Home About us Contact
|
Home About us Contact | ||
|
|
||
Sites Distinct (site + distinct)
Selected AbstractsAllosteric Regulation of ProteasesCHEMBIOCHEM, Issue 18 2008Patrick Hauske Abstract Allostery is a basic principle of control of enzymatic activities based on the interaction of a protein or small molecule at a site distinct from an enzyme's active center. Allosteric modulators represent an alternative approach to the design and synthesis of small-molecule activators or inhibitors of proteases and are therefore of wide interest for medicinal chemistry. The structural bases of some proteinaceous and small-molecule allosteric protease regulators have already been elucidated, indicating a general mechanism that might be exploitable for future rational design of small-molecule effectors. [source] Caldesmon is a cytoskeletal target for PKC in endotheliumJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2006Natalia V. Bogatcheva Abstract We have previously shown that treatment of bovine endothelial cell (EC) monolayers with phorbol myristate acetate (PMA) leads to the thinning of cortical actin ring and rearrangement of the cytoskeleton into a grid-like structure, concomitant with the loss of endothelial barrier function. In the current work, we focused on caldesmon, a cytoskeletal protein, regulating actomyosin interaction. We hypothesized that protein kinase C (PKC) activation by PMA leads to the changes in caldesmon properties such as phosphorylation and cellular localization. We demonstrate here that PMA induces both myosin and caldesmon redistribution from cortical ring into the grid-like network. However, the initial step of PMA-induced actin and myosin redistribution is not followed by caldesmon redistribution. Co-immunoprecipitation experiments revealed that short-term PMA (5 min) treatment leads to the weakening of caldesmon ability to bind actin and, to the lesser extent, myosin. Prolonged incubation (15,60 min) with PMA, however, strengthens caldesmon complexes with actin and myosin, which correlates with the grid-like actin network formation. PMA stimulation leads to an immediate increase in caldesmon Ser/Thr phosphorylation. This process occurs at sites distinct from the sites specific for ERK1/2 phosphorylation and correlates with caldesmon dissociation from the actomyosin complex. Inhibition of ERK-kinase MEK fails to abolish grid-like structure formation, although reducing PMA-induced weakening of the cortical actin ring, whereas inhibition of PKC reverses PMA-induced cytoskeletal rearrangement. Our results suggest that PKC-dependent phosphorylation of caldesmon is involved in PMA-mediated complex cytoskeletal changes leading to the EC barrier compromise. J. Cell. Biochem. 99: 1593,1605, 2006. © 2006 Wiley-Liss, Inc. [source] Fibrinolysis is amplified by converting ,2 -antiplasmin from a plasmin inhibitor to a substrateJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2007I. Y. SAZONOVA Summary., ,2 -antiplasmin (,2 -AP) is the fast serpin inhibitor of plasmin and appears to limit the success of treatment for thrombosis. We examined the mechanisms through which monoclonal antibodies (mAbs) against ,2 -AP amplify fibrinolysis. The mAbs RWR, 49 and 77 interfered with the ability of ,2 -AP to inhibit plasmin, microplasmin and trypsin. In solution, mAbs 49 and 77 bound to ,2 -AP with 5-fold to 10-fold higher relative affinity than mAb-RWR, while mAb-RWR bound with greater avidity to immobilized or denatured ,2 -AP. Binding studies with chimeric ,2 -APs revealed that none of the mAbs bound to sites in ,2 -AP that form putative contacts with plasmin, namely the carboxy terminal lysines of ,2 -AP, or the reactive center loop in the serpin domain of ,2 -AP. Rather, mAb-RWR recognized an epitope in the amino-terminus of ,2 -AP (L13GNQEPGGQTALKSPPGVCS32) near the site at which ,2 -AP cross-links to fibrin. mAbs 49 and 77 bound to another conformational epitope in the serpin domain of ,2 -AP. mAbs 49 and 77 markedly increased the stoichiometry of plasmin inhibition by ,2 -AP (from 1.1 ± 0.1 to 51 ± 4 and 67 ± 7) indicating that they convert ,2 -AP from an inhibitor to a substrate of plasmin. This was confirmed by sodium