Stereoselective synthesis of antiviral synguanol (1) is described. Reaction of 6-benzyloxy-2-(dimethylaminomethyleneamino)purine (10) with ethyl (cis,trans)-2-chloro-2-(chloromethyl) cyclopropane-1-carboxylate (2c) under the conditions of alkylation-elimination gave (Z)-6- benzyloxy-2-formylamino-9-[(2-carbethoxycyclopropylidene)methyl]purine (11) but no E,N9-isomer. Minor amounts of (Z)-6-benzyloxy-2-formylamino-7-[(2-carbethoxy-cyclopropylidene)methyl]purine (13) were also obtained. Hydrolysis of compounds 11 and 13 in 80% acetic acid afforded (Z)-9-[2-(carbethoxycyclopropylidene)methyl]guanine (14) and (Z)-7-[2-(carbethoxy- cyclopropylidene)methyl]guanine (15). Reduction of 14 furnished synguanol (1). Reaction of N4-acetylcytosine (7) with ester 2c led to (Z,E)-1-(2-carbethoxycyclopropropylidenemethyl)cytosine (8, Z/E ratio 6.1:1). Basicity of purine base, lower reactivity of alkylation intermediates as well as interaction of the purine N3 or cytosine O2 atoms with the carbonyl group of ester moiety seem to be essential for the observed high stereoselectivity of the alkylation-elimination. The Z-selectivity is interpreted in terms of E1cB mechanism leading to a transitory “cyclic” cyclopropenes which undergo a cyclopropene-methylenecyclopropane rearrangement. 相似文献
α-Tocopheryl succinate (α-TOS) is a promising anti-cancer agent due to its selectivity for cancer cells. It is important to understand whether long-term exposure of tumour cells to the agent will render them resistant to the treatment. Exposure of the non-small cell lung carcinoma H1299 cells to escalating doses of α-TOS made them resistant to the agent due to the upregulation of the ABCA1 protein, which caused its efflux. Full susceptibility of the cells to α-TOS was restored by knocking down the ABCA1 protein. Similar resistance including ABCA1 gene upregulation was observed in the A549 lung cancer cells exposed to α-TOS. The resistance of the cells to α-TOS was overcome by its mitochondrially targeted analogue, MitoVES, that is taken up on the basis of the membrane potential, bypassing the enhanced expression of the ABCA1 protein. The in vitro results were replicated in mouse models of tumours derived from parental and resistant H1299 cells. We conclude that long-term exposure of cancer cells to α-TOS causes their resistance to the drug, which can be overcome by its mitochondrially targeted counterpart. This finding should be taken into consideration when planning clinical trials with vitamin E analogues. 相似文献
As we have shown previously, yeast Mmi1 protein translocates from the cytoplasm to the outer surface of mitochondria when vegetatively growing yeast cells are exposed to oxidative stress. Here we analyzed the effect of heat stress on Mmi1 distribution. We performed domain analyses and found that binding of Mmi1 to mitochondria is mediated by its central alpha-helical domain (V-domain) under all conditions tested. In contrast, the isolated N-terminal flexible loop domain of the protein always displays nuclear localization. Using immunoelectron microscopy we confirmed re-location of Mmi1 to the nucleus and showed association of Mmi1 with intact and heat shock-altered mitochondria. We also show here that mmi1Δ mutant strains are resistant to robust heat shock with respect to clonogenicity of the cells. To elucidate this phenotype we found that the cytosolic Mmi1 holoprotein re-localized to the nucleus even in cells heat-shocked at 40°C. Upon robust heat shock at 46°C, Mmi1 partly co-localized with the proteasome marker Rpn1 in the nuclear region as well as with the cytoplasmic stress granules defined by Rpg1 (eIF3a). We co-localized Mmi1 also with Bre5, Ubp3 and Cdc48 which are involved in the protein de-ubiquitination machinery, protecting protein substrates from proteasomal degradation. A comparison of proteolytic activities of wild type and mmi1Δ cells revealed that Mmi1 appears to be an inhibitor of the proteasome. We conclude that one of the physiological functions of the multifunctional protein module, Mmi1, is likely in regulating degradation and/or protection of proteins thereby indirectly regulating the pathways leading to cell death in stressed cells. 相似文献
Leptospirosis is a global zoonotic disease. Although important for the assessment of the burden of leptospirosis, data on the duration of the illness and the occurrence of post-leptospirosis complaints are not well documented. Hence the main objective of this study was to estimate the occurrence of persistent complaints and duration of hospital stay in laboratory confirmed leptospirosis patients in the Netherlands during 1985 to 2010. Additionally, several risk factors potentially impacting on the occurrence of post-leptospirosis complaints were investigated.
