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1.
Gloushankova NA 《Biochemistry. Biokhimii?a》2008,73(7):742-750
2.
Cell—cell interactions in bacterial populations 总被引:5,自引:0,他引:5
In developing bacterial populations many essential processes, such as division, genetic transformation, sporulation, and synthesis of antibiotics and secondary metabolites, are regulated by intercellular communication mediated by secretion of signaling molecules, such as homoserine lactones and peptides. Another intercellular communication type, namely a physical contact between cells (cell aggregation), plays a key role in formation of biofilms or cellular consortia and in cell proliferation under unfavorable conditions. The mechanisms involved in these two types of bacterial communication are discussed in this review.Translated from Biokhimiya, Vol. 69, No. 11, 2004, pp. 1555–1564.Original Russian Text Copyright © 2004 by Voloshin, Kaprelyants 相似文献
3.
Molecular signal transduction in vascular cell apoptosis 总被引:18,自引:0,他引:18
GengYJ 《Cell research》2001,11(4):253-264
INTRODUCTIONApoptosis represents a model of genetically pro--grammed ce1l death and a major mechanism bywhiCh tissue removes unwanted, aged or damagedce1ls. Although cells of mammalian tissues consist ofa broad dtwsity of phenotypes and g6notypes, during the developmeat of apoptosis, all cell types un-dergo similar morphological alteratiOns include chro-matin compaction and margination, nuclear conden-sation and fragmentation, and cell body sbIinkageand b1ebbingf1l. Characteristic apopto… 相似文献
4.
Summary A key issue in human embryonic stem (ES) cell culture that has largely been ignored is the high degree of variability in the
murine embryonic fibroblast (MEF) feeder cell density, which has been reported by different studies and protocols. Presumably,
too low a feeder cell density would result in insufficient levels of secreted factors, extracellular matrix, and cellular
contacts provided by the feeder cells for the maintenance of human ES cells in the undifferentiated state. Too high a feeder
cell density, on the other hand, may result in a more rapid depletion of nutrients and oxygen within the in vitro culture
milieu, as well as physically hinder the attachment and growth of ES colonies during serial passaging. Preliminary investigations
by our group revealed that an elevated MEF cell density of 32,000 cells/cm2, above the recommended value of 20,000 cells/cm2, appeared to be highly detrimental to the attachment and growth of serially passaged ES colonies of the H9 line (WiCell Research
Institute Inc., Wilmington, MA, USA). At the edge of ES colonies that have attached to the higher density feeder layer (32,000
cells/cm2), the ES cells appear to stack up to form a “bulge.” This was not observed under the recommended feeder cell density of 20,000
cells/cm2. By contrast, other established ES cell lines are routinely propagated at much higher feeder densities of 60,000 to 70,000
cells/cm2. This report briefly discusses the issue of MEF feeder cell density in relation to our preliminary observations, and the
results of other studies. 相似文献
5.
Phosphotyrosine proteins involvement, particularly cortactin, was studied in cell–cell contacts of cultured bovine corneal
endothelial (BCE) cells. These proteins, including α-catenin, vinculin and cortactin, are localized at cell–cell contacts
separate from the cortical actin ring. Approximately 50% of cortactin isoforms p80 and p85 were associated with the Triton-insoluble
fraction while phosphotyrosine proteins were in the soluble fraction. Disruption of cell–cell contacts by EDTA treatment was
associated with a decrease in cortactin isoforms p80 (26%) and p85 (57%). Cortactin isoform p85 was phosphorylated at Y466, expressed in reattaching cells and associated with the Triton-soluble fraction, whereas cortactin isoform p80 was phosphorylated
at Y421 and associated with the Triton-insoluble fraction. In sub-confluent cultures, pY421-cortactin was localized at the leading edge and pY466-cortactin at a perinuclear area. In confluent cultures both pY466- and pY421-cortactin isoforms were localized at the cell–cell contacts. In conclusion, in BCE cells, the most prominent appearance of
cortactin was at the cell–cell contacts separate from the cortical actin ring. Isoform p80 was phosphorylated at Y421 and associated with the Triton-insoluble fraction and isoform p85 was phosphorylated at Y466 and associated with the Triton-insoluble fraction. 相似文献
6.
