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At least 307 records · Page 17Linked to original sources
PubMed2003

Complement component C1q induces endothelial cell adhesion and spreading through a docking/signaling partnership of C1q receptors and integrins.

The interaction of C1q with endothelial cells elicits a multiplicity of biologic responses. Although these specific responses are thought to be mediated by the interaction of C1q with proteins of the endothelial cell surface, the molecular identity of the participant(s) has not been clearly defined. In this study, we examined the role of two C1q-binding proteins, cC1q-R/CR and gC1q-R/p33, on C1q-mediated adhesion and spreading of human dermal microvascular endothelial cells (HDMVECs). A specific and dose-dependent adhesion and spreading was observed when HDMVECs were cultured in microtiter plate wells coated with concentrations of C1q ranging from 0 to 50 microg/ml. The extent of adhesion and spreading was similar to the adhesion seen on collagen-coated wells. Furthermore, the effect of C1q was mimicked by either polyclonal anti-cC1q-R or mAb 60.11, but not with isotype- and species-matched control IgG. More importantly, however, a 100% inhibition of spreading but not adhesion to C1q-coated wells was observed when HDMVECs were cultured in the presence of 30 mM of the peptide GRRGDSP but not GRRGESP. Furthermore, while anti-beta1 integrin antibody blocked adhesion and spreading, antialpha5 integrin only blocked spreading. Since earlier studies have shown that zinc induces the exposure of hydrophobic sites in the C-terminus of gC1q-R including the putative high-molecular weight kininogen (HK)-binding site corresponding to residues 204-218, we also examined the effect of zinc on antibody binding to cell surface gC1q-R. Flow cytometric data show that the binding of mAb 74.5.2, which recognizes residues 204-218, is greatly enhanced when endothelial cells were incubated in the presence of 50 microM zinc. In summary, our data show that: (a) C1q-mediated endothelial cell adhesion and spreading requires the cooperation of both C1q receptors and 1 integrins, and possibly other membrane-spanning molecules, and (b) zinc can induce the exposure of hydrophobic sites in the C-terminal domain of gC1q-R allowing a more efficient binding of mAb 74.5.2 and HK.

Antibodies, Monoclonal↗
PubMed2002

Physicochemical and sensory characteristic changes in fortified peanut spreads after 3 months of storage at different temperatures.

Three amino acid-balanced, vitamin- and mineral-fortified peanut spreads were stored at 4, 23, and 40 degrees C for 3 months. These were 69.6% peanut/19% soybean-40.5% fat, 61.9% peanut/19% soybean-44.5% fat, and 74.1% peanut/14% nonfat dry milk (NFDM)-40% fat. The peanut spreads were fortified with vitamin A, thiamin, riboflavin, vitamin B(6), vitamin C, calcium, and iron to provide 33.3% of the Recommended Dietary Allowances for children. Water-soluble vitamins were quite stable in deaerated peanut spreads. The antioxidant activity of phytochemicals in soybean prevented vitamin A degradation in soy-containing spreads, whereas the NFDM spread lost 70% of the initial content. Instron analysis detected major changes in texture when peanut spreads were stored at 40 degrees C, suggesting that the polymorphic form of lipid transformed and the proper crystallization of stabilizer was destroyed. Panelists did not detect the texture changes in peanut spreads stored at different temperatures. At 40 degrees C, the primary deteriorative changes in sensory quality were increased browning and the development of "soybean" and "oxidized" flavors as well as decreased "roasted peanutty" flavor.

Adult↗
PubMed2002

Role of protein kinase C during insulin mediated skeletal muscle cell spreading.

