Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cell Communication”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources
PubMed2000

Involvement of gap junctional communication in myogenesis.

Cell-to-cell communication plays important roles in development and in tissue morphogenesis. Gap junctional intercellular communication (GJIC) has been implicated in embryonic development of various tissues and provides a pathway to exchange ions, secondary messengers, and metabolites through the intercellular gap junction channels. Although GJIC is absent in adult skeletal muscles, the formation of skeletal muscles involves a sequence of complex events including cell-cell interaction processes where myogenic cells closely adhere to each other. Much experimental evidence has shown that myogenic precursors and developing muscle fibers can directly communicate through junctional channels. This review summarizes current knowledge on the GJIC and developmental events involved in the formation of skeletal muscle fibers and describes recent progress in the investigation of the role of GJIC in myogenesis: evidence of gap junctions in somitic and myotomal tissue as well as in developing muscle fibers in situ, GJIC between perfusion myoblasts in culture, and involvement of GJIC in cytodifferentiation of skeletal muscle cells and in myoblast fusion. A model of intercellular signaling is proposed where GJIC participates to coordinate a multicellular population of interacting myogenic precursors to allow commitment to the skeletal muscle fate.

Animals↗
PubMed1998

A growing family of Notch ligands.

Signaling through Notch-like receptors is an evolutionarily well-conserved mechanism for cell-cell communication. Transmembrane ligands of the DSL (Delta, Serrate, LAG-2) family signal to Notch receptors on a neighboring cell, which results in an intracellular signaling cascade, influencing cellular differentiation. Recently published data shed new light on the repertoire of ligands and on processing of Notch receptors. One report provides evidence for a novel, more distantly related ligand of the Delta-type in mouse, DII3 (Delta-like 3). Ectopic expression of DII3 perturbs primary neurogenesis in frog embryos in a manner expected for a bona fide Notch ligand. Two reports provide new information about processing of Notch receptors. A novel protease, Kuzbanian, is identified, which cleaves the Notch receptor at the extracellular side. Biochemical experiments show that the cleavage probably occurs during intracellular trafficking, and that only processed Notch receptors appear at the cell surface. Taken together, these reports extend our knowledge about an important event in cell-cell communication--how Notch ligands and receptors meet and interact.

Animals↗
PubMed2000

Intercellular communication and cell proliferation in precision-cut rat liver slices: effect of medium composition and DDT.

Gap junctional intercellular communication (GJIC) and cell proliferation were studied in control and 1,1'-bis(p-chlorophenyl)-2, 2,2,-trichloroethane (DDT) treated precision-cut liver slices of rat by evaluating connexin 32 (Cx32) expression and 5-bromo-2'-deoxyuridine (BrdU) incorporation. In addition, the effect of different culture media (RPMI and WME) on control and DDT influenced Cx32 expression and cell proliferation was determined. Cx32 expression in control precision-cut liver slices was maintained during 8 h of culturing, but decreased after prolonged culturing. Control cell proliferation was significantly higher when WME was used as culture medium than when RPMI was used. In slices treated with DDT Cx32 expression was decreased. In slices cultured in RPMI medium, this decrease preceded a dose-dependent increase in cell proliferation. These results show the usefulness of precision-cut liver slices in studying cellular proliferation and intercellular communication.

Animals↗
PubMed1997

Interfollicular fibroblasts in the human thyroid gland: recognition of a CD34 positive stromal cell network communicated by gap junctions and terminated by autonomic nerve endings.