Hydrogen peroxide (H2O2) is widely regarded as a cytotoxic agent whose levels must be minimized by the action of antioxidant defence enzymes. In fact, H2O2 is poorly reactive in the absence of transition metal ions. Exposure of certain human tissues to H2O2 may be greater than is commonly supposed; levels of H2O2 in the human body may be controlled not only by catabolism but also by excretion, and H2O2 could play a role in the regulation of renal function and as an antibacterial agent in the urine. Cell culture is a widely used method for the investigation of "physiological" processes such as signal transduction and regulation of gene expression, but chemical reactions involving cell culture media are rarely considered. Addition of reducing agents to commonly used cell-culture media can lead to generation of substantial amounts of H2O2. Some or all of the reported effects of ascorbic acid and polyphenolic compounds (e.g., quercetin, catechin, epigallocatechin, epigallocatechin gallate) on cells in culture may be due to H2O2 generation by interaction of these compounds with cell culture media. 相似文献
7.
Lok J Gupta P Guo S Kim WJ Whalen MJ van Leyen K Lo EH 《Neurochemical research》2007,32(12):2032-2045
Historically, the neuron has been the conceptual focus for almost all of neuroscience research. In recent years, however,
the concept of the neurovascular unit has emerged as a new paradigm for investigating both physiology and pathology in the
CNS. This concept proposes that a purely neurocentric focus is not sufficient, and emphasizes that all cell types in the brain
including neuronal, glial and vascular components, must be examined in an integrated context. Cell–cell signaling and coupling
between these different compartments form the basis for normal function. Disordered signaling and perturbed coupling form
the basis for dysfunction and disease. In this mini-review, we will survey four examples of this phenomenon: hemodynamic neurovascular
coupling linking blood flow to brain activity; cellular communications that evoke the blood–brain barrier phenotype; parallel
systems that underlie both neurogenesis and angiogenesis in the CNS; and finally, the potential exchange of trophic factors
that may link neuronal, glial and vascular homeostasis.
Special issue in honor of Naren Banik. 相似文献
8.
Activation—induced cell death in B lymphocytes 总被引:10,自引:2,他引:8
Upon encountering the antigen(Ag),the immune system can either develop a specific immune response of enter a specific state of unresponsiveness,tolerance.The response of B cells to their specific Ag can be activation and proliferation,leading to the immune response,or anergy and activation-induced cell death(AICD),leading to tolerance.AICD in B lymphocytes is a highly regulated event initiated by crosslinking of the B cell receptor (BCR).BCR engagement initiates several signaling events such as activation of PLCγ,Ras,and PI3K,which generally speaking,lead to survival.However,in the absence of survival signals(CD40 or IL-4R engagement),BCR crosslinking can also promote apoptotic signal transduction pathways such as activation of effector caspases,expression of pro-apoptotic genes,and inhibition of pro-survival genes.The complex interplay between survival and death signals determines the B cell fate and, consequently,the immune response. 相似文献
9.
Putative epidermal stem cell convert into corneal epithelium-like cell under corneal tissue in vitro
GAO Nan WANG ZhiChong HUANG Bing GE Jian LU Rong ZHANG KeFei FAN ZhiGang LU Li PENG Zhan CUI GuangHui 《中国科学:生命科学英文版》2007,50(1):101-110
Rhesus putative epidermal stem cells are being investigated for their potential use in regenerative corneal epithelium-like cells, which may provide a practical source of autologous seed cells for the construction of bioengineered corneas. The goal of this study was to investigate the potential of epi-dermal stem cells for trans-differentiation into corneal epithelium-like cells. Rhesus putative epidermal stem cells were isolated by type IV collagen attachment method. Flow cytometry analysis, immuno-histology and RT-PCR were conducted to identify the expression of specific markers (β1, α6 integrin, K15, K1/K10, K3/K12 and CD71) on the isolated rapid attaching cells. The isolated cells were cocultured with human corneal limbal stroma and corneal epithelial cells. After coculture, the expression of the same specific markers was evaluated in order to identify expression difference caused by the coculture conditions. K3/K12 expression was analyzed in coculture cells on day 2, 4, 6, 8 and 10. Putative epi-dermal stem cells in conditioned culture media were used as control. Putative epidermal stem cells were predominant in rapid attaching cells by type IV collagen attachment isolation. Before being co-cultured, the rhesus putative epidermal stem cells expressed K15, α6 and β1 integrin, but no CD71, K1/K10 and K3/K12. After coculture, these cells expressed K3/K12 (a marker of corneal epithelial cells), K15 and β 1 integrin, but no K1/K10. Cells being not coculture converted into terminally differentiated cells expressing K1/K10. These results indicate that rhesus putative epidermal stem cells can trans-differentiate into corneal epithelium-like cells and, therefore, may have potential therapeutic application as autologous seed cells for the construction of bioengineered corneas. 相似文献
10.
