An adenosine derivative promotes mitochondrial supercomplexes reorganization and restoration of mitochondria structure and bioenergetics in a diethylnitrosamine-induced hepatocellular carcinoma model.

Hepatocellular carcinoma (HCC) progression is associated with dysfunctional mitochondria and bioenergetics impairment. However, no data about the relationship between mitochondrial supercomplexes (hmwSC) formation and ATP production rates in HCC are available. Our group has developed an adenosine derivative, IFC-305, which improves mitochondrial function, and it has been proposed as a therapeutic candidate for HCC. We aimed to determine the role of IFC-305 on both mitochondrial structure and bioenergetics in a sequential cirrhosis-HCC model in rats. Our results showed that IFC-305 administration decreased the number and size of liver tumors, reduced the expression of tumoral markers, and reestablished the typical architecture of the hepatic parenchyma. The livers of treated rats showed a reduction of mitochondria number, recovery of the mtDNA/nDNA ratio, and mitochondrial length. Also, IFC-305 increased cardiolipin and phosphatidylcholine levels and promoted hmwSC reorganization with changes in the expression levels of hmwSC assembly-related genes. IFC-305 in HCC modified the expression of several genes encoding elements of electron transport chain complexes and increased the ATP levels by recovering the complex I, III, and V activity. We propose that IFC-305 restores the mitochondrial bioenergetics in HCC by normalizing the quantity, morphology, and function of mitochondria, possibly as part of its hepatic restorative effect.

Calcium Induces Mitochondrial Oxidative Stress Because of its Binding to Adenine Nucleotide Translocase.

Several studies have demonstrated that the mitochondrial membrane switches from selective to non-selective permeability because of its improved matrix Ca2+ accumulation and oxidative stress. This process, known as permeability transition, evokes severe dysfunction in mitochondria through the opening of a non-specific pore, whose chemical nature is still under discussion. There are some proposals regarding the components of the pore structure, e.g., the adenine nucleotide translocase and dimers of the F1 Fo-ATP synthase. Our results reveal that Ca2+ induces oxidative stress, which not only increases lipid peroxidation and ROS generation but also brings about both the collapse of the transmembrane potential and the membrane release of cytochrome c. Additionally, it is shown that Ca2+ increases the binding of the probe eosin-5-maleimide to adenine nucleotide translocase. Interestingly, these effects are diminished after the addition of ADP. It is suggested that pore opening is caused by the binding of Ca2+ to the adenine nucleotide translocase.

Las enfermedades transmitidas por vectores y el potencial uso de Wolbachia, una bacteria endocelular obligada, para erradicarlas / Vector-borne diseases and the potential use of Wolbachia, an obligate endocellular bacterium, to eradicate them

Resumen Según la Organización Mundial de la Salud (OMS), 17% de las enfermedades infecciosas reportadas en el mundo son transmitidas por vectores artrópodos. Una alternativa para bloquear la transmisión es infectar a los vectores con una bacteria endocelular llamada Wolbachia. Diferentes investigaciones han demostrado que Wolbachia acorta la vida del mosquito, aumenta su resistencia ante la infección de algunos virus como dengue, Zika y Chikungunya, y provoca incompatibilidad citoplasmática, por lo que al liberar mosquitos machos infectados con Wolbachia en una población de hembras no infectadas los productos no son viables, disminuyendo drásticamente la población total. En el presente artículo se incluye una descripción general de las enfermedades infecciosas más comunes transmitidas por vectores así como una revisión del uso de Wolbachia como una posible herramienta para controlar su propagación.

Abstract According to the World and Health Organization (WHO), 17% of the worldwide reported infectious diseases are vector-borne. One alternative for blocking the transmission of these infectious agents is to infect the vectors with the endocellular bacterium Wolbachia. Several studies have shown that Wolbachia shortens mosquitos' lifespan and increases their resistance to some virus like Dengue, Zika or Chikungunya. Wolbachia also causes cytoplasmic incompatibility, so, when Wolbachia-infected male mosquitoes are released among an uninfected female population, the production of an offspring is not viable and the mosquito population decreases drastically. This article includes an overview of the most common vector-borne infectious diseases as well as a review of the use of Wolbachia as a possible tool for controlling the spread of vector-borne diseases.

Newly synthesized cAMP is integrated at a membrane protein complex signalosome to ensure receptor response specificity.

