Die altersabhängige axiale Haarkraft einer nordeuropäischen Kohorte und deren Relation zur axialen Haarkraft in PSD-Patienten.

Die Forschungserkenntnisse letzter Jahre über die Ätiologie des Pilonidalsinus bekräftigten die zentrale pathogenetische Rolle des scharfen, in die Haut der Rima ani eindringenden Kopfhaares. Die mechanischen Eigenschaften des eindringenden Haares beeinflussen den Akt der Hautpenetration. In diesem Kontext scheint die axiale Kraft direkt die Penetrationspotenz des Haares zu bestimmen. Im Rahmen dieser Arbeit wurden die Terminalhaare aus den drei anatomischen Regionen, Protuberantia occipitalis externa (Hinterkopf), Glabella sakralis (unterer Rücken) und dem kranialseitigen Drittel der Interglutealfalte von 342 gesunden und 83 PSD-erkrankten Probanden asserviert und auf die axiale Kraft untersucht um die Variationen der Haarsteifigkeit in beiden Probandenpopulationen zu analysieren. Die Hinterkopfhaare der gesamten untersuchten Population wiesen starke altersabhängige Veränderungen der axialen Festigkeit mit höchsten Werten in der zweiten und dritten Lebensdekade auf, was sich mit der Hauptinzidenz der Sinuserkrankung in der Bevölkerung deckte. Des Weiteren konnte nachgewiesen werden, dass die analysierten Kopf- und Rumpfhaare der stärker behaarten Sinuspatienten deutlich steifer im Vergleich zu Haaren der gesunden Probanden waren. In Anbetracht dieser Ergebnisse lässt sich erneut das steife, scharfe Kopfhaar als der Hauptakteur in der Pathogenese des Pilonidalsinus erkennen. Ferner öffnet die Beobachtung der signifikant vermehrten Rumpfbehaarung der Sinuspatienten einen Raum für Diskussion über die potenziell pathogenetische Rolle der sogenannten Catching-Zone - ein behaartes Areal intergluteal, welches die herabfallenden Kopfhaare fängt und durch die Verlängerung der Stehzeit der Haare in diesem Region die Wahrscheinlichkeit des Eindringens erhöht. Nicht nur bestärken die Ergebnisse der vorliegenden Arbeit die Karydakis´sche Hypothese des eindringenden Haares, sondern sie ergänzen sie weiter um neue Erkenntnisse in der Pathogenese der Sinuserkrankung.The research findings of recent years on the etiology of the pilonidal sinus have confirmed the central pathogenetic role of the sharp occipital hair that penetrates the skin of anal cleft. The mechanical properties of the hair affect the act of skin penetration. In this context, the hair stiffness seems to directly determine its penetrating potential. As part of this work, the terminal hair from three anatomical regions such as Protuberantia occipitalis externa (back of the head), Glabella sacralis (lower back) and the cranial third of the intergluteal fold were collected from a total of 342 healthy persons and 83 PSD-patients and tested for their axial hairforce in order to analyze the variations in hair stiffness in both populations. The occipital hair of the entire population showed strong, age-dependent changes in axial strength with the highest values in the second and third decades of life, which corresponded to the main incidence of sinus disease in the population. Furthermore it could be shown that the analyzed head and trunk hair of the more hairy PSD-patients were significantly stiffer compared to the hair of the healthy persons. In view of these results, the stiff, sharp occipital hair can again be recognized as the main actor in the pathogenesis of the pilonidal sinus. In addition, the observation of the significantly hairier trunks of the sinus patients opens a space for discussion about the possible pathogenetic role of the so-called catching zone – an exceptionally hairy area in the intergluteal fold that catches the falling head hair and increases the likelihood of penetration of the skin by prolonging the time the hair stays in this region. Not only do the results of the present work strengthen the Karydakis hypothesis of penetrating hair, but also supplement it with new findings in the pathogenesis of sinus disease

