing an important role in preserving the integrity of the active site for substrate binding, stability of heme-bound gaseous ligands, and potential NO production.
- Publikační typ
- časopisecké články MeSH
Filamentous hemagglutinin (FHA) mediates adherence and plays an important role in lower respiratory tract infections by pathogenic Bordetellae. The mature FHA proteins of B. pertussis (Bp-FHA) and the B. bronchiseptica (Bb-FHA) are generated by processing of the respective FhaB precursors by the autotransporter subtilisin-type protease SphB1. We have used bottom-up proteomics with differential 16O/18O labeling and show that despite high-sequence conservation of the corresponding FhaB segments, the mature Bp-FHA (~ 230 kDa) and Bb-FHA (~ 243 kDa) proteins are processed at different sites of FhaB, after the Ala-2348 and Lys-2479 residues, respectively. Moreover, protease surface accessibility probing by on-column (on-line) digestion of the Bp-FHA and Bb-FHA proteins yielded different peptide patterns, revealing structural differences in the N-terminal and C-terminal domains of the Bp-FHA and Bb-FHA proteins. These data indicate specific structural variations between the highly homologous FHA proteins.
- Publikační typ
- časopisecké články MeSH
Mitochondrial uncoupling protein-2 (UCP2) mediates free fatty acid (FA)-dependent H+ translocation across the inner mitochondrial membrane (IMM), which leads to acceleration of respiration and suppression of mitochondrial superoxide formation. Redox-activated mitochondrial phospholipase A2 (mt-iPLA2γ) cleaves FAs from the IMM and has been shown to acts in synergy with UCP2. Here, we tested the mechanism of mt-iPLA2γ-dependent UCP2-mediated antioxidant protection using lipopolysaccharide (LPS)-induced pro-inflammatory and pro-oxidative responses and their acute influence on the overall oxidative stress reflected by protein carbonylation in murine lung and spleen mitochondria and tissue homogenates. We provided challenges either by blocking the mt-iPLA 2γ function by the selective inhibitor R-bromoenol lactone (R-BEL) or by removing UCP2 by genetic ablation. We found that the basal levels of protein carbonyls in lung and spleen tissues and isolated mitochondria were higher in UCP2-knockout mice relative to the wild-type (wt) controls. The administration of R-BEL increased protein carbonyl levels in wt but not in UCP2-knockout (UCP2-KO) mice. LPS further increased the protein carbonyl levels in UCP2-KO mice, which correlated with protein carbonyl levels determined in wt mice treated with R-BEL. These results are consistent with the UCP2/mt-iPLA 2γ antioxidant mechanisms in these tissues and support the existence of UCP2-synergic mt-iPLA 2γ-dependent cytoprotective mechanism in vivo.
- Publikační typ
- časopisecké články MeSH
Glutamate carboxypeptidase II (GCPII), also known as prostate-specific membrane antigen (PSMA) or folate hydrolase, is a metallopeptidase expressed predominantly in the human brain and prostate. GCPII expression is considerably increased in prostate carcinoma, and the enzyme also participates in glutamate excitotoxicity in the brain. Therefore, GCPII represents an important diagnostic marker of prostate cancer progression and a putative target for the treatment of both prostate cancer and neuronal disorders associated with glutamate excitotoxicity. For the development of novel therapeutics, mouse models are widely used. However, although mouse GCPII activity has been characterized, a detailed comparison of the enzymatic activity and tissue distribution of the mouse and human GCPII orthologs remains lacking. In this study, we prepared extracellular mouse GCPII and compared it with human GCPII. We found that mouse GCPII possesses lower catalytic efficiency but similar substrate specificity compared with the human protein. Using a panel of GCPII inhibitors, we discovered that inhibition constants are generally similar for mouse and human GCPII. Furthermore, we observed highest expression of GCPII protein in the mouse kidney, brain, and salivary glands. Importantly, we did not detect GCPII in the mouse prostate. Our data suggest that the differences in enzymatic activity and inhibition profile are rather small; therefore, mouse GCPII can approximate human GCPII in drug development and testing. On the other hand, significant differences in GCPII tissue expression must be taken into account when developing novel GCPII-based anticancer and therapeutic methods, including targeted anticancer drug delivery systems, and when using mice as a model organism.
- Publikační typ
- časopisecké články MeSH
Fructose-1-phosphate (F1P) is the preferred effector of the catabolite repressor/activator (Cra) protein of the soil bacterium Pseudomonas putida but its ability to bind other metabolic intermediates in vivo is unclear. The Cra protein of this microorganism (Cra(PP)) was submitted to mobility shift assays with target DNA sequences (the PfruB promoter) and candidate effectors fructose-1,6-bisphosphate (FBP), glucose 6-phosphate (G6P), and fructose-6-phosphate (F6P). 1 mM F1P was sufficient to release most of the Cra protein from its operators but more than 10 mM of FBP or G6P was required to free the same complex. However, isothermal titration microcalorimetry failed to expose any specific interaction between Cra(PP) and FBP or G6P. To solve this paradox, transcriptional activity of a PfruB-lacZ fusion was measured in wild-type and ΔfruB cells growing on substrates that change the intracellular concentrations of F1P and FBP. The data indicated that PfruB activity was stimulated by fructose but not by glucose or succinate. This suggested that Cra(PP) represses expression in vivo of the cognate fruBKA operon in a fashion dependent just on F1P, ruling out any other physiological effector. Molecular docking and dynamic simulations of the Cra-agonist interaction indicated that both metabolites can bind the repressor, but the breach in the relative affinity of Cra(PP) for F1P vs FBP is three orders of magnitude larger than the equivalent distance in the Escherichia coli protein. This assigns the Cra protein of P. putida the sole role of transducing the presence of fructose in the medium into a variety of direct and indirect physiological responses.
- Publikační typ
- časopisecké články MeSH
