1,721,015 research outputs found
Esplorando la connessione tra metabolismo e ferroptosi: un focus sull'enzima piruvato deidrogenasi
Full text linkLa ferroptosi è una forma di morte cellulare regolata, dovuta alla perossidazione lipidica dipendente dal ferro. La ferroptosi viene innescata dalla mancata attività dell’enzima glutathione perossidasi 4 (GPx4), che catalizza la riduzione glutatione (GSH)-dipendente degli idroperossidi di membrana ad alcoli corrispondenti. Oltre all’inattivazione di GPx4, la ferroptosi avviene quando sono soddisfatte altre condizioni: -la presenza del metabolismo aerobico che porta alla continua formazione di tracce di idroperossidi a partire dai fosfolipidi contenenti acidi grassi polinsaturi; - la disponibilità di ferro ridotto dal pool labile di ferro. In accordo con il ruolo critico delle tracce di LOOH, di recente abbiamo proposto che la ferroptosi possa essere dovuta alla perdita del controllo omeostatico tra l’ambiente ossidativo dovuto al metabolismo aerobico e l’attività di GPx4. L’ipotesi di lavoro è che O2•- derivante dal metabolismo aerobico sia responsabile delle tracce di LOOH che iniziano la perossidazione lipidica e di conseguenza la ferroptosi. Questo lavoro è stato volto alla ricerca della relazione tra metabolismo aerobico mitocondriale e ferroptosi dovuta a deplezione di GSH, con un focus sul sito di produzione ed il meccanismo reazione che porta alla formazione di tracce di PL-OOH dalle quali il ferro innesca la perossidazione lipidica se l’attività di GPx4 è insufficiente.
Nel nostro modello, non abbiamo rilevato il coinvolgimento della catena respiratoria ma abbiamo osservato chela piruvato deidrogenasi sostiene la ferroptosi. Silenziando alternativamente la subunità E1 o E3 abbiamo stabilito che la fonte dell’anione superossido è data dall’autossidazione della diidrolipoamide. A questo riguardo, abbiamo osservato che la deplezione di GSH attiva la produzoine di anione superossido attraverso l’inibizione della chinasi (PDK) che inibisce la piruvato deidrogenasi. Infine abbiamo dimostrato che l’autofagia svolge un ruolo nel mediare la ferroptosi dovuta a deplezione di GPx4.Ferroptosis is a form of regulated cell death operated by iron-dependent lipid peroxidation. Ferroptosis is primed by the missing or insufficient activity of the Glutathione Seleno-Peroxidase 4 (GPx4), which catalyzes the glutathione (GSH)-dependent reduction of lipid hydroperoxides to the corresponding alcohols. Besides GPx4 inactivation, ferroptosis occurs when other conditions are satisfied: -oxygen metabolism leading to the continuous formation of traces of LOOH from phospholipid-containing polyunsaturated fatty acids; - availability of ferrous iron from the labile iron pool. Consistently with the critical role of the traces of LOOH, we recently proposed that ferroptosis follows the loss of homeostatic control between the oxidative challenge posed by aerobic metabolism and GPx4 activity. The working hypothesis, supported by acknowledged chemical mechanisms, was that O2•- arising from aerobic metabolism accounts for the formation of the tiny amounts of LOOH sparking iron-dependent LPO and thus ferroptosis.
This work aimed to shed light on the relationship between aerobic mitochondrial metabolism and ferroptosis induced by GSH depletion, focusing on the site of production and the mechanism of reactions leading to the indispensable formation of traces amounts PL-OOH from which iron initiates LPO when GPx4 activity is insufficient.
In our cell model, we failed to detect a role of respiratory chain. We observed instead that the pyruvate dehydrogenase complex supports ferroptosis. By silencing either the E1 or the E3 subunit of the pyruvate dehydrogenase complex, the autoxidation of dihydrolipoamide emerges as the source of superoxide. In this respect, we observed that GSH depletion activates superoxide production, through the inhibition of the specific kinase that inhibits pyruvate dehydrogenase. Finally, we observed the contribution of autophagy in mediating ferroptosis due to GSH depletion
Tyrosine phosphorylation and liver regeneration: A glance at intracellular transducers.