Methods/Principal Findings
The duration of the acute phase of leptospirosis was 16 days (IQR 12–23); 10 days (IQR 7–16) were spent hospitalized. Eighteen fatal cases were excluded from this analysis. Complaints of leptospirosis patients by passive case investigations (CPC) derived from files on ambulant consultations occurring one month after hospital discharge, revealed persistent complaints in 108 of 236 (45.8%) laboratory confirmed cases. Data on persistent complaints after acute leptospirosis (PCAC), assessed in 225 laboratory confirmed leptospirosis cases collected through questionnaires during 1985-1993, indicated 68 (30.2%) PCAC cases. Frequently reported complaints included (extreme) fatigue, myalgia, malaise, headache, and a weak physical condition. These complaints prolonged in 21.1% of the cases beyond 24 months after onset of disease. There was no association between post-leptospirosis complaints and hospitalization. However, individuals admitted at the intensive care unit (ICU) were twice as likely to have continuing complaints after discharge adjusting for age and dialysis (OR 2.0 95% CI 0.8-4.8). No significant association could be found between prolongation of complaints and infecting serogroup, although subgroup analysis suggest that infection with serogroups Sejroe (OR 4.8, 95%CI 0.9-27.0) and icterohaemorrhagiae (OR 2.0, 95%CI 0.9-4.3 CI) are more likely to result in CPC than infections with serogroup Grippotyphosa.
Conclusion/Significance
In addition to the acute disease, persistent complaints have an impact on the burden of leptospirosis. 相似文献
Mitochondria have emerged as an intriguing target for anti-cancer drugs, inherent to vast majority if not all types of tumours. Drugs that target mitochondria and exert anti-cancer activity have become a focus of recent research due to their great clinical potential (which has not been harnessed thus far). The exceptional potential of mitochondria as a target for anti-cancer agents has been reinforced by the discouraging finding that even tumours of the same type from individual patients differ in a number of mutations. This is consistent with the idea of personalised therapy, an elusive goal at this stage, in line with the notion that tumours are unlikely to be treated by agents that target only a single gene or a single pathway. This endows mitochondria, an invariant target present in all tumours, with an exceptional momentum. This train of thoughts inspired us to define a class of anti-cancer drugs acting by way of mitochondrial ‘destabilisation’, termed ‘mitocans’. In this communication, we define mitocans (many of which have been known for a long time) and classify them into several classes based on their molecular mode of action. We chose the targets that are of major importance from the point of view of their role in mitochondrial destabilisation by small compounds, some of which are now trialled as anti-cancer agents. The classification starts with targets at the surface of mitochondria and ending up with those in the mitochondrial matrix. The purpose of this review is to present in a concise manner the classification of compounds that hold a considerable promise as potential anti-cancer drugs. 相似文献
Mitochondrial respiratory chain is organised into supramolecular structures that can be preserved in mild detergent solubilisates and resolved by native electrophoretic systems. Supercomplexes of respiratory complexes I, III and IV as well as multimeric forms of ATP synthase are well established. However, the involvement of complex II, linking respiratory chain with tricarboxylic acid cycle, in mitochondrial supercomplexes is questionable. Here we show that digitonin-solubilised complex II quantitatively forms high molecular weight structures (CIIhmw) that can be resolved by clear native electrophoresis. CIIhmw structures are enzymatically active and differ in electrophoretic mobility between tissues (500 – over 1000 kDa) and cultured cells (400–670 kDa). While their formation is unaffected by isolated defects in other respiratory chain complexes, they are destabilised in mtDNA-depleted, rho0 cells. Molecular interactions responsible for the assembly of CIIhmw are rather weak with the complexes being more stable in tissues than in cultured cells. While electrophoretic studies and immunoprecipitation experiments of CIIhmw do not indicate specific interactions with the respiratory chain complexes I, III or IV or enzymes of the tricarboxylic acid cycle, they point out to a specific interaction between CII and ATP synthase. 相似文献
