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Biomedical subjects

E A Turley

Publications and source records attributed to E A Turley.

66 records · Page 4Linked to original sources
PubMed1985

Localization of hyaluronate and hyaluronate-binding protein on motile and non-motile fibroblasts.

The distribution of a hyaluronate-binding (HABP) and rhodamine B-isothiocyanate (RITC)-labeled hyaluronate (HA) were studied on both actively motile and stationary chick heart fibroblasts to assess the relationship of these molecules to each other, to other extracellular matrix molecules, to membrane protrusions and to adhesion sites. RITC-HA and HABP, detected by indirect immunofluorescence, were concentrated in the perinuclear region, the leading lamella and retraction processes of actively motile cells, although RITC-HA also occurred diffusely over the rest of the cell body. Double immunofluorescence confirmed that HA and HABP co-localized in the former three regions, suggesting that, at these locations, the HABP may act as a cell surface-binding site for HA. With increasing culture confluency and consequent slowing of fibroblast motility, the localization of both polymers changed to a uniform and diffuse distribution over the cell body and processes. On actively motile cells, RITC-HA and HABP did not co-distribute with fibronectin, heparan sulfate proteoglycan or laminin. Areas coated with RITC-HA and HABP often contained specialized adhesion sites as determined by interference reflection microscopy (IRM) but neither polymer appeared to particularly localize to adhesion sites. However, the occurrence of RITC-HA and HABP in the leading lamellae of motile cells consistently coincided with ruffling activity. These results are discussed with respect to a possible instructive role of HA in cell motility.

Animals↗
PubMed1985

Effect of epidermal growth factor/urogastrone on glycosaminoglycan synthesis and accumulation in vitro in the developing mouse palate.

Epidermal growth factor/urogastrone (EGF-URO) has previously been implicated in murine secondary-palate formation. We report here that, in correlation with its effects on palate fusion, EGF-URO in physiological amounts (1.7 nmol/l) markedly affects glycosaminoglycan (GAG) production in organ cultures of mouse palate tissue; the effects of EGF-URO are dependent on the developmental stage of the palate. GAG production, particularly that of hyaluronic acid (HA), is stimulated two- to eight-fold by EGF-URO in cultures of palate tissue obtained between days 11-12 and 13-15 of development; by the time of birth, EGF-URO no longer stimulates GAG production in such cultures. EGF-URO increases the amount and alters the distribution of HA within the palate. The results suggest a role for EGF-URO and for HA in the process of normal palatal development.

Animals↗
PubMed1985

Effects of hyaluronate and hyaluronate binding proteins on cell motile and contact behaviour.

The effects of hyaluronate on the morphology, motile and social behaviour of embryonic chick heart fibroblasts were examined in the presence or absence of hyaluronate binding proteins (HABP). HABP were inserted onto fibroblasts after treating cells with 0.2 M-urea. Such treatment increased the binding of [125I]HABP to cell monolayers: at saturation, binding was increased threefold compared to untreated monolayers. Generally, the distribution of added HABP was similar to that of endogenous HABP as detected by immunochemistry. [3H]hyaluronate bound to HABP-treated monolayers in amounts that were proportional to the amount of HABP added. HABP alone reduced cell motility, decreased cell underlapping (measured as a nuclear overlap ratio) and promoted cell spreading. Hyaluronate added by itself had no significant effect on cell behaviour. However, in the presence of HABP, hyaluronate increased cell motility, reduced cell spreading, promoted the appearance of surface blebbing and ruffles, and significantly increased the nuclear overlap ratio. These biological effects were proportional to the amounts of hyaluronate and HABP that bound to heart fibroblasts. Fibronectin, bovine serum albumin or sulphated glycosaminoglycans added together with HABP did not mimic the effects of hyaluronate and had little effect additional to HABP alone. The role of HABP as a putative cell binding molecule for hyaluronate and the relationship of hyaluronate to cell social and motile behaviour are discussed in the light of these findings.

Animals↗
PubMed1985

Glycosaminoglycan production by murine melanoma variants in vivo and in vitro.