Protein kinase C (PKC) is known to play important roles in integrin mediated cell spreading. This study investigated the role of PKC during insulin mediated muscle cell spreading, which was independent of integrin alpha5. We found that PKC-alpha becomes active and localise to membrane during insulin mediated cell spreading. We also found that PKC activation is essential for cell spreading stimulated by insulin and this activation enhances the cell spreading. PKC activation increased the tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin as well as tyrosine kinase activity of FAK. We also observed that PKC activation enhanced the FAK associated PI 3-kinase activity and also increased the activation of ERK-1/-2. Moreover, the effect of PKC activation on insulin mediated cell spreading as well as tyrosine phosphorylation of FAK and paxillin depends upon integrity of actin cytoskeleton. Thus, PKC is an important signaling protein during insulin mediated muscle cell spreading.

Actin Cytoskeleton↗
PubMed1996

Superficial spreading type of early gastric cancer.

To determine the clinicopathological features of the superficial spreading type of early gastric cancer, which is defined as early gastric cancer in which the product of the longest diameter of the tumour and the diameter perpendicular to it is greater than 25 cm2, they were compared retrospectively with those of small-sized early gastric cancers, which are defined as tumours smaller than 2 x 2 cm2. The superficial spreading type accounted for 5.46% of all early gastric cancers. The distinguishing histopathological features of superficial spreading lesions were: a diffuse type of cancer, submucosal invasion and advanced lymph node involvement. Of the 32 patients with superficial spreading lesions, eight underwent an additional resection as a continuance of the first gastrectomy, because of an indistinct tumour margin. More extensive lymph node dissection was also performed on the group with superficial spreading lesions. There was no difference in 5 year survival rate between the two groups (superficial spreading type, 96.0% vs small-sized type, 95.1%). The most appropriate treatment for superficial spreading lesions is a wide surgical resection with extensive lymph node dissection.

Female↗
PubMed2003

Safety of long-term consumption of plant sterol esters-enriched spread.

OBJECTIVE: To evaluate both efficacy and safety in humans of long-term consumption of spreads containing plant sterol esters. DESIGN: Randomized double-blind placebo-controlled parallel trial. SUBJECTS: : Hundred and eighty-five healthy volunteers (35-64 y). INTERVENTION: Volunteers daily consumed 20 g spread enriched with 1.6 g plant sterols as fatty acid esters or a control spread for 1 y. They continued their habitual diet and lifestyle. Outcome measures included efficacy markers such as total and LDL-cholesterol, a large range of safety parameters, and reporting of adverse events. RESULTS: Consumption of the plant sterol ester-enriched spread consistently lowered total and LDL cholesterol during the 1 y period on average by 4 and 6%, respectively (0.01 < P < 0.05). Plant sterols intake did on average not result in a lower carotenoid concentration (when expressed per LDL-cholesterol) after 52 weeks (P>0.05). However, carotenoid concentrations changed over time. Plant sterols intake reduced lipid adjusted alpha- and beta-carotene-concentrations by only 15-25% after 1 y, relative to control. Lipid-adjusted fat-soluble vitamin concentrations remained unchanged. Plant sterol concentrations in serum were increased from 2.76 to 5.31 ( micro mol/mmol total cholesterol) for campesterol (P<0.0001) and from 1.86 to 2.47 ( micro mol/mmol total cholesterol) for beta-sitosterol (P<0.0001). The increase in total plant sterol concentration in red blood cells (5.29-9.62 micro g/g) did not affect red blood cell deformability. Hormone levels in males (free and total testosterone) and females (luteinizing hormone, follicle stimulating hormone, beta-estradiol and progesterone) as well as all clinical chemical and hematological parameters measured were unaffected. Adverse events reported were not different between subjects consuming control spread and subjects consuming plant sterol esters-enriched spread. CONCLUSION: Consumption of a plant sterol esters-enriched spread is an effective way to consistently lower blood cholesterol concentrations and is safe to use over a long period of time.

Adult↗
PubMed2001

Suppression of cell spreading by v-Crk requires Ras-MEK-MAP kinase signaling.