Spatiotemporal regulation of cAMP within the cell is required to achieve receptor-specific responses. The mechanism through which the cell selects a specific response to newly synthesized cAMP is not fully understood. In hepatocyte plasma membranes, we identified two functional and independent cAMP-responsive signaling protein macrocomplexes that produce, use, degrade, and regulate their own nondiffusible (sequestered) cAMP pool to achieve their specific responses. Each complex responds to the stimulation of an adenosine G protein-coupled receptor (Ado-GPCR), bound to either A2A or A2B , but not simultaneously to both. Each isoprotein involved in each signaling cascade was identified by measuring changes in cAMP levels after receptor activation, and its participation was confirmed by antibody-mediated inactivation. A2A -Ado-GPCR selective stimulation activates adenylyl cyclase 6 (AC6), which is bound to AKAP79/150, to synthesize cAMP which is used by two other AKAP79/150-tethered proteins: protein kinase A (PKA) and phosphodiesterase 3A (PDE3A). In contrast, A2B -Ado-GPCR stimulation activates D-AKAP2-attached AC5 to generate cAMP, which is channeled to two other D-AKAP2-tethered proteins: guanine-nucleotide exchange factor 2 (Epac2) and PDE3B. In both cases, prior activation of PKA or Epac2 with selective cAMP analogs prevents de novo cAMP synthesis. In addition, we show that cAMP does not diffuse between these protein macrocomplexes or 'signalosomes'. Evidence of coimmunoprecipitation and colocalization of some proteins belonging to each signalosome is presented. Each signalosome constitutes a minimal functional signaling unit with its own machinery to synthesize and regulate a sequestered cAMP pool. Thus, each signalosome is devoted to ensure the transmission of a unique and unequivocal message through the cell.

The branched mitochondrial respiratory chain from Debaryomyces hansenii: components and supramolecular organization.

The branched respiratory chain in mitochondria from the halotolerant yeast Debaryomyces hansenii contains the classical complexes I, II, III and IV plus a cyanide-insensitive, AMP-activated, alternative-oxidase (AOX). Two additional alternative oxidoreductases were found in this organism: an alternative NADH dehydrogenase (NDH2e) and a mitochondrial isoform of glycerol-phosphate dehydrogenase (MitGPDH). These monomeric enzymes lack proton pump activity. They are located on the outer face of the inner mitochondrial membrane. NDH2e oxidizes exogenous NADH in a rotenone-insensitive, flavone-sensitive, process. AOX seems to be constitutive; nonetheless, most electrons are transferred to the cytochromic pathway. Respiratory supercomplexes containing complexes I, III and IV in different stoichiometries were detected. Dimeric complex V was also detected. In-gel activity of NADH dehydrogenase, mass spectrometry, and cytochrome c oxidase and ATPase activities led to determine the composition of the putative supercomplexes. Molecular weights were estimated by comparison with those from the yeast Y. lipolytica and they were IV2, I-IV, III2-IV4, V2, I-III2, I-III2-IV, I-III2-IV2, I-III2-IV3 and I-III2-IV4. Binding of the alternative enzymes to supercomplexes was not detected. This is the first report on the structure and organization of the mitochondrial respiratory chain from D. hansenii.

The acrosomal matrix from guinea pig sperm contains structural proteins, suggesting the presence of an actin skeleton.

The mammalian sperm acrosome contains a large number of hydrolytic enzymes. When the acrosomal reaction and fertilization occur, these enzymes are released in an orderly fashion, suggesting that the acrosomal matrix is highly organized. It was decided to determine the identity of the structural scaffold underlying the organization of the acrosome. In permeabilized acrosomes and in the Triton X-100-extracted acrosomal matrices from guinea pig sperm, we used indirect immunofluorescence, immunogold labeling, and Western blotting to identify F-actin, spectrin, myosin, calmodulin, and gelsolin. These proteins were detected in the acrosomal matrix for the first time. In noncapacitated, intact spermatozoa the addition of the F-actin monomerizing agent cytochalasin D resulted in loss of the acrosome, suggesting that F-actin is needed to preserve an intact acrosome. Our results suggest that the acrosomal architecture is supported by a dynamic F-actin skeleton, which probably regulates the differential rate of release of the acrosomal enzymes during acrosomal reaction and fertilization.

Actin, myosin, cytokeratins and spectrin are components of the guinea pig sperm nuclear matrix.

The nuclear matrix (NM) of somatic cells is an internal nuclear framework structure, with a structural function and participation in DNA replication and transcription. The NM has been described in mouse, hamster and human spermatozoa. In this study, an NM structural component of the guinea pig sperm nucleus was obtained by removing nuclear proteins and DNA from DTT-CTAB nuclei. Removal was achieved with high ionic strength salt and microccocal nuclease treatments including a heparin treatment to cause a slight swelling of the nucleus and facilitate material extraction. Actin, myosin, cytokeratins and spectrin were detected associated to NM by indirect immunofluorescence, immunogold staining and Western blotting analysis using specific antibodies. The presence of NM in guinea pig sperm nucleus is shown for the first time and some of its components are identified. This is also the first report on cytokeratins and myosin presence in guinea pig sperm. A retarding effect of nuclear decondensation caused by heparin is induced after phalloidin and/or diacetyl-monoxime (a myosin ATPase activity inhibitor) treatment, suggesting a role for F-actin and myosin in the maintenance of nuclear stability in sperm. The actin role was supported by the decondensing effect that citochalasin D and gelsolin had on sperm nuclei.