Quantitative analysis of the effect of tubulin isotype expression on sensitivity of cancer cell lines to a set of novel colchicine derivatives

<p>Abstract</p> <p>Background</p> <p>A maximum entropy approach is proposed to predict the cytotoxic effects of a panel of colchicine derivatives in several human cancer cell lines. Data was obtained from cytotoxicity assays performed with 21 drug molecules from the same family of colchicine compounds and correlate these results with independent tubulin isoform expression measurements for several cancer cell lines. The maximum entropy method is then used in conjunction with computed relative binding energy values for each of the drug molecules against tubulin isotypes to which these compounds bind with different affinities.</p> <p>Results</p> <p>We have found by using our analysis that <it>αβ</it>I and <it>αβ</it>III tubulin isoforms are the most important isoforms in establishing predictive response of cancer cell sensitivity to colchicine derivatives. However, since <it>αβ</it>I tubulin is widely distributed in the human body, targeting it would lead to severe adverse side effects. Consequently, we have identified tubulin isotype <it>αβ</it>III as the most important molecular target for inhibition of microtubule polymerization and hence cancer cell cytotoxicity. Tubulin isotypes <it>αβ</it>I and <it>αβ</it>II are concluded to be secondary targets.</p> <p>Conclusions</p> <p>The benefit of being able to correlate expression levels of specific tubulin isotypes and the resultant cell death effect is that it will enable us to better understand the origin of drug resistance and hence design optimal structures for the elimination of cancer cells. The conclusion of the study described herein identifies tubulin isotype <it>αβ</it>III as a target for optimized chemotherapy drug design.</p

Structural polymorphism of intramolecular quadruplex of human telomeric DNA: effect of cations, quadruplex-binding drugs and flanking sequences

G-quadruplex structures formed in the telomeric DNA are thought to play a role in the telomere function. Drugs that stabilize the G-quadruplexes were shown to have anticancer effects. The structures formed by the basic telomeric quadruplex-forming unit G3(TTAG3)3 were the subject of multiple studies. Here, we employ 125I-radioprobing, a method based on analysis of the distribution of DNA breaks after decay of 125I incorporated into one of the nucleotides, to determine the fold of the telomeric DNA in the presence of TMPyP4 and telomestatin, G-quadruplex-binding ligands and putative anticancer drugs. We show that d[G3(TTAG3)3125I-CT] adopts basket conformation in the presence of NaCl and that addition of either of the drugs does not change this conformation of the quadruplex. In KCl, the d[G3(TTAG3)3125I-CT] is most likely present as a mixture of two or more conformations, but addition of the drugs stabilize the basket conformation. We also show that d[G3(TTAG3)3125I-CT] with a 5′-flanking sequence folds into (3+1) type 2 conformation in KCl, while in NaCl it adopts a novel (3+1) basket conformation with a diagonal central loop. The results demonstrate the structural flexibility of the human telomeric DNA; and show how cations, quadruplex-binding drugs and flanking sequences can affect the conformation of the telomeric quadruplex

Elevated polyamines induce c-MYC overexpression by perturbing quadruplex–WC duplex equilibrium

The biological role of quadruplexes and polyamines has been independently associated with cancer. However, quadruplex-polyamine mediated transcriptional regulation remain unaddressed. Herein, using c-MYC quadruplex model, we have attempted to understand quadruplex–polyamine interaction and its role in transcriptional regulation. We initially employed biophysical approach involving CD, UV and FRET to understand the role of polyamines (spermidine and spermine) on conformation, stability, molecular recognition of quadruplex and to investigate the effect of polyamines on quadruplex–Watson Crick duplex transition. Our study demonstrates that polyamines affect the c-MYC quadruplex conformation, perturb its recognition properties and delays duplex formation. The relative free energy difference (ΔΔG°) between the duplex and quadruplex structure indicate that polyamines stabilize and favor c-MYC quadruplex over duplex. Further, we investigated the influence of polyamine mediated perturbation of this equilibrium on c-MYC expression. Our results suggest that polyamines induce structural transition of c-MYC quadruplex to a transcriptionally active motif with distinctive molecular recognition property, which drives c-MYC expression. These findings may allow exploiting quadruplex–polyamines interaction for developing antiproliferative strategies to combat aberrant gene expression