While epithelial structure and functions have been substantially investigated in many organs, the mesenchymal elements have received less attention. Compared with follicular epithelial cells, there are a few morphological studies on the stroma of human thyroid gland. In order to characterize more fully and assess its possible functions, 15 samples of surgical and autopsy human thyroid tissue were studied by classical histology, immunohistochemistry, transmission electron microscopy, electron microscopic immunohistochemistry, and scanning electron microscopy. In human thyroid gland, the interfollicular connective tissue surrounding the follicles contained collagenous matrix, fibroblasts, unmyelinated nerve fibers with Schwann cells, small blood vessels, lymphatics, lymphocytes, plasma cells, macrophages, and mast cells. At the ultrastructural level, gap junctions between the cytoplasmic processes of interfollicular fibroblasts constituted a novel observation. Immunohistochemistry using a monoclonal antibody against Cx43 confirmed the distribution of gap junctions between stromal fibroblastic cells, which was compatible with the ultrastructural findings. The frequent and intimate association of fibroblastic processes with nerve terminals was also shown. Interfollicular stromal fibroblasts also stained with CD34. The main constituent of the human thyroid stromal tissue was a CD34 positive reticular network involving fibroblasts, mononuclear cells and nerve terminals. It represents a highly ordered stroma, with potential structural and functional similarities to the stroma of bone marrow (Yamazaki and Allen, 1990).

Adult↗
PubMed1978

Investigation of human urogenital tract tumors of papovavirus etiology: brief communication.

Cells cultured from human urogenital cancer and other cancers as well as cells from noncancerous tissues were examined by immunofluorescent staining with antibodies to T-antigens and capsid antigens of papovaviruses BK virus (BKV), JC virus, and simian virus 40(SV40), and to capsid antigens of herpes simplex virus types 1 and 2 and human cytomegalovirus (CMV). Cells from early passage cultures of 123 primary tissues and from 14 continuous lines derived from transitional or renal cell carcinoma were tested. None of the cell preparations was specifically stained with any of the antisera. A serologic comparison of patients with bladder cancer, patients with prostate cancer, and normal control groups of BKV hemagglutination-inhibiting and SV40-neutralizing antibodies showed no differences among the 3 groups. None of the sera in the 3 groups had SV40 or BKV T-antibodies. In tests of supernatants of 35 primary cultures for presence of virus, a single isolation, that of a cytomegalovirus, was made. The study revealed no evidence that infection with papovaviruses of the SV40-polyoma subgroup has any part in the production of bladder and prostate cancer.

Animals↗
PubMed2004

The adipocyte as an endocrine cell.

Communication between adipose and other tissues has been hypothesized since at least the 1940s to be bidirectional. Despite this expectation, early progress was largely limited to adipose tissue's role in metabolism and storage of fatty acids, its development, and its response to endocrine and neural cues. However, efforts of the last decade have identified several molecules that are secreted from adipocytes, apparently for the purpose of signaling to other tissues. Cloning of the mouse obesity gene in 1994 is perhaps the most famous impetus for recognition that adipocytes are active in the regulation of multiple body functions. The product of this gene, leptin, has since been found to inhibit feeding, enhance energy expenditure, and stimulate gonadotropes. Evidence for the roles of other adipocyte-derived signals is being generated. Resistin is a protein that can cause whole-body insulin resistance. Its expression is correlated with body fatness and is inhibited by thiazolidinediones, perhaps mediating the association of type 2 diabetes with obesity, and the effectiveness of these drugs. Resistin and a related molecule, RELM alpha, can also inhibit differentiation of preadipocytes. Adiponectin/Acrp30 secretion from adipocytes is diminished in obese states. This protein can enhance use of fatty acids in lean tissues, inhibit glucose production by liver, and consequently decrease both blood glucose and BW. Adiponectin may also be responsible for the effectiveness of thiazolidinediones, given that these drugs promote adiponectin secretion. Secretion of complement proteins has been observed in adipocytes, and these interact to generate a signal called acylation-stimulating protein, which can promote triacylglycerol synthesis. These signals seem to be largely unique to adipocytes. Other signals are derived from adipose tissue, and it is unlikely that all the adipocyte's endocrine signals have been identified. Certainly, there is much to learn about how these signals function; however, it is clear that these biomedical research discoveries comprise a useful model for our study of growth and development in livestock.

Adipocytes↗
PubMed2001

Gap-junctional communication is required for the maturation process of osteoblastic cells in culture.

