Structure-functional organization of eukaryotic high-affinity copper importer CTR1 determines its ability to transport copper, silver and cisplatin

It was shown recently, that high affinity Cu(I) importer eukaryotic protein CTR1 can also transport in vitro abiogenic Ag(I) ions and anticancer drug cisplatin. At present there is no rational explanation how CTR1 can transfer platinum group, which is different by coordination properties from highly similar Cu(I) and Ag(I). To understand this phenomenon we analyzed 25 sequences of chordate CTR1 proteins, and found out conserved patterns of organization of N-terminal extracellular part of CTR1 which correspond to initial metal binding. Extracellular copper-binding motifs were qualified by their coordination properties. It was shown that relative position of Met- and His-rich copper-binding motifs in CTR1 predisposes the extracellular CTR1 part to binding of copper, silver and cisplatin. Relation between tissue-specific expression of CTR1 gene, steady-state copper concentration, and silver and platinum accumulation in organs of mice in vivo was analyzed. Significant positive but incomplete correlation exists between these variables. Basing on structural and functional peculiarities of N-terminal part of CTR1 a hypothesis of coupled transport of copper and cisplatin has been suggested, which avoids the disagreement between CTR1-mediated cisplatin transport in vitro, and irreversible binding of platinum to Met-rich peptides.     

Structure-functional organization of eukaryotic high-affinity copper importer CTR1 determines its ability to transport copper,silver, and cisplatin

It was shown recently, that high affinity Cu(I) importer eukaryotic protein CTR1 can also transport in vitro abiogenic Ag(I) ions and anticancer drug cisplatin. At present, there is no rational explanation how CTR1 can transfer platinum group which is different by coordination properties from highly similar Cu(I) and Ag(I). To understand the phenomenon, we analyzed 25 sequences of chordate CTR1 proteins and found out the conserved patterns of organization of N-terminal extracellular part of CTR1 which is responsible for initial metal binding. Extracellular copper-binding motifs were qualified by their coordination properties. It was shown that the relative position of methionine- and histidine-rich copper-binding motifs predisposes the extracellular CTR1 region to binding of copper, silver, and cisplatin. Relation between the tissuespecific expression of the CTR1 gene, steady-state copper concentration, and silver and platinum accumulation in organs of mice in vivo were analyzed. Significant positive yet incomplete correlation was found to exist between these variables. Basing on structural and functional peculiarities of N-terminal part of CTR1 a hypothesis of coupled transport of copper and cisplatin has been suggested which avoids disagreement between CTR1-mediated cisplatin transport in vitro and irreversible binding of platinum to Met-rich peptides.     

Intracellular signaling pathways regulating radioresistance of human prostate carcinoma cells

Radiation therapy plays an important role in the management of prostate carcinoma. However, the problem of radioresistance and molecular mechanisms by which prostate carcinoma cells overcome cytotoxic effects of radiation therapy remains to be elucidated. In order to investigate possible intracellular mechanisms underlying the prostate carcinoma recurrences after radiotherapy, we have established three radiation-resistant prostate cancer cell lines, LNCaP-IRR, PC3-IRR, and Du145-IRR derived from the parental LNCaP, PC3, and Du145 prostate cancer cells by repetitive exposure to ionizing radiation. LNCaP-IRR, PC3-IRR, and Du145-IRR cells (prostate carcinoma cells recurred after radiation exposure (IRR cells)) showed higher radioresistance and cell motility than parental cell lines. IRR cells exhibited higher levels of androgen and epidermal growth factor (EGF) receptors and activation of their downstream pathways, such as Ras-mitogen-activated protein kinase (MAPK) and phosphatidyl inositol 3-kinase (PI3K)-Akt and Jak-STAT. In order to define additional mechanisms involved in the radioresistance development, we determined differences in the proteome profile of parental and IRR cells using 2-D DIGE followed by computational image analysis and MS. Twenty-seven proteins were found to be modulated in all three radioresistant cell lines compared to parental cells. Identified proteins revealed capacity to interact with EGF and androgen receptors related signal transduction pathways and were involved in the regulation of intracellular routs providing cell survival, increased motility, mutagenesis, and DNA repair. Our data suggest that radioresistance development is accompanied by multiple mechanisms, including activation of cell receptors and related downstream signal transduction pathways. Identified proteins regulated in the radioresistant prostate carcinoma cells can significantly intensify activation of intracellular signaling that govern cell survival, growth, proliferation, invasion, motility, and DNA repair. In addition, such analyses may be utilized in predicting cellular response to radiotherapy.     

HMG1 domains: the victims of circumstance

The method of circular dichroism (CD) was used to compare DNA behavior during its interaction with linker histone H1 and with non-histone chromosomal protein HMG1 at different ionic strength and at different protein content in the system. The role of negatively charged C-terminal fragment of HMG1 was analyzed using recombinant protein HMG1-(A + B), which lacks the C terminal amino acid sequence. The psi-type CD spectra were common for DNA interaction with histone H1, but no spectra of this type were observed in HMG1-DNA systems even at high ionic strength. The CD spectrum of the truncated recombinant protein at high salt concentration somewhat resembled the psi-type spectrum. Two very intense positive bands were located near 215 nm and near 273 nm, and the whole CD spectrum was positive. The role of C-terminal tail of HMG1 in formation of the ordered DNA-protein complexes is discussed.     

