Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The high affinity fibronectin receptor (FNR) is expressed by hematopoietic cells, fibroblasts, and proliferating epidermal cells. Expression of this integrin is altered by chemical and viral transformation, suggesting that FNR dysfunction may play a role in growth control. This study demonstrates that exposing FA-K562 cells to glycine-arginine-glycine-aspartate-serine (GRGDS), a peptide ligand of the FNR, specifically stimulates p34/cdc2- and cyclin A-associated kinase activities. This occurs within 2 h of peptide addition. The 110-kDa form of the retinoblastoma protein appears within 3 h of GRGDS addition, consistent with activation of a G1/S kinase. DNA staining profiles demonstrate that GRGDS induces cell cycle progression within 24 h. Increased anchorage-independent growth is subsequently observed in GRGDS-treated FA-K562 cells. The control peptide, GRGES, which cannot bind the FNR, has none of these effects. This demonstrates that an extracellular integrin ligand can regulate cell proliferation. Furthermore, these results suggest that integrins link the extracellular environment and intracellular growth regulators.
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PMID:Fibronectin receptor modulates cyclin-dependent kinase activity. 146 91

SV40 T antigen can induce senescent human diploid fibroblasts to synthesize DNA; however, the cells fail to go through mitosis. In this study, we examined the expression of the cdc2 and cyclin B genes, which are required for completion of mitosis, to determine whether defects in their expression occurred when SV40-transformed human cells entered the phase of crisis. If defects were observed it would indicate that immortalization by the virus involved reexpression of these genes. We found that the expression of cdc2 was unimpaired at both the RNA and protein levels, but that cyclin B expression was decreased in cells in crisis when compared with precrisis (mortal) and postcrisis (immortal) cells. Tritiated thymidine uptake demonstrated that the majority of cells in crisis were not actively cycling. Consistent with the latter observation we found that cyclin A, which is required for cells to traverse through S to G2, was downregulated in these cells. Since many of the results obtained with cells in crisis were similar to what is observed in normal human cells when they become senescent, we analyzed the expression of the genes fibronectin and sdi1 (a gene recently cloned from senescent cells that codes for an inhibitor of DNA synthesis). Both genes were overexpressed in cells during crisis, as is the case with senescent cells. The results are discussed in terms of the two-stage model previously proposed to explain the process of immortalization of human diploid fibroblasts by SV40.
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PMID:SV40-transformed human cells in crisis exhibit changes that occur in normal cellular senescence. 751 Feb 51

This study demonstrates that perturbation of the fibronectin receptor (FNR), a member of the integrin family of adhesion receptors, can stimulate growth of non-transformed epithelial cells but not of transformed epithelial cells. Using the non-adherent cell line FA-K562 we demonstrate that growth stimulation via FNR ligands occurs rapidly and independently of any effects on cell adhesion. Low valence FNR ligands such as glycine-arginine-glycine-aspartate-serine (GRGDS) are the most potent stimulators of the cell cycle regulatory kinase cdc2. Partial synchronization and Western blotting studies suggest that GRGDS affects cdc2/cyclin A complexes in cells in S/G2 phase of the cell cycle. These studies suggest that FNR-mediated growth control appears to be a common feature of transformation. These data suggest that the FNR may be physiologically important in growth control, especially in the presence of low valence, proteolytic degradation fragments of FN. Furthermore, escape from FNR-mediated growth control may be a common feature of transformation.
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PMID:Growth signalling through the alpha 5 beta 1 fibronectin receptor. 753 71

The regulation of epithelial cell cycle progression by extracellular matrix proteins was investigated in mink lung epithelial cells (Mv1Lu cells) and primary human keratinocytes. Exogenous type V collagen was able to mimic all of the inhibitory effects of type 1 transforming growth factor beta (TGF-beta1). No significant inhibitory effect was observed with collagen types I, III, and IV; laminin; or fibronectin. The type V collagen used was not contaminated with TGF-betas. TGF-beta1 increased the rate of type V collagen protein secretion in Mv1Lu cells, which occurred coincident with DNA synthesis inhibition. Both TGF-beta1 and type V collagen inhibited retinoblastoma protein phosphorylation and the expression of cyclin-dependent kinase (cdk) 4 and cdk2, but not p27Kip expression. Mv1Lu cells constitutively expressing the SV40 T antigen or cdk4 were resistant to the inhibitory effects of both TGF-beta1 and type V collagen. Our results demonstrate that type V collagen is a novel and specific epithelial cell cycle inhibitor and suggest that it may act as an autocrine mediator of the inhibitory effects of TGF-beta1.
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PMID:Type V collagen is an epithelial cell cycle inhibitor that is induced by and mimics the effects of transforming growth factor beta1. 960 63