We investigated the attachment and spreading of v-Crk-transformed cells, v-Crk3Y1, on fibronectin. Transformation by v-Crk virtually suppressed the spreading, but not the attachment, of cells on fibronectin. This suppression of cell spreading was not correlated with the suppression of integrin alpha5 and beta1 expression. However, the spreading of v-Crk3Y1 on fibronectin was dramatically restored by either expression of dominant-negative Ras or treatment with manumycin A, a Ras farnesyltransferase inhibitor. Moreover, both expression of dominant-negative MEK1 and treatment of cells with U0126, a MEK1 inhibitor, restored the cell spreading of v-Crk3Y1. In contrast, neither treatment with LY294002, a PI3K inhibitor, nor expression of dominant-negative C3G showed no effect on cell spreading on fibronectin. Taken together, our results suggest that, among multiple signaling pathways activated by v-Crk, the Ras-MEK1-MAP kinase cascade plays a pivotal role in the suppression of cell spreading on fibronectin, but C3G and the PI3 kinase do not.

Animals↗
PubMed1999

Analysis of initial failure site and spread pattern in endometrial carcinoma: a Japanese experience.

Kasamatsu T, Shiromizu K, Takahashi M, Matsumoto K, Shirai T. Analysis of initial failure site and spread pattern in endometrial carcinoma: a Japanese experience. This retrospective study was undertaken in an attempt to identify initial failure sites and spread patterns in patients with endometrial carcinoma in Japan. A retrospective clinicopathologic review of 272 patients treated from 1983 to 1994 at Saitama Cancer Center was performed. Patients underwent total hysterectomy, bilateral salpingo-oophorectomy and pelvic lymphadenectomy. Postoperative external radiation was given to the patients with deep myometrial invasion, high grade tumor, and/or lymph node metastasis. Following surgery, chemotherapy was given to the patients with extrapelvic metastasis. Of the 272 patients, 262 had no residual disease after initial treatment and 10 had confirmed residual disease. Of the 262 patients, 32 (12.2%) suffered recurrence. The recurrence rates for stage I, II, III, and IV were 5.6% (10/178), 5.7% (2/35), 35.3% (18/51), and 100% (2/2), respectively. Of the 32 patients who failed, 6 (18.8%) experienced local failure, 13 (40.6%) had distant failure without peritoneal spread, and 13 (40.6%) had distant failure with peritoneal spread. In distant failure, the incidence of peritoneal spread was highest (50.0%, 13/26), closely followed by that of pulmonary metastasis (46.2%, 12/26). Furthermore, of those patients with residual disease, peritoneal spread was found in 80% (8 of 10). Five of the six patients (83.3%) with local failure survive, but all patients with peritoneal spread have died. Peritoneal dissemination is an important failure pattern and should be considered a top priority in an attempt to improve survival in patients with endometrial carcinoma.

Journal Article↗
PubMed2006

Molecular dynamics simulation of nanodroplet spreading enhanced by linear surfactants.

We utilize molecular dynamics simulations to probe the surfactant-mediated spreading of a Lennard-Jones liquid droplet on a solid surface. The surfactants are linear hexamers that are insoluble in the liquid and reduce the surface tension of the liquid-vapor interface. We study how the interaction of the surfactant hexamers with the solid substrate influences spreading, as well as the dependence of spreading on surfactant concentration. We find that the spreading speed is strongly influenced by the attraction of the hydrophobic surfactant tail to the solid surface. When this attraction is sufficiently strong, surfactant molecules partition to the liquid-solid interface and facilitate spreading. This partitioning can lead to an inhomogeneous distribution of surfactant over the liquid-vapor interface, which could drive the Marangoni convection. We also observe that the surfactant molecules can assemble into micelles on the solid surface. The repulsion between micelles at the liquid-solid interface can lead to break-off and migration of the micelles from the liquid-solid to the gas-solid interface and spreading is facilitated in this way. Our model system contains features that are believed to underlie superspreading in experimental studies of droplet spreading.

Journal Article↗
PubMed2001

Clinicopathologic features and endoscopic treatment of superficially spreading colorectal neoplasms larger than 20 mm.