Osteoblastic cells in long-term culture undergo a phenotypic maturation process leading to extracellular matrix (ECM) production and bone nodule (BN) formation. Cell-to-cell communication via gap junctions (GJC) can be detected between osteoblastic cells within 24 h of plating. We evaluated, in long-term cultures of osteoblastic cells, the effect of inhibiting GJC on the phenotypic maturation process and the expression of specific genes associated with this process. MC3T3-E1 cells were plated, and, after 24 h (day 0), cells were exposed to 18-alpha-glycyrrhetinic acid (AGA), a nontoxic reversible inhibitor of GJC. GJC, alkaline phosphatase (AP) activity, BN formation, and the relative level of transcripts encoding osteocalcin (OC), bone sialoprotein (bSP), osteopontin (OP), collagen alpha1 type I (alpha1ICol), and elongation factor-1a (EF1a) were evaluated on day 0 and every 4-7 days thereafter through day 30. GJC was assessed by fluorescent dye transfer. Gene expression was analyzed by northern blot and semiquantitative reverse transcription-polymerase chain reaction. GJC was detectable at day 0 and increased with time in culture. AGA (100 micromol/L) strongly inhibited GJC at all timepoints tested. Moreover, AGA-exposed cells showed a dose-dependent decrease in AP activity and a delay in the appearance of BN. This delayed phenotypic expression coincided with an inhibitory effect on the expression of the osteoblast-specific genes OC and bSP. Expression of alpha1ICol mRNA was also affected, but to a lesser extent, whereas OP and EF1a were not affected. Similar results were obtained with oleamide, an additional reversible inhibitor of GJC. In contrast, cells exposed to either vehicle or 100 micromol/L glycyrrhizic acid (a noninhibitory glycoside of 18-beta-glycyrrhetinic acid) were indistinguishable from untreated cells for all parameters evaluated. We conclude that GJC inhibition interferes with the maturation process of osteoblastic cells in culture, possibly by affecting signals regulating the expression of genes involved in the maturation/differentiation of the osteoblastic phenotype.

3T3 Cells↗
PubMed1990

Mechanical stimulation and intercellular communication increases intracellular Ca2+ in epithelial cells.

Intercellular communication of epithelial cells was examined by measuring changes in intracellular calcium concentration ([Ca2+]i). Mechanical stimulation of respiratory tract ciliated cells in culture induced a wave of increasing Ca2+ that spread, cell by cell, from the stimulated cell to neighboring cells. The communication of these Ca2+ waves between cells was restricted or blocked by halothane, an anesthetic known to uncouple cells. In the absence of extracellular Ca2+, the mechanically stimulated cell showed no change or a decrease in [Ca2+]i, whereas [Ca2+]i increased in neighboring cells. Iontophoretic injection of inositol 1,4,5-trisphosphate (IP3) evoked a communicated Ca2+ response that was similar to that produced by mechanical stimulation. These results support the hypothesis that IP3 acts as a cellular messenger that mediates communication through gap junctions between ciliated epithelial cells.

Animals↗
PubMed1996

Control of daughter cell fates during asymmetric division: interaction of Numb and Notch.

During development of the Drosophila peripheral nervous system, a sensory organ precursor (SOP) cell undergoes rounds of asymmetric divisions to generate four distinct cells of a sensory organ. Numb, a membrane-associated protein, is asymmetrically segregated into one daughter cell during SOP division and acts as an inherited determinant of cell fate. Here, we show that Notch, a transmembrane receptor mediated cell-cell communication, functions as a binary switch in cell fate specification during asymmetric divisions of the SOP and its daughter cells in embryogenesis. Moreover, numb negatively regulates Notch, probably through direct protein-protein interaction that requires the phosphotyrosine-binding (PTB) domain of Numb and either the RAM23 region or the very C-terminal end of Notch. Notch then positively regulates a transcription factor encoded by tramtrack (ttk). This leads to Ttk expression in the daughter cell that does not inherit Numb. Thus, the inherited determinant Numb bestows a bias in the machinery for cell-cell communication to allow the specification of distinct daughter cell fates.

