Mitochondrial protein synthesis in HeLa cells

The role of mitochondria in rheumatic diseases

The mitochondrion is an intracellular organelle thought to originate from endosymbiosis between an ancestral eukaryotic cell and an α-proteobacterium. Mitochondria are the powerhouses of the cell, and can control several important processes within the cell, such as cell death. Conversely, dysregulation of mitochondria possibly contributes to the pathophysiology of several autoimmune diseases. Defects in mitochondria can be caused by mutations in the mitochondrial genome or by chronic exposure to pro-inflammatory cytokines, including type I interferons. Following the release of intact mitochondria or mitochondrial components into the cytosol or the extracellular space, the bacteria-like molecular motifs of mitochondria can elicit pro-inflammatory responses by the innate immune system. Moreover, antibodies can target mitochondria in autoimmune diseases, suggesting an interplay between the adaptive immune system and mitochondria. In this Review, we discuss the roles of mitochondria in rheumatic diseases such as systemic lupus erythematosus, antiphospholipid syndrome and rheumatoid arthritis. An understanding of the different contributions of mitochondria to distinct rheumatic diseases or manifestations could permit the development of novel therapeutic strategies and the use of mitochondria-derived biomarkers to inform pathogenesis.

The advantageous role of annexin A1 in cardiovascular disease

The inflammatory response protects the human body against infection and injury. However, uncontrolled and unresolved inflammation can lead to tissue damage and chronic inflammatory diseases. Therefore, active resolution of inflammation is essential to restore tissue homeostasis. This review focuses on the pro-resolving molecule annexin A1 (ANXA1) and its derived peptides. Mechanisms instructed by ANXA1 are multidisciplinary and affect leukocytes as well as endothelial cells and tissue resident cells like macrophages and mast cells. ANXA1 has an outstanding role in limiting leukocyte recruitment and different aspects of ANXA1 as modulator of the leukocyte adhesion cascade are discussed here. Additionally, this review details the therapeutic relevance of ANXA1 and its derived peptides in cardiovascular diseases since atherosclerosis stands out as a chronic inflammatory disease with impaired resolution and continuous leukocyte recruitment.

A metabolic phenotype based on mitochondrial ribosomal protein expression as a predictor of lymph node metastasis in papillary thyroid carcinoma

Metabolic reprogramming has been regarded as an essential component of malignant transformation. However, the clinical significance of metabolic heterogeneity remains poorly characterized. The aim of this study was to characterize metabolic heterogeneity in thyroid cancers via the analysis of the expression of mitochondrial ribosomal proteins (MRPs) and genes involved in oxidative phosphorylation (OxPhos), and investigate potential prognostic correlations. Gene set enrichment analysis (GSEA) verified by reverse transcription polymerase chain reaction and gene network analysis was performed using public repository data. Cross-sectional observational study was conducted to classify papillary thyroid cancer (PTC) by the expression of MRP L44 (MRPL44) messenger RNA (mRNA), and to investigate the clinicopathological features. GSEA clearly showed that the expression of OxPhos and MRP gene sets was significantly lower in primary thyroid cancer than in matched normal thyroid tissue. However, 8 of 49 primary thyroid tumors (16.3%) in the public repository did not show a reduction in OxPhos mRNA expression. Remarkably, strong positive correlations between MRPL44 expression and those of OxPhos and MRPs such as reduced nicotinamide adenine dinucleotide dehydrogenase (ubiquinone) 1 α subcomplex, 5; succinate dehydrogenase complex, subunit D; cytochrome c, somatic; adenosine triphosphate synthase, H+ transporting, mitochondrial Fo complex, subunit C1 (subunit 9); and MRP S5 (MRPS5) (P < 0.0001) were clearly denoted, suggesting that MRPL44 is a representative marker of OxPhos and MRP expressions. In laboratory experiments, metabolic heterogeneity in oxygen consumption, extracellular acidification rates (ECARs), and amounts of OxPhos complexes were consistently observed in BCPAP, TPC1, HTH-7, and XTC.UC1 cell lines. In PTCs, metabolic phenotype according to OxPhos amount defined by expression of MRPL44 mRNA was significantly related to lymph node metastasis (LNM) (P < 0.001). Furthermore, multivariate analysis clearly indicated that expression of MRPL44 is associated with an increased risk of lateral neck LNM (odds ratio 9.267, 95% confidence interval 1.852-46.371, P = 0.007). MRPL44 expression may be a representative marker of metabolic phenotype according to OxPhos amount and a useful predictor of LNM.