BACKGROUND: A colorectal neoplasm that spreads superficially over the mucosa is known as a laterally spreading tumor. The clinicopathologic features of these large lesions and the efficacy and safety of endoscopic mucosal resection (EMR) were studied retrospectively. METHODS: Surgically or endoscopically resected laterally spreading tumors larger than 20 mm in diameter were studied. Lesions were divided into 2 macroscopic subtypes: F-type, composed of superficially spreading lesions with a flat and smooth surface, and G-type, composed of superficially spreading aggregates of nodules that form relatively flat, broad-based lesions with granulonodular and uneven surfaces. RESULTS: Thirty-three lesions were of the F-type and 87 the G-type. G-type (mean +/- SD, 35.3 +/- 11.4 mm) lesions were significantly larger (p < 0.01) than F-type (26.0 +/- 7.2 mm) lesions. F-type lesions had a significantly higher frequency of invasive cancer (27.2%) than G-types (10.3%)(p < 0.05). Of the 120 lesions, 81 (67.5%) were resected endoscopically. Patients with 78 of these lesions were followed postoperatively for 60.8 +/- 20.1 months. The rate of local recurrence of endoscopically treated tumors as determined at colonoscopy was 7.4% (6/78). These lesions were completely resected endoscopically. Distant metastases were not detected. Thirteen (16.0%) patients had local bleeding after EMR that was stopped endoscopically. Microperforation of the colonic wall as a result of EMR was diagnosed in 1 (1.2%) of 81 cases. CONCLUSIONS: Laterally spreading tumors larger than 20 mm, especially those of the G-type, have a low rate of invasion despite their relatively large size. The F-type lesion has a higher malignant potential than the G-type. EMR is an effective and safe treatment for the large laterally spreading tumor.

Adenoma↗
PubMed1995

Cell surface calreticulin is a putative mannoside lectin which triggers mouse melanoma cell spreading.

B16 mouse melanoma cells adhere to and spread on laminin. We have previously shown that cell spreading is uncoupled from adhesion when unglycosylated laminin is used as a substratum; spreading was restored by a Pronase digest of laminin which became inactive when it was specifically depleted of its mannoside peptides; spreading was also specifically restored by mannosides such as mannan, Man9, and Man6, but not Man3. The effector mannosides bind to a cell surface receptor, previously shown by direct and indirect methods. We have now identified the receptor as cell surface calreticulin by isolating it via mannan affinity chromatography and showing its sequence identity with mouse calreticulin. Anti-calreticulin antibodies confirm this identity, decorate the B16 cell surface, and block cell spreading. Purified B16 cell calreticulin from whole cell lysates successfully competes with cell surface calreticulin and prevents cell spreading. The composite data implicate cell surface calreticulin as a putative lectin that must be occupied to initiate spreading of laminin-adherent B16 cells.

Amino Acid Sequence↗
PubMed2000

Regulation of Rac and Cdc42 pathways by G(i) during lysophosphatidic acid-induced cell spreading.

The pertussis toxin-sensitive G protein, G(i), has been implicated in lysophosphatidic acid-induced cell mitogenesis and migration, but the mechanisms remain to be detailed. In the present study, we found that pertussis toxin blocks lysophosphatidic acid-induced cell spreading of NIH 3T3 fibroblasts on fibronectin. This prevention of cell spreading was eliminated by the expression of constitutively active mutants of Rho family small GTP-binding proteins, Rac and Cdc42, but not by Rho. In addition, activation of the endogenous forms was suppressed by pertussis toxin, indicating that G(i)-induced cell spreading is mediated through the Rac and Cdc42 pathway. Transfection of constitutively active mutants of G alpha(i) and G alpha(11) and G beta gamma subunits enhanced spreading of pertussis toxin-treated cells. G beta(1) with G gamma(12), a major G gamma form in fibroblasts, was more effective for increasing cell spreading than G beta(1)gamma(2) or G beta(1) plus G gamma(12)S2A, a mutant in which Ser-2, a phosphorylation site for protein kinase C, is replaced with alanine. In addition, a protein kinase C inhibitor diminished G beta(1)gamma(12)-induced cell spreading, suggesting a role for phosphorylation of the protein. These findings indicate that both G alpha(i) and G beta gamma stimulate Rac and Cdc42 pathways with lysophosphatidic acid-induced cell spreading on fibronectin.

