Browsing by Subject "Signal transduction"
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- PublicationOpen AccessMast cells and wound healing: Still an open question(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2025) Fernández Guarino, Montserrat; Bacci, Stefano
- PublicationOpen AccessNuclear protein kinase C isoforms: key players in multiple cell functions?(Murcia : F. Hernández, 2003) Martelli, A.M.; Faenza, I.; Billi, A.M.; Falà, F.; Cocco, L.; Manzoli, L.Protein kinase C (PKC) isozymes are a family of serine/threonine protein kinases categorized into three subfamilies: classical, novel, and atypical. PKC isozymes, whose expression is cell type-specific and developmentally regulated, are key transducers in many agonist-induced signaling cascades. To date at least 10 different PKC isotypes have been identified and are believed to play distinct regulatory roles. PKC isoforms are catalytically activated by several lipid cofactors, including diacylglycerol. PKC is thought to reside in the cytoplasm in an inactive conformation and to translocate to the plasma membrane or cytoplasmic organelles upon cell activation by different stimuli. However, a sizable body of evidence collected over the last 15 years has shown PKC to be capable of translocating to the nucleus. Furthermore, PKC isoforms can reside within the nucleus. Studies from independent laboratories have to led to the identification of several nuclear proteins which act as PKC substrates as well as to the characterization of some nuclear PKC-binding proteins which may be of fundamental importance for finely tuning PKC function in this peculiar cell microenvironment. Most likely, nuclear PKC isozymes are involved in the regulation of several important biological processes such as cell proliferation and differentiation, neoplastic transformation, and apoptosis. In this review, we shall summarize the most intriguing evidence about the roles played by nuclear PKC isozymes.
- PublicationOpen AccessPhosphatidylinositide 3-kinase AKT in radiation responses(Murcia : F. Hernández, 2004) Zhan, M.; Han, Z.C.Ionizing or ultraviolet radiation-induced cellular survival signaling pathways induce development of cancer and insensitivity of tumor cells to radiation therapy. Accumulating evidence suggests that the phosphatidylinositide 3-kinase (PI3K)/AKT signal pathway is a major contributor to radioresistance. In many cell types PI3K/AKT signaling is a key cytoprotective response downstream of the EGFR family receptors and mediated carcinogenesis. Cytokines, such as HGF, IGF-I, and IL-6 also protects cells against apoptosis induced by radiation through PI3K/AKT pathway. The mechanics by which PI3K/AKT signaling functions in radiation responses may include its regulation of mitochondrial proteins, transcription factors, translation machinery, and cell-cycle progression. In addition, cross-talk between the PI3K/AKT pathway and mitogen-activated protein kinases, protein kinase A, and protein kinase C signal pathway may also play an important role.
- PublicationRestrictedRegulatory role of PI3K-protein kinase B on the release of interleukin-1β in peritoneal macrophages from the ascites of cirrhotic patients(British Society for Immunology, 2014-07-29) Ruiz Alcaraz, Antonio José; Antón, G.; Miras López, M.; Francés, R.; Such, J.; Martínez-Esparza Alvargonzález, María Concepción; García Peñarrubia, María del Pilar; Tapia Abellán, Ana; Bioquímica y Biología Molecular B e InmunologíaGreat effort has been paid to identify novel targets for pharmaceutical intervention to control inflammation associated with different diseases. We have studied the effect of signalling inhibitors in the secretion of the proinflammatory and profibrogenic cytokine interleukin (IL)-1β in monocyte-derived macrophages (M-DM) obtained from the ascites of cirrhotic patients and compared with those obtained from the blood of healthy donors. Peritoneal M-DM were isolated from non-infected ascites of cirrhotic patients and stimulated in vitro with lipopolysaccharide (LPS) and heat-killed Candida albicans in the presence or absence of inhibitors for c-Jun N-terminal kinase (JNK), mitogen-activated protein kinase kinase 1 (MEK1), p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K). The IL1B and CASP1 gene expression were evaluated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The expression of IL-1β and caspase-1 were determined by Western blot. IL-1β was also assayed by enzyme-linked immunosorbent assay (ELISA) in cell culture supernatants. Results revealed that MEK1 and JNK inhibition significantly reduced the basal and stimulated IL-1β secretion, while the p38 MAPK inhibitor had no effect on IL-1β levels. On the contrary, inhibition of PI3K increased the secretion of IL-1β from stimulated M-DM. The activating effect of PI3K inhibitor on IL-1β release was mediated mainly by the enhancement of the intracellular IL-1β and caspase-1 content release to the extracellular medium and not by increasing the corresponding mRNA and protein expression levels. These data point towards the role of MEK1 and JNK inhibitors, in contrast to the PI3K-protein kinase B inhibitors, as potential therapeutic tools for pharmaceutical intervention to diminish hepatic damage by reducing the inflammatory response mediated by IL-1β associated with liver failure.
- PublicationOpen AccessSignaling pathways mediated by tumor necrosis factor a(Murcia : F. Hernández, 2000) Leong, K.G.; Karsan, A.Tumor necrosis factor a (TNFa) has been shown to trigger many signaling pathways. Following oligomerization by TNFa, the receptors TNF-RI and TNF-RI1 associate with adapter molecules via specific protein-protein interactions. The subsequent recruitment of downstream molecules to the receptor complex enables propagation of the TNFa signal. l k o cellular responses to TNFa have been well documented, the induction of cell death and the activation of gene transcription for cell survival. TNFa-induced apoptosis involves the activation of caspase cascades, which culminate in the cleavage of specific cellular substrates to effect cell death. TNFa has also been implicated in various caspase-independent cell death processes. Two transcription factors activated by TNFa are nuclear factor KB (NFKB) and activating protein 1 (AP-1). Pathways that promote the activation of these transcription factors involve signaling molecules such as kinases, phospholipases, and sphingomyelinases. In addition to increased survival (anti-apoptotic) gene expression, NFKB and AP-1 also induce the expression of genes involved in inflammation, cell growth, and signal regulation. The past decade has witnessed the identification of numerous signaling intermediates implicated in TNFa cellular responses. This article reviews the molecular mechanisms of TNFa signal transduction. In particular, pathways involved in cell death and transcription factor activation are discussed.
- PublicationOpen AccessThe SH2 and SH3 adapter Nck: a two-gene family and a linker between tyrosine kinases and multiple signaling networks(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2000) Li, W.; She, H.SH2 and SH3 adapter proteins connect cell surface tyrosine kinases to intracellular signaling networks. For instance, the SH3-SH2-SH3 adapter Grb2 links receptor tyrosine kinases to the Ras pathway. Nck, composed of three SH3 domains and one SH2 domain, represents a two-gene (alpha and beta) family in mammals. Ncka and Nck13 are expressed in the same cells and appear to have distinct signaling specificity. Studies show that Nck plays a role in cell mitogenesis and morphogenesis. The former uses Ras-dependent and Ras-independent pathways. The latter appears to coordinate with the Cdc42/Rac>PAK lIWASp>actin cytoskeleton pathway. Understanding the specificity of Ncka and NckB signal transduction will provide answers for the previously often conflicting observations.