130,519 research outputs found
PDGF and TGF-beta partially prevent 2-deoxy-D-ribose-induced apoptosis in the fat body cell line IPLB-LdFB from the insect Lymantria dispar
No full textThe IPLB-LdFB cell line from the fat body of the insect Lymantria dispar shows the presence of immunoreactive, platelet-derived growth factor (PDGF)-AB and transforming growth factor (TGF)-beta 1 molecules, as well as the corresponding plasma membrane-like receptors, i.e. PDGFR-alpha, PDGFR-beta and TGFR-beta type II. Cytofluorimetric and morphological studies reveal that the reducing sugar 2-deoxy-D-ribose (dRib), an apoptotic agent for human cells, induces apoptosis in a concentration- and time-dependent manner even in IPLB-LdFB cells. PDGF-AB and TGF-beta 1 partially counteract the effect of dRib, indicating a survival role of these factors in this apoptotic model of insect cells. (C) 1999 Elsevier Science Ltd. All rights reserved
Platelet-derived growth factor and transforming growth factor-β induce shape changes in invertebrate immunocytes via multiple signalling pathways and provoke the expression of Fos-, Jun- and SMAD-family members
No full textRecently, we have found that platelet-derived growth factor (PDGF)-AB and transforming growth factor (TGF)-β1 induce shape changes in the immunocytes of the mollusc Mytilus galloprovincialis. Here we report that calphostin C and H-89, which specifically inhibit PKC and PKA, respectively, completely or in part inhibit the above effect. These data indicate the involvement of both pathways in growth factor-induced conformational changes in molluscan immunocytes. Furthermore, we show the presence of immunoreactive molecules for the Fos B, Jun D and Smad4 transcription factors. Stimulation by PDGF-AB or TGF-β1 up-regulate the intranuclear levels of these factors. Copyright (C) 1999 Elsevier Science Inc
Involvement of PI 3-kinase, PKA and PKC in PDGF- and TGF-β-mediated prevention of 2-deoxy-D-ribose-induced apoptosis in the insect cell line, IPLB-LdFB
No full textActivation of phosphatidylinositol (PI) 3-kinase, protein kinase A (PKA) and protein kinase C (PKC) is associated with the survival effect elicited by PDGF-AB and TGF-β1 against the apoptotic inducer 2-deoxy-D-ribose (dRib) in the fat body cell line, IPLB-LdFB, from the insect Lymantria dispar. dRib induces apoptosis and provokes mitochondrial membrane depolarization (MMD). The antioxidant N-acetyl-L-cysteine annuls only the first effect. These findings suggest that apoptosis and MMD are provoked by two different mechanisms, and that dRib induces apoptosis by oxidative stress. © 2001 Academic Press
PDGF- and TGF-beta-induced changes in cell shape of invertebrate immunocytes: effect of calcium entry blockers
No full textThe cellular activity of hemocytes from the marine mollusc Mytilus galloprovincialis was studied using computer-assisted microscopic image analysis. PDGF-AB and TGF-beta 1 caused changes in cellular shape and induced the immunocytes to migrate in a chemotactic manner. The effect of PDGF-AB was more potent than that of TGF-beta 1, and the responses were dose-correlated for PDGF-AB, while they were dose-dependent up to 5 pg/ml for TGF-beta 1. Moreover, the PDGF-AB response was extracellular Ca2+-independent, while TGF-beta 1 was Ca2+-dependent
The CRH-ACTH-biogenic amine axis in invertebrate immunocytes activated by PDGF and TGF-beta
No full textIn immunocytes from the mollusc Mytilus galloprovincialis, the major pathway followed by platelet-derived growth factor (PDGF)-AB and transforming growth factor (TGF)-beta 1 in provoking the release of norepinephrine, epinephrine and dopamine into cell-free hemolymph (serum) is mediated by a corticotropin-releasing hormone-adrenocorticotropin hormone (CRH-ACTH) biogenic amine axis, This axis not only annulled the inhibiting properties of PDGF-AB, it even reversed the latter's effect, while the inducing effect of TGF-beta 1 was amplified. These findings show that non-classical immune-neuroendocrine molecules, such as PDGF-AB and TGF-beta 1, are involved in building stress response, using the same conserved mechanisms present from invertebrates to vertebrates. (C) 1998 Federation of European Biochemical Societies
Platelet-derived growth factor and transforming growth factor-β in invertebrate immune and neuroendocrine interactions: Another sign of conservation in evolution