Animals↗
PubMed1992

The permeability of reconstituted liposomes containing the purified lens fiber cell integral membrane proteins MP20, MP26 and MP70.

A number of lens fiber cell integral membrane proteins have been localized to junctional regions where they have been proposed to play a role in either mediating or controlling cell-to-cell communication. We have examined the effect of three lens fiber cell membrane proteins, MP20, MP26 and MP70, on the permeability properties of unilamellar phospholipid liposomes. This approach has been previously used to examine the channel-forming properties of MP26. Liposome permeability was determined by measuring the effect of Co2+ on the quenching of the fluorescence of N-4-nitrobenzo-2-oxa-1,3 diazole phosphatidyl ethanolamine (NBD-PE)-containing liposomes as described previously by Scaglione and Rintoul (Invest. Ophthalmol. Vis. Sci. 30:961-966, 1989). The effect of all three proteins on liposome permeability was similar. Permeability was dependent on the protein/phospholipid ratio and was not significantly affected by agents known to modify gap junctional permeability in vivo. Glycophorin A, a non-channel-forming integral membrane protein derived from erythrocytes, was also shown to increase the permeability of unilamellar phospholipid liposomes. The ability of a non-channel membrane protein to increase Co2+ quenching of NBD-PE-containing liposomes (presumably in a nonspecific manner) indicates that reports describing the permeability of lens membrane protein-containing liposomes should be interpreted with caution in terms of their relationship to cell-to-cell communication.

Animals↗
PubMed1985

Diacylglycerol downregulates junctional membrane permeability. TMB-8 blocks this effect.

We tested the question whether junctional cell-to-cell communication is regulated by the diacylglycerol branch of the phosphoinositide transmembrane signal pathway. Cultured epithelial rat liver cells were treated with the synthetic diacylglycerol 1-oleoyl-2-acetyl glycerol, while their junctional permeability was probed with the microinjected 443-dalton fluorescent tracer Lucifer Yellow. The treatment reduced junctional permeability (without affecting Lucifer permeability of nonjunctional cell membrane). The effect was dose dependent, with a threshold of about 25 micrograms diacylglycerol/ml in sparse cultures and about 50 micrograms/ml in confluent cultures. The reduction of junctional permeability began within 3 min of diacylglycerol application, peaked within 20 min, and reversed spontaneously within 90 min. The phorbol ester TPA mimicked the diacylglycerol effect, but the (spontaneous) reversal was slower. We propose that cell-to-cell communication is under dual physiological control: an up-regulatory one, as exerted by the cyclic AMP signal route (Loewenstein, W.R., 1985, Biochem. Soc. Symp. London, 50: 43-58), and a downregulatory one, by the diacylglycerol signal route. TMB-8 (54-70 microM)--a blocker of intracellular Ca2+ mobilization--impeded the diacylglycerol action on junctional permeability. It prevented the effect of low diacylglycerol doses completely and it markedly reduced the effect of high doses. (It also counteracted the effect of TPA.) Ca2+ thus emerges as a possible candidate for a role in the junctional downregulation by the diacylglycerol signal route. We tentatively advance two models. In one, leaning closely on the Calcium Hypothesis of cell-to-cell channel regulation (Loewenstein, W.R., 1966, Ann. N.Y. Acad. Sci. 137:441-472), Ca2+ mediates the action of the route on the channel. In the other, Ca2+ acts farther removed from the channel, on protein kinase C. Calmidazolium (5-10 microM)--an inhibitor of calmodulinactivated proteins--did not prevent the diacylglycerol-induced reduction of junctional permeability. Nor did sodium orthovanadate (25 or 50 microM)--an inhibitor of tyrosyl phosphatase--prevent the reversal of diacylglycerol-induced (or TPA-induced) reduction of junctional permeability.

Animals↗
PubMed1979

Effect of 2-4-dinitrophenol on intercellular communication in mammalian cardiac fibres.