3T3 Cells↗
PubMed2002

ADAM12/syndecan-4 signaling promotes beta 1 integrin-dependent cell spreading through protein kinase Calpha and RhoA.

The ADAMs (a disintegrin and metalloprotease) comprise a large family of multidomain proteins with cell-binding and metalloprotease activities. The ADAM12 cysteine-rich domain (rADAM12-cys) supports cell attachment using syndecan-4 as a primary cell surface receptor that subsequently triggers beta(1) integrin-dependent cell spreading, stress fiber assembly, and focal adhesion formation. This process contrasts with cell adhesion on fibronectin, which is integrin-initiated but syndecan-4-dependent. In the present study, we investigated ADAM12/syndecan-4 signaling leading to cell spreading and stress fiber formation. We demonstrate that syndecan-4, when present in significant amounts, promotes beta(1) integrin-dependent cell spreading and stress fiber formation in response to rADAM12-cys. A mutant form of syndecan-4 deficient in protein kinase C (PKC)alpha activation or a different member of the syndecan family, syndecan-2, was unable to promote cell spreading. GF109203X and Gö6976, inhibitors of PKC, completely inhibited ADAM12/syndecan-4-induced cell spreading. Expression of syndecan-4, but not syn4DeltaI, resulted in the accumulation of activated beta(1) integrins at the cell periphery in Chinese hamster ovary beta1 cells as revealed by 12G10 staining. Further, expression of myristoylated, constitutively active PKCalpha resulted in beta(1) integrin-dependent cell spreading, but additional activation of RhoA was required to induce stress fiber formation. In summary, these data provide novel insights into syndecan-4 signaling. Syndecan-4 can promote cell spreading in a beta(1) integrin-dependent fashion through PKCalpha and RhoA, and PKCalpha and RhoA likely function in separate pathways.

ADAM Proteins↗
PubMed2005

p130cas but not paxillin is essential for Caco-2 intestinal epithelial cell spreading and migration on collagen IV.

We have previously observed that collagen IV regulates Caco-2 intestinal epithelial cell spreading and migration via Src kinase and stimulates Src-dependent tyrosine phosphorylation of p130cas. We observed that collagen IV also stimulated Src-dependent phosphorylation of both paxillin Tyr31 and paxillin Tyr118. Caco-2 transfection with paxillin or p130cas siRNAs inhibited expression of these proteins by more than 90% for at least 5 days after transfection. Although p130cas siRNA inhibited cell spreading on collagen IV by 33%, three different paxillin siRNAs did not inhibit cell spreading. p130cas siRNA did not affect Src Tyr416 or Src Tyr527 phosphorylation, FAK Tyr397 phosphorylation, or Src-dependent phosphorylation of FAK Tyr925, suggesting that p130cas did not inhibit cell spreading by altering FAK or Src activity. Rat p130cas expression after siRNA knock-out of endogenous human p130cas in Caco-2 cells reduced cell spreading inhibition by 71%. In contrast, expression of rat p130cas from which the Src-phosphorylated substrate domain was deleted did not rescue siRNA inhibition of cell spreading. Combined treatment with siRNAs to Crk and CrkL, which bind to the p130cas substrate domain, inhibited cell spreading by 54%. Both p130cas siRNA and the combined Crk/CrkL siRNAs strongly inhibited (52 and 46% inhibition, respectively) Caco-2 sheet migration on collagen IV and noticeably inhibited lamellipodial extension, whereas paxillin siRNA only inhibited migration by 18% and did not noticeably affect lamellipodial extension. These results suggest that Src may regulate Caco-2 migration on collagen IV via both p130cas and paxillin but that Src phosphorylation of p130cas is more important for this process.

Animals↗
PubMed2006

Interaction of N-WASP with hnRNPK and its role in filopodia formation and cell spreading.