Neutrophils and intravascular immunity in the liver during infection and sterile inflammation

The liver is a target of many inflammatory pathologies of both infectious and noninfectious etiology. As key effectors of the innate immune system, neutrophils are critical for defense against microbial infections but are often the source of profound collateral damage to host tissues during disease states. In this article based on the authors' presentation at the 2011 Society of Toxicologic Pathology Annual Symposium, they review the molecular mechanisms of neutrophil recruitment to the liver in response to sepsis/endotoxemia, as well as sterile inflammation, and discuss variations in the molecular choreography of neutrophil trafficking in response to these different insults. Furthermore, the authors discuss the functional contributions of neutrophils within the liver microvasculature during severe sepsis, including their contributions to both host defense and organ damage. Given that inappropriate neutrophilic inflammation contributes to the pathogenesis of many liver diseases, a thorough understanding of the molecular mechanisms that regulate the recruitment of neutrophils to the liver, and their functions therein, may reveal new avenues for therapeutic interventions to treat inflammatory liver pathologies.

Cellular and molecular choreography of neutrophil recruitment to sites of sterile inflammation

Liberation of damage-associated molecular patterns (DAMPs) following tissue injury and necrotic cell death leads to the induction of sterile inflammation. A hallmark of acute inflammation is the recruitment of neutrophils to injured tissues. This review focuses on the journey of neutrophils to sites of sterile inflammation and the cellular and molecular mechanisms that choreograph this complex voyage. We review the pathway of leukocyte recruitment, with emphasis on recent additions to our understanding of intravascular neutrophil migration. The contributions of various tissue-resident sentinel cell populations to the detection of danger signals (DAMPs) and coordination of neutrophil recruitment and migration are discussed. In addition, we highlight recent data on the control of neutrophil chemotaxis towards sites of sterile inflammation, including new insight into the temporal and spatial regulation of chemoattractant guidance signals that direct cell migration. Given that inappropriate neutrophilic inflammation is a cornerstone in the pathogenesis of many diseases, a complete understanding of the choreography of neutrophil recruitment to sites of sterile inflammation may uncover new avenues for therapeutic interventions to treat inflammatory pathologies.

Inhibition of T-lymphocyte colony formation by inhibitors of mitochondrial protein synthesis

A double layer technique which requires an underlayer of peripheral blood leucocytes, in addition to phytohaemmagglutinin (PHA) in the overlayer, to obtain good T-lymphocyte colony formation, was used to assess the effect of two inhibitors of mitochondrial protein synthesis, chloramphenicol and ethidium bromide. A significant inhibition of the colony growth of peripheral blood T lymphocytes was observed when either of the drugs was incorporated in the underlayer. The inhibitory effect was always smaller (c. 50%) when the drugs were added to the overlayer. These findings point to the existence of a T-lymphocyte colony stimulating factor(s), released mainly by the leucocyte-rich underlayer and essential for T-colony formation, the production of which is inhibited by these mitochonrial inhibitors.

Microanalysis and X-ray fluorescence spectrometry of platelets in diseases with elevated muscle calcium

Electron microscopic X-ray microanalysis and X-ray fluorescence spectrometry were done on platelets from patients with Duchenne muscular dystrophy and idiopathic scoliosis (both these conditions are known to be associated with increased intramyofibre calcium). A significant increase in calcium and phosphorus concentrations was found in the dense granules and whole cells of both conditions. The findings suggest that idiopathic scoliosis like Duchenne muscular dystrophy is a multisystem disease with detectable changes in platelets.

On the adaptation of cultured chick embryo cells to growth in the presence of chloramphenicol

We have found that tryptose phosphate broth (TPB) prevents the inhibitory effect of chloramphenicol (CAM) on the cell proliferation of chick embryo fibroblasts. Study of growth parameters indicated that no lag or adaptation period appeared necessary for TPB-exposed chick cell populations to grow in the presence of CAM suggesting that a particular cell type was not selected. TPB did not prevent the inhibitory effect of CAM on the mitochondrial protein-synthesizing system. This was supported by cytochrome oxidase activity measurements, studies on the incorporation of 35S-metionine into mitochondrial proteins, electron microscopic observation of alterations in mitochondrial structure. Oxygen consumption was reduced by 95% and cyanide, 2-4-dinitrophenol, and salicylhydroxamic acid do not significantly affect the residual respiration. Analyses of reduced-minus-oxidized-cytochrome spectra of CAM-treated chick cells demonstrate the disappearance of the absorption bands of cytochromes aa3, b559, c1, and c. The presence of a type b cytochrome with maxima at 552 and 557 nm was observed. The results obtained indicate that long-term cultures of CAM-treated chick embryo cells cultivated in the presence of TPB grow with mitochondria devoid of a functional respiratory chain.

Selective effects of enucleation and transfer of heterologous nuclei on cytoplasmic organelles in Amoeba proteus

The ultrastructural changes in the cytoplasm of lethal hybrids obtained by nuclear transplantation between different strains of Amoeba proteus were compared with those of enucleated amebae. It was found that, whereas the Golgi complex and glycocalyx degenerated first in enucleated cells, mitochondria and endosymbiotes became abnormal first in the hybrids. The selective effects are attributed to the presence of nucleic acids in the mitochondria and endosymbiotes and hence to the different interactions they would have with the nuclear genome.