Glycosaminoglycan (GAG) synthesis of B-16 melanoma metastatic variants was examined in vivo and in vitro to begin to assess the relationship between the presence of these polymers and the process of primary invasion and metastasis. The variants that were examined for GAG production included the F-1 line that exhibits low metastatic potential, the F-10 line selected for high metastatic potential, and the BL6 line selected for high invasiveness. The F-1 cell line was routinely less invasive than the F-10 and BL6 lines when injected s.c. into the legs of irradiated Swiss Webster mice. All cell lines formed palpable tumors after s.c. injection, but histological sections revealed early and extensive invasion in only F-10 and BL6 tumors. The F-1 tumors were surrounded by a connective tissue capsule and did not begin to invade into host tissue until this structure disappeared approximately 16 days after injection of tumor cells. Some consistent alterations in GAG synthesis, particularly the release of hyaluronic acid and heparan sulfate, were observed among the cell lines in vivo and in vitro, although differences observed in vitro were small and variable. In vivo all tumors were surrounded by a hyaluronic acid-rich zone that was concentrated at the tumor-stromal interface and was transitory. Hyaluronate occurred as a diffuse band around BL6 and F-10 tumors but was confined to a capsule surrounding the less aggressive F-1 tumor. In vitro the BL6 and F-10 cell lines released larger amounts of heparan sulfate and hyaluronic acid than did the F-1 cell line. Differences in release of chondroitin sulfate by the cell lines were not observed. Differences in trypsin-releasable GAG, presumably associated with the glycocalyx, were also not apparent. These results link the release in vitro and organization in vivo of hyaluronic acid and heparan sulfate to invasion and metastasis.

Animals↗
PubMed1984

Proteoglycans and cell adhesion. Their putative role during tumorigenesis.

In this review, evidence that proteoglycans are involved in cell adhesion and related behavior is considered, together with their putative role(s) during tumorigenesis. Proteoglycans are large, carboxylated and/or sulfated structures that interact with specific binding sites on cell surfaces. Their distribution and synthesis in tissues alter with the onset of tumorigenesis so that hyaluronic acid is generally increased and heparan sulfate decreased in the developing tumor and surrounding tissue. However, the precise role of proteoglycans during the tumorigenic process is far from clarified. Data suggest any putative roles will be related to the adhesive properties that these molecules confer to cells. Hyaluronic acid and chondroitin sulfate appear to be weakly adhesive molecules that may promote 'transformed' characteristics when they occur on cells in large amounts. These characteristics include reduced cell spreading, increased cell motility, as well as reduced contact inhibition. Consistent with such properties, neither hyaluronic acid nor chondroitin sulfate are localized in specialized adhesion sites such as focal or close contacts. In contrast, heparan sulfate is associated with increased cell-substratum adhesion and is involved in the spreading of cells onto fibronectin and other substrata. Its presence is generally associated with reduced motility and with a well-spread morphology. Unlike hyaluronate and chondroitin sulfate, heparan sulfate is found in specialized contacts. These adhesive properties of proteoglycans predict an instructive role in tumor development, and recent experiments have defined an involvement of these molecules in metastatic arrest. Additional studies utilizing invasive and metastatic tumor variants including tumor cells that employ different mechanisms to invade are required to clarify the role of proteoglycans in tumor progression.

Animals↗
PubMed1983

Substrata formed by combinations of extracellular matrix components alter neural crest cell motility in vitro.

Extracellular matrix components such as collagen, fibronectin and sulphated glycosaminoglycans can act as substrata that promote neural crest motility in vitro, in the absence of serum. The cells appear to be less adhesive and move more randomly on collagen or chondroitin sulphate substrata than on fibronectin substrata. Cells do not spread or become motile on plastic dishes to which hyaluronate has been bound, presumably owing to weak adhesion to this surface. Hyaluronate added to the medium alone has little effect on cell motility. When combinations of matrix molecules are used as substrata, however, the presence of fibronectin increases spreading, directional persistence of cell motility and speed of movement above that observed on collagen alone. When added to fibronectin, chondroitin sulphate appears to reduce adhesions slightly, since the cells are more rounded. Hyaluronate added in the medium significantly reduces the extent, speed and directionality of movement on fibronectin substrata. The presence of collagen in combination with fibronectin plus glycosaminoglycans does not have a noticeable effect on cell motile behaviour, beyond that observed with fibronectin alone. The effects of combinations of matrix compounds on neural crest cell motility are thus predictable, and can be explained in terms of the known adhesive properties and reported binding interactions of these molecules. These studies in vitro are compared with neural crest cell motility in vivo.