N-WASP is a member of the WASP family of proteins, which play essential roles in actin dynamics during cell adhesion and migration. hnRNPK is a member of the heterogeneous nuclear ribonucleoprotein complex, which has also been implicated in the regulation of cell spreading. Here, we identify a direct interaction between N-WASP and hnRNPK. We show that this interaction is mediated by the N-terminal WH1 domain of N-WASP and the segment of hnRNPK containing its K interaction (KI) domain. Furthermore, these two proteins are co-localized at the cell periphery in the spreading initiation center during the early stage of cell spreading. We found that co-expression of hnRNPK with N-WASP reverses the stimulation of cell spreading by N-WASP, and this effect is correlated with hnRNPK binding to N-WASP. Expression of hnRNPK does not affect subcellular localization of N-WASP protein. However, co-expression of hnRNPK with N-WASP reduced filopodia formation stimulated by N-WASP in spreading cells. Together, these results identify hnRNPK as a new negative regulator of N-WASP and suggest that hnRNPK may regulate the initial stage of cell spreading by direct association with N-WASP in the spreading initiation center.

Animals↗
PubMed2007

Protease-activating receptor-4 induces full platelet spreading on a fibrinogen matrix: involvement of ERK2 and p38 and Ca2+ mobilization.

Although the involvement of protease-activating receptor PAR1 and PAR4 is well established in platelet aggregation, their role in platelet adhesion and spreading has yet to be characterized. We investigated platelet adhesion and spreading on a fibrinogen matrix after PAR1 and PAR4 stimulation in correlation with the activation of two MAPKs, ERK2 and p38. Of the two PAR-activating peptides (PAR-APs), PAR1-AP and PAR4-AP, which both induce adhesion, only PAR4-AP induced full platelet spreading. Although both PAR1-AP and PAR4-AP induced ADP secretion, which is required for platelet spreading, only PAR4-AP induced sustained Ca(2+) mobilization. In these conditions of PAR4 induction, ERK2 and p38 activation were involved in platelet spreading but not in platelet adhesion. p38 phosphorylation was dependent on ADP signaling through P2Y12, its receptor. ERK2 phosphorylation was triggered through integrin alphaIIbbeta3 outside-in signaling and was dependent on the Rho pathway. ERK2 and p38 activation induced phosphorylation of the myosin light chain and actin polymerization, respectively, necessary for cytoskeleton reorganization. These findings provide the first evidence that thrombin requires PAR4 for the full spreading response. ERK2 and p38 and sustained Ca(2+) mobilization, involved in PAR4-induced platelet spreading, contribute to the stabilization of platelet thrombi at sites of high thrombin production.

Actins↗
PubMed1997

Dye spread through gap junctions in the corneal epithelium of the rabbit.

PURPOSE: Microelectrode dye injection of 5,6-carboxyfluorescein was used to investigate gap junctional communication in the corneal epithelium. METHODS: Dye injection started in the superficial layer and proceeded stepwise into the underlying epithelial layers until spread was observed. Intracellular [Ca2+] was manipulated by exposing the cornea to the calcium ionophore A23187 (global increase) or by increasing the [Ca2+] in the injection electrode (source cell increase). Intracellular pH was manipulated by exposing the cornea to nigericin in a low-pH KCI Ringer's (global decrease) or by lowering the pH in the injection electrode (source cell decrease). Heptanol was tested for its ability to uncouple gap junctions. Gap junctional communication was based on the layer at which spread was first observed and on the apparent dye travel distance from the point of injection. RESULTS: Control dye spread occurred, on average, in the third layer from the surface. Increased [Ca2+] in the source cell resulted in an initial spread occurring in the second layer. Globally increasing [Ca2+] with A23187 resulted in no change in the average initial spread layer. Lowering intracellular pH of the source cell did not affect the initial dye spread layer. Globally lowering intracellular pH resulted in significant gap junctional inhibition in a time-dependent manner. Dye spread distance was not significantly affected by [Ca2+] or pH manipulations. Heptanol (2.5 mM) completely inhibited dye coupling. CONCLUSION: All cell layers of the corneal epithelium contain functional gap junctions, although it appears that intercellular communication in the superficial layers does not occur under our control conditions. Intercellular communication through these junctions can be altered by various manipulations of [Ca2+] and pH.