Systematics on the threshold of the XXI century. Traditional principles and fundamentals from today's point of view

Systematics as regarded is a purely theoretical domain of biology, and its product, system, as a specific biological theory, or a topologo-genetic model of the biota. Linnaeus was the first to introduce the idea of system and the systematic approach into the natural history. The advent of evolutionism brought new meaning to the old term "affinity", so Linnaeus' slogan of natural system got new life, and Linnaeus taxonomy assimilated the evolutionary ideology quite naturally and much easier than many other departments of biology. The difference between natural and artificial systems is remaining, and it is in their goals, as formulated by Linnaeus: heuristic of the former and cataloguing of the latter. Linnaeus' clairvoyance discovered the existence of an infrageneric level of genetic integration provable by naturalists' experience. He chose for it the designation of "species" and laid it down as primary, basic unit of his system. This is plainly evident from his own writings; the story about Linnaean species being products of a logical division of genera is a pure fiction. Modern populational model of species, by 3 important criteria, appears to be more akin to the Linneaean one than to the ideas of Lamarckism and early Darwinism. Systematic approach focuses rather on the interrelations among elements and their relative position, then on the properties and qualities of separately treated individual elements. In the development of systematics the aspect of "nexification" (study of connections) has been continuously gaining attention especially regarding the nomenclature where connotation has been totally forced out by denotation.     

Initial stages of interaction of Azospirillum brasilense bacteria with wheat germ roots: adsorption, deformation of root hairs

The initial stages of colonization of wheat roots by cells of Azospirillum brasilense strains 75 and 80 isolated from soils of the Saratov oblast were studied. The adsorption of azospirilla on root hairs of soft spring wheats rapidly increased in the first hours of incubation, going then to a plateau phase. Within the first 15 h of incubation, exponential-phase cells were adsorbed more intensively than stationary-phase cells. Conversely, stationary-phase cells were adsorbed more intensively than exponential-phase cells, if the period of azospirilla incubation with the wheat roots was extended. As the time of incubation increased, the attachment of azospirilla to the wheat roots became stronger. The effect of cell attachment to root hairs was strain-dependent; the number of adsorbed cells of a given strain of azospirilla was greater in the case of host wheat cultivars. The deformation of wheat root hairs was affected by the polysaccharide-containing complexes isolated from the capsular material of azospirilla. The suggestion is made that common receptor systems are involved in the adsorption of azospirilla on roots and in root hair deformation.     

Cervical intraepithelial neoplasia: Telomerase activity and splice pattern of hTERT mRNA

Cervical cancers are characterized by the persistence of human papilloma virus (HPV) genome that is found in tissue samples starting from the early stages of tumor progression. Just like in other tumors, the activation of telomerase was observed in cervical carcinomas, but information about its expression was controversial. The aim of this study is to find possible correlations between the presence of HPV sequences, activity of telomerase and expression of different spliced forms of hTERT RNA in cervical intraepithelial neoplasias (CIN). The results show that HPV DNA is present in 60% of normal tissue adjacent to CIN lesions and up to 84% in CIN samples. Telomerase activity was found in 28% of adjacent normal tissue and in 68% of CIN II–III. hTERT RNA that encodes an active enzyme was present almost in all CIN samples. Variations in levels of telomerase activity are possibly not regulated by the splicing forms of hTERT mRNA with deletions.     

Melting of crosslinked DNA: VI. Comparison of influence of interstrand crosslinks and other chemical modifications formed by antitumor compounds on DNA stability

A computer modeling of thermodynamic properties of a long DNA of N base pairs that includes omega interstrand crosslinks (ICLs), or omega chemical modifications involving one strand (monofunctional adducts, intrastrand crosslinks) has been carried out. It is supposed in our calculation that both types of chemical modifications change the free energy of the helix-coil transition at sites of their location by deltaF. The value deltaF>0 corresponds to stabilization, i.e., to the increase in melting temperature. It is also taken into account that ICLs form additional loops in melted regions and prohibit strand dissociation after full DNA melting. It is shown that the main effect of interstrand crosslinks on the stability of long DNA's is caused by the formation of additional loops in melted regions. This formation increases DNA melting temperature (T(m)) much stronger than replacing omega base pairs of AT type with GC. A prohibition of strand dissociation after crosslinking, which strongly elevates the melting temperature of oligonucleotide duplexes, does not influence melting behavior of long DNA's (N>/=1000 bp). As was demonstrated earlier for the modifications involving one or the other strand, the dependence of the shift of melting temperature deltaT(m) on the relative number of modifications r = omega/(2N) is a linear function for any deltaF, and deltaT(m)(r) identical with 0 for the ideal modifications (deltaF=0). We have shown that deltaT(m)(r) is the same for periodical and random distribution if the absolute value of deltaF is less 2 kcal. The absolute value of deltaT(m)(r) at deltaF>2 kcal and deltaF<-2 kcal is higher for periodical distribution. For interstrand crosslinks, the character of the dependence deltaT(m)(r) is quite different. It is nonlinear, and the shape of the corresponding curve is strongly dependent on deltaF. For "ideal" interstrand crosslinks (deltaF=0), the function deltaT(m)(r) is not zero. It is monotone positive nonlinear, and its slope decreases with r. If r<0.004, then the entropy stabilizing effect of interstrand crosslinking itself exceeds the influence of a distortion of the double helix at sites of their location. The resulting deltaT(m)(r) is positive even in the case of the infinite destabilization at sites of the ICLs (deltaF--> -infinity). In general, stabilizing influence of interstrand crosslinks is almost fully compensated for by local structural distortions caused by them if 0相似文献