Culture of murine embryonic fibroblasts, but not vascular smooth muscle cells, on a fibronectin matrix significantly shortens their transit time through the S phase of the cell cycle. This shortening corresponds to an increase in both cyclin A protein levels and active cyclin A/cdk2 complex. The increase in cyclin A protein appears due to a translational/post-translational mechanism since there is no increase in cyclin A mRNA following culture of the cells on fibronectin. Treatment of cells cultured on fibronectin with a short pulse of the S phase chemotherapeutic agent camptothecin, resulted in a relative protection from cell death when compared to cells cultured on tissue culture plastic. Thus, while the cells have increased rate of transit through S phase fibronectin-mediated signaling protects the cells from S phase mediated apoptosis. In addition, fibroblasts constitutively expressing a mutant E2F1 transcription factor (E2F1d87) have a lengthened S phase, due to a truncation of the cyclin A/cdk2 binding domain. Culture of these mutant- expressing cells on fibronectin did not shorten their S phase duration in spite of the fact that cyclin A levels and active cyclin A/cdk2 complex were significantly elevated. Thus, although the fibronectin signaling mechanisms culminating in elevated cyclin A were intact in these mutant E2F1 expressing cells, they were insensitive to the effects of this elevated cyclin A. The effect of the mutant E2F1d87 on slowing transit through S phase appears dominant over the effect of elevated cyclin A.
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PMID:Cyclin A levels, the duration of S phase and sensitivity to a chemotherapeutic agent are altered in fibroblasts cultured on a fibronectin matrix. 968 92

Adherent cells assemble fibronectin into a fibrillar matrix on their apical surface. The fibril formation is initiated by fibronectin binding to the integrins alpha5 beta1 and alphav beta3, and is completed by a process that includes fibronectin self-assembly. We found that a 76- amino acid fragment of fibronectin (III1-C) that forms one of the self-assembly sites caused disassembly of preformed fibronectin matrix without affecting cell adhesion. Treating attached fibroblasts or endothelial cells with III1-C inhibited cell migration and proliferation. Rho-dependent stress fiber formation and Rho-dependent focal contact protein phosphorylation were also inhibited, whereas Cdc42 was activated, leading to actin polymerization into filopodia. ACK (activated Cdc42-binding kinase) and p38 MAPK (mitogen-activated protein kinase), two downstream effectors of Cdc42, were activated, whereas PAK (p21-activated kinase) and JNK/SAPK (c-Jun NH2-terminal kinase/ stress-activated protein kinase) were inhibited. III1-C treatment also modulated activation of JNK and ERK (extracellular signal-regulated kinases) in response to growth factors, and reduced the activity of the cyclin E-cdk2 complex. These results indicate that the absence of fibronectin matrix causes activation of Cdc42, and that fibronectin matrix is required for Rho activation and cell cycle progression.
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PMID:Fibronectin matrix regulates activation of RHO and CDC42 GTPases and cell cycle progression. 976 37

Expression of full-length p16(INK4a) blocks alphavbeta3 integrin-dependent cell spreading on vitronectin but not collagen IV. Similarly, G1-associated cell cycle kinases (CDK) inhibitory (CKI) synthetic peptides derived from p16(INK4a), p18(INK4c) and p21(Cip1/Waf1), which can be delivered directly into cells from the tissue culture medium, do not affect non-alphavbeta3-dependent spreading on collagen IV, laminin and fibronectin at concentrations that inhibit cell cycle progression in late G1. The alphavbeta3 heterodimer remains intact after CKI peptide treatment but is immediately dissociated from the focal adhesion contacts. Treatment with phorbol 12-myristate 13-acetate (PMA) allows alphavbeta3 to locate to the focal adhesion contacts and the cells to spread on vitronectin in the presence of CKI peptides. The cdk6 protein is found to suppress p16(INK4a)-mediated inhibition of spreading and is also shown to localize to the ruffling edge of spreading cells, indicating a function for cdk6 in controlling matrix-dependent cell spreading. These results demonstrate a novel G1 CDK-associated integrin regulatory pathway that acts upstream of alphavbeta3-dependent activation of PKC as well as a novel function for the p16(INK4a) tumour suppressor protein in regulating matrix-dependent cell migration.
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PMID:The p16(INK4a) tumour suppressor protein inhibits alphavbeta3 integrin-mediated cell spreading on vitronectin by blocking PKC-dependent localization of alphavbeta3 to focal contacts. 1020 65

Differential gene expression between the androgen sensitive human prostate cancer cell line LNCaP and an insensitive clonal variant, LNCaP-r, was demonstrated by suppression subtractive hybridization. Twenty-one sequences were identified of which 9 are homologous to known genes, 11 are represented by expressed sequence tags (ESTs), and 1 is novel. We present data for 5 of 7 sequences confirmed to be differentially expressed by Northern blot analysis and semiquantitative RT-PCR. Only one gene, fibronectin (FN), was highly overexpressed (>60-fold) in LNCaP-r cells, consistent with previously reported overexpression of FN in prostate cancer. Four sequences were down-regulated in LNCaP-r cells, including an inactive variant of the E2 ubiquitin conjugating enzyme (UEV-1), a novel metalloproteinase-related collagenase (PM5), and a potential tumor suppressor gene (breast basic conserved gene, BBC1). UEV-1 is multifunctional, regulates the cell cycle via cdk1, has homology to MMS2 and likewise functions as a DNA protection protein, and also has homology to TSG101. Aberrant splice variants of TSG101 occur frequently in both breast and prostate cancer, but its mechanism of action is unknown. FN, BBC1, and UEV-1 localize to regions of chromosomal aberration (2q3.4, 16q24.3, and 20q13.2, respectively) associated with advanced prostate cancer and thus may be highly relevant to disease progression.
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PMID:Differentially expressed genes in hormone refractory prostate cancer: association with chromosomal regions involved with genetic aberrations. 1032 86