Spiteller G 《Prostaglandins, leukotrienes, and essential fatty acids》2002,67(2-3):151-162
Evidence is presented that mammalian and plant cells respond equally to any event which changes their cell membrane structure. Proliferation, wounding or aging induces generation of lipidhydroperoxides from cell wall phospholipids. These are transformed to signalling compounds, some of these induce apoptosis. If the exerted impact exceeds a certain level, the original enzymic reaction switches to a non-enzymic one which produces peroxylradicals. The latter are not liberated enzymically. Peroxylradicals generate a second set of signalling compounds, but cause also severe damage: they epoxidize double bonds, and oxidize proteins, sugars and nucleic acids. Such reactions occur in all inflammatory diseases. Lipidhydoperoxides and their degradation products are incorporated in fat. Apparently, these compounds are transferred partly to LDL. Such LDL is still recognized by the cell LDL receptor. Toxic lipid peroxidation products are therefore introduced into cells and might be able to damage cells from inside long before the typical signs of atherosclerosis and other chronic diseases become visible. 相似文献
11.
Takatani M Nakama T Kubo K Manabe S Nakahara Y Ito Y Nakahara Y 《Glycoconjugate journal》2000,17(6):361-375
As part of a program to explore the structural requirement of N-glycans in the carbohydrate-mediated biological interactions, N-linked pentasaccharide core structure was stereochemically modified in terms of glycosidic linkage. Three isomers, -D-Man-(13)-[-D-Man-(16)]--D-Man-(14)--D-GlcNAc-(14)--D-GlcNAc-L-Asn, -D-Man-(13)-[-D-Man-(16)]--D-Man-(14)--D-GlcNAc-(14)--D-GlcNAc-L-Asn, and -D-Man-(13)-[-D-man-(16)]--D-Man-(14)--D-GlcNAc-(14)--D-GlcNAc-L-Asn, were synthesized. Synthesis of the pentasaccharide with natural linkage is also described. 相似文献
12.
Identification of amino acids involved in the binding of hMIP-1α to CC-CKR1, a MIP-lα receptor found on neutrophils 总被引:2,自引:0,他引:2
Crisman Jacqueline M. Crisman Jacqueline M. Elder Patrick J. Wilkie Neil M. Kolattukudy Pappachan E. 《Molecular and cellular biochemistry》1999,195(1-2):245-256
Human macrophage inflammatory protein-1 (hMIP-1) and human macrophage inflammatory protein-1 (hMIP-1) are chemokines involved in a diverse range of immunological effects. Both hMIP-1 and hMIP-1 are involved in the activation of monocytes and THP-1 cells probably through a common receptor(s). However, only hMIP-1 can bind to neutrophils with high affinity, presumably through CC-CKR1 (CKR1). Since the structure of these two proteins is highly conserved, non-conserved amino acids must define the disparate binding patterns that these two proteins exhibit. Measurements of binding, chemotaxis and calcium influx conducted with hMIP-1 and hMIP-1 chimeric proteins and mutants show that two amino acids (37K and 43L) are important in the binding and signaling of hMIP-1 through CKR1. Furthermore, we also show that mutations of the three charged amino acids at the C-terminus of hMIP-1 and hMIP-1 (amino acids 61, 65 and 67), do not adversely affect the binding to THP-1 cells. 相似文献
13.
-Dystroglycan (-DG) is a membrane-associated, extracellular glycoprotein. It is anchored to the cell-membrane by binding to the transmembrane glycoprotein -dystroglycan (-DG) to form an /-DG-complex. It was discovered that the bovine peripheral nerve -DG possesses the Ser/Thr linked tetrasaccharide as the major constituent of the O-linked carbohydrates, which was proposed to contribute laminin binding activity of this glycoprotein.This structure has a striking feature in terms of the mode of linkage between oligosaccharide and the core protein. It has a mannose residue linked to the core protein through Ser/Thr residue. A similar structure was proposed to exist in brain derived HNK-1 immunoreactive O-glycans. Being interested in the structural novelty and potential biological significance of this type of glycan chains, the chemical synthesis of Ser/Thr linked mannose containing tetrasaccharide was investigated. Tetrasaccharide donor was constructed from monosaccharide blocks and coupled with Ser/Thr derivatives. Subsequent deprotection afforded target tetraosyl serine. Furthermore, synthetic routes to lower homologues, namely Gal--(1,4)-GlcNAc--(1,2)-Man--Ser and GlcNAc--(1,2)-Man--Ser were also provided. 相似文献
14.
