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91.
Responses of transformed Catharanthus roseus roots to femtomolar concentrations of salicylic acid. 总被引:1,自引:0,他引:1
Ileana Echevarría-Machado Rosa María Escobedo-G M Alfonso Larqué-Saavedra 《Plant Physiology and Biochemistry》2007,45(6-7):501-507
Catharanthus roseus transformed roots were cultured in the presence of salicylic acid (SA) at concentrations between 0.1 fM and 100 pM and the effect on root growth was evaluated. Significant morphological changes in the lateral roots were recorded on day two in the SA treatment. Presence of SA increased root cap size and caused the appearance of lateral roots closer to the root tip. The bioassay was sensitive enough to allow testing of low concentrations of other growth regulators that may affect root morphology and physiology. 相似文献
92.
Emilie Leroy Jean-Philippe Defour Takeshi Sato Sharmila Dass Vitalina Gryshkova Myat M. Shwe Judith Staerk Stefan N. Constantinescu Steven O. Smith 《The Journal of biological chemistry》2016,291(6):2974-2987
Ligand binding to the extracellular domain of the thrombopoietin receptor (TpoR) imparts a specific orientation on the transmembrane (TM) and intracellular domains of the receptors that is required for physiologic activation via receptor dimerization. To map the inactive and active dimeric orientations of the TM helices, we performed asparagine (Asn)-scanning mutagenesis of the TM domains of the murine and human TpoR. Substitution of Asn at only one position (S505N) activated the human receptor, whereas Asn substitutions at several positions activated the murine receptor. Second site mutational studies indicate that His499 near the N terminus of the TM domain is responsible for protecting the human receptor from activation by Asn mutations. Structural studies reveal that the sequence preceding His499 is helical in the murine receptor but non-helical in peptides corresponding to the TM domain of the inactive human receptor. The activating S505N mutation and the small molecule agonist eltrombopag both induce helix in this region of the TM domain and are associated with dimerization and activation of the human receptor. Thus, His499 regulates the activation of human TpoR and provides additional protection against activating mutations, such as oncogenic Asn mutations in the TM domain. 相似文献
93.
Echevarría-Machado I Martínez-Estévez M Muñoz-Sánchez JA Loyola-Vargas VM Hernández-Sotomayor SM De Los Santos-Briones C 《Molecular biotechnology》2007,35(3):297-309
We have previously reported that Catharanthus roseus transformed roots contain at least two phosphatidylinositol 4,5-bisphosphate-phospholipase C (PLC) activities, one soluble
and the other membrane associated. Detergent, divalent cations, and neomycin differentially regulate these activities and
pure protein is required for a greater understanding of the function and regulation of this enzyme. In this article we report
a partia purification of membrane-associated PLC. We found that there are at least two forms of membrane-associated PLC in
transformed roots of C. roseus. These forms were separated on the basis of their affinity for heparin. One form shows an affinity for heparin and elutes
at approx 600 mM KCl. This form has a molecular mass of 67 kDa by size exclusion chromatography and Western blot analysis, whereas the other
form does not bind to heparin and has a molecular mass of 57 kDa. Possible differential regulation of these forms during transformed
root growth is discussed. 相似文献
94.
Assembly of the cytosolic coat protein I (COPI) complex at the ER-Golgi interface is directed by the ADP ribosylation factor1 (Arf1) and its guanine nucleotide exchange factor (GBF1). Rab1b GTPase modulates COPI recruitment, but the molecular mechanism underlying this action remains unclear. Our data reveal that in vivo expression of the GTP-restricted Rab1b mutant (Rab1Q67L) increased the association of GBF1 and COPI to peripheral structures localized at the ER exit sites (ERES) interface. Active Rab1b also stabilized Arf1 on Golgi membranes. Furthermore, we characterized GBF1 as a new Rab1b effector, and showed that its N-terminal domain was involved in this interaction. Rab1b small interfering RNA oligonucleotide assays suggested that Rab1b was required for GBF1 membrane association. To further understand how Rab1b functions in ER-to-Golgi transport, we analyzed GFP-Rab1b dynamics in HeLa cells. Time-lapse microscopy indicated that the majority of the Rab1b-labeled punctuated structures are relatively short-lived with limited-range movements. FRAP of Golgi GFP-Rab1bwt showed rapid recovery (t(1/2) 120 s) with minimal dependence on microtubules. Our data support a model where Rab1b-GTP induces GBF1 recruitment at the ERES interface and at the Golgi complex where it is required for COPII/COPI exchange or COPI vesicle formation, respectively. 相似文献
95.
