bims-resufa 2022-11-13 papers

Issue of 2022‒11‒13
two papers selected by
Vera Strogolova
Strong Microbials, Inc

Int J Mol Sci. 2022 Nov 03. pii: 13476. [Epub ahead of print]23(21):

Quantitative Proteomics Analysis Reveals That Cyclooxygenase-2 Modulates Mitochondrial Respiratory Chain Complex IV in Cardiomyocytes.

Maria Soledad Alvarez, Estefanía Núñez, Marina Fuertes-Agudo, Carme Cucarella, Maria Fernandez-Velasco, Lisardo Boscá, Jesús Vázquez, Rodrigue Rossignol, Paloma Martin-Sanz, Marta Casado.

The biochemical mechanisms of cell injury and myocardial cell death after myocardial infarction remain unresolved. Cyclooxygenase 2 (COX-2), a key enzyme in prostanoid synthesis, is expressed in human ischemic myocardium and dilated cardiomyopathy, but it is absent in healthy hearts. To assess the role of COX-2 in cardiovascular physiopathology, we developed transgenic mice that constitutively express functional human COX-2 in cardiomyocytes under the control of the α-myosin heavy chain promoter. These animals had no apparent phenotype but were protected against ischemia-reperfusion injury in isolated hearts, with enhanced functional recovery and diminished cellular necrosis. To further explore the phenotype of this animal model, we carried out a differential proteome analysis of wild-type vs. transgenic cardiomyocytes. The results revealed a tissue-specific proteomic profile dominated by mitochondrial proteins. In particular, an increased expression of respiratory chain complex IV proteins was observed. This correlated with increased catalytic activity, enhanced respiratory capacity, and increased ATP levels in the heart of COX-2 transgenic mice. These data suggest a new link between COX-2 and mitochondria, which might contribute to the protective cardiac effects of COX-2 against ischemia-reperfusion injury.

Keywords: COX-2; mitochondria; prostaglandins; respiratory capacity; transgenic animals

DOI: https://doi.org/10.3390/ijms232113476

Parasitol Int. 2022 Oct 29. pii: S1383-5769(22)00159-3. [Epub ahead of print]92 102695

Biochemical characterization of mitochondria from adult worms and plerocercoid larvae of Spirometra mansoni shows mixed populations of anaerobic and aerobic mitochondria.

Shinzaburo Takamiya, Takeshi Nakamura, Daigo Tsubokawa, Naotoshi Tsuji, Koichi Fukuda, Hiroshi Yamasaki, Tsutomu Fujimura, Hikari Taka, Naoko Kaga, Momoko Kobayashi-Tanabe, Motoo Matsuda, Toshihiro Mita.

The mitochondria of adult and plerocercoid Spirometra mansoni were characterized in isolated mitochondria and in situ by electron microscopic histochemistry with special attention to the respiratory chain. Although the specific activities of the constituent enzyme complexes of succinate oxidase are fairly similar in adult and plerocercoid mitochondria, those of succinate oxidase and NADH-FRD are approximately 4- and 25-fold higher in adult mitochondria than in plerocercoid mitochondria, respectively. Quinone analysis by high performance liquid chromatography and mass spectrometry showed that adult and plerocercoid mitochondria contained both rhodoquinone-10 and ubiquinone-10 at concentrations of 4.98 and 0.106 nmol mg-1 for adult, and 0.677 and 0.137 nmol mg-1 for plerocercoid, respectively. Inhibition studies on the succinate-oxidase system of adult mitochondria showed that they possessed both cyanide-sensitive and -insensitive succinate oxidases, the latter of which produces hydrogen peroxide. Adult mitochondria, when NADH was used as a substrate, were shown to produce hydrogen peroxide, and the production of hydrogen peroxide decreased to undetectable levels in the presence of fumarate. The specific activities of NADH-fumarate reductase and cytochrome c oxidase were significantly higher in mature proglottids than in immature and gravid proglottids. Isopycnic density-gradient centrifugation analyses and in situ electron microscopic histochemistry revealed that both adult and plerocercoid mitochondria were heterogeneous in terms of respiratory function and physicochemical properties. The physiological significance of adult and plerocercoid mitochondria is discussed in relation to the oxygen tension of their parasitic habitats.

Keywords: Adult; Aerobic mitochondria; Anaerobic mitochondria; NADH-fumarate reductase; Plerocercoid; Respiratory chain; Spirometra mansoni

DOI: https://doi.org/10.1016/j.parint.2022.102695