Alcohols↗
PubMed1991

An RGD spacing of 440 nm is sufficient for integrin alpha V beta 3-mediated fibroblast spreading and 140 nm for focal contact and stress fiber formation.

The synthetic peptide Gly-Arg-Gly-Asp-Tyr (GRGDY), which contains the RGD sequence of several adhesion molecules, was covalently grafted to the surface of otherwise poorly adhesive glass substrates and was used to determine the minimal number of ligand-receptor interactions required for complete spreading of human foreskin fibroblasts. Well-defined adhesion substrates were prepared with GRGDY between 10(-3) fmol/cm2 and 10(4) fmol/cm2. As the adhesion ligand surface concentration was varied, several distinct morphologies of adherent cells were observed and categorized. The population of fully spread cells at 4 h reached a maximum at 1 fmol/cm2, with no further increases up to 10(4) fmol/cm2. Although maximal cell spreading was obtained at 1 fmol/cm2, focal contacts and stress fibers failed to form at RGD surface concentrations below 10 fmol/cm2. The minimal peptide spacings obtained in this work correspond to 440 nm for spreading and 140 nm for focal contact formation, and are much larger than those reported in previous studies with adsorbed adhesion proteins, adsorbed RGD-albumin conjugates, or peptide-grafted polyacrylamide gels. Vitronectin receptor antiserum specific for integrin alpha V beta 3 blocked cell adhesion and spreading on substrates containing 100 fmol/cm2 of surface-bound GRGDY, while fibronectin receptor antiserum specific for alpha 5 beta 1 did not. Furthermore, alpha V beta 3 was observed to cluster into focal contacts in spread cells, but alpha 5 beta 1 did not. It was thus concluded that a peptide-to-peptide spacing of 440 nm was required for alpha V beta 3-mediated cellular spreading, while 140 nm was required for alpha V beta 3-mediated focal contact formation and normal stress fiber organization in human foreskin fibroblasts; these spacings represent much fewer ligands than were previously thought to be required.

Amino Acid Sequence↗
PubMed2000

The cysteine-rich domain of human ADAM 12 supports cell adhesion through syndecans and triggers signaling events that lead to beta1 integrin-dependent cell spreading.

The ADAMs (a disintegrin and metalloprotease) family of proteins is involved in a variety of cellular interactions, including cell adhesion and ecto- domain shedding. Here we show that ADAM 12 binds to cell surface syndecans. Three forms of recombinant ADAM 12 were used in these experiments: the cys-teine-rich domain made in Escherichia coli (rADAM 12-cys), the disintegrin-like and cysteine-rich domain made in insect cells (rADAM 12-DC), and full-length human ADAM 12-S tagged with green fluorescent protein made in mammalian cells (rADAM 12-GFP). Mesenchymal cells specifically and in a dose-dependent manner attach to ADAM 12 via members of the syndecan family. After binding to syndecans, mesenchymal cells spread and form focal adhesions and actin stress fibers. Integrin beta1 was responsible for cell spreading because function-blocking monoclonal antibodies completely inhibited cell spreading, and chondroblasts lacking beta1 integrin attached but did not spread. These data suggest that mesenchymal cells use syndecans as the initial receptor for the ADAM 12 cysteine-rich domain-mediated cell adhesion, and then the beta1 integrin to induce cell spreading. Interestingly, carcinoma cells attached but did not spread on ADAM 12. However, spreading could be efficiently induced by the addition of either 1 mM Mn(2+) or the beta1 integrin-activating monoclonal antibody 12G10, suggesting that in these carcinoma cells, the ADAM 12-syndecan complex fails to modulate the function of beta1 integrin.

ADAM Proteins↗