A thermodynamic overview of naturally occurring intramolecular DNA quadruplexes

Loop length and its composition are important for the structural and functional versatility of quadruplexes. To date studies on the loops have mainly concerned model sequences compared with naturally occurring quadruplex sequences which have diverse loop lengths and compositions. Herein, we have characterized 36 quadruplex-forming sequences from the promoter regions of various proto-oncogenes using CD, UV and native gel electrophoresis. We examined folding topologies and determined the thermodynamic profile for quadruplexes varying in total loop length (5–18 bases) and composition. We found that naturally occurring quadruplexes have variable thermodynamic stabilities (ΔG37) ranging from −1.7 to −15.6 kcal/mol. Overall, our results suggest that both loop length and its composition affect quadruplex structure and thermodynamics, thus making it difficult to draw generalized correlations between loop length and thermodynamic stability. Additionally, we compared the thermodynamic stability of quadruplexes and their respective duplexes to understand quadruplex–duplex competition. Our findings invoke a discussion on whether biological function is associated with quadruplexes with lower thermodynamic stability which undergo facile formation and disruption, or by quadruplexes with high thermodynamic stability

ACVR1, a Therapeutic Target of Fibrodysplasia Ossificans Progressiva, Is Negatively Regulated by miR-148a

Fibrodysplasia ossificans progressiva (FOP) is a rare congenital disorder of skeletal malformations and progressive extraskeletal ossification. There is still no effective treatment for FOP. All FOP individuals harbor conserved point mutations in ACVR1 gene that are thought to cause ACVR1 constitutive activation and activate BMP signal pathway. The constitutively active ACVR1 is also found to be able to cause endothelial-to-mesenchymal transition (EndMT) in endothelial cells, which may cause the formation of FOP lesions. MicroRNAs (miRNAs) play an essential role in regulating cell differentiation. Here, we verified that miR-148a directly targeted the 3′ UTR of ACVR1 mRNA by reporter gene assays and mutational analysis at the miRNA binding sites, and inhibited ACVR1 both at the protein level and mRNA level. Further, we verified that miR-148a could inhibit the mRNA expression of the Inhibitor of DNA binding (Id) gene family thereby suppressing the BMP signaling pathway. This study suggests miR-148a is an important mediator of ACVR1, thus offering a new potential target for the development of therapeutic agents against FOP

Crystallization and characterization of the thallium form of the Oxytricha nova G-quadruplex

The crystal structure of the Tl(+) form of the G-quadruplex formed from the Oxytricha nova telomere sequence, d(G(4)T(4)G(4)), has been solved to 1.55 Å. This G-quadruplex contains five Tl(+) ions, three of which are interspersed between adjacent G-quartet planes and one in each of the two thymine loops. The structure displays a high degree of similarity to the K(+) crystal structure [Haider et al. (2002), J. Mol. Biol., 320, 189–200], including the number and location of the monovalent cation binding sites. The highly isomorphic nature of the two structures, which contain such a large number of monovalent binding sites (relative to nucleic acid content), verifies the ability of Tl(+) to mimic K(+) in nucleic acids. Information from this report confirms and extends the assignment of (205)Tl resonances from a previous report [Gill et al. (2005), J. Am. Chem. Soc., 127, 16 723–16 732] where (205)Tl NMR was used to study monovalent cation binding to this G-quadruplex. The assignment of these resonances provides evidence for the occurrence of conformational dynamics in the thymine loop region that is in slow exchange on the (205)Tl timescale