The effect of 2-4-dinitrophenol (DNP) on cell communication, in canine Purkinje fibres, was investigated. It was found that DNP (0.5 MM) suppressed the electrical coupling in about 10 min. This effect of DNP was largely due to an increment in intracellular longitudinal resistance. The longitudinal movement of fluorescein (mol. wt. 320) along Purkinje strands, followed with the cut-end method, was also suppressed by DNP (0.5 mM). The decoupling action of DNP was related to release of Ca from intracellular stores and increase in free (Ca)i. The intracellular injection of EDTA reestablished the electrical coupling of Purkinje cells previously uncoupled by DNP. The results described in this paper indicate that cell communication in heart fibres is greatly dependent on the synthesis of high energy phosphate bonds.

Adenosine Triphosphate↗
PubMed1979

Gap junctional communication in the post-implantation mouse embryo.

We studied the extent of cell-to-cell communication via junctional channels in in vitro-implanted mouse blastocysts by monitoring ionic coupling and the spread of two injected low molecular weight dyes, fluorescein and Lucifer yellow. In the early attached embryos, both trophoblasts and cells of the inner cell mass (ICM) were ionically coupled to one another. Dye injections in either trophoblasts or ICM cells resulted in spread to the entire embryo. As older and more developed embryos were examined, the spread of injected dye was progressively more limited. In the most developed embryos examined, dye injected into a cell in the ICM region resulted in spread throughout the ICM but not into the surrounding trophoblast cells, while dye injected into a trophoblast cell did not spread to any other cell in the embryo. Simultaneous monitoring of ionic coupling and dye injections in embryos of intermediate stages in this transition revealed that the trophoblast and ICM cells were ionically coupled, even across the apparent boundary where no dye was observed to pass. In the latest stage embryos examined in which no injected dye was observed to move out of the ICM, ionic coupling was still observed between the cells of the ICM and the trophoblasts. Furthermore, in the more developed embryos, dye injected into the ICM region frequently was not transferred to all the cells of the ICM, thus suggesting a further compartmentalization of due spread within the ICM. Our observations that ionic coupling is more extensive than the detectable spread of injected dyes may perhaps reflect a reduced number of junctional channels. With fewer channels less dye would pass between cells, so that, together with continuous quenching, the transfer of injected dye would not be detectable. This partial segregation of cell-to-cell communication as indicated by the limited dye spread may parallel specific differentiation processes, in particular that of giant trophoblast, embryonic ectoderm and extraembryonic endoderm differentiation.

Animals↗
PubMed1995

Nuclear/growth factors.

The now classical model for cell-cell communication espouses that information travels between cells in the form of molecules that bind specific cell-surface receptors and trigger signal-transducing mechanisms that eventually lead to transcriptional modifications. Here we gather the available information suggesting that some growth factors may also act by interfering directly with gene transcription, following their internalization and nuclear translocation. Among these factors are bona fide growth factors such as Fibroblast Growth Factor-1 and -2 and Schwannoma Derived Growth Factor, for which internalization and nuclear translocation have been demonstrated. Conversely, we propose that some isoforms of nuclear factors of the homeoprotein family could pass from cell to cell. The implications of the model are presented in the context of the specificity of cellular interactions.

Animals↗
PubMed1992

Correlation of increased levels of Ha-ras T24 protein with extent of loss of gap junction function in rat liver epithelial cells.

Although it is known that cells transformed by ras and other oncogenes show reduced gap junction function, to date there has been no investigation of the quantitative relationship between intracellular levels of ras oncoprotein and loss of cell-cell communication. Using the rat liver epithelial cell line MTR6, which carries a zinc-inducible metallothionein ras T24 (MTrasT24) fusion gene, we showed a direct correlation between the accumulation of ras T24 protein and the loss of dye transfer as measured by interactive laser cytometry. After stimulation with zinc sulfate, changes in both parameters were rapid and measurable by 24 h. Similarly, there was a dose-response relationship between loss of gap junction function and increase in ras T24 protein. Northern analysis of two gap junction proteins (connexins 43 and 32) showed no differences between cells that expressed high levels of ras and control cells. These data demonstrate that the degree of loss of gap junction function is dependent on the amount of increase in ras T24 protein levels, but the mechanism by which these changes are effected remains unclear.