We evaluated the effect of beta1-integrin receptor engagement on the expression and activity of cell cycle regulatory proteins in CD34(+) cells under conditions that mimic the steady-state marrow microenvironment and in the presence of supraphysiological concentrations of interleukin-3 (IL3) and stem cell factor (SCF). Adhesion of CD34(+) progenitors to fibronectin (FN) was similar whether IL3 or SCF was present or absent. Engagement of beta1-integrins blocked S-phase entry of CD34(+) cells in the absence of IL3 or SCF, whereas addition of 10 ng/mL IL3 or SCF prevented such a block in S-phase entry. In the absence of IL3 or SCF, cyclin-E levels were significantly lower and p27(KIP1) levels significantly higher in FN-adherent than in FN-nonadherent cells, or than in poly-L-lysine (PLL)-adherent or (PLL)-nonadherent cells. Cyclin-dependent-kinase (cdk)-2 activity was decreased and levels of cyclin-E-cdk2 complexes were lower in FN-adherent than in PLL-adherent cells. In contrast, cyclin-E and p27(KIP1) protein levels and cdk2 activity in cells adherent to FN in the presence of IL3 or SCF were similar to those in PLL-adherent and FN-nonadherent or PLL-nonadherent cells. In conclusion, under physiological cytokine conditions, integrin engagement prevents S-phase entrance of CD34(+) cells, which is associated with elevated levels of the contact-dependent cyclin kinase inhibitor p27(KIP1). Supraphysiological concentrations of IL3 or SCF prevent p27(KIP1) elevation and override the integrin-mediated inhibition of entry into S phase.
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PMID:Opposing effects of engagement of integrins and stimulation of cytokine receptors on cell cycle progression of normal human hematopoietic progenitors. 1064 95

The use of so-called protein scaffolds has recently attracted considerable attention in biochemistry in the context of generating novel types of ligand receptors for various applications in research and medicine. This development started with the notion that immunoglobulins owe their function to the composition of a conserved framework region and a spatially well-defined antigen-binding site made of peptide segments that are hypervariable both in sequence and in conformation. After the application of antibody engineering methods along with library techniques had resulted in first successes in the selection of functional antibody fragments, several laboratories began to exploit other types of protein architectures for the construction of practically useful binding proteins. Properties like small size of the receptor protein, stability and ease of production were the focus of this work. Hence, among others, single domains of antibodies or of the immunoglobulin superfamily, protease inhibitors, helix-bundle proteins, disulphide-knotted peptides and lipocalins were investigated. Recently, the scaffold concept has even been adopted for the construction of enzymes. However, it appears that not all kinds of polypeptide fold which may appear attractive for the engineering of loop regions at a first glance will indeed permit the construction of independent ligand-binding sites with high affinities and specificities. This review will therefore concentrate on the critical description of the structural properties of experimentally tested protein scaffolds and of the novel functions that have been achieved on their basis, rather than on the methodology of how to best select a particular mutant with a certain activity. An overview will be provided about the current approaches, and some emerging trends will be identified. (c) 2000 John Wiley & Sons, Ltd. Abbreviations used: ABD albumin-binding domain of protein G APPI Alzheimer's amyloid beta-protein precursor inhibitor BBP bilin-binding protein BPTI bovine (or basic) pancreatic trypsin inhibitor BSA bovine serum albumin CBD cellulose-binding domain of cellobiohydrolase I CD circular dichroism Cdk2 human cyclin-dependent kinase 2 CDR complementarity-determining region CTLA-4 human cytotoxic T-lymphocyte associated protein-4 FN3 fibronectin type III domain GSH glutathione GST glutathione S-transferase hIL-6 human interleukin-6 HSA human serum albumin IC(50) half-maximal inhibitory concentration Ig immunoglobulin IMAC immobilized metal affinity chromatography K(D) equilibrium constant of dissociation K(i) equilibrium dissociation constant of enzyme inhibitor LACI-D1 human lipoprotein-associated coagulation inhibitor pIII gene III minor coat protein from filamentous bacteriophage f1 PCR polymerase-chain reaction PDB Protein Data Bank PSTI human pancreatic secretory trypsin inhibitor RBP retinol-binding protein SPR surface plasmon resonance TrxA E. coli thioredoxin
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PMID:Engineered protein scaffolds for molecular recognition. 1093 55


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