D. V. Ignatov Yu. I. Prokof'ev V. P. Timofeev A. Yu. Misharin 《Russian Journal of Bioorganic Chemistry》2004,30(2):184-190
3-Hexadecanoyloxy-5-cholest-8(14)-en-15-one, 3-hexadecanoyloxy-5-cholest-8(14)-en-15-one, 15-hexadecanoyloxy-5-cholest-8(14)-en-3-ol, 15-hexadecanoyloxy-5-cholest-8(14)-en-3-ol, 15-hexadecanoyloxy-5-cholest-8(14)-en-3-one, and 15-hexadecanoyloxy-5-cholest-8(14)-en-3-one were synthesized and their chromatographic and 1H NMR characteristics were determined. 相似文献
15.
Structural studies of the glycopeptides of B-chain of cinnamomin – a type II ribosome-inactivating protein by nuclear magnetic resonance 总被引:1,自引:0,他引:1
Zheng Pu Yiming Li Fa-jian Hou Fahu He Naixia Zhang Houming Wu Wang-Yi Liu 《Glycoconjugate journal》2000,17(11):749-759
Cinnamomin is a plant type II ribosome-inactivating protein (RIP) isolated from the seeds of Cinnamomum camphora. It consists of two nonidentical polypeptide chains (A- and B-chain) held together through one disulfide linkage. Its A- and B-chain contain 0.3% and 3.9% sugars respectively. The B-chain of cinnamomin was digested by pronase E and then the liberated glycopeptides were separated from non-glycopeptides by gel filtration chromatography on a Bio-Gel P-4 column. Three crude glycopeptides were obtained by continuing chromatography over anion-exchange resin (AG1-X2) in the buffer of 2% pyridine-acetic acid (pH 8.3) with a polygradient elution system. Through further purification by the gel filtration chromatography and HPLC, three major glycopeptides, GP1, GP2 and GP3 were obtained. Mainly by two-dimensional Nuclear Magnetic Resonance (NMR) including TOCSY, DQF-COSY, NOESY, HMQC and HMBC, their primary structures were analyzed as: Man1,3Man1,6(Man1,3)(Xyl1,2)Man1,4GlcNAc1,4GlcNAc1-(Gly-)Asn-Asn-Thr(GP1), Man1,6(Man1,3)(Xyl1,2)Man1,4GlcNAc1,4(Fuc1,3)GlcNAc1-Asn-Ala-Thr(GP2),Man1,6(Man1,3)Man1,6(Man1,2 Man1,3)Man1,4GlcNAc1,4GlcNAc1-(Ala-)Asn-Gly-Thr(GP3). 相似文献
16.
Valentina Gelfanova Yein-Gei Lai Vasily Gelfanov Shiey-Cheng Tzou Yi-Fang Tu Dr. Nan-Shih Liao 《Journal of biomedical science》1999,6(4):269-276
The immune responses of the intestine mucosa feature the noninflammatory type, such as IgA production and oral tolerance. Th2 type cytokines have been implicated in the induction of these noninflammatory responses. In the present study, cytokine responses of CD8+ and CD4+ TCR+ intestinal intraepithelial lymphocyte ( iIEL) subsets to TCR stimulation under the influence of IL-12, IL-4, or CD28 costimulation were examined. IL-12 enhanced production of IL-10 and IFN- by the CD8+ iIEL significantly but only marginally affected the CD8+ subset, whereas IL-4 induced IL-4, IL-5, and IL-10 production and augmented TGF- production by both subsets. CD28 costimulation induced production of Th2 cytokines by CD4+ iIEL in the absence of exogenous IL-4. Unlike lymph node CD4+ cells, the CD28 costimulation-induced Th2 differentiation of CD4+ iIEL was not inhibited by IFN-. These results demonstrate active cytokine production by CD4+, CD8+, as well as CD8+ iIEL. The Th2-skewed cytokine profile of CD8+ iIEL and the IFN--resistance of Th2 differentiation of the CD4+ iIEL suggest that both iIEL subsets contribute to the induction of noninflammatory mucosal immune responses. 相似文献
17.