dodecylsulfate polyacrylamide gel electrophoresis analysis showing cleavage of ,2 -AP by plasmin in the presence of these mAbs. In summary, these mAbs appear to act at sites distinct from known ,2 -AP,plasmin contacts to enhance fibrinolysis by converting ,2 -AP from an inhibitor to a plasmin substrate. [source] Factors affecting carbon dioxide laser treatment for oral precancer: A patient cohort studyLASERS IN SURGERY AND MEDICINE, Issue 1 2009O. Hamadah DDS Abstract Background Although the benefits of CO2 laser surgery in oral precancer management have been evaluated, little consideration has been given to the factors which may influence treatment outcome, especially amongst patients developing recurrence or malignant transformation. Study Design Seventy eight patients (51 males, 27 females; mean age 57.8 years) undergoing CO2 laser excision of single, new dysplastic oral precancer lesions (OPLs) were followed up for a minimum of 2 years and the influence of clinico-pathological parameters, socio-demographic factors and the presence or absence of residual dysplasia in excision margins upon clinical outcome were examined. Results Seventy three percent of patients were smokers and 78% consumed alcohol regularly. The majority of lesions were leukoplakias arising in the floor of mouth and ventro-lateral tongue and moderate or severe dysplasia accounted for 86% of histopathological diagnoses. Patient follow up ranged from 24 to 119 months (mean 58 months). Sixty four percent of patients were disease free at most recent clinical follow up, whilst 32% developed local recurrent dysplasia or new site dysplasia with 4% developing oral squamous cell carcinoma (but at sites distinct from their initial OPL). Excision margins were clear in 55% of cases, but 19% showed mild, 21% moderate and 5% severe dysplasia on histopathological examination. No statistically significant associations were seen between patients' age, gender, lesion appearance, site of origin, histopathological grading, presence of dysplasia in resection margins, or alcohol consumption and clinical outcome. Smokers, however, were at significantly higher risk of dysplasia recurrence compared to ex-smokers or non-smokers (P,=,0.04). Conclusions In the absence of agreed treatment protocols for OPLs, we recommend CO2 laser surgery as an effective treatment modality offering precise lesion excision, full histopathological assessment, minimal post-operative morbidity and a 64% disease free clinical outcome. Regular patient follow up is encouraged due to the persistence of field cancerisation effects. Lasers Surg. Med. 41:17,25, 2009. © 2008 Wiley-Liss, Inc. [source] Differential dye coupling reveals lateral giant escape circuit in crayfishTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2003Brian L. Antonsen Abstract The lateral giant (LG) escape circuit of crayfish mediates a coordinated escape triggered by strong attack to the abdomen. The LG circuit is one of the best understood of small systems, but models of the circuit have mostly been limited to simple ball-and-stick representations, which ignore anatomical details of contacts between circuit elements. Many of the these contacts are electrical; here we use differential dye coupling, a technique which could help reveal connection patterns in many neural circuits, to reveal in detail the circuit within the terminal abdominal ganglion. Sensory input from the tailfan forms a somatotopic map on the projecting LG dendrites, which together with interafferent coupling mediates a lateral excitatory network that selectively amplifies strong, phasic, converging input to LG. Mechanosensory interneurons contact LG at sites distinct from the primary afferents and so maximize their summated effect on LG. Motor neurons and premotor interneurons are excited near the initial segments of the LGs and innervate muscles for generating uropod flaring and telson flexion. Previous research has shown that spatial patterns of input are important for signal integration in LG; this map of electrical contact points will help us to understand synaptic processing in this system. J. Comp. Neurol. 466:1,13, 2003. © 2003 Wiley-Liss, Inc. [source] | |||||||||||||