Animals↗
PubMed1980

The control of adrenocortical cytodifferentiation by extracellular matrix.

Adult rat adrenal cortical cells maintained in medium supplemented with horse serum (HS) from cohesive epithelial islands secrete large amounts of corticosterone. Such cells do not produce detectable extracellular material (ECM) and are not motile. Cultures exposed to fetal calf serum supplements (FCS) produce metachromatic ECM, modulate to a fibroblastic morphology, and become motile. Within 24 h, steroid production by these cells drop 100-fold. Cells now resemble myofibroblastic "stem" cells of the adrenal cortical capsule, and express structural and functional bimorphism by exhibiting a myofibroblastic phenotype while retaining responsiveness to adrenocorticotropic hormone (ACTH) and limited corticosteroid secreting capacity. Exposure of the myofibroblastic cells to ACTH in FCS overrides the effect of FSC: ECM disappears, steroid production increases several fold, and cells develop an epithelial morphology. The possibility that ECM produced in response to FCS may be responsible for the alteration from a highly differentiated, non-motile adrenocortical cell to a less differentiated, motile adrenocortical stem cell was investigated by inhibition studies using 6-diazo-5-oxo-L-nor-leucine (DON) and by exogenously added components of ECM. DON, a glutamine analogue, inhibited the synthesis of metachromatic ECM in FCS, and prevented the modulation to a fibroblastic morphology, onset of motility, and decrease in steroid production. Addition of hyaluronic acid, but not of chondroitin sulfate, to the epithelioid secretory cells promoted a drop in steroid production and slight alteration in morphology and movement. Both results are consistent with the possibility that metachromatic ECM production is responsible for the reversion of the steroid secretory to the myofibroblastic phenotype. This effect was mimicked by maintaining cells on polystyrene surfaces that were sulfonated to a negative charge density similar to that of ECM. This result implies that the negative charge of ECM may contribute to the expression of the adrenocortical stem cell phenotype, and that its effect is extracellular. A possible physiologic role for ECM-mediated control of adrenal cortical differentiation is proposed.

Adrenal Cortex↗
PubMed1979

Spontaneous glycosylation of glycosaminoglycan substrates by adherent fibroblasts.

SV40-transformed mouse fibroblasts migrate upon, and spontaneously glycosylate, plastic substrates derivatized with chondroitin-6 sulfate and hyaluronic acid. Autoradiography of cultures prelabeled with 3H-glucose and 3H-galactose demonstrates the presence of silver grains near adherent cells. Silver grains are particularly dense near cells cultured on chondroitin sulfate. No significant grains are observed on control dishes or dishes derivatized with polygalacturonic acid. Radioactive material left by cells is not removed by boiling the dishes in 8 M urea and 10% sodium dodecylsulfate, suggesting that it is covalently linked to the derivatized plastic. Acid hydrolysis shows that the radioactive material consists of glucuronic acid and N-acetylglucosamine when the prelabeled cells are cultured on hyaluronic acid. When cells are cultured on chondroitin sulfate, the radioactive product consists only of glucuronic and and N-acetylgalactosamine sulfate. Sonicates of prelabeled cells or the supernatants from cultures of intact prelabeled cells add no SDS-urea-resistant radioactivity to dishes derivatized with these glycosaminoglycans.

Animals↗
PubMedDate not supplied

Active erk regulates microtubule stability in H-ras-transformed cells.

Increasing evidence suggests that activated erk regulates cell functions, at least in part, by mechanisms that do not require gene transcription. Here we show that the map kinase, erk, decorates microtubules (MTs) and mitotic spindles in both parental and mutant active ras-transfected 10T1/2 fibroblasts and MCF10A breast epithelial cells. Approximately 20% of total cellular erk decorated MTs in both cell lines. A greater proportion of activated erk was associated with MTs in the presence of mutant active H-ras than in parental cells. Activation of erk by the ras pathway coincided with a decrease in the stability of MT, as detected by a stability marker. The MKK1 inhibitor, PD98059 and transfection of a dominant negative MKK1 blocked ras-induced instability of MTs but did not modify the association of erk with MTs or affect MT stability of the parental cells. These results indicate that the subset of active erk kinase that associates with MTs contributes to their instability in the presence of a mutant active ras. The MT-associated subset of active erk likely contributes to the enhanced invasive and proliferative abilities of cells containing mutant active H-ras.

Acetylation↗