Animals↗
PubMed1983

A novel cell-to-cell interaction between mast cells and other cell types.

Time-lapse cinephotomicrography and transmission electron microscopy (TEM) have been used to study the interactions between rat mast cells and different cell monolayers in culture (fibroblasts, vascular endothelial cells and cardiac muscle cells). This report documents a novel form of behavior between mast cells and certain other cell types. We have tentatively termed this cellular behavior 'transgranulation', which involves sequential changes not seen in control cells, including: (1) formation of a granule-containing mast cell pseudopod that becomes closely applied to an adjacent cell; (2) development of specialized plasma membrane interrelationships between apposing cells; (3) alteration of granules and perigranular membranes within the mast cell pseudopod; (4) occasional transfer of exocytosed mast cell granules to the cytoplasm of the adjacent cell; (5) presence of a specialized inclusion body in the mast cell; and finally, (6) either withdrawal of the pseudopod by the mast cell, or casting-off of the pseudopod from the mast cell, leaving it on the surface of the adjacent cell (pseudopod translocation). These mast cell interactions occur specifically with fibroblasts and endothelial cells in vitro and are never observed with cardiac muscle cells or non-cellular substrates. Our investigations of rat mesenteries in situ confirm that these cell-cell interactions also occur in vivo. We suggest it represents a form of cell-to-cell communication involving secretion from a mast cell pseudopod to another cell type. The significance of specialized contacts between mast cells and other cell types in vivo is discussed.

Animals↗
PubMed2004

Membrane traffic during embryonic development: epithelial formation, cell fate decisions and differentiation.

The analysis of membrane trafficking has in the past mainly dealt with single cells in culture. Recent studies of membrane trafficking in Drosophila focus on how cells are organized in tissues and form epithelia during embryogenesis. During these processes, the specific involvement of distinct biosynthetic and endocytic routes is starting to be understood. Once organized in epithelia, cells communicate with each other to make cell fate decisions through morphogen gradients and lateral inhibition. Endocytosis seems to play unexpected roles in shaping morphogen gradients and in biasing lateral inhibition events. Once committed to a developmental program, cells differentiate. In the case of neurons, trafficking through the biosynthetic and endocytic pathways may give the necessary speed of response and versatility to axons that navigate through a changing environment during pathfinding.

Animals↗
PubMed2004

Tomato phytochemicals and prostate cancer risk.

Mounting evidence over the past decade suggests that the consumption of fresh and processed tomato products is associated with reduced risk of prostate cancer. The emerging hypothesis is that lycopene, the primary red carotenoid in tomatoes, may be the principle phytochemical responsible for this reduction in risk. A number of potential mechanisms by which lycopene may act have emerged, including serving as an important in vivo antioxidant, enhancing cell-to-cell communication via increasing gap junctions between cells, and modulating cell-cycle progression. Although the effect of lycopene is biologically relevant, the tomato is also an excellent source of nutrients, including folate, vitamin C, and various other carotenoids and phytochemicals, such as polyphenols, which also may be associated with lower cancer risk. Tomatoes also contain significant quantities of potassium, as well as some vitamin A and vitamin E. Our laboratory has been interested in identifying specific components or combination of components in tomatoes that are responsible for reducing prostate cancer risk. We carried out cell culture trials to evaluate the effects of tomato carotenoids and tomato polyphenols on growth of prostate cancer cells. We also evaluated the ability of freeze-dried whole-tomato powder or lycopene alone to reduce growth of prostate tumors in rats. This paper reviews the epidemiological evidence, evaluating the relationship between prostate cancer risk and tomato consumption, and presents experimental data from this and other laboratories that support the hypothesis that whole tomato and its phytochemical components reduce the risk of prostate cancer.

Animals↗