No full textGrowth factor-like molecules have been found in various invertebrate species. In particular, we have reported the presence of platelet-derived growth factor (PDGF)-AB and transforming growth factor-beta (TGF-beta )1 immunoreactive molecules in molluscs, insects and annelids. Moreover, PDGF-AB and TGF-beta1 affect the main immune functions, such as phagocytosis, chemotaxis and cell motility. Changes in cell shape are induced via interactions of growth factors with their respective specific receptors. The extracellular signals are transduced by the activation of classical signal transduction pathways, such as those involving PKA and PKC, and pivotal transcription regulators, i.e. the Fos, Jun and SMAD proteins. The two growth factors intervene in stress responses by activating the CRH-ACTH-biogenic amine axis. Exogenous administration of PDGF-AB and TGF-PI in a molluscan wound provokes an accelerated migration of immunocytes and fibroblasts to the injured area, stimulating granulation tissue formation and wound re-epithelialization. These findings suggest that these molecules are ancestral and that their function is well conserved and crucial in the maintenance of invertebrate homeostasis. (C) 2001 Elsevier Science Inc. All rights reserved
The growth-inhibitory block of TGF-beta is located close to the G1/S border in the cell cycle
No full textTransforming growth factor-beta (TGF-beta) inhibits DNA synthesis in dense cultures of young human embryonic fibroblasts and antagonizes the mitogenic action of platelet-derived growth factor (PDGF). The inhibition of the PDGF-BB action by TGF-beta was independent of the induction of mRNAs for the PDGF-A chain and PDGF-beta receptor, the predominant types of PDGF receptor in human fibroblasts. The TGF-beta-mediated inhibition did not influence the expression of various genes that are involved in the transition from the arrested (GO) state to the S phase of the cell cycle. Indeed, TGF-beta upregulated the "early" genes c-myc, c-fos, and junB and downregulated the growth arrest-specific (gas) genes. These results suggest that the inhibition of DNA synthesis by TGF-beta in human fibroblasts is independent of modulation of expression of early and gas genes, placing the TGF-beta block comparatively late in the GO to S transition. In cultures of senescent human fibroblasts TGF-beta stimulated DNA synthesis but, nevertheless, had the same effect as in young cells on the expression of PDGF chains and receptor genes, as well as on early and gas genes, with the exception of a significantly lower induction of c-fos
Immunocytochemical evidence of PDGF- and TGF-beta-like molecules in invertebrate and vertebrate immunocytes: An evolutionary approach
No full textImmunoreactive platelet-derived growth factor-AB and transforming growth factor-beta 1 were demonstrated in invertebrate and vertebrate immunocytes by an immunocytochemical procedure. These factors are only present in phagocytic cells among invertebrate immunocytes, whereas in vertebrate immunocytes they are found in monocytes, granulocytes, lymphocytes, thrombocytes and platelets. These results, in agreement with previous reports, represent further evidence in favour of the hypothesis that Nature has followed a conservative strategy in using a common pool of signal molecules that have been highly conserved throughout evolution
Comparative and morphofunctional studies on Mytilus galloprovincialis hemocytes: presence of two aging-related hemocyte stages
No full textMorphological and functional studies were performed on hemocytes from young and adult Mytilus galloprovincialis. The results obtained suggest that only one cell type in two different stages, young or old, is present, consistently with the Mix's one-cell-type model. However, both young and old hemocytes appear capable of carrying out similar functions and express common signal molecules; thus, their differences in cytology and number appear to be due to cellular aging
PDGF and TGF-beta induce cell shape changes in invertebrate immunocytes via specific cell surface receptors
No full textThe presence of PDGF receptor-alpha- and -beta- and TGF-beta-receptor (type II)-like molecules on the plasma membranes of the immunocytes of the mollusc Mytilus galloprovincialis was demonstrated by an immunocytochemical procedure. Furthermore, the present study provides evidence that PDGF-AB and TGF-beta 1 provoke cell shape changes in immunocytes via interactions with the respective receptors and that these extracellular signals are transduced along the phosphoinositide signaling pathway
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