The mode and nature of the binding of chlorpromazine (CPZ), a psychotropic drug, with milk proteins – -lactalbumin (with substantial amounts of -helix, -sheet and random coil), -lactoglobulin (a major -sheeted protein) and s-casein (a random coiled protein) have been studied spectrofluorometrically and spectropolarimetrically. The binding affinity of CPZ for unfolded proteins is comparatively less than that of folded proteins although the number of binding sites is smaller in the latter case, due to the greater extent of binding of CPZ for folded proteins. Thermodynamic analysis reveals that CPZ binds to -lactalbumin and s-casein in an endothermic (Ho is positive) and hydrophobic manner but with -lactoglobulin in an exothermic (Ho is negative) manner. Far UV Circular dichroic studies reveal that CPZ increases the secondary structure of the major -sheeted protein, -lactoglobulin possibly by increasing the relative contact orders (non-local contacts) within the residues. On the other hand, for proteins possessing random coil, it increases the unfolded state of the protein. CPZ does not affect local contacts in a-helix when its interaction is compared with a major -helical protein, myoglobin. 相似文献
18.
2-Macroglobulin (2M) is a protease inhibitor that has separate binding sites for transforming growth factor- (TGF-) and -amyloid peptide (A), both of which have been identified in the 2M sequence. In the 3D-structure of 2M, TGF- occupies the 2M central cavity, overlapping with the space that can accommodate up to two molecules of protease. As a result, ternary 2M–protease complexes (2 mol protease/mol 2M) have been reported to not bind TGF-. The goal of the present study was to test whether binding of A to 2M is controlled by steric constraints imposed by associated proteases, similarly to TGF-. We confirmed that binary 2M–trypsin complex (1 mol trypsin/mol 2M) binds increased amounts of TGF-1, compared with native 2M, while ternary 2M–trypsin complex binds substantially decreased amounts of TGF-1. By contrast, A-binding to binary and ternary 2M–trypsin complex was equivalent. In both cases, binding was substantially increased compared with the negligible level observed with native 2M. Plasmin is a large protease (Mr ~82,000) that substantially occupies the 2M central cavity; however, 2M–plasmin complex also bound increased amounts of A, compared with native 2M. We conclude that A accesses its binding site, in 2M, from outside the 2M central cavity. The TGF--and A-binding sites are spatially separated not only in the primary sequence of 2M, but also in the 3D-structure. 相似文献
19.
Jun Ogawa Atsushi Ryouno Sheng-Xue Xie Vohra M. Rakesh Retno Indrati Hisashi Miyakawa Tamio Ueno Sakayu Shimizu 《Biotechnology letters》1999,21(8):711-713
Cells of Alcaligenes xylosoxidans containing N-carbamoyl-L--amino acid amidohydrolase strictly distinguished the configuration of not only the -carbon but also the -carbon of N-carbamoyl--methylphenylalanine, and produced threo-l--methylphenylalanine specifically from a mixture of the four stereoisomers. 相似文献
20.
N. M. Vladimirova E. N. Sautkina T. I. Murav'eva T. V. Ovchinnikova N. A. Potapenko 《Russian Journal of Bioorganic Chemistry》2003,29(2):127-138
Functionally active preparations of Na+,K+-ATPase isozymes from calf brain that contain catalytic subunits of three types (1, 2, and 3) were obtained using two approaches: a selective removal of contaminating proteins by the Jorgensen method and a selective solubilization of the enzyme with subsequent reconstitution of their membrane structure by the Esmann method. The ouabain inhibition constants were determined for the isozymes. The real isozyme composition of the Na+ pump from the grey matter containing glial cells and the brain stem containing neurons was determined. The plasma membranes of glial cells were shown to contain mainly Na+,K+-ATPase of the 11 type and minor amounts of isozymes of the 22(1) and the 31(2) type. The axolemma contains 21 and 31 isozymes. A carbohydrate analysis indicated that 11 enzyme preparations from the brain grey matter substantially differ from the renal enzymes of the same composition in the glycosylation of the 1 isoform. An enhanced sensitivity of the 3 catalytic subunit of Na+,K+-ATPase from neurons to endogenous proteolysis was found. A point of specific proteolysis in the amino acid sequence PNDNR492 Y493 was localized (residue numbering is that of the human 3 subunit). This sequence corresponds to one of the regions of the greatest variability in 1-, 2-, 3-, and 4-subunits, but at the same time, it is characteristic of the 3 isoforms of various species. The presence of the 3 isoform of tubulin (cytoskeletal protein) was found for the first time in the high-molecular-mass Na+,K+-ATPase 31 isozyme complex isolated from the axolemma of brain stem neurons, and its binding to the 3 catalytic subunit was shown. 相似文献