The expression of MMP‐1 and MMP‐9 is up‐regulated by smooth muscle cells after their cross‐talk with macrophages in high glucose conditions 下载免费PDF全文
Razvan Daniel Macarie Mihaela Vadana Letitia Ciortan Monica M. Tucureanu Andrea Ciobanu Dragos Vinereanu Ileana Manduteanu Maya Simionescu Elena Butoi 《Journal of cellular and molecular medicine》2018,22(9):4366-4376
Patients with diabetes mellitus have an increased risk of myocardial infarction and coronary artery disease‐related death, exhibiting highly vulnerable plaques. Many studies have highlighted the major role of macrophages (MAC) and smooth muscle cells (SMC) and the essential part of metalloproteases (MMPs) in atherosclerotic plaque vulnerability. We hypothesize that in diabetes, the interplay between MAC and SMC in high glucose conditions may modify the expression of MMPs involved in plaque vulnerability. The SMC‐MAC cross‐talk was achieved using trans‐well chambers, where human SMC were grown at the bottom and human MAC in the upper chamber in normal (NG) or high (HG) glucose concentration. After cross‐talk, the conditioned media and cells were isolated and investigated for the expression of MMPs, MCP‐1 and signalling molecules. We found that upon cross‐talk with MAC in HG, SMC exhibit: (i) augmented expression of MMP‐1 and MMP‐9; (ii) significant increase in the enzymatic activity of MMP‐9; (iii) higher levels of soluble MCP‐1 chemokine which is functionally active and involved in MMPs up‐regulation; (iv) activated PKCα signalling pathway which, together with NF‐kB are responsible for MMP‐1 and MMP‐9 up‐regulation, and (v) impaired function of collagen assembly. Taken together, our data indicate that MCP‐1 released by cell cross‐talk in diabetic conditions binds to CCR2 and triggers MMP‐1 and MMP‐9 over‐expression and activity, features that could explain the high vulnerability of atherosclerotic plaque found at diabetic patients. 相似文献
96.
Franca Serafini-Cessi Nadia Malagolini Stefania Guerrini Ileana Turrini 《Glycoconjugate journal》1995,12(6):773-779
We have previously shown that human colon carcinoma CaCo-2 cells express the Sda-1,4-N-acetylgalactosaminyltransferase (Sda-GalNAc-transferase) and that the enzyme activity correlates with the degree of enterocytic differentiation. Here we report that a large amount of this glycosyltransferase is released in soluble form, particularly when CaCo-2 cells are maintained in culture for more than 3 weeks in order to ensure an higher degree of enterocyte differentiation. The soluble enzyme was concentrated and partially purified by Blue-Sepharose and fetuin-Sepharose chromatography. The substrate specificity of the partially purified enzyme was similar to that of Sda-enzyme from epithelial cells of colon mucosa, and for its activity strictly required the presence in acceptors of NeuAc in 2,3-linkage to subterminal galactose. Among the low molecular glycans tested, NeuAc2,3Gal1,4GlcNAc appeared to be the best acceptor, whereas sialyl-Lewisx and sialyl-Lewisa did not serve as acceptors, indicating that the fucosylation of sub-terminal GlcNAc hindered the transferase activity. Contrary to this, the activity towards a disialylated acceptor such as di-sialyl-lacto-N-tetraose was reduced but not abolished. When CaCo-2 cells were cultured on porous membranes and the transferase activity assayed in medium collected from chambers corresponding to either the apical or basolateral face of highly differentiated CaCo-2 cells, a preferential release from the basolateral surface was found. Considering that Sda-GalNAc-transferase is mainly located in the large intestine, current results support the notion that colonic cells largely contribute to the presence of the enzyme in human plasma. 相似文献
97.