The nucleus-encoded 17β-hydroxysteroid dehydrogenase type 10 (17β-HSD10) regulates cyclophilin D (cypD) in the mitochondrial matrix. CypD regulates opening of mitochondrial permeability transition pores. Both mechanisms may be affected by amyloid β peptides accumulated in mitochondria in Alzheimer's disease (AD). In order to clarify changes occurring in brain mitochondria, we evaluated interactions of both mitochondrial proteins in vitro (by surface plasmon resonance biosensor) and detected levels of various complexes of 17β-HSD10 formed in vivo (by sandwich ELISA) in brain mitochondria isolated from the transgenic animal model of AD (homozygous McGill-R-Thy1-APP rats) and in cerebrospinal fluid samples of AD patients. By surface plasmon resonance biosensor, we observed the interaction of 17β-HSD10 and cypD in a direct real-time manner and determined, for the first time, the kinetic parameters of the interaction (ka 2.0?×?105 M1s?1, kd 5.8?×?104 s?1, and KD 3.5?×?10–10 M). In McGill-R-Thy1-APP rats compared to controls, levels of 17β-HSD10–cypD complexes were decreased and those of total amyloid β increased. Moreover, the levels of 17β-HSD10–cypD complexes were decreased in cerebrospinal fluid of individuals with AD (in mild cognitive impairment as well as dementia stages) or with Frontotemporal lobar degeneration (FTLD) compared to cognitively normal controls (the sensitivity of the complexes to AD dementia was 92.9%, that to FTLD 73.8%, the specificity to AD dementia equaled 91.7% in a comparison with the controls but only 26.2% with FTLD). Our results demonstrate the weakened ability of 17β-HSD10 to regulate cypD in the mitochondrial matrix probably via direct effects of amyloid β. Levels of 17β-HSD10–cypD complexes in cerebrospinal fluid seem to be the very sensitive indicator of mitochondrial dysfunction observed in neurodegeneration but unfortunately not specific to AD pathology. We do not recommend it as the new biomarker of AD.
The classical definition posits hybrid sterility as a phenomenon when two parental taxa each of which is fertile produce a hybrid that is sterile. The first hybrid sterility gene in vertebrates, Prdm9, coding for a histone methyltransferase, was identified in crosses between two laboratory mouse strains derived from Mus mus musculus and M. m. domesticus subspecies. The unique function of PRDM9 protein in the initiation of meiotic recombination led to the discovery of the basic molecular mechanism of hybrid sterility in laboratory crosses. However, the role of this protein as a component of reproductive barrier outside the laboratory model remained unclear. Here, we show that the Prdm9 allelic incompatibilities represent the primary cause of reduced fertility in intersubspecific hybrids between M. m. musculus and M. m. domesticus including 16 musculus and domesticus wild-derived strains. Disruption of fertility phenotypes correlated with the rate of failure of synapsis between homologous chromosomes in meiosis I and with early meiotic arrest. All phenotypes were restored to normal when the domesticus Prdm9dom2 allele was substituted with the Prdm9dom2H humanized variant. To conclude, our data show for the first time the male infertility of wild-derived musculus and domesticus subspecies F1 hybrids controlled by Prdm9 as the major hybrid sterility gene. The impairment of fertility surrogates, testes weight and sperm count, correlated with increasing difficulties of meiotic synapsis of homologous chromosomes and with meiotic arrest, which we suppose reflect the increasing asymmetry of PRDM9-dependent DNA double-strand breaks. 相似文献