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381.
An activating mutation in sos-1 identifies its Dbl domain as a critical inhibitor of the epidermal growth factor receptor pathway during Caenorhabditis elegans vulval development
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Modzelewska K Elgort MG Huang J Jongeward G Lauritzen A Yoon CH Sternberg PW Moghal N 《Molecular and cellular biology》2007,27(10):3695-3707
Proper regulation of receptor tyrosine kinase (RTK)-Ras-mitogen-activated protein kinase (MAPK) signaling pathways is critical for normal development and the prevention of cancer. SOS is a dual-function guanine nucleotide exchange factor (GEF) that catalyzes exchange on Ras and Rac. Although the physiologic role of SOS and its CDC25 domain in RTK-mediated Ras activation is well established, the in vivo function of its Dbl Rac GEF domain is less clear. We have identified a novel gain-of-function missense mutation in the Dbl domain of Caenorhabditis elegans SOS-1 that promotes epidermal growth factor receptor (EGFR) signaling in vivo. Our data indicate that a major developmental function of the Dbl domain is to inhibit EGF-dependent MAPK activation. The amount of inhibition conferred by the Dbl domain is equal to that of established trans-acting inhibitors of the EGFR pathway, including c-Cbl and RasGAP, and more than that of MAPK phosphatase. In conjunction with molecular modeling, our data suggest that the C. elegans mutation, as well as an equivalent mutation in human SOS1, activates the MAPK pathway by disrupting an autoinhibitory function of the Dbl domain on Ras activation. Our work suggests that functionally similar point mutations in humans could directly contribute to disease. 相似文献
382.
Involvement of COX-1 in A3 adenosine receptor-mediated contraction through endothelium in mice aorta
Ansari HR Nadeem A Tilley SL Mustafa SJ 《American journal of physiology. Heart and circulatory physiology》2007,293(6):H3448-H3455
We investigated whether A(3) adenosine receptor (A(3)AR) is involved in endothelium-mediated contraction through cyclooxygenases (COXs) with the use of wild-type (WT) and A(3) knockout (A(3)KO) mice aorta. A(3)AR-selective agonist, Cl-IBMECA, produced a concentration-dependent contraction (EC(50): 2.9 +/- 0.2 x 10(-9) M) in WT mouse aorta with intact endothelium (+E) and negligible effects in A(3)KO +E aorta. At 10(-7) M, contractions produced by Cl-IBMECA were 29% in WT +E, while being insignificant in A(3)KO +E aorta. Cl-IBMECA-induced responses were abolished in endothelium-denuded tissues (-E), in both WT and A(3)KO aorta. A(3)AR gene and protein expression were reduced by 74 and 72% (P < 0.05), respectively, in WT -E compared with WT +E aorta, while being undetected in A(3)KO +E/-E aorta. Indomethacin (nonspecific COXs blocker, 10(-5) M), SC-560 (specific COX-1 blocker, 10(-8) M), SQ 29549 (thromboxane prostanoid receptor antagonist, 10(-6) M), and furegrelate (thromboxane synthase inhibitor, 10(-5) M) inhibited Cl-IBMECA-induced contraction significantly. Cl-IBMECA-induced thromboxane B(2) production was also attenuated significantly by indomethacin, SC-560, and furegrelate in WT +E aorta, while having negligible effects in A(3)KO +E aorta. NS-398 (specific COX-2 blocker) produced negligible inhibition of Cl-IBMECA-induced contraction in both WT +E and A(3)KO +E aorta. Cl-IBMECA-induced increase in COX-1 and thromboxane prostanoid receptor expression were significantly inhibited by MRS1523, a specific A(3)AR antagonist in WT +E aorta. Expression of both A(3)AR and COX-1 was located mostly on endothelium of WT and A(3)KO +E aorta. These results demonstrate for the first time the involvement of COX-1 pathway in A(3)AR-mediated contraction via endothelium. 相似文献
383.
Si Lhyam Myint Nikola Zlatkov Kyaw Min Aung Eric Toh Annika Sjöström Aftab Nadeem Marylise Duperthuy Bernt Eric Uhlin Sun Nyunt Wai 《Biochimica et Biophysica Acta (BBA)/General Subjects》2021,1865(7):129912
BackgroundA prevailing action of the Type VI secretion system (T6SS) in several Gram-negative bacterial species is inter-bacterial competition. In the past several years, many effectors of T6SS were identified in different bacterial species and their involvement in inter-bacterial interactions were described. However, possible defence mechanisms against T6SS attack among prey bacteria were not well clarified yet.MethodsEscherichia coli was assessed for susceptibility to T6SS-mediated killing by Vibrio cholerae. TheT6SS-mediated bacterial killing assays were performed in absence or presence of different protease inhibitors and with different mutant E. coli strains. Expression levels of selected proteins were monitored using SDS-PAGE and immunoblot analyses.ResultsThe T6SS-mediated killing of E. coli by V. cholerae was partly blocked when the serine protease inhibitor Pefabloc was present. E. coli lacking the periplasmic protease inhibitor Ecotin showed enhanced susceptibility to killing by V. cholerae. Mutations affecting E. coli membrane stability also caused increased susceptibility to killing by V. cholerae. E. coli lacking the maltodextrin porin protein LamB showed reduced susceptibility to killing by V. cholerae whereas E. coli with induced high levels of LamB showed reduced survival in inter-bacterial competition.ConclusionsOur study identified two proteins in E. coli, the intrinsic protease inhibitor Ecotin and the outer membrane porin LamB, that influenced E. coli susceptibility to T6SS-mediated killing by V. cholerae.General significanceWe envision that it is feasible to explore these findings to target and modulate their expression to obtain desired changes in inter-bacterial competition in vivo, e.g. in the gastrointestinal microbiome. 相似文献
384.
Ilyas Muhammad Nisar Mohammad Khan Nadeem Hazrat Ali Khan Aamir Hamid Hayat Kashif Fahad Shah Khan Aziz Ullah Abid 《Journal of Plant Growth Regulation》2021,40(3):926-944
Journal of Plant Growth Regulation - Anthropogenic activities in the past and present eras have created global warming and consequently a storm of drought stress, affecting both plants and animals.... 相似文献
385.
The role of mycorrhizae and plant growth promoting rhizobacteria (PGPR) in improving crop productivity under stressful environments 总被引:4,自引:0,他引:4
Sajid Mahmood Nadeem Maqshoof Ahmad Zahir Ahmad Zahir Arshad Javaid Muhammad Ashraf 《Biotechnology advances》2014
Both biotic and abiotic stresses are major constrains to agricultural production. Under stress conditions, plant growth is affected by a number of factors such as hormonal and nutritional imbalance, ion toxicity, physiological disorders, susceptibility to diseases, etc. Plant growth under stress conditions may be enhanced by the application of microbial inoculation including plant growth promoting rhizobacteria (PGPR) and mycorrhizal fungi. These microbes can promote plant growth by regulating nutritional and hormonal balance, producing plant growth regulators, solubilizing nutrients and inducing resistance against plant pathogens. In addition to their interactions with plants, these microbes also show synergistic as well as antagonistic interactions with other microbes in the soil environment. These interactions may be vital for sustainable agriculture because they mainly depend on biological processes rather than on agrochemicals to maintain plant growth and development as well as proper soil health under stress conditions. A number of research articles can be deciphered from the literature, which shows the role of rhizobacteria and mycorrhizae alone and/or in combination in enhancing plant growth under stress conditions. However, in contrast, a few review papers are available which discuss the synergistic interactions between rhizobacteria and mycorrhizae for enhancing plant growth under normal (non-stress) or stressful environments. Biological interactions between PGPR and mycorrhizal fungi are believed to cause a cumulative effect on all rhizosphere components, and these interactions are also affected by environmental factors such as soil type, nutrition, moisture and temperature. The present review comprehensively discusses recent developments on the effectiveness of PGPR and mycorrhizal fungi for enhancing plant growth under stressful environments. The key mechanisms involved in plant stress tolerance and the effectiveness of microbial inoculation for enhancing plant growth under stress conditions have been discussed at length in this review. Growth promotion by single and dual inoculation of PGPR and mycorrhizal fungi under stress conditions have also been discussed and reviewed comprehensively. 相似文献
386.
Effect of gibberellic acid on the vase life and oxidative activities in senescing cut gladiolus flowers 总被引:2,自引:0,他引:2
Tariq Saeed Imran Hassan Nadeem Akhtar Abbasi Ghulam Jilani 《Plant Growth Regulation》2014,72(1):89-95
Cut flowers face the problem of short display life and lose their aesthetic value rapidly. In order to enhance the vase life of gladiolus, its cut spikes were subjected to different levels of gibberellic acid (GA3), viz., 0, 25, 50, 100 and 200 mg L?1 in vase solution, during two consecutive years 2010 and 2011. The GA3 treatment significantly influenced the vase quality attributes and antioxidants capacity of gladiolus cut flowers. Gibberellic acid at 25 mg L?1 caused the longest time taken to open the floret and increased the floret opening, vase life duration and fresh weight. The highest antioxidative activities of superoxide dismutase and free radicals scavenging were also recorded with GA3 at 25 mg L?1. The highest peroxidase, catalase activity and the lowest membrane leakage were recorded with GA3 at 50 mg L?1. Present study concludes that GA3 applied at lower concentrations (25 mg L?1) renders greater beneficial effects on vase life quality, membrane stability and antioxidant activities in gladiolus cut spike, and further higher application rates cause no improvement in the flower longevity. 相似文献
387.
Hassan Imran Afridi Tasneem Gul Kazi Farah Naz Talpur Atif Kazi Sadaf Sadia Arain Salma Aslam Arain Kapil Dev Brahman Abdul Haleem Panhwar Naeemullah Mariam Shezadi Jamshed Ali 《Biological trace element research》2014,160(2):185-196
The abnormal metabolism of metal ions plays an important role in health and disease conditions; hence, the studies about them have received much interest. The objective of this study was to evaluate the association between trace and toxic elements zinc (Zn), cadmium (Cd), selenium (Se), and mercury (Hg) in biological samples (scalp hair, blood, and urine) of hypertensive patients (n?=?257), residents of Hyderabad, Pakistan. For comparison purpose, the biological samples of age-matched healthy controls were selected as referents. The concentrations of trace and toxic elements were measured by atomic absorption spectrophotometer prior to microwave-assisted acid digestion. The validity and accuracy of the methodology was checked using certified reference materials and by the conventional wet acid digestion method. The recovery of all studied elements was found in the range of 96.4–99.1 % in certified reference materials. The results of this study showed that the mean values of Cd and Hg were significantly higher in scalp hair, blood, and urine samples of hypertensive patients than in referents (P?<?0.001), whilst the concentrations of Zn and Se were lower in the scalp hair and blood, but higher in the urine samples of hypertensive patients. The deficiency of Zn and Se and the high exposure of toxic metals may be synergistic with risk factors associated with hypertension. 相似文献
388.
Nadeem Ahmad Ansari Moinuddin Abdul Rouf Mir Safia Habib Khursheed Alam Asif Ali Rizwan Hasan Khan 《Cell biochemistry and biophysics》2014,70(2):857-865
In diabetes, protein glycation mostly occurs at intrachain lysine residues resulting in the formation of early stage Amadori products which are finally converted to advance glycation end products (AGEs). Several studies have reported autoantibodies against AGEs in diabetes but not much data are found in respect of Amadori products. In this study, poly-l-lysine (PLL) was glycated with 50 mM glucose and the resultant Amadori products were estimated by fructosamine or nitroblue tetrazolium assay. We report high content of Amadori products in PLL upon glycation. Glycated PLL showed marked hyperchromicity in the UV spectrum, ellipticity changes in CD spectroscopy, and variations in ε-methylene protons shift in NMR. It was better recognized by autoantibodies in type 2 diabetics compared to the native PLL. Induced antibodies against glycated PLL were successfully used to probe early glycation in the IgG isolated from diabetes type 2 patients. Role of Amadori products of glycated proteins in the induction of autoantibodies in type 2 diabetes as well as in associated secondary complications has been discussed. 相似文献
389.
Bacterial strains with ability to suppress Colletotrichum falcatum were isolated from the rhizosphere of sugarcane. Thirty nine candidates, chosen on the basis of in vitro antagonism, inhibited
C. falcatum growth by 15–65% on test plates. Twenty two isolates causing 50% or more in vitro inhibition were screened for their root
colonization ability and biocontrol activity on micropropagated sugarcane plants under greenhouse conditions. Twelve strains
suppressed red rot infection in plantlets, but no significant correlation was observed between in vitro pathogen inhibition
and in vivo disease suppression. However, isolates showing root colonization over 5.2 log10 CFU g−1 of soil showed highest suppression of C. falcatum and reduction of red rot disease. Six strains with the capability to maintain a significant population in the sugarcane rhizosphere
and with a high potential to control red rot were identified by 16S rDNA as Ochrobacterum intermedium NH-5, Pseudomonas putida NH-50, Bacillus subtilis NH-100, Bacillus subtilis NH-160, Bacillus sp NH-217 and Stenotrophomonas maltophilia NH-300. 相似文献
390.