Sara Faranda Annalisa Frattini Ileana Zucchi Cristina Patrosso Luciano Milanesi Cristina Montagna Paolo Vezzoni 《Genomics》1996,34(3):323
Two new genes were identified and mapped by searching the EST databases with genomic sequences obtained from putative CpG islands of the rodent–human hybrid X3000. Previous mapping of these CpG islands in the proximity of the host cell factor (HCFC1) and GdX genes automatically localized these two new genes to Xq28 in the interval between the L1 cell adhesion molecule (L1CAM) and the glucose-6-phosphate dehydrogenase (G6PD) loci. Both genes are relatively short, contain an ORF of 261 and 105 amino acids, respectively, and are ubiquitously expressed. Combining sequencing of selected CpG islands, derived from hybrids containing small portions of the human genome, with an EST database search is an easy method of identifying and mapping new genes to specific regions of the genome. 相似文献
98.
L G Lee S L Spurgeon C R Heiner S C Benson B B Rosenblum S M Menchen R J Graham A Constantinescu K G Upadhya J M Cassel 《Nucleic acids research》1997,25(14):2816-2822
We have synthesized a set of four energy transfer dyes and demonstrated their use in automated DNA sequencing. The donor dyes are the 5- or 6-carboxy isomers of 4'-aminomethylfluorescein and the acceptor dyes are a novel set of four 4,7-dichloro-substituted rhodamine dyes which have narrower emission spectra than the standard, unsubstituted rhodamines. A rigid amino acid linker, 4-aminomethylbenzoic acid, was used to separate the dyes. The brightness of each dye in an automated sequencing instrument equipped with a dual line argon ion laser (488 and 514 nm excitation) was 2-2.5 times greater than the standard dye-primers with a 2 times reduction in multicomponent noise. The overall improvement in signal-to-noise was 4- to 5-fold. The utility of the new dye set was demonstrated by sequencing of a BAC DNA with an 80 kb insert. Measurement of the extinction coefficients and the relative quantum yields of the dichlororhodamine components of the energy transfer dyes showed their values were reduced by 20-25% compared with the dichlororhodamine dyes alone. 相似文献
99.
Ileana Echevarría-Machado Ana Ramos-Díaz Ligia Brito-Argáez Graciela Racagni-Di Palma Víctor M Loyola-Vargas S M Teresa Hernández-Sotomayor 《Plant Physiology and Biochemistry》2005,43(9):874-881
Recent results, fundamentally obtained from animal tissues, suggest that polyamines (Pas), essential compounds for the growth and development of all life organisms, may interact with a signal transduction cascade. Because Pas are highly positive charged compounds, their binding with phospholipids involved in signal transduction is likely to be the case. In this work, the in vivo effect of Pas on some important components of phospholipid signal transduction pathway was studied, by the first time, in plant tissue. Endogenous Pas content varied during the culture cycle of Coffea arabica cells: putrescine (Put) levels increased at the end of the stationary phase, both spermidine (Spd) and spermine (Spm) accumulated at the beginning of the linear growth phase. Cells that were incubated with Put presented a significant increase in phospholipase D (PLD) (EC: 3.1.4.4) activity, phospholipase C (PLC) (EC: 3.1.4.3) activity decreased, and the effect on lipid kinases was less marked. However, the incubation of the cells with Spd and Spm significantly stimulated the lipid kinases activities, fundamentally increased the formation of phosphatidyl inositol 4-phosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP2), while the effect on PLC and PLD activities was minor when compared with the cells treated with Put. The results presented here suggest that Pas may modulate the cellular signal of C. arabica cells by differentially affecting components of the phospholipid cascade. 相似文献
100.
For a number of years, sirtuin enzymes have been appreciated as effective “sensors” of the cellular environment to rapidly transmit information to diverse cellular pathways. Much effort was placed into exploring their roles in human cancers and aging. However, a growing body of literature brings these enzymes to the spotlight in the field of virology. Here, we discuss sirtuin functions in the context of viral infection, which provide regulatory points for therapeutic intervention against pathogens. 相似文献