No full textLiver regeneration (LR) is a compensatory growth that occurs in response to resection or injury of the liver aimed at restoring the liver mass and maintaining body homeostasis. The activation of intracellular signaling pathways due to extracellular stimuli mainly reflects a highly coordinated spatial and temporal organization of phosphotyrosine-based signals generated by the concerted action of three basic functional modules, namely protein tyrosine kinases, protein tyrosine phosphatases, and the Src homology 2 (SH2) domain. In this review, we have selected a set of signaling proteins downstream of activated cytokine and growth factor receptors that highlight the multifaceted aspects of tyrosine phosphorylation with their impact on the course of LR. Besides being a process of remarkable biological interest, LR has recently emerged as a model for dissecting molecular mechanisms underlying diverse pathophysiological states, offering new perspectives in primarily, but not only, managing life-threatening liver diseases
Motif Analysis of Phosphosites Discloses a Potential Prominent Role of the Golgi Casein Kinase (GCK) in the Generation of Human Plasma Phospho-Proteome
No full textBy comparing the recurrent features of sequences surrounding 86 Ser/Thr residues phosphorylated in peptides from human plasma collected from literature with those generated from the whole human phosphoproteome, and from repertoires of validated substrates of the acidophilic protein kinases CK2 and Golgi casein kinase (GCK), the following conclusions can be drawn: (i) the contribution of Pro-directed and basophilic kinases to the plasma phosphoproteome is negligible, if any, while the contribution of acidophilic kinases is by far predominant; (ii) the plasma weblogo profile is closely reminiscent of that generated by GCK in its substrates, while it neatly differentiates from that generated by CK2; (iii) 58 plasma phosphosites out of 86 display the canonical consensus for GCK (S/T-x-E/pS), while that for CK2 (S/T-x-x-E/D/pS) is found in 15 peptides, all of which also conform to the GCK signature. These observations, in conjunction with a very similar situation disclosed by analyzing the phosphopeptides of the human cerebrospinal fluid collected from literature, support the view that GCK may play a major role in the phosphorylation of proteins secreted into body fluids
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Analysis of tyrosine-phosphorylated proteins in rat brain mitochondria
No full textMitochondrial protein phosphorylation is emerging as a central event in mitochondrial signaling. In particular, tyrosine phosphorylation is proving to be an unappreciated mechanism involved in regulation of mitochondrial functions. Tyrosine kinases and phosphatases have been identified in mitochondrial compartments and there is a steadily increasing number of new identified tyrosine-phosphorylated proteins implicated in a wide spectrum of mitochondrial functions. The deciphering of the tyrosine phosphorylation signaling in mitochondria is strictly linked to the definition of the entire mitochondrial tyrosine phosphoproteome. This chapter describes methods to analyze tyrosine phosphorylation in brain mitochondria: identification of new substrates by biochemical and mass spectrometry approaches and bioinformatic tools to analyze the potential effect of tyrosine phosphorylation on the structure/activity of a protein
Viral proteins and Src family kinases: Mechanisms of pathogenicity from a “liaison dangereuse”
No full textSetting up of an innovative procedure for redox proteomics and its application for definition of the redox status of a cellular model.
No full textHuman proteome contains 214.000 cysteine residues. In the subset of protein not-free thiols, these are alkylated or, most frequently, oxidized. While disulfides, the largely most abundant oxidized form, have a pivotal role in driving protein folding, recently, their reversible formation also came to the stage as the final outcome of cell signaling pathways under the control of the nucleophilic/electrophilic tone. Specific high throughput procedures, collectively known as redox proteomics, have been developed to pinpoint these functional redox transition. Here we present an approach for pairwise comparison, integrating differential labeling with cys reactive probes and chromatographic isolation of redox sensitive proteins
Arachidonic acid-induced IL-6 expression is mediated by PKCalpha activation in osteoblastic cells
No full textThere are several pieces of evidence supporting the important role that essential fatty acids (EFAs) and their metabolites play in regulating calcium and bone metabolism, and their relevance to the pathobiology of bone disease, with particular reference to modulating effects on cytokines. We found that arachidonic acid (AA) triggers a cell signal in osteoblasts and leads to the expression of IL-6. To explore the biochemical pathways involved in AA induction of cytokine gene expression, we evaluated the potential protein kinase C (PKC) dependent mechanism accounting for the AA effect on IL-6 gene expression. The osteoblast-like cell line MG-63 was pretreated with calphostin C, a PKC inhibitor, or phorbol 12-myristate 13-acetate (PMA) for an extended period, a condition which causes PKC downregulation, and subsequently with AA. After these treatments, IL-6 gene expression was no longer evident. We also showed that PKC and, in particular, PKC cc, which are both recruited to the particulate fraction, undergo proteolysis and autophosphorylation; all of these steps are required for PKC activation and, subsequently, for AA-induced signaling. It is interesting that other unsaturated fatty acids, such as oleic acid (OA) or eicosapentaenoic acid (EPA), are unable to induce either PKC